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16 pages, 6436 KiB

Open AccessArticle

L-Aminoguanidine Induces Imbalance of ROS/RNS Homeostasis and Polyamine Catabolism of Tomato Roots after Short-Term Salt Exposure

by Ágnes Szepesi, László Bakacsy, Attila Fehér, Henrietta Kovács, Péter Pálfi, Péter Poór, Réka Szőllősi, Orsolya Kinga Gondor, Tibor Janda, Gabriella Szalai, Christian Lindermayr, László Szabados and Laura Zsigmond

Antioxidants 2023, 12(8), 1614; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox12081614 - 15 Aug 2023

Viewed by 1369

Abstract

Polyamine (PA) catabolism mediated by amine oxidases is an important process involved in fine-tuning PA homeostasis and related mechanisms during salt stress. The significance of these amine oxidases in short-term responses to salt stress is, however, not well understood. In the present study, [...] Read more.

Polyamine (PA) catabolism mediated by amine oxidases is an important process involved in fine-tuning PA homeostasis and related mechanisms during salt stress. The significance of these amine oxidases in short-term responses to salt stress is, however, not well understood. In the present study, the effects of L-aminoguanidine (AG) on tomato roots treated with short-term salt stress induced by NaCl were studied. AG is usually used as a copper amine oxidase (CuAO or DAO) inhibitor. In our study, other alterations of PA catabolism, such as reduced polyamine oxidase (PAO), were also observed in AG-treated plants. Salt stress led to an increase in the reactive oxygen and nitrogen species in tomato root apices, evidenced by in situ fluorescent staining and an increase in free PA levels. Such alterations were alleviated by AG treatment, showing the possible antioxidant effect of AG in tomato roots exposed to salt stress. PA catabolic enzyme activities decreased, while the imbalance of hydrogen peroxide (H₂O₂), nitric oxide (NO), and hydrogen sulfide (H₂S) concentrations displayed a dependence on stress intensity. These changes suggest that AG-mediated inhibition could dramatically rearrange PA catabolism and related reactive species backgrounds, especially the NO-related mechanisms. More studies are, however, needed to decipher the precise mode of action of AG in plants exposed to stress treatments. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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20 pages, 3825 KiB

Open AccessArticle

Influence of Increased Radiation Background on Antioxidative Responses of Helianthus tuberosus L.

by Oksana B. Polivanova, Kirill N. Tiurin, Anastasia B. Sivolapova, Svetlana V. Goryunova and Sergey V. Zhevora

Antioxidants 2023, 12(4), 956; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox12040956 - 18 Apr 2023

Cited by 2 | Viewed by 1228

Abstract

As a result of the accident at the Chornobyl Nuclear Power Plant, significant territories were exposed to ionizing radiation. Some isotopes, such as ¹³⁷Cs, are capable of making a significant impact on living organisms in the long-term perspective. The generation of reactive [...] Read more.

As a result of the accident at the Chornobyl Nuclear Power Plant, significant territories were exposed to ionizing radiation. Some isotopes, such as ¹³⁷Cs, are capable of making a significant impact on living organisms in the long-term perspective. The generation of reactive oxygen species is one mechanism by which ionizing radiation affects living organisms, initiating mechanisms of antioxidant protection. In this article, the effect of increased ionizing radiation on the content of non–enzymatic antioxidants and the activity of antioxidant defense enzymes of Helianthus tuberosum L. was studied. This plant is widely distributed in Europe and characterized by high adaptability to abiotic factors. We found that the activity of antioxidant defense enzymes, such as catalase and peroxidase, weakly correlated with radiation exposure. The activity of ascorbate peroxidase, on the contrary, is strongly positively correlated with radiation exposure. The samples growing on the territory with constant low exposure to ionizing radiation were also characterized by an increased concentration of ascorbic acid and water-soluble phenolic compounds compared to the controls. This study may be useful for understanding the mechanisms underlying the adaptive reactions of plants under prolonged exposure to ionizing radiation. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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17 pages, 3528 KiB

Open AccessArticle

Zn Supplementation Mitigates Drought Effects on Cotton by Improving Photosynthetic Performance and Antioxidant Defense Mechanisms

by Touhidur Rahman Anik, Mohammad Golam Mostofa, Md. Mezanur Rahman, Md. Arifur Rahman Khan, Protik Kumar Ghosh, Sharmin Sultana, Ashim Kumar Das, Md. Saddam Hossain, Sanjida Sultana Keya, Md. Abiar Rahman, Nusrat Jahan, Aarti Gupta and Lam-Son Phan Tran

Antioxidants 2023, 12(4), 854; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox12040854 - 01 Apr 2023

Cited by 3 | Viewed by 1521

Abstract

Drought is recognized as a paramount threat to sustainable agricultural productivity. This threat has grown more severe in the age of global climate change. As a result, finding a long-term solution to increase plants’ tolerance to drought stress has been a key research [...] Read more.

Drought is recognized as a paramount threat to sustainable agricultural productivity. This threat has grown more severe in the age of global climate change. As a result, finding a long-term solution to increase plants’ tolerance to drought stress has been a key research focus. Applications of chemicals such as zinc (Zn) may provide a simpler, less time-consuming, and effective technique for boosting the plant’s resilience to drought. The present study gathers persuasive evidence on the potential roles of zinc sulphate (ZnSO₄·7H₂O; 1.0 g Kg⁻¹ soil) and zinc oxide (ZnO; 1.0 g Kg⁻¹ soil) in promoting tolerance of cotton plants exposed to drought at the first square stage, by exploring various physiological, morphological, and biochemical features. Soil supplementation of ZnSO₄ or ZnO to cotton plants improved their shoot biomass, root dry weight, leaf area, photosynthetic performance, and water-use efficiency under drought stress. Zn application further reduced the drought-induced accumulations of H₂O₂ and malondialdehyde, and electrolyte leakage in stressed plants. Antioxidant assays revealed that Zn supplements, particularly ZnSO₄, reduced reactive oxygen species (ROS) accumulation by increasing the activities of a range of ROS quenchers, such as catalase, ascorbate peroxidase, glutathione S-transferase, and guaiacol peroxidase, to protect the plants against ROS-induced oxidative damage during drought stress. Increased leaf relative water contents along with increased water-soluble protein contents may indicate the role of Zn in improving the plant’s water status under water-deficient conditions. The results of the current study also suggested that, in general, ZnSO₄ supplementation more effectively increased cotton drought tolerance than ZnO supplementation, thereby suggesting ZnSO₄ as a potential chemical to curtail drought-induced detrimental effects in water-limited soil conditions. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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10 pages, 956 KiB

Open AccessCommunication

GmMPK6 Positively Regulates Salt Tolerance through Induction of GmRbohI1 in Soybean

by Seungmin Son, Jitae Kim, Chung Sun An, Song Lim Kim, Hyoungseok Lee and Jong Hee Im

Antioxidants 2023, 12(3), 601; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox12030601 - 28 Feb 2023

Cited by 2 | Viewed by 1327

Abstract

Salt stress is a critical environmental stress that impairs plant growth and development, especially in crop productivity; therefore, understanding the salt response in plants is the basis for their development of salt tolerance. Under salinity, soybean mitogen-activated protein kinase 6 (GmMPK6) is activated [...] Read more.

Salt stress is a critical environmental stress that impairs plant growth and development, especially in crop productivity; therefore, understanding the salt response in plants is the basis for their development of salt tolerance. Under salinity, soybean mitogen-activated protein kinase 6 (GmMPK6) is activated and positively regulates reactive oxygen species (ROS) generation. However, it is not yet elucidated how GmMPK6 regulates ROS generation and its role in salt tolerance. Here, we show that GmMPK6, solely activated in NaCl treatment, and gene expression of GmRbohI1 was not only reduced by MPK inhibitor SB202190 in NaCl treatment, but also increased in a GMKK1-expressing protoplast. Furthermore, SB202190 and the NADPH-oxidase inhibitor, diphenyleneiodonium chloride, increased susceptibility to salt stress. The expression of GmRD19A was induced by NaCl treatment, but this expression was compromised by SB202190. Consequently, we revealed that GmMPK6 induces ROS generation through the transcriptional regulation of GmRbohI1 and increases salt tolerance in soybean. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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26 pages, 11011 KiB

Open AccessArticle

Bacterial Volatiles (mVOC) Emitted by the Phytopathogen Erwinia amylovora Promote Arabidopsis thaliana Growth and Oxidative Stress

by Ambra S. Parmagnani, Chidananda Nagamangala Kanchiswamy, Ivan A. Paponov, Simone Bossi, Mickael Malnoy and Massimo E. Maffei

Antioxidants 2023, 12(3), 600; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox12030600 - 28 Feb 2023

Cited by 3 | Viewed by 2108

Abstract

Phytopathogens are well known for their devastating activity that causes worldwide significant crop losses. However, their exploitation for crop welfare is relatively unknown. Here, we show that the microbial volatile organic compound (mVOC) profile of the bacterial phytopathogen, Erwinia amylovora, enhances Arabidopsis [...] Read more.

Phytopathogens are well known for their devastating activity that causes worldwide significant crop losses. However, their exploitation for crop welfare is relatively unknown. Here, we show that the microbial volatile organic compound (mVOC) profile of the bacterial phytopathogen, Erwinia amylovora, enhances Arabidopsis thaliana shoot and root growth. GC-MS head-space analyses revealed the presence of typical microbial volatiles, including 1-nonanol and 1-dodecanol. E. amylovora mVOCs triggered early signaling events including plasma transmembrane potential Vm depolarization, cytosolic Ca²⁺ fluctuation, K⁺-gated channel activity, and reactive oxygen species (ROS) and nitric oxide (NO) burst from few minutes to 16 h upon exposure. These early events were followed by the modulation of the expression of genes involved in plant growth and defense responses and responsive to phytohormones, including abscisic acid, gibberellin, and auxin (including the efflux carriers PIN1 and PIN3). When tested, synthetic 1-nonanol and 1-dodecanol induced root growth and modulated genes coding for ROS. Our results show that E. amylovora mVOCs affect A. thaliana growth through a cascade of early and late signaling events that involve phytohormones and ROS. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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22 pages, 975 KiB

Open AccessArticle

Exogenous Application of Calcium Ameliorates Salinity Stress Tolerance of Tomato (Solanum lycopersicum L.) and Enhances Fruit Quality

by Md. Moshiul Islam, Khurshida Jahan, Arpita Sen, Tahmina Akter Urmi, M. Moynul Haque, Hayssam M. Ali, Manzer H. Siddiqui and Yoshiyuki Murata

Antioxidants 2023, 12(3), 558; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox12030558 - 23 Feb 2023

Cited by 9 | Viewed by 1938

Abstract

Tomato is affected by various biotic and abiotic stresses, especially salinity, which drastically hinders the growth and yield of tomato. Calcium (Ca) is a vital macronutrient which plays physiological and biochemical roles in plants. Hence, we studied the protective roles of Ca against [...] Read more.

Tomato is affected by various biotic and abiotic stresses, especially salinity, which drastically hinders the growth and yield of tomato. Calcium (Ca) is a vital macronutrient which plays physiological and biochemical roles in plants. Hence, we studied the protective roles of Ca against salinity stress in tomato. There were eight treatments comprising control (nutrient solution), 5 mM Ca, 10 mM Ca, 15 mM Ca, 12 dS m⁻¹ NaCl, 12 dS m⁻¹ NaCl + 5 mM Ca, 12 dS m⁻¹ NaCl + 10 mM Ca and 12 dS m⁻¹ NaCl + 15 mM Ca, and two tomato varieties: BARI tomato-2 and Binatomato-5. Salinity significantly decreased the plant-growth and yield attributes, relative water content (RWC), photosynthetic pigments (SPAD value) and the uptake of K, Ca and Mg in leaves and roots. Salinity-induced oxidative stress was present in the form of increased Na⁺ ion concentration, hydrogen peroxide (H₂O₂) content and lipid peroxidation (MDA). Ca application reduced oxidative stress through the boosting of antioxidant enzymatic activity. Exogenous Ca application enhanced proline and glycine betaine content and reduced Na⁺ uptake, which resulted in the inhibition of ionic toxicity and osmotic stress, respectively. Hence, Ca application significantly increased the growth and yield attributes, RWC, SPAD value, and uptake of K, Ca and Mg. Calcium application also had a significant effect on the fruit quality of tomato and the highest total soluble solid, total sugar, reducing sugar, β-carotene, vitamin C and juice pH were found for the combined application of NaCl and Ca. Therefore, application of Ca reversed the salt-induced changes through increasing osmoprotectants, activation of antioxidants enzymes, and by optimizing mineral nutrient status. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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23 pages, 7530 KiB

Open AccessArticle

Phosphorus Availability Affects the Photosynthesis and Antioxidant System of Contrasting Low-P-Tolerant Cotton Genotypes

by Mirezhatijiang Kayoumu, Asif Iqbal, Noor Muhammad, Xiaotong Li, Leilei Li, Xiangru Wang, Huiping Gui, Qian Qi, Sijia Ruan, Ruishi Guo, Xiling Zhang, Meizhen Song and Qiang Dong

Antioxidants 2023, 12(2), 466; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox12020466 - 12 Feb 2023

Cited by 15 | Viewed by 1919

Abstract

Phosphorus (P) is an essential macronutrient, and an important component of plant metabolism. However, little is known about the effects of low P availability on P absorption, the photosynthetic electron transport chain, and the antioxidant system in cotton. This study used cotton genotypes [...] Read more.

Phosphorus (P) is an essential macronutrient, and an important component of plant metabolism. However, little is known about the effects of low P availability on P absorption, the photosynthetic electron transport chain, and the antioxidant system in cotton. This study used cotton genotypes (sensitive FJA and DLNTDH and tolerant BX014 and LuYuan343) with contrasting low-P tolerance in a hydroponic experiment under 15 µM, 50 µM, and 500 μM P concentrations. The results showed that low P availability reduced plant development and leaf area, shoot length, and dry weight in FJA and DLNADH, compared to BX014 and LuYuan343. The low P availability decreased the gas-exchange parameters such as the net photosynthetic rate, transpiration rate, and stomatal conductance, and increased the intercellular CO₂ concentration. Chlorophyll a fluorescence demonstrated that the leaves’ absorption and trapped-energy flux were largely steady. In contrast, considerable gains in absorption and trapped-energy flux per reaction center resulted from decreases in the electron transport per reaction center under low-P conditions. In addition, low P availability reduced the activities of antioxidant enzymes and increased the content of malondialdehyde in the cotton genotypes, especially in FJA and DLNTDH. Moreover, low P availability reduced the activity of PEPC and generated a decline in the content of ATP and NADPH. Our research can provide a theoretical physiological basis for the growth and tolerance of cotton under low-P conditions. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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22 pages, 6948 KiB

Open AccessArticle

High Light Intensity Triggered Abscisic Acid Biosynthesis Mediates Anthocyanin Accumulation in Young Leaves of Tea Plant (Camellia sinensis)

by Chenxi Gao, Yue Sun, Jing Li, Zhe Zhou, Xuming Deng, Zhihui Wang, Shaoling Wu, Lin Lin, Yan Huang, Wen Zeng, Shiheng Lyu, Jianjun Chen, Shixian Cao, Shuntian Yu, Zhidan Chen, Weijiang Sun and Zhihui Xue

Antioxidants 2023, 12(2), 392; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox12020392 - 06 Feb 2023

Cited by 6 | Viewed by 2541

Abstract

There is increasing interest in the production and consumption of tea (Camellia sinensis L.) processed from purple–leaved cultivar due to their high anthocyanin content and health benefits. However, how and why seasonal changes affect anthocyanin accumulation in young tea leaves still remains [...] Read more.

There is increasing interest in the production and consumption of tea (Camellia sinensis L.) processed from purple–leaved cultivar due to their high anthocyanin content and health benefits. However, how and why seasonal changes affect anthocyanin accumulation in young tea leaves still remains obscured. In this study, anthocyanin and abscisic acid (ABA) contents in young leaves of Zifuxing 1 (ZFX1), a cultivar with new shoots turning to purple in Wuyi Mountain, a key tea production region in China, were monitored over four seasons. Young leaves produced in September were highly purplish, which was accompanied with higher anthocyanin and ABA contents. Among the environmental factors, the light intensity in particular was closely correlated with anthocyanin and ABA contents. A shade experiment also indicated that anthocyanin content significantly decreased after 168 h growth under 75% shade, but ABA treatment under the shade conditions sustained anthocyanin content. To confirm the involvement of ABA in the modulation of anthocyanin accumulation, anthocyanin, carotenoids, chlorophyll, ABA, jasmonic acid (JA), and salicylic acid (SA) in the young leaves of four cultivars, including ZFX1, Zijuan (ZJ), wherein leaves are completely purple, Rougui (RG) and Fudingdabaicha (FDDB) wherein leaves are green, were analyzed, and antioxidant activities of the leaf extracts were tested. Results showed that ABA, not other tested hormones, was significantly correlated with anthocyanin accumulation in the purple–leaved cultivars. Cultivars with higher anthocyanin contents exhibited higher antioxidant activities. Subsequently, ZFX1 plants were grown under full sun and treated with ABA and fluridone (Flu), an ABA inhibitor. ABA treatment elevated anthocyanin level but decreased chlorophyll contents. The reverse was true to those treated with Flu. To pursue a better understanding of ABA involvement in anthocyanin accumulation, RNA–Seq was used to analyze transcript differences among ABA– or Flu–treated and untreated ZFX1 plants. Results indicated that the differentially expressed genes in ABA or Flu treatment were mainly ABA signal sensing and metabolism–related genes, anthocyanin accumulation-related genes, light–responsive genes, and key regulatory MYB transcription factors. Taking all the results into account, a model for anthocyanin accumulation in ZFX1 cultivar was proposed: high light intensity caused reactive oxygen stress, which triggered the biosynthesis of ABA; ABA interactions with transcription factors, such as MYB-enhanced anthocyanin biosynthesis limited chlorophyll and carotenoid accumulation; and transport of anthocyanin to vacuoles resulting in the young leaves of ZFX1 with purplish coloration. Further research is warranted to test this model. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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15 pages, 2781 KiB

Open AccessArticle

Comparative Transcriptomics Reveal Metabolic Rather than Genetic Control of Divergent Antioxidant Metabolism in the Primary Root Elongation Zone of Water-Stressed Cotton and Maize

by Jian Kang, Sidharth Sen, Melvin J. Oliver and Robert E. Sharp

Antioxidants 2023, 12(2), 287; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox12020287 - 27 Jan 2023

Cited by 1 | Viewed by 1562

Abstract

Under water stress, the primary root elongation zones of cotton and maize exhibit both conserved and divergent metabolic responses, including variations in sulfur and antioxidant metabolism. To explore the relative importance of metabolic and genetic controls of these responses for each species, and [...] Read more.

Under water stress, the primary root elongation zones of cotton and maize exhibit both conserved and divergent metabolic responses, including variations in sulfur and antioxidant metabolism. To explore the relative importance of metabolic and genetic controls of these responses for each species, and the extent to which responses are mediated by similar gene expression networks within the framework of ortholog groups, comparative transcriptomics analyses were conducted under conditions of equivalent tissue water stress. Ortholog analysis revealed that 86% of the transcriptome response to water stress was phylogenetically unrelated between cotton and maize. Elevated transcript abundances for genes involved in abscisic acid (ABA) biosynthesis and signaling, as well as key enzymes that enable osmotic adjustment, were conserved between the species. In contrast, antioxidant responses, at least with regard to glutathione metabolism and anti-oxidative enzymes, did not exhibit such a transcript abundance adaptive signature. In particular, previously characterized differential responses of the glutathione and sulfur metabolic pathways between cotton and maize were not evident in the transcriptomic responses. The findings indicate that the antioxidant response in both species results from a metabolic acclimation to water stress, and thus represents an example of water stress-related metabolic plasticity. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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21 pages, 7522 KiB

Open AccessArticle

Identification and Expression Profiling of Two Saudi Arabia Catalase Genes from Wheat and Barley in Response to Abiotic and Hormonal Stresses

by Mouna Ghorbel, Malek Besbes, Najla Haddaji, Nouha Bouali and Faiçal Brini

Antioxidants 2022, 11(11), 2208; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11112208 - 08 Nov 2022

Cited by 4 | Viewed by 1539

Abstract

Catalase is a crucial enzyme in antioxidant defense systems protecting eukaryotes from oxidative stress. These proteins are present in almost all living organisms and play important roles in controlling plant responses to biotic and abiotic stresses by catalyzing the decomposition of H₂ [...] Read more.

Catalase is a crucial enzyme in antioxidant defense systems protecting eukaryotes from oxidative stress. These proteins are present in almost all living organisms and play important roles in controlling plant responses to biotic and abiotic stresses by catalyzing the decomposition of H₂O₂. Despite their importance, little is known about their expression in the majority of monocotyledonous species. Here, we isolated and characterized two novel catalase genes from Triticum turgidum and Hordeum vulgare, designated as TtCAT1 and HvCAT1, respectively. Phylogenetic analysis revealed that TtCAT1 and HvCAT1 presented 492 aa and shared an important identity with other catalase proteins belonging to subfamily 1. Using bioinformatic analysis, we predicted the 3D structure models of TtCAT1 and HvCAT1. Interestingly, analysis showed that the novel catalases harbor a peroxisomal targeting signal (PTS1) located at their C-terminus portion, as shown for other catalase proteins. In addition, this motif is responsible for the in silico peroxisomal localization of both proteins. Finally, RT-qPCR analysis showed that TtCAT1 and HvCAT1 are highly expressed in leaves in normal conditions but faintly in roots. Moreover, both genes are upregulated after the application of different stresses such as salt, osmotic, cold, heavy metal, and hormonal stresses. The positive responses of TtCAT1 and HvCAT1 to the various stimuli suggested that these proteins can help to protect both species against environmental stresses. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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18 pages, 2335 KiB

Open AccessArticle

Titanium Oxide and Zinc Oxide Nanoparticles in Combination with Cadmium Tolerant Bacillus pumilus Ameliorates the Cadmium Toxicity in Maize

by Tayyab Shafiq, Humaira Yasmin, Zafar Abbas Shah, Asia Nosheen, Parvaiz Ahmad, Prashant Kaushik and Ajaz Ahmad

Antioxidants 2022, 11(11), 2156; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11112156 - 31 Oct 2022

Cited by 13 | Viewed by 2370

Abstract

The efficiency of Cd-tolerant plant growth-promoting bacteria (PGPB), zinc oxide nanoparticles (ZnO NPs), and titanium dioxide nanoparticles (TiO₂) in maize growing in Cd-rich conditions was tested in the current study. The best Cd-tolerant strain, Bacillus pumilus, exhibited plant growth stimulation [...] Read more.

The efficiency of Cd-tolerant plant growth-promoting bacteria (PGPB), zinc oxide nanoparticles (ZnO NPs), and titanium dioxide nanoparticles (TiO₂) in maize growing in Cd-rich conditions was tested in the current study. The best Cd-tolerant strain, Bacillus pumilus, exhibited plant growth stimulation in vivo and in vitro experiments. We determined the toxic concentrations (30 (ppm)) of both NPs for plant growth. B. pumilus, ZnO NPs (20 (ppm)), and TiO₂ NPs (10 (ppm)) had a synergistic effect on plant growth promotion in Cd-contaminated soil (120 (ppm)) in a pot experiment. Both alone and in combination, these therapies reduced Cd toxicity, resulting in improved stress metabolism and defense responses. The combined treatments showed increased relative water content, photosynthetic pigments, proline, total sugars, and proteins and significantly reduced lipid peroxidation. Moreover, this combination increased the levels of minerals and antioxidants and reduced Cd bioaccumulation in shoots and roots by 40–60%. Our in silico pipeline presented a novel picture of the participation of ZnO–TiO₂ protein interaction in both B. pumilus and maize. These findings provide fresh insights on the use of B. pumilus, ZnO, and TiO₂ NPs, both separately and in combination, as a viable and environmentally benign strategy for reducing Cd stress in maize. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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12 pages, 1169 KiB

Open AccessArticle

Mitochondria Specific Antioxidant, MitoTEMPO, Modulates Cd Uptake and Oxidative Response of Soybean Seedlings

by Dalir Fayazipour, Joanna Deckert, Gholamali Akbari, Elias Soltani and Jagna Chmielowska-Bąk

Antioxidants 2022, 11(11), 2099; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11112099 - 25 Oct 2022

Cited by 4 | Viewed by 1538

Abstract

Numerous reports find that Cd induces formation of reactive oxygen species (ROS) in plants. However, a general ROS pool is usually studied, without distinction of their production site. In the present study, we applied a mitochondria-specific antioxidant, MitoTEMPO, to elucidate the role of [...] Read more.

Numerous reports find that Cd induces formation of reactive oxygen species (ROS) in plants. However, a general ROS pool is usually studied, without distinction of their production site. In the present study, we applied a mitochondria-specific antioxidant, MitoTEMPO, to elucidate the role of mitochondria-derived ROS in the response of soybean seedlings to short-term (48 h) Cd stress. The obtained results showed that Cd caused a reduction in root length and fresh weight and increase in the level of superoxide anion, hydrogen peroxide, markers of lipid peroxidation (thiobarbituric reactive substances, TBARS) and markers of RNA oxidation (8-hydroxyguanosine, 8-OHG) in seedling roots. Application of MitoTEMPO affected Cd uptake in a dose-dependent manner and diminished the Cd-dependent induction of superoxide anion and lipid peroxidation. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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17 pages, 6661 KiB

Open AccessArticle

Integrated Physiological, Transcriptomic, and Proteomic Analyses Reveal the Regulatory Role of Melatonin in Tomato Plants’ Response to Low Night Temperature

by Xiaolong Yang, Yumeng Zhang, Ting Liu, Jiali Shi, Mingfang Qi, Yufeng Liu and Tianlai Li

Antioxidants 2022, 11(10), 2060; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11102060 - 19 Oct 2022

Cited by 2 | Viewed by 1857

Abstract

Melatonin is a direct free radical scavenger that has been demonstrated to increase plants’ resistance to a variety of stressors. Here, we sought to examine the effect of melatonin on tomato seedlings subjected to low night temperatures using an integrated physiological, transcriptomic, and [...] Read more.

Melatonin is a direct free radical scavenger that has been demonstrated to increase plants’ resistance to a variety of stressors. Here, we sought to examine the effect of melatonin on tomato seedlings subjected to low night temperatures using an integrated physiological, transcriptomic, and proteomic approach. We found that a pretreatment with 100 μM melatonin increased photosynthetic and transpiration rates, stomatal apertures, and peroxidase activity, and reduced chloroplast damage of the tomato plant under a low night temperature. The melatonin pretreatment reduced the photoinhibition of photosystem I by regulating the balance of both donor- and acceptor-side restriction of PSI and by increasing electron transport. Furthermore, the melatonin pretreatment improved the photosynthetic performance of proton gradient regulation 5 (SlPGR5) and SlPGR5-like photosynthetic phenotype 1 (SlPGRL1)-suppressed transformants under a low night temperature stress. Transcriptomic and proteomic analyses found that the melatonin pretreatment resulted in the upregulation of genes and proteins related to transcription factors, signal transduction, environmental adaptation, and chloroplast integrity maintenance in low night temperature-stressed tomato plants. Collectively, our results suggest that melatonin can effectively improve the photosynthetic efficiency of tomato plants under a low night temperature and provide novel insights into the molecular mechanism of melatonin-mediated abiotic stress resistance. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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23 pages, 6212 KiB

Open AccessArticle

Exogenously-Sourced Salicylic Acid Imparts Resilience towards Arsenic Stress by Modulating Photosynthesis, Antioxidant Potential and Arsenic Sequestration in Brassica napus Plants

by Koser Bano, Bharty Kumar, Mohammed Nasser Alyemeni and Parvaiz Ahmad

Antioxidants 2022, 11(10), 2010; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11102010 - 11 Oct 2022

Cited by 14 | Viewed by 1718

Abstract

In the current study, salicylic acid (SA) assesses the physiological and biochemical responses in overcoming the potential deleterious impacts of arsenic (As) on Brassica napus cultivar Neelam. The toxicity caused by As significantly reduced the observed growth and photosynthetic attributes and accelerated the [...] Read more.

In the current study, salicylic acid (SA) assesses the physiological and biochemical responses in overcoming the potential deleterious impacts of arsenic (As) on Brassica napus cultivar Neelam. The toxicity caused by As significantly reduced the observed growth and photosynthetic attributes and accelerated the reactive oxygen species (ROS). Plants subjected to As stress revealed a significant (p ≤ 0.05) reduction in the plant growth and photosynthetic parameters, which accounts for decreased carbon (C) and sulfur (S) assimilation. Foliar spray of SA lowered the oxidative burden in terms of hydrogen peroxide (H₂O₂), superoxide anion (O₂^•−), and lipid peroxidation in As-affected plants. Application of SA in two levels (250 and 500 mM) protected the Brassica napus cultivar from As stress by enhancing the antioxidant capacity of the plant by lowering oxidative stress. Among the two doses, 500 mM SA was most effective in mitigating the adverse effects of As on the Brassica napus cultivar. It was found that SA application to the Brassica napus cultivar alleviated the stress by lowering the accumulation of As in roots and leaves due to the participation of metal chelators like phytochelatins, enhancing the S-assimilatory pathway, carbohydrate metabolism, higher cell viability in roots, activity of ribulose 1, 5-bisphosphate carboxylase (Rubisco), and proline metabolism through the active participation of γ-glutamyl kinase (GK) and proline oxidase (PROX) enzyme. The current study shows that SA has the capability to enhance the growth and productivity of B. napus plants cultivated in agricultural soil polluted with As and perhaps other heavy metals. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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17 pages, 5039 KiB

Open AccessArticle

The Putative Auto-Inhibitory Domain of Durum Wheat Catalase (TdCAT1) Positively Regulates Bacteria Cells in Response to Different Stress Conditions

by Mouna Ghorbel, Kaouthar Feki, Sana Tounsi, Nouha Bouali, Malek Besbes and Faiçal Brini

Antioxidants 2022, 11(9), 1820; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11091820 - 15 Sep 2022

Cited by 6 | Viewed by 1350

Abstract

Catalase is a crucial enzyme in the antioxidant defense system protecting organisms from oxidative stress. Proteins of this kind play important roles in controlling plant response to biotic and abiotic stresses by catalyzing the decomposition of H₂O₂. The durum [...] Read more.

Catalase is a crucial enzyme in the antioxidant defense system protecting organisms from oxidative stress. Proteins of this kind play important roles in controlling plant response to biotic and abiotic stresses by catalyzing the decomposition of H₂O₂. The durum wheat catalase 1, TdCAT1, has been previously isolated and characterized. Here, using bio-informatic analysis, we showed that durum wheat catalase 1 TdCAT1 harbors different novel conserved domains. In addition, TdCAT1 contains various phosphorylation residues and S-Nitrosylation residues located at different positions along the protein sequence. TdCAT1 activity decreased after treatment with λ−phosphatase. On the other hand, we showed that durum wheat catalase 1 (TdCAT1) exhibits a low CAT activity in vitro, whereas a deleted form of TdCAT1 has better activity compared to the full-length protein (TdCAT460), suggesting that TdCAT1 could present a putative autoinhibitory domain in its C-terminal portion. Moreover, we showed that TdCAT1 positively regulates E. coli cells in response to salt, ionic and osmotic stresses as well as heavy metal stress in solid and liquid mediums. Such effects had not been reported and lead us to suggest that the durum wheat catalase 1 TdCAT1 protein could play a positive role in response to a wide array of abiotic stress conditions. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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26 pages, 7104 KiB

Open AccessArticle

Whole-Genome Identification of APX and CAT Gene Families in Cultivated and Wild Soybeans and Their Regulatory Function in Plant Development and Stress Response

by Muqadas Aleem, Saba Aleem, Iram Sharif, Maida Aleem, Rahil Shahzad, Muhammad Imran Khan, Amina Batool, Gulam Sarwar, Jehanzeb Farooq, Azeem Iqbal, Basit Latief Jan, Prashant Kaushik, Xianzhong Feng, Javaid Akhter Bhat and Parvaiz Ahmad

Antioxidants 2022, 11(8), 1626; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11081626 - 22 Aug 2022

Cited by 7 | Viewed by 2690

Abstract

Plants coevolved with their antioxidant defense systems, which detoxify and adjust levels of reactive oxygen species (ROS) under multiple plant stresses. We performed whole-genome identification of ascorbate peroxidase (APX) and catalase (CAT) families in cultivated and wild soybeans. In cultivated and wild soybean [...] Read more.

Plants coevolved with their antioxidant defense systems, which detoxify and adjust levels of reactive oxygen species (ROS) under multiple plant stresses. We performed whole-genome identification of ascorbate peroxidase (APX) and catalase (CAT) families in cultivated and wild soybeans. In cultivated and wild soybean genomes, we identified 11 and 10 APX genes, respectively, whereas the numbers of identified CAT genes were four in each species. Comparative phylogenetic analysis revealed more homology among cultivated and wild soybeans relative to other legumes. Exon/intron structure, motif and synteny blocks are conserved in cultivated and wild species. According to the Ka/Ks value, purifying selection is a major force for evolution of these gene families in wild soybean; however, the APX gene family was evolved by both positive and purifying selection in cultivated soybean. Segmental duplication was a major factor involved in the expansion of APX and CAT genes. Expression patterns revealed that APX and CAT genes are differentially expressed across fourteen different soybean tissues under water deficit (WD), heat stress (HS) and combined drought plus heat stress (WD + HS). Altogether, the current study provides broad insights into these gene families in soybeans. Our results indicate that APX and CAT gene families modulate multiple stress response in soybeans. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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20 pages, 9357 KiB

Open AccessArticle

Ameliorative Effects of Silicon against Salt Stress in Gossypium hirsutum L.

by Leilei Li, Qian Qi, Hengheng Zhang, Qiang Dong, Asif Iqbal, Huiping Gui, Mirezhatijiang Kayoumu, Meizhen Song, Xiling Zhang and Xiangru Wang

Antioxidants 2022, 11(8), 1520; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11081520 - 04 Aug 2022

Cited by 12 | Viewed by 4059

Abstract

Silicon (Si) could alleviate the adverse effect of salinity in many crops, but the effect in cotton remains unclear. In this study, we evaluated the role of Si in regulating the salt stress tolerance of cotton by analyzing the induced morpho-physiological changes. A [...] Read more.

Silicon (Si) could alleviate the adverse effect of salinity in many crops, but the effect in cotton remains unclear. In this study, we evaluated the role of Si in regulating the salt stress tolerance of cotton by analyzing the induced morpho-physiological changes. A hydroponic experiment was conducted by using contrasting salt-tolerant cotton genotypes (sensitive Z0102; tolerant Z9807) and four treatments (CK, control; CKSi, 0.4 mM Si; NaCl, 150 mM NaCl; NaClSi, 150 mM NaCl+0.4 mM Si). The results showed that Si significantly enhanced the net photosynthesis rate and improved the growth of cotton seedling under salt stress in both salt-sensitive and salt-tolerant genotypes. Exogenous Si significantly reduced the accumulation of reactive oxygen species (ROS) and decreased the malondialdehyde (MDA) content in salt-stressed cotton. In addition, the application of Si up-regulated the expression of CAT1, SODCC and POD, and significantly enhanced the antioxidant enzymatic activities, such as catalase (CAT) and peroxidase (POD), of the salt-stressed cotton seedlings. Further, Si addition protected the integrity of the chloroplast ultrastructure, including key enzymes in photosynthesis such as ferredoxin-NADP reeducates (FNR), ATP synthase (Mg²⁺Ca²⁺-ATPase) and ribulose-1, 5-bisphosphate carboxylase/oxygenase (RubisCO), and the structure and function of the photosynthetic apparatus PSII from salt stress. Moreover, Si significantly increased the effective stomatal density and stomatal aperture in the salt-stressed cotton seedlings. Taken together, Si could likely ameliorate adverse effects of salt stress on cotton by improving the ROS scavenging ability and photosynthetic capacity. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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20 pages, 2982 KiB

Open AccessArticle

An In Vitro and In Silico Perspective Study of Seed Priming with Zinc on the Phytotoxicity and Accumulation Pattern of Arsenic in Rice Seedlings

by Shuvasish Choudhury, Debojyoti Moulick, Muhammed Khairujjaman Mazumder, Binaya Kumar Pattnaik, Dibakar Ghosh, Lakshminarayana R. Vemireddy, Adil Aldhahrani, Mohamed Mohamed Soliman, Ahmed Gaber and Akbar Hossain

Antioxidants 2022, 11(8), 1500; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11081500 - 30 Jul 2022

Cited by 11 | Viewed by 2243

Abstract

Arsenic (As) contamination of the rice agro-ecosystem is a major concern for rice farmers of South East Asia as it imposes a serious threat to human and animal life; thus, there is an unrelenting need to explore the ways by which arsenic stress [...] Read more.

Arsenic (As) contamination of the rice agro-ecosystem is a major concern for rice farmers of South East Asia as it imposes a serious threat to human and animal life; thus, there is an unrelenting need to explore the ways by which arsenic stress mitigation could be achieved. In the present investigation, we explore the effect of zinc (Zn²⁺) supplementation using the seed priming technique for the mitigation of As-induced stress responses in developing rice seedlings. In addition to the physiological and biochemical attributes, we also studied the interactive effect of Zn²⁺ in regulating As-induced changes by targeting antioxidant enzymes using a computational approach. Our findings suggest that Zn²⁺ and As can effectively modulate redox homeostasis by limiting ROS production and thereby confer protection against oxidative stress. The results also show that As had a significant impact on seedling growth, which was restored by Zn²⁺ and also minimized the As uptake. A remarkable outcome of the present investigation is that the varietal difference was significant in determining the efficacy of the Zn²⁺ priming. Further, based on the findings of computational studies, we observed differences in the surface overlap of the antioxidant target enzymes of rice, indicating that the Zn²⁺ might have foiled the interaction of As with the enzymes. This is undoubtedly a fascinating approach that interprets the mode of action of the antioxidative enzymes under the metal/metalloid-tempted stress condition in rice by pointing at designated targets. The results of the current investigation are rationally significant and may be the pioneering beginning of an exciting and useful method of integrating physiological and biochemical analysis together with a computational modelling approach for evaluating the stress modulating effects of Zn²⁺ seed priming on As-induced responses in developing rice seedlings. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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17 pages, 1614 KiB

Open AccessArticle

The Activity of the Durum Wheat (Triticum durum L.) Catalase 1 (TdCAT1) Is Modulated by Calmodulin

by Mouna Ghorbel, Kaouthar Feki, Sana Tounsi, Najla Haddaji, Moez Hanin and Faiçal Brini

Antioxidants 2022, 11(8), 1483; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11081483 - 29 Jul 2022

Cited by 10 | Viewed by 1517

Abstract

Plant catalases (CAT) are involved in the cellular scavenging of the reactive oxygen species during developmental processes and in response to abiotic and biotic stresses. However, little is known about the regulation of the CAT activity to ensure efficient antioxidant function. Using bioinformatic [...] Read more.

Plant catalases (CAT) are involved in the cellular scavenging of the reactive oxygen species during developmental processes and in response to abiotic and biotic stresses. However, little is known about the regulation of the CAT activity to ensure efficient antioxidant function. Using bioinformatic analyses, we showed that durum wheat catalase 1 (TdCAT1) harbors highly conserved cation-binding and calmodulin binding (CaMBD) domains which are localized at different positions of the protein. As a result, the catalytic activity of TdCAT1 is enhanced in vitro by the divalent cations Mn²⁺ and Fe²⁺ and to a lesser extent by Cu²⁺, Zn²⁺, and Mg²⁺. Moreover, the GST-pull down assays performed here revealed that TdCAT1 bind to the wheat CaM (TdCaM1.3) in a Ca²⁺-independent manner. Furthermore, the TdCaM1.3/Ca²⁺ complex is stimulated in a CaM-dose-dependent manner by the catalytic activity of TdCAT1, which is further increased in the presence of Mn²⁺ cations. The catalase activity of TdCAT1 is enhanced by various divalent cations and TdCaM1.3 in a Ca-dependent manner. Such effects are not reported so far and raise a possible role of CaM and cations in the function of CATs during cellular response to oxidative stress. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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22 pages, 3406 KiB

Open AccessArticle

Silicon- and Boron-Induced Physio-Biochemical Alteration and Organic Acid Regulation Mitigates Aluminum Phytotoxicity in Date Palm Seedlings

by Saqib Bilal, Adil Khan, Muhammad Imran, Abdul Latif Khan, Sajjad Asaf, Ahmed Al-Rawahi, Masoud Sulaiman Abood Al-Azri, Ahmed Al-Harrasi and In-Jung Lee

Antioxidants 2022, 11(6), 1063; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11061063 - 27 May 2022

Cited by 8 | Viewed by 2063

Abstract

The current study aimed to understand the synergistic impacts of silicon (Si; 1.0 mM) and boron (B; 10 µM) application on modulating physio-molecular responses of date palm to mitigate aluminum (Al³⁺; 2.0 mM) toxicity. Results revealed that compared to sole Si [...] Read more.

The current study aimed to understand the synergistic impacts of silicon (Si; 1.0 mM) and boron (B; 10 µM) application on modulating physio-molecular responses of date palm to mitigate aluminum (Al³⁺; 2.0 mM) toxicity. Results revealed that compared to sole Si and B treatments, a combined application significantly improved plant growth, biomass, and photosynthetic pigments during Al toxicity. Interestingly, Si and B resulted in significantly higher exudation of organic acid (malic acids, citric acids, and acetic acid) in the plant’s rhizosphere. This is also correlated with the reduced accumulation and translocation of Al in roots (60%) and shoots (56%) in Si and B treatments during Al toxicity compared to in sole Al³⁺ treatment. The activation of organic acids by combined Si + B application has significantly regulated the ALMT1, ALMT2 and plasma membrane ATPase; PMMA1 and PMMA3 in roots and shoots. Further, the Si-related transporter Lsi2 gene was upregulated by Si + B application under Al toxicity. This was also validated by the higher uptake and translocation of Si in plants. Al-induced oxidative stress was significantly counteracted by exhibiting lower malondialdehyde and superoxide production in Si + B treatments. Experiencing less oxidative stress was evident from upregulation of CAT and Cyt-Cu/Zn SOD expression; hence, enzymatic activities such as polyphenol oxidase, catalase, peroxidase, and ascorbate peroxidase were significantly activated. In the case of endogenous phytohormones, Si + B application demonstrated the downregulation of the abscisic acid (ABA; NCED1 and NCED6) and salicylic acid (SA; PYL4, PYR1) biosynthesis-related genes. Consequently, we also noticed a lower accumulation of ABA and rising SA levels under Al-stress. The current findings illustrate that the synergistic Si + B application could be an effective strategy for date palm growth and productivity against Al stress and could be further extended in field trails in Al-contaminated fields. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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19 pages, 4925 KiB

Open AccessArticle

Flavonoid Profiles and Antioxidant Potential of Monochoria angustifolia (G. X. Wang) Boonkerd & Tungmunnithum, a New Species from the Genus Monochoria C. Presl

by Duangjai Tungmunnithum, Samantha Drouet, Laurine Garros, Jose Manuel Lorenzo and Christophe Hano

Antioxidants 2022, 11(5), 952; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11050952 - 12 May 2022

Cited by 1 | Viewed by 1838

Abstract

Plants of the genus Monochoria have long been utilized in food, cosmetics, and traditional herbal treatments. Thailand has the highest species diversity of this genus and a new member, Monochoria angustifolia (G. X. Wang) Boonkerd & Tungmunnithum has been recently described. This plant [...] Read more.

Plants of the genus Monochoria have long been utilized in food, cosmetics, and traditional herbal treatments. Thailand has the highest species diversity of this genus and a new member, Monochoria angustifolia (G. X. Wang) Boonkerd & Tungmunnithum has been recently described. This plant is called “Siam Violet Pearl” as a common name or “Khimuk Si Muang Haeng Siam” as its vernacular name with the same meaning in the Thai language. Despite their importance, little research on Monochoria species has been conducted. This study, thus, provides the results to fill in this gap by: (i) determining flavonoid phytochemical profiles of 25 natural populations of M. angustifolia covering the whole floristic regions in Thailand, and (ii) determining antioxidant activity using various antioxidant assays to investigate probable mechanisms. The results revealed that M. angustifolia presents a higher flavonoid content than the outgroup, M. hastata. Our results also revealed that flavonoids might be used to investigate Monochoria evolutionary connections and for botanical authentication. The various antioxidant assays revealed that M. angustifolia extracts preferentially act through a hydrogen atom transfer antioxidant mechanism. Pearson correlation analysis indicated significant correlations, emphasizing that the antioxidant capacity is most probably due to the complex action of several phytochemicals rather than that of a single molecule. Together, these results showed that this new species provide an attractive alternative starting material with phytochemical variety and antioxidant potential for the phytopharmaceutical industry. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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24 pages, 2462 KiB

Open AccessArticle

Antioxidant Metabolism Underlies Different Metabolic Strategies for Primary Root Growth Maintenance under Water Stress in Cotton and Maize

by Jian Kang, Priyamvada Voothuluru, Elizabeth Hoyos-Miernyk, Danny Alexander, Melvin J. Oliver and Robert E. Sharp

Antioxidants 2022, 11(5), 820; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11050820 - 22 Apr 2022

Cited by 8 | Viewed by 1808

Abstract

The divergence of metabolic responses to water stress in the elongation zone of cotton and maize primary roots was investigated by establishing water-deficit conditions that generated steady root elongation at equivalent tissue water potentials. In water-stressed cotton roots, cell elongation was maintained in [...] Read more.

The divergence of metabolic responses to water stress in the elongation zone of cotton and maize primary roots was investigated by establishing water-deficit conditions that generated steady root elongation at equivalent tissue water potentials. In water-stressed cotton roots, cell elongation was maintained in the apical 3 mm but was progressively inhibited with further displacement from the apex. These responses are similar to previous findings in maize, providing the foundation for comparisons of metabolic responses in regions of growth maintenance and inhibition between the species. Metabolomics analyses showed region-specific and species-specific changes in metabolite abundance in response to water stress, revealing both conserved responses including osmolyte accumulation, and key differences in antioxidative and sulfur metabolism. Quantitative assessment showed contrasting glutathione responses in the root elongation zone between the species, with glutathione levels declining in cotton as stress duration progressed, whereas in maize, glutathione levels remained elevated. Despite the lesser glutathione response in cotton, hydrogen peroxide levels were low in water-stressed cotton compared with maize roots and were associated with higher catalase, ascorbate peroxidase, and superoxide dismutase activities in cotton. The results indicate alternative metabolic strategies underlying the responses of primary root growth to water stress between cotton and maize. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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25 pages, 4078 KiB

Open AccessArticle

Low-Intensity Blue Light Supplemented during Photoperiod in Controlled Environment Induces Flowering and Antioxidant Production in Kalanchoe

by Jingli Yang, Jinnan Song and Byoung Ryong Jeong

Antioxidants 2022, 11(5), 811; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11050811 - 21 Apr 2022

Cited by 8 | Viewed by 2109

Abstract

Kalanchoe (Kalanchoe blossfeldiana) is a qualitative short-day plant with a high aesthetic value. When the night length is less than a specified cultivar-dependent critical value, however, it does not develop flowers. This study investigated the effects of low-intensity supplementary or night [...] Read more.

Kalanchoe (Kalanchoe blossfeldiana) is a qualitative short-day plant with a high aesthetic value. When the night length is less than a specified cultivar-dependent critical value, however, it does not develop flowers. This study investigated the effects of low-intensity supplementary or night interrupting (NI) blue (B) light on the plant performance and flower induction in kalanchoe ‘Rudak’. During the photoperiod in a closed-type plant factory with day/night temperatures of 23 °C/18 °C, white (W) LEDs were utilized to produce a photosynthetic photon flux density (PPFD) of 300 μmol m⁻² s⁻¹, and B LEDs were used to give supplementary/NI light at a PPFD of 10 μmol m⁻² s⁻¹. The control plants were exposed to a 10-h short day (SD, positive control) or a 13-h long day (LD, negative control) treatment without any B light. The B light was used for 4 h either (1) to supplement the W LEDs at the end of the SD (SD + 4B) and LD (LD + 4B), or (2) to provide night interruption (NI) in the SD (SD + NI-4B) and LD (LD + NI-4B). The LD + 4B and LD + NI-4B significantly enhanced plant growth and development, followed by the SD + 4B and SD + NI-4B treatments. In addition, the photosynthesis, physiological parameters, and activity of antioxidant systems were improved in those treatments. Except in the LD and LD + NI-4B, all plants flowered. It is noteworthy that kalanchoe ‘Rudak’ flowered in the LD + 4B treatment and induced the greatest number of flowers, followed by SD + NI-4B and SD + 4B. Plants grown in the LD + 4B treatment had the highest expression levels of certain monitored genes related to flowering. The results indicate that a 4-h supplementation of B light during the photoperiod in both the SD and LD treatments increased flower bud formation, promoted flowering, and enhanced plant performance. Kalanchoe ‘Rudak’ flowered especially well in the LD + 4B, presenting a possibility of practically inducing flowering in long-day seasons with B light application. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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22 pages, 2871 KiB

Open AccessArticle

Melatonin Application Alleviates Stress-Induced Photosynthetic Inhibition and Oxidative Damage by Regulating Antioxidant Defense System of Maize: A Meta-Analysis

by Ihsan Muhammad, Li Yang, Shakeel Ahmad, Ibrahim S. M. Mosaad, Abdullah Ahmed Al-Ghamdi, Arshad Mehmood Abbasi and Xun-Bo Zhou

Antioxidants 2022, 11(3), 512; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11030512 - 08 Mar 2022

Cited by 39 | Viewed by 4202

Abstract

Melatonin is effective in modulating metabolism and regulating growth and development in many plants under biotic and abiotic stress. However, there is no systematic quantification of melatonin effects on maize growth, gas exchange, chlorophyll content, and the antioxidant defense system. A meta-analysis was [...] Read more.

Melatonin is effective in modulating metabolism and regulating growth and development in many plants under biotic and abiotic stress. However, there is no systematic quantification of melatonin effects on maize growth, gas exchange, chlorophyll content, and the antioxidant defense system. A meta-analysis was conducted on thirty-two currently available published articles to evaluate the effect of stress types, study types, and maize varieties on response ratio (lnRR₊₊) of “melatonin” to “control (no melatonin)” on plant growth, enzyme activities, gas exchange parameters, and photosynthetic pigments. Our findings revealed that melatonin application overall increased plant height, leaf area, root length, fresh and dry root weight and shoot weight, superoxide dismutase (SOD), peroxide (POD), catalase (CAT), ascorbate peroxidase (APX), soluble sugar and protein, photosynthetic rate, stomatal conductance, transpiration rate, chlorophyll, and carotenoid in maize leaf under stress conditions. In contrast, melatonin application decreased the levels of hydrogen peroxide (H₂O₂), superoxide anion (O_2⁻), malondialdehyde (MDA), and electrolyte leakage. The categorical meta-analysis demonstrated that melatonin application to chilling stress resulted in higher SOD activity followed by salt stress. Melatonin application to all stress types resulted in higher POD, CAT and APX activities, except Cd stress, which had no effect on POD and decreased CAT by 38% compared to control. Compared to control, melatonin resulted in lower reactive oxygen species (ROS) and electrolyte leakage under no stress, Cd, drought, salt, lead, heat, and chilling stress in all study types (pot, growth chamber, hydroponic, and field), except O₂ content which was not affected in pot and growth chamber studies. It was concluded that melatonin alleviates oxidative damage by improving stress tolerance, regulating the antioxidant defense system, and increasing leaf chlorophyll content compared to control. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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21 pages, 2276 KiB

Open AccessEditor’s ChoiceArticle

Impact of Combined Heat and Salt Stresses on Tomato Plants—Insights into Nutrient Uptake and Redox Homeostasis

by Bruno Sousa, Francisca Rodrigues, Cristiano Soares, Maria Martins, Manuel Azenha, Teresa Lino-Neto, Conceição Santos, Ana Cunha and Fernanda Fidalgo

Antioxidants 2022, 11(3), 478; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11030478 - 28 Feb 2022

Cited by 16 | Viewed by 3528

Abstract

Currently, salinity and heat are two critical threats to crop production and food security which are being aggravated by the global climatic instability. In this scenario, it is imperative to understand plant responses to simultaneous exposure to different stressors and the cross-talk between [...] Read more.

Currently, salinity and heat are two critical threats to crop production and food security which are being aggravated by the global climatic instability. In this scenario, it is imperative to understand plant responses to simultaneous exposure to different stressors and the cross-talk between underlying functional mechanisms. Thus, in this study, the physiological and biochemical responses of tomato plants (Solanum lycopersicum L.) to the combination of salinity (100 mM NaCl) and heat (42 °C; 4 h/day) stress were evaluated. After 21 days of co-exposure, the accumulation of Na⁺ in plant tissues was superior when salt-treated plants were also exposed to high temperatures compared to the individual saline treatment, leading to the depletion of other nutrients and a harsher negative effect on plant growth. Despite that, neither oxidative damage nor a major accumulation of reactive oxygen species took place under stress conditions, mostly due to the accumulation of antioxidant (AOX) metabolites alongside the activation of several AOX enzymes. Nonetheless, the plausible allocation of resources towards the defense pathways related to oxidative and osmotic stress, along with severe Na toxicity, heavily compromised the ability of plants to grow properly when the combination of salinity and heat was imposed. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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17 pages, 4691 KiB

Open AccessArticle

A Computational Study of the Role of Secondary Metabolites for Mitigation of Acid Soil Stress in Cereals Using Dehydroascorbate and Mono-Dehydroascorbate Reductases

by Shuvasish Choudhury, Muhammed Khairujjaman Mazumder, Debojyoti Moulick, Parul Sharma, Sandeep Kumar Tata, Dibakar Ghosh, Hayssam M. Ali, Manzer H. Siddiqui, Marian Brestic, Milan Skalicky and Akbar Hossain

Antioxidants 2022, 11(3), 458; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11030458 - 25 Feb 2022

Cited by 14 | Viewed by 2277

Abstract

The present study investigates the potential ameliorative role of seven secondary metabolites, viz., ascorbate (AsA), reduced glutathione (GSH), jasmonic acid (JA), salicylic acid (SA), serotonin (5-HT), indole–3–acetic acid (IAA) and gibberellic acid (GA3), for mitigation of aluminium (Al³⁺) and manganese (Mn [...] Read more.

The present study investigates the potential ameliorative role of seven secondary metabolites, viz., ascorbate (AsA), reduced glutathione (GSH), jasmonic acid (JA), salicylic acid (SA), serotonin (5-HT), indole–3–acetic acid (IAA) and gibberellic acid (GA3), for mitigation of aluminium (Al³⁺) and manganese (Mn²⁺) stress associated with acidic soils in rice, maize and wheat. The dehydroascorbate reductase (DHAR) and mono-dehydroascorbate reductase (MDHAR) of the cereals were used as model targets, and the analysis was performed using computational tools. Molecular docking approach was employed to evaluate the interaction of these ions (Al³⁺ and Mn²⁺) and the metabolites at the active sites of the two target enzymes. The results indicate that the ions potentially interact with the active sites of these enzymes and conceivably influence the AsA–GSH cycle. The metabolites showed strong interactions at the active sites of the enzymes. When the electrostatic surfaces of the metabolites and the ions were generated, it revealed that the surfaces overlap in the case of DHAR of rice and wheat, and MDHAR of rice. Thus, it was hypothesized that the metabolites may prevent the interaction of ions with the enzymes. This is an interesting approach to decipher the mechanism of action of secondary metabolites against the metal or metalloid - induced stress responses in cereals by aiming at specific targets. The findings of the present study are reasonably significant and may be the beginning of an interesting and useful approach towards comprehending the role of secondary metabolites for stress amelioration and mitigation in cereals grown under acidic soil conditions. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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17 pages, 3241 KiB

Open AccessArticle

Interactive Effects of Melatonin and Nitrogen Improve Drought Tolerance of Maize Seedlings by Regulating Growth and Physiochemical Attributes

by Shakeel Ahmad, Guo-Yun Wang, Ihsan Muhammad, Yu-Xin Chi, Muhammad Zeeshan, Jamal Nasar and Xun-Bo Zhou

Antioxidants 2022, 11(2), 359; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11020359 - 11 Feb 2022

Cited by 40 | Viewed by 4002

Abstract

Melatonin plays an important role in numerous vital life processes of animals and has recently captured the interests of plant biologists because of its potent role in plants. As well as its possible contribution to photoperiodic processes, melatonin is believed to act as [...] Read more.

Melatonin plays an important role in numerous vital life processes of animals and has recently captured the interests of plant biologists because of its potent role in plants. As well as its possible contribution to photoperiodic processes, melatonin is believed to act as a growth regulator and/or as a direct free radical scavenger/indirect antioxidant. However, identifying a precise concentration of melatonin with an optimum nitrogen level for a particular application method to improve plant growth requires identification and clarification. This work establishes inimitable findings by optimizing the application of melatonin with an optimum level of nitrogen, alleviating the detrimental effects of drought stress in maize seedlings. Maize seedlings were subjected to drought stress of 40–45% field capacity (FC) at the five-leaf stage, followed by a soil drenching of melatonin 100 µM and three nitrogen levels (200, 250, and 300 kg ha⁻¹) to consider the changes in maize seedling growth. Our results showed that drought stress significantly inhibited the physiological and biochemical parameters of maize seedlings. However, the application of melatonin with nitrogen remarkably improved the plant growth attributes, chlorophyll pigments, fluorescence, and gas exchange parameters. Moreover, melatonin and nitrogen application profoundly reduced the reactive oxygen species (ROS) accumulation by increasing maize antioxidant and nitrogen metabolism enzyme activities under drought-stress conditions. It was concluded that the mitigating potential of 100 µM melatonin with an optimum level of nitrogen (250 kg N ha⁻¹) improves the plant growth, photosynthetic efficiency, and enzymatic activity of maize seedling under drought-stress conditions. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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21 pages, 4948 KiB

Open AccessArticle

Elevated CO₂ Differentially Mitigated Oxidative Stress Induced by Indium Oxide Nanoparticles in Young and Old Leaves of C3 and C4 Crops

by Ibrahim I. Shabbaj, Hamada AbdElgawad, Mansour A. Balkhyour, Abdurazag Tammar and Mahmoud M. Y. Madany

Antioxidants 2022, 11(2), 308; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11020308 - 03 Feb 2022

Cited by 16 | Viewed by 1907

Abstract

Soil contamination with indium (In) oxide nanoparticles (In₂O₃-NPs) threatens plant growth and development. However, their toxicity in plants under ambient (aCO₂) and elevated (eCO₂) conditions is scarcely studied. To this end, this study was conducted [...] Read more.

Soil contamination with indium (In) oxide nanoparticles (In₂O₃-NPs) threatens plant growth and development. However, their toxicity in plants under ambient (aCO₂) and elevated (eCO₂) conditions is scarcely studied. To this end, this study was conducted to investigate In₂O₃-NPs toxicity in the young and old leaves of C3 (barley) and C4 (maize) plants and to understand the mechanisms underlying the stress mitigating impact of eCO₂. Treatment of C3 and C4 plants with In₂O₃-NPs significantly reduced growth and photosynthesis, induced oxidative damage (H₂O₂, lipid peroxidation), and impaired P and Fe homeostasis, particularly in the young leaves of C4 plants. On the other hand, this phytotoxic hazard was mitigated by eCO₂ which improved both C3 and C4 growth, decreased In accumulation and increased phosphorus (P) and iron (Fe) uptake, particularly in the young leaves of C4 plants. Moreover, the improved photosynthesis by eCO₂ accordingly enhanced carbon availability under the challenge of In₂O₃-NPs that were directed to the elevated production of metabolites involved in antioxidant and detoxification systems. Our physiological and biochemical analyses implicated the role of the antioxidant defenses, including superoxide dismutase (SOD) in stress mitigation under eCO₂. This was validated by studying the effect of In₂O₃-stress on a transgenic maize line (TG) constitutively overexpressing the AtFeSOD gene and its wild type (WT). Although it did not alter In accumulation, the TG plants showed improved growth and photosynthesis and reduced oxidative damage. Overall, this work demonstrated that C3 was more sensitive to In₂O₃-NPs stress; however, C4 plants were more responsive to eCO₂. Moreover, it demonstrated the role of SOD in determining the hazardous effect of In₂O₃-NPs. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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21 pages, 1638 KiB

Open AccessArticle

High Redox Status as the Basis for Heavy Metal Tolerance of Sesuvium portulacastrum L. Inhabiting Contaminated Soil in Jeddah, Saudi Arabia

by Emad A. Alsherif, Turki M. Al-Shaikh, Omar Almaghrabi and Hamada AbdElgawad

Antioxidants 2022, 11(1), 19; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11010019 - 22 Dec 2021

Cited by 6 | Viewed by 2461

Abstract

Because sewage sludge is contaminated with heavy metals, its disposal in the soil may pose risks to the ecosystem. Thus, heavy metal remediation is necessary to reduce the associated risks. The goal of this research is to introduce a heavy metal resistant species [...] Read more.

Because sewage sludge is contaminated with heavy metals, its disposal in the soil may pose risks to the ecosystem. Thus, heavy metal remediation is necessary to reduce the associated risks. The goal of this research is to introduce a heavy metal resistant species and to assess its phytoremediation, oxidative damage markers and stress tolerance mechanisms. To this end, field research was done to compare the vegetation of polluted sites to that of a healthy site. We found 42 plant species identified in the study, Sesuvium portulacastrum L. was chosen because of its high relative density (10.3) and maximum frequency (100 percent) in the most contaminated areas. In particular, S. portulacastrum plants were characterized by strong Cu, Ni, and As uptake. At the organ level, to control growth reduction and oxidase damage, particularly in roots, increased detoxification (e.g., metallothionein, phytochelatins) and antioxidants mechanisms (e.g., tocopherols, glutathione, peroxidases). On the other hand, flavonoids content and the activity of glutathione-S transferase, glutathione reductase and dehydroascorbate reductase were increased manly in the shoots. These biochemical markers can be applied to select tolerance plant species grown under complex heavy metal contamination. Our findings also introduced S. portulacastrum to reduce soil contamination0associated risks, making the land resource available for agricultural production. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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21 pages, 7376 KiB

Open AccessArticle

Biochar and Chitosan Regulate Antioxidant Defense and Methylglyoxal Detoxification Systems and Enhance Salt Tolerance in Jute (Corchorus olitorius L.)

by Mirza Hasanuzzaman, Md. Rakib Hossain Raihan, Ebtihal Khojah, Bassem N. Samra, Masayuki Fujita and Kamrun Nahar

Antioxidants 2021, 10(12), 2017; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox10122017 - 19 Dec 2021

Cited by 22 | Viewed by 3285

Abstract

We investigated the role of biochar and chitosan in mitigating salt stress in jute (Corchorus olitorius L. cv. O-9897) by exposing twenty-day-old seedlings to three doses of salt (50, 100, and 150 mM NaCl). Biochar was pre-mixed with the soil at 2.0 [...] Read more.

We investigated the role of biochar and chitosan in mitigating salt stress in jute (Corchorus olitorius L. cv. O-9897) by exposing twenty-day-old seedlings to three doses of salt (50, 100, and 150 mM NaCl). Biochar was pre-mixed with the soil at 2.0 g kg⁻¹ soil, and chitosan-100 was applied through irrigation at 100 mg L⁻¹. Exposure to salt stress notably increased lipid peroxidation, hydrogen peroxide content, superoxide radical levels, electrolyte leakage, lipoxygenase activity, and methylglyoxal content, indicating oxidative damage in the jute plants. Consequently, the salt-stressed plants showed reduced growth, biomass accumulation, and disrupted water balance. A profound increase in proline content was observed in response to salt stress. Biochar and chitosan supplementation significantly mitigated the deleterious effects of salt stress in jute by stimulating both non-enzymatic (e.g., ascorbate and glutathione) and enzymatic (e.g., ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, glutathione reductase superoxide dismutase, catalase, peroxidase, glutathione S-transferase, glutathione peroxidase) antioxidant systems and enhancing glyoxalase enzyme activities (glyoxalase I and glyoxalase II) to ameliorate reactive oxygen species damage and methylglyoxal toxicity, respectively. Biochar and chitosan supplementation increased oxidative stress tolerance and improved the growth and physiology of salt-affected jute plants, while also significantly reducing Na⁺ accumulation and ionic toxicity and decreasing the Na⁺/K⁺ ratio. These findings support a protective role of biochar and chitosan against salt-induced damage in jute plants. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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18 pages, 4010 KiB

Open AccessArticle

Strigolactones Modulate Cellular Antioxidant Defense Mechanisms to Mitigate Arsenate Toxicity in Rice Shoots

by Mohammad Golam Mostofa, Chien Van Ha, Md. Mezanur Rahman, Kien Huu Nguyen, Sanjida Sultana Keya, Yasuko Watanabe, Misao Itouga, Abeer Hashem, Elsayed Fathi Abd_Allah, Masayuki Fujita and Lam-Son Phan Tran

Antioxidants 2021, 10(11), 1815; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox10111815 - 15 Nov 2021

Cited by 15 | Viewed by 2268

Abstract

Metalloid contamination, such as arsenic poisoning, poses a significant environmental problem, reducing plant productivity and putting human health at risk. Phytohormones are known to regulate arsenic stress; however, the function of strigolactones (SLs) in arsenic stress tolerance in rice is rarely investigated. Here, [...] Read more.

Metalloid contamination, such as arsenic poisoning, poses a significant environmental problem, reducing plant productivity and putting human health at risk. Phytohormones are known to regulate arsenic stress; however, the function of strigolactones (SLs) in arsenic stress tolerance in rice is rarely investigated. Here, we investigated shoot responses of wild-type (WT) and SL-deficient d10 and d17 rice mutants under arsenate stress to elucidate SLs’ roles in rice adaptation to arsenic. Under arsenate stress, the d10 and d17 mutants displayed severe growth abnormalities, including phenotypic aberrations, chlorosis and biomass loss, relative to WT. Arsenate stress activated the SL-biosynthetic pathway by enhancing the expression of SL-biosynthetic genes D10 and D17 in WT shoots. No differences in arsenic levels between WT and SL-biosynthetic mutants were found from Inductively Coupled Plasma-Mass Spectrometry analysis, demonstrating that the greater growth defects of mutant plants did not result from accumulated arsenic in shoots. The d10 and d17 plants had higher levels of reactive oxygen species, water loss, electrolyte leakage and membrane damage but lower activities of superoxide dismutase, ascorbate peroxidase, glutathione peroxidase and glutathione S-transferase than did the WT, implying that arsenate caused substantial oxidative stress in the SL mutants. Furthermore, WT plants had higher glutathione (GSH) contents and transcript levels of OsGSH1, OsGSH2, OsPCS1 and OsABCC1 in their shoots, indicating an upregulation of GSH-assisted arsenic sequestration into vacuoles. We conclude that arsenate stress activated SL biosynthesis, which led to enhanced arsenate tolerance through the stimulation of cellular antioxidant defense systems and vacuolar sequestration of arsenic, suggesting a novel role for SLs in rice adaptation to arsenic stress. Our findings have significant implications in the development of arsenic-resistant rice varieties for safe and sustainable rice production in arsenic-polluted soils. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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21 pages, 1979 KiB

Open AccessArticle

Differences in Cadmium Accumulation, Detoxification and Antioxidant Defenses between Contrasting Maize Cultivars Implicate a Role of Superoxide Dismutase in Cd Tolerance

by Aya Mahmoud, Hamada AbdElgawad, Badreldin A. Hamed, Gerrit T.S. Beemster and Nadia M. El-Shafey

Antioxidants 2021, 10(11), 1812; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox10111812 - 15 Nov 2021

Cited by 12 | Viewed by 2135

Abstract

Cadmium (Cd), a readily absorbed and translocated toxic heavy metal, inhibits plant growth, interrupts metabolic homeostasis and induces oxidative damage. Responses towards Cd-stress differ among plant cultivars, and the complex integrated relationships between Cd accumulation, detoxification mechanisms and antioxidant defenses still need to [...] Read more.

Cadmium (Cd), a readily absorbed and translocated toxic heavy metal, inhibits plant growth, interrupts metabolic homeostasis and induces oxidative damage. Responses towards Cd-stress differ among plant cultivars, and the complex integrated relationships between Cd accumulation, detoxification mechanisms and antioxidant defenses still need to be unraveled. To this end, 12 Egyptian maize cultivars were grown under Cd-stress to test their Cd-stress tolerance. Out of these cultivars, tolerant (TWC360 and TWC321), moderately sensitive (TWC324) and sensitive (SC128) cultivars were selected, and we determined their response to Cd in terms of biomass, Cd accumulation and antioxidant defense system. The reduction in biomass was highly obvious in sensitive cultivars, while TWC360 and TWC321 showed high Cd-tolerance. The cultivar TWC321 showed lower Cd uptake concurrently with an enhanced antioxidant defense system. Interestingly, TWC360 accumulated more Cd in the shoot, accompanied with increased Cd detoxification and sequestration. A principal component analysis revealed a clear separation between the sensitive and tolerant cultivars with significance of the antioxidant defenses, including superoxide dismutase (SOD). To confirm the involvement of SOD in Cd-tolerance, we studied the effect of Cd-stress on a transgenic maize line (TG) constitutively overexpressing AtFeSOD gene in comparison to its wild type (WT). Compared to their WT, the TG plants showed less Cd accumulation and improved growth, physiology, antioxidant and detoxification systems. These results demonstrate the role of SOD in determining Cd-tolerance. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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14 pages, 2376 KiB

Open AccessArticle

Characteristics of the Polyphenolic Profile and Antioxidant Activity of Cone Extracts from Conifers Determined Using Electrochemical and Spectrophotometric Methods

by Malgorzata Latos-Brozio, Anna Masek, Ewa Chrzescijanska, Anna Podsędek and Dominika Kajszczak

Antioxidants 2021, 10(11), 1723; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox10111723 - 28 Oct 2021

Cited by 12 | Viewed by 2037

Abstract

The aim of the study was to analyze the polyphenolic profile of cone extracts of Douglas fir, Scots pine and Korean fir, and to study their antioxidant activity. The mechanism of electro-oxidation of polyphenols (such as procyanidins and catechins) from cone extracts was [...] Read more.

The aim of the study was to analyze the polyphenolic profile of cone extracts of Douglas fir, Scots pine and Korean fir, and to study their antioxidant activity. The mechanism of electro-oxidation of polyphenols (such as procyanidins and catechins) from cone extracts was investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV), as well as spectrophotometric methods—ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate)), DPPH (2,2-diphenyl-1-picrylhydrazyl), FRAP (Ferric Reducing Antioxidant Power ) and CUPRAC (CUPric Reducing Antioxidant Capacity). The scientific novelty of the research is the comprehensive analysis of cone extracts in terms of antioxidant properties. Due to the high polyphenol content, the extracts showed significant ability to reduce oxidative reactions, as well as the ability to scavenge free radicals and transition metal ions. Douglas fir, Scots pine and Korean fir cone extracts can potentially be used as natural stabilizers, preservatives and antimicrobial substances in the food industry and in medications. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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15 pages, 1791 KiB

Open AccessArticle

Antioxidative Responses of Duckweed (Lemna minor L.) to Phenol and Rhizosphere-Associated Bacterial Strain Hafnia paralvei C32-106/3

by Olga Radulović, Slaviša Stanković, Olja Stanojević, Zoran Vujčić, Biljana Dojnov, Milana Trifunović-Momčilov and Marija Marković

Antioxidants 2021, 10(11), 1719; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox10111719 - 28 Oct 2021

Cited by 6 | Viewed by 2370

Abstract

Duckweed (L. minor) is a cosmopolitan aquatic plant of simplified morphology and rapid vegetative reproduction. In this study, an H. paralvei bacterial strain and its influence on the antioxidative response of the duckweeds to phenol, a recalcitrant environmental pollutant, were investigated. [...] Read more.

Duckweed (L. minor) is a cosmopolitan aquatic plant of simplified morphology and rapid vegetative reproduction. In this study, an H. paralvei bacterial strain and its influence on the antioxidative response of the duckweeds to phenol, a recalcitrant environmental pollutant, were investigated. Sterile duckweed cultures were inoculated with H. paralvei in vitro and cultivated in the presence or absence of phenol (500 mg L⁻¹), in order to investigate bacterial effects on plant oxidative stress during 5 days. Total soluble proteins, guaiacol peroxidase expression, concentration of hydrogen peroxide and malondialdehyde as well as the total ascorbic acid of the plants were monitored. Moreover, bacterial production of indole-3-acetic acid (IAA) was measured in order to investigate H. paralvei’s influence on plant growth. In general, the addition of phenol elevated all biochemical parameters in L. minor except AsA and total soluble proteins. Phenol as well as bacteria influenced the expression of guaiacol peroxidase. Different isoforms were associated with phenol compared to isoforms expressed in phenol-free medium. Considering that duckweeds showed increased antioxidative parameters in the presence of phenol, it can be assumed that the measured parameters might be involved in the plant’s defense system. H. paralvei is an IAA producer and its presence in the rhizosphere of duckweeds decreased the oxidative stress of the plants, which can be taken as evidence that this bacterial strain acts protectively on the plants during phenol exposure. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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34 pages, 14912 KiB

Open AccessArticle

Genome-Wide Transcriptome Profiling, Characterization, and Functional Identification of NAC Transcription Factors in Sorghum under Salt Stress

by Himani Punia, Jayanti Tokas, Anurag Malik, Sonali Sangwan, Anju Rani, Shikha Yashveer, Saleh Alansi, Maha J. Hashim and Mohamed A. El-Sheikh

Antioxidants 2021, 10(10), 1605; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox10101605 - 13 Oct 2021

Cited by 19 | Viewed by 3384

Abstract

Salinity stress has become a significant concern to global food security. Revealing the mechanisms that enable plants to survive under salinity has immense significance. Sorghum has increasingly attracted researchers interested in understanding the survival and adaptation strategies to high salinity. However, systematic analysis [...] Read more.

Salinity stress has become a significant concern to global food security. Revealing the mechanisms that enable plants to survive under salinity has immense significance. Sorghum has increasingly attracted researchers interested in understanding the survival and adaptation strategies to high salinity. However, systematic analysis of the DEGs (differentially expressed genes) and their relative expression has not been reported in sorghum under salt stress. The de novo transcriptomic analysis of sorghum under different salinity levels from 60 to 120 mM NaCl was generated using Illumina HiSeq. Approximately 323.49 million high-quality reads, with an average contig length of 1145 bp, were assembled de novo. On average, 62% of unigenes were functionally annotated to known proteins. These DEGs were mainly involved in several important metabolic processes, such as carbohydrate and lipid metabolism, cell wall biogenesis, photosynthesis, and hormone signaling. SSG 59-3 alleviated the adverse effects of salinity by suppressing oxidative stress (H₂O₂) and stimulating enzymatic and non-enzymatic antioxidant activities (SOD, APX, CAT, APX, POX, GR, GSH, ASC, proline, and GB), as well as protecting cell membrane integrity (MDA and electrolyte leakage). Significant up-regulation of transcripts encoding the NAC, MYB, and WRYK families, NHX transporters, the aquaporin protein family, photosynthetic genes, antioxidants, and compatible osmolyte proteins were observed. The tolerant line (SSG 59-3) engaged highly efficient machinery in response to elevated salinity, especially during the transport and influx of K⁺ ions, signal transduction, and osmotic homeostasis. Our data provide insights into the evolution of the NAC TFs gene family and further support the hypothesis that these genes are essential for plant responses to salinity. The findings may provide a molecular foundation for further exploring the potential functions of NAC TFs in developing salt-resistant sorghum lines. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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18 pages, 3560 KiB

Open AccessArticle

Genome-Wide Characterization of Glutathione Peroxidase (GPX) Gene Family in Rapeseed (Brassica napus L.) Revealed Their Role in Multiple Abiotic Stress Response and Hormone Signaling

by Wei Li, Xuemin Huai, Peitao Li, Ali Raza, Muhammad Salman Mubarik, Madiha Habib, Sajid Fiaz, Binbin Zhang, Jun Pan and Rao Sohail Ahmad Khan

Antioxidants 2021, 10(9), 1481; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox10091481 - 17 Sep 2021

Cited by 25 | Viewed by 4271

Abstract

Plant glutathione peroxidases (GPXs) are the main enzymes in the antioxidant defense system that sustain H₂O₂ homeostasis and normalize plant reaction to abiotic stress conditions. To understand the major roles of the GPX gene family in rapeseed (Brassica napus [...] Read more.

Plant glutathione peroxidases (GPXs) are the main enzymes in the antioxidant defense system that sustain H₂O₂ homeostasis and normalize plant reaction to abiotic stress conditions. To understand the major roles of the GPX gene family in rapeseed (Brassica napus L.), for the first time, a genome-wide study identified 25 BnGPX genes in the rapeseed genome. The phylogenetic analysis discovered that GPX genes were grouped into four major groups (Group I–Group IV) from rapeseed and three closely interrelated plant species. The universal investigation uncovered that the BnGPXs gene experienced segmental duplications and positive selection pressure. Gene structure and motifs examination recommended that most of the BnGPX genes demonstrated a comparatively well-maintained exon-intron and motifs arrangement within the identical group. Likewise, we recognized five hormones-, four stress-, and numerous light-reactive cis-elements in the promoters of BnGPXs. Five putative bna-miRNAs from two families were also prophesied, targeting six BnGPXs genes. Gene ontology annotation results proved the main role of BnGPXs in antioxidant defense systems, ROS, and response to stress stimulus. Several BnGPXs genes revealed boosted expression profiles in many developmental tissues/organs, i.e., root, seed, leaf, stem, flower, and silique. The qRT-PCR based expression profiling exhibited that two genes (BnGPX21 and BnGPX23) were suggestively up-regulated against different hormones (ABA, IAA, and MeJA) and abiotic stress (salinity, cold, waterlogging, and drought) treatments. In short, our discoveries provide a basis for additional functional studies on the BnGPX genes in future rapeseed breeding programs. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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20 pages, 3509 KiB

Open AccessArticle

Silicon Improves the Redox Homeostasis to Alleviate Glyphosate Toxicity in Tomato Plants—Are Nanomaterials Relevant?

by Cristiano Soares, Pedro Nadais, Bruno Sousa, Edgar Pinto, Isabel M. P. L. V. O. Ferreira, Ruth Pereira and Fernanda Fidalgo

Antioxidants 2021, 10(8), 1320; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox10081320 - 23 Aug 2021

Cited by 12 | Viewed by 3062

Abstract

Given the widespread use of glyphosate (GLY), this agrochemical is becoming a source of contamination in agricultural soils, affecting non-target plants. Therefore, sustainable strategies to increase crop tolerance to GLY are needed. From this perspective and recalling silicon (Si)’s role in alleviating different [...] Read more.

Given the widespread use of glyphosate (GLY), this agrochemical is becoming a source of contamination in agricultural soils, affecting non-target plants. Therefore, sustainable strategies to increase crop tolerance to GLY are needed. From this perspective and recalling silicon (Si)’s role in alleviating different abiotic stresses, the main goal of this study was to assess if the foliar application of Si, either as bulk or nano forms, is capable of enhancing Solanum lycopersicum L. tolerance to GLY (10 mg kg⁻¹). After 28 day(s), GLY-treated plants exhibited growth-related disorders in both shoots and roots, accompanied by an overproduction of superoxide anion (O₂^•−) and malondialdehyde (MDA) in shoots. Although plants solely exposed to GLY have activated non-enzymatic antioxidant mechanisms (proline, ascorbate and glutathione), a generalized inhibition of the antioxidant enzymes was found, suggesting the occurrence of great redox disturbances. In response to Si or nano-SiO₂ co-application, most of GLY phytotoxic effects on growth were prevented, accompanied with a better ROS removal, especially by an upregulation of the main antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Overall, results pointed towards the potential of both sources of Si to reduce GLY-induced oxidative stress, without major differences between their efficacy. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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Review

Jump to: Research

26 pages, 2910 KiB

Open AccessReview

Accumulation of Proline in Plants under Contaminated Soils—Are We on the Same Page?

by Sofia Spormann, Pedro Nadais, Filipa Sousa, Mafalda Pinto, Maria Martins, Bruno Sousa, Fernanda Fidalgo and Cristiano Soares

Antioxidants 2023, 12(3), 666; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox12030666 - 08 Mar 2023

Cited by 27 | Viewed by 4004

Abstract

Agricultural soil degradation is occurring at unprecedented rates, not only as an indirect effect of climate change (CC) but also due to intensified agricultural practices which affect soil properties and biodiversity. Therefore, understanding the impacts of CC and soil degradation on plant physiology [...] Read more.

Agricultural soil degradation is occurring at unprecedented rates, not only as an indirect effect of climate change (CC) but also due to intensified agricultural practices which affect soil properties and biodiversity. Therefore, understanding the impacts of CC and soil degradation on plant physiology is crucial for the sustainable development of mitigation strategies to prevent crop productivity losses. The amino acid proline has long been recognized for playing distinct roles in plant cells undergoing osmotic stress. Due to its osmoprotectant and redox-buffering ability, a positive correlation between proline accumulation and plants’ tolerance to abiotic stress has been pointed out in numerous reviews. Indeed, proline quantification is used systematically by plant physiologists as an indicator of the degree of tolerance and a measurement of the antioxidant potential in plants under stressful conditions. Moreover, the exogenous application of proline has been shown to increase resilience to several stress factors, including those related to soil degradation such as salinity and exposure to metals and xenobiotics. However, recent data from several studies often refer to proline accumulation as a signal of stress sensitivity with no clear correlation with improved antioxidant activity or higher stress tolerance, including when proline is used exogenously as a stress reliever. Nevertheless, endogenous proline levels are strongly modified by these stresses, proving its involvement in plant responses. Hence, one main question arises—is proline augmentation always a sign of improved stress resilience? From this perspective, the present review aims to provide a more comprehensive understanding of the implications of proline accumulation in plants under abiotic stress induced by soil degradation factors, reinforcing the idea that proline quantification should not be employed as a sole indicator of stress sensitivity or resilience but rather complemented with further biochemical and physiological endpoints. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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20 pages, 2748 KiB

Open AccessReview

Metabolic Pathway of Natural Antioxidants, Antioxidant Enzymes and ROS Providence

by Bernhard Huchzermeyer, Ekta Menghani, Pooja Khardia and Ayushi Shilu

Antioxidants 2022, 11(4), 761; https://0-doi-org.brum.beds.ac.uk/10.3390/antiox11040761 - 11 Apr 2022

Cited by 38 | Viewed by 4592

Abstract

Based on the origin, we can classify different types of stress. Environmental factors, such as high light intensity, adverse temperature, drought, or soil salinity, are summarized as abiotic stresses and discriminated from biotic stresses that are exerted by pathogens and herbivores, for instance. [...] Read more.

Based on the origin, we can classify different types of stress. Environmental factors, such as high light intensity, adverse temperature, drought, or soil salinity, are summarized as abiotic stresses and discriminated from biotic stresses that are exerted by pathogens and herbivores, for instance. It was an unexpected observation that overproduction of reactive oxygen species (ROS) is a common response to all kinds of stress investigated so far. With respect to applied aspects in agriculture and crop breeding, this observation allows using ROS production as a measure to rank the stress perception of individual plants. ROS are important messengers in cell signaling, but exceeding a concentration threshold causes damage. This requires fine-tuning of ROS production and degradation rates. In general, there are two options to control cellular ROS levels, (I) ROS scavenging at the expense of antioxidant consumption and (II) enzyme-controlled degradation of ROS. As antioxidants are limited in quantity, the first strategy only allows temporarily buffering of a certain cellular ROS level. This way, it prevents spells of eventually damaging ROS concentrations. In this review, we focus on the second strategy. We discuss how enzyme-controlled degradation of ROS integrates into plant metabolism. Enzyme activities can be continuously operative. Cellular homeostasis can be achieved by regulation of respective gene expression and subsequent regulation of the enzyme activities. A better understanding of this interplay allows for identifying traits for stress tolerance breeding of crops. As a side effect, the result also may be used to identify cultivation methods modifying crop metabolism, thus resulting in special crop quality. Full article

(This article belongs to the Special Issue Antioxidant Mechanisms in Plants)

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