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Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops

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A special issue of Plants (ISSN 2223-7747). This special issue belongs to the section "Crop Physiology and Crop Production".

Deadline for manuscript submissions: closed (20 August 2022) | Viewed by 22870

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Special Issue Editors

Prof. Dr. Dezhi Wu

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Guest Editor

Agricultural College, Hunan Agricultural University, Changsha, China
Interests: crop biotechnology; genomics; molecular mechanism of crop salt tolerance; ion transporters
Special Issues, Collections and Topics in MDPI journals

Dr. Peng Zhang

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Co-Guest Editor

China National Rice Research Institute, Hangzhou, Hangzhou 310006, China
Interests: abiotic stress tolerance; GWAS; rice molecular breeding
Special Issues, Collections and Topics in MDPI journals

Dr. Hanhua Tong

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Co-Guest Editor

China National Rice Research Institute, Hangzhou 310006, China
Interests: crop abiotic stress resistance; crop nutrient utilization; rice breeding
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Abiotic stress caused by either natural or human activities has become a great threat to sustainable agricultural production in the world, such as drought, salinity, high or low temperature, nutrient deficiency, and heavy metal stresses. It is a big challenge to produce enough crop food to feed the growing global population. Abiotic stresses seriously affect crop growth and development, eventually leading to yield loss. Under an abiotic stress condition, crops may suffer from osmotic and oxidative stress, photosynthetic and metabolic damage, nutrient imbalance, and ion toxicity. To deal with these stresses, crops have developed a series of tolerance mechanisms, including osmotic adjustment through compatible solutes in the cytoplasm, reactive oxygen species (ROS) scavenging systems through anti-oxidative enzymes, and nutrient homeostasis through membrane channels and transporters. However, progress in developing tolerant crops is significantly hampered by the complexity of the physiological and genetic mechanisms of abiotic stress tolerance.

Dr. Dezhi Wu
Dr. Peng Zhang
Dr. Hanhua Tong
Guest Editors

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Keywords

Abiotic stress
Crop physiology
Genetic regulation
Metabolomics
Molecular response
Proteomics
Transcriptomics

Related Special Issue

Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops II in Plants (14 articles)

Published Papers (13 papers)

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Research

13 pages, 2200 KiB

Open AccessArticle

Genomic Characteristics of Elite Maize Inbred Line 18-599 and Its Transcriptional Response to Drought and Low-Temperature Stresses

by Yang Cao, Jingtao Qu, Haoqiang Yu, Qingqing Yang, Wanchen Li and Fengling Fu

Plants 2022, 11(23), 3242; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11233242 - 25 Nov 2022

Viewed by 927

Abstract

Elite inbred line 18-599 was developed via triple test cross from introduced hybrid P78599 and used as parents of dozens of maize hybrids adapting to the diverse ecological conditions of the maize ecological region in Southwest China. In this study, its genomic DNA was resequenced and aligned with the B73 genome sequence to identify single nucleotide polymorphism (SNP), and insertion (In) and deletion (Del) loci. These loci were aligned with those between B73 and 1020 inbred lines in the HapMap database to identify specific variation loci of 18-599. The results showed that there were 930,439 specific SNPs and 358,750 InDels between 18-599 and the 1020 lines. In total, 21,961 of them showed significant impacts on the functions of 12,297 genes, such as frameshift, change of splicing site, stop gain, change of start site, and stop loss. Phylogenetic analysis showed that 18-599 was closely related to inbred lines ZEAxujRAUDIAAPE and 2005-4, but far from some inbred lines directly isolated from P78599. This result indicated that 18-599 not only pyramided the elite genes of P78599, but also acquired genetic divergence during the repetitive backcrosses of triple test cross to confer its elite agronomic characteristics. Subsequently, the RNA of 18-599 was sequenced. The aligned 9713 and 37,528 of the 165,098 unigenes were screened and aligned with annotated transcripts of the B73 genome differentially expressed under drought and low-temperature stress, respectively, and their functions were involved in the responses to these stresses. The quantitative PCR results of fourteen random genes verified the RNA sequencing results. These findings suggest that the transcriptional responses of many resistance-related genes were an important mechanism for 18-599 to adapt to diverse ecological conditions. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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12 pages, 2337 KiB

Open AccessArticle

Genome-Wide Association Study of Zinc Toxicity Tolerance within a Rice Core Collection (Oryza sativa L.)

by Kaizhen Zhong, Lihong Xie, Shikai Hu, Gaoneng Shao, Zhonghua Sheng, Guiai Jiao, Ling Wang, Ying Chen, Shaoqing Tang, Xiangjin Wei, Peng Zhang and Peisong Hu

Plants 2022, 11(22), 3138; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11223138 - 16 Nov 2022

Cited by 1 | Viewed by 1016

Abstract

Zinc (Zn) is an essential micronutrient for rice, but it is toxic at a high concentration, especially in acid soils. It is yet unknown which genes regulate Zn tolerance in rice. In the present study, a genome-wide association study (GWAS) was performed for Zn tolerance in rice at the seedling stage within a rice core collection, named Ting’s core collection, which showed extensive phenotypic variations in Zn toxicity with high-density single-nucleotide polymorphisms (SNPs). A total of 7 and 19 quantitative trait loci (QTL) were detected using root elongation (RE) and relative root elongation (RRE) under high Zn toxicity, respectively. Among them, 24 QTL were novel, and qRRE15 was located in the same region where 3 QTL were reported previously. In addition, qRE4 and qRRE9 were identical. Furthermore, we found eight candidate genes that are involved in abiotic and biotic stress, immunity, cell expansion, and phosphate transport in the loci of qRRE8, qRRE9, and qRRE15. Moreover, four candidate genes, i.e., Os01g0200700, Os06g0621900, Os06g0493600, and Os06g0622700, were verified correlating to Zn tolerance in rice by quantitative real time-PCR (qRT-PCR). Taken together, these results provide significant insight into the genetic basis for Zn toxicity tolerance and tolerant germplasm for developing rice tolerance to Zn toxicity and improving rice production in Zn-contaminated soils. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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19 pages, 9558 KiB

Open AccessArticle

Effects of Weak and Strong Drought Conditions on Physiological Stability of Flowering Soybean

by Shuang Song, Zhipeng Qu, Xinyu Zhou, Xiyue Wang and Shoukun Dong

Plants 2022, 11(20), 2708; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11202708 - 13 Oct 2022

Cited by 2 | Viewed by 1207

Abstract

Soybean is an important food crop in the world. Drought can seriously affect the yield and quality of soybean; however, studies on extreme drought—weak and strong—are absent. In this study, drought-tolerant soybean Heinong 44 (HN44) and sensitive soybean Heinong 65 (HN65) were used as the test varieties, and the effects of strong and weak droughts on the physiological stability of soybean were explored through the drought treatment of soybean at the early flowering stage. The results showed that the contents of malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and superoxide anions (

O_{2}^{\cdot -}

) increased with the increase in the degree of drought. The plant height and relative water content decreased, and photosynthesis was inhibited. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and the total antioxidant capacity (T-AOC) showed a trend of first increasing and then decreasing. Through contribution analysis, CAT changed the most, and the role of SOD gradually increased with the aggravation of drought. With the aggravation of drought, the contents of soluble sugar (SSC) and proline (Pro) increased gradually, and the content of soluble protein (SP) increased initially and then decreased. According to contribution analysis, SSC had the highest contribution to osmotic adjustment. SSC and Pro showed an upward trend with the aggravation of drought, indicating that their role in drought was gradually enhanced. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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11 pages, 2179 KiB

Open AccessCommunication

Biochar and Cropping Systems Changed Soil Copper Speciation and Accumulation in Sweet Corn and Soybean

by Wenting Yang, Yuzhuo Pan, Xia Yu, Shihao Xiao, Weihu Wang and Meijuan Lu

Plants 2022, 11(18), 2375; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11182375 - 12 Sep 2022

Cited by 1 | Viewed by 1349

Abstract

In order to explore the effects of biochar and cropping systems on soil copper (Cu) speciation and copper accumulation in sweet corn (Zea mays L. var. Rugosa Bonaf.) and soybean (Glycine max (L.) Merr.), three ratios of biochar (C0, 0%, C1, 2%, C2, 5% by mass ratio, (w/w)) and three cropping systems (monocropped sweet corn, MC; monocropped soybean, MS; sweet corn–soybean intercropping, CS) were studied under three Cu levels (Cu0, 0 mg·kg⁻¹, Cu1, 200 mg·kg⁻¹, and Cu2, 400 mg·kg⁻¹) in a pot experiment. The following results were obtained: (1) Compared with C0, adding biochar (C1, C2) could significantly reduce the Cu concentration in sweet corn, and C2 significantly reduced the Cu concentration in soybean under Cu1 and Cu2; the Cu concentrations in sweet corn and soybeans under Cu1 were lower than 10 mg·kg⁻¹. (2) Compared with MC or MS, C2 significantly reduced the Cu concentration (below the detection limit) in sweet corn and the Cu concentration (1.65 mg·kg⁻¹) in soybean straw in CS under Cu1. The Cu concentration in sweet corn ears and soybean straw in CS under Cu2 also decreased significantly, reaching 1.84 and 10.36 mg·kg⁻¹, respectively. (3) Compared with C0, C2 significantly reduced the soil acid-soluble Cu concentration under Cu1 and Cu2, but significantly increased soil oxidated Cu concentration. (4) Compared with MC, the concentration of soil acid-soluble Cu was significantly decreased in CSC1 under Cu2. Under Cu1, the concentrations of reducible Cu were significantly increased in CSC1 and CSC2, and the oxidizable Cu concentration was increased in CSC2. In conclusion, sweet corn–soybean intercropping combined with biochar 5% (w/w) is beneficial to reducing the concentration of acid-soluble Cu, and increases the concentration of oxidizable Cu in copper-contaminated soil. Under Cu1 (200 mg·kg⁻¹), the Cu concentrations in sweet corn and soybean were lower than 10 mg·kg⁻¹, which meets the national food safety standard of China. Under Cu2 (400 mg·kg⁻¹), the Cu concentration in sweet corn was lower than 10 mg·kg⁻¹, but it was higher than 10 mg·kg⁻¹ in soybean. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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17 pages, 3088 KiB

Open AccessEditor’s ChoiceArticle

Effects of Different Drought Degrees on Physiological Characteristics and Endogenous Hormones of Soybean

by Qi Zhou, Yongping Li, Xiaojing Wang, Chao Yan, Chunmei Ma, Jun Liu and Shoukun Dong

Plants 2022, 11(17), 2282; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11172282 - 31 Aug 2022

Cited by 19 | Viewed by 1949

Abstract

Drought affects crop developmentnand growth. To explore the physiological effects of drought stress on soybean, HeiNong44 (HN44) and HeiNong65 (HN65) varieties were used as experimental materials and PEG-6000 was used as the osmotic medium. The antioxidant enzyme activity, osmotic adjustment substance content, antioxidant capacity, and endogenous hormone content of the two soybean varieties were studied under different drought degrees and different treatment durations. Drought stress caused significant physiological changes in soybean. The antioxidant enzyme activities, osmoregulation substance content, and total antioxidant capacity (T-AOC) of HN65 and HN44 showed an increasing trend under mild and moderate drought, however, they first increased and then decreased under severe drought conditions. Following the extension of treatment time, malondialdehyde (MDA) showed an increasing trend. As drought increased, gibberellin (GA) content showed a decreasing trend, while abscisic acid (ABA), salicylic acid (SA), and zeatin nucleoside (ZA) content showed an increasing trend. The auxin (IAA) content of the two varieties showed opposite change trends. In short, drought had a significant impact on the physiology of these two soybean varieties; however, overall, the drought resistance of HN65 was lower than that of HN44. This study provides a research theoretical basis for addressing the drought resistance mechanism and the breeding of drought resistant soybean varieties. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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16 pages, 3848 KiB

Open AccessArticle

Metabolome Analysis under Aluminum Toxicity between Aluminum-Tolerant and -Sensitive Rice (Oryza sativa L.)

by Lihua Xie, Huijuan Li, Zhengzheng Zhong, Junjie Guo, Guocheng Hu, Yu Gao, Zhihua Tong, Meilan Liu, Songping Hu, Hanhua Tong and Peng Zhang

Plants 2022, 11(13), 1717; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11131717 - 28 Jun 2022

Cited by 4 | Viewed by 1609

Abstract

Aluminum (Al) solubilizes into trivalent ions (Al³⁺) on acidic soils, inhibiting root growth. Since about 13% of global rice cultivation is grown on acidic soils, improving Al tolerance in rice may significantly increase yields. In the present study, metabolome analysis under Al toxicity between the Al-tolerant variety Nipponbare and the Al-sensitive variety H570 were performed. There were 45 and 83 differential metabolites which were specifically detected in Nipponbare and H570 under Al toxicity, respectively. Furthermore, the results showed that 16 lipids out of 45 total metabolites were down-regulated, and 7 phenolic acids as well as 4 alkaloids of 45 metabolites were up-regulated in Nipponbare, while 12 amino acids and their derivatives were specifically detected in H570, of which 11 amino acids increased, including L-homoserine and L-methionine, which are involved in cysteine synthesis, L-ornithine and L-proline, which are associated with putrescine synthesis, and 1-aminocyclopropane-1-carboxylate, which is associated with ethylene synthesis. The contents of cysteine and s-(methyl) glutathione, which were reported to be related to Al detoxification in rice, decreased significantly. Meanwhile, putrescine was accumulated in H570, while there was no significant change in Nipponbare, so we speculated that it might be an intermediate product of Al detoxification in rice. The differential metabolites detected between Al-tolerant and -sensitive rice variants in the present study might play important roles in Al tolerance. These results provide new insights in the mechanisms of Al tolerance in rice. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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11 pages, 1750 KiB

Open AccessArticle

A Novel High-Affinity Potassium Transporter IbHKT-like Gene Enhances Low–Potassium Tolerance in Transgenic Roots of Sweet Potato (Ipomoea batatas (L.) Lam.)

by Wei Jiang, Rong Jin, Danfeng Wang, Yufeng Yang, Peng Zhao, Ming Liu, Aijun Zhang and Zhonghou Tang

Plants 2022, 11(11), 1389; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11111389 - 24 May 2022

Cited by 5 | Viewed by 1383

Abstract

The high-affinity potassium transporters (HKT) mediate K⁺-Na⁺ homeostasis in plants. However, the function of enhancing low-potassium tolerance in sweet potato [Ipomoea batatas (L.) Lam.] remains unrevealed. In this study, a novel HKT transporter homolog IbHKT-like gene was cloned from sweet potato, which was significantly induced by potassium deficiency stress. IbHKT-like overexpressing transgenic roots were obtained from a sweet potato cultivar Xuzishu8 using an Agrobacterium rhizogenes-mediated root transgenic system in vivo. Compared with the CK, whose root cells did not overexpress the IbHKT-like gene, overexpression of the IbHKT-like gene protected cell ultrastructure from damage, and transgenic root meristem cells had intact mitochondria, endoplasmic reticulum, and Golgi dictyosomes. The steady-state K⁺ influx increased by 2.2 times in transgenic root meristem cells. Overexpression of the IbHKT-like gene also improved potassium content in the whole plant, which increased by 63.8% compared with the CK plants. These results could imply that the IbHKT-like gene, as a high-affinity potassium transporter gene, may play an important role in potassium deficiency stress responses. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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14 pages, 2962 KiB

Open AccessArticle

Changes in Carbon and Nitrogen Metabolites before, at, and after Anthesis for Wheat Cultivars in Response to Reduced Soil Water and Zinc Foliar Application

by Rasha E. Mahdy, Sameera A. Alghamdi, Ahmed Amro and Suzan A. Tammam

Plants 2022, 11(9), 1261; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11091261 - 06 May 2022

Cited by 2 | Viewed by 1474

Abstract

Water deficit stress is one of the major constraints for commercial agriculture, as it disturbs the metabolic processes in plant. Identification of carbon and nitrogen receptors that act on drought resistance helps in breeding for drought resistance varieties. Zn fertilizer can regulate multiple antioxidant defense systems at the transcriptional level in response to drought. Two field experiments were conducted in 2018–2019 and 2019–2020 seasons to explore the effectiveness of foliar application of zinc oxide on soluble sugar, soluble proteins, and free amino acids under normal irrigation and drought-stressed environments. Three Egyptian wheat cultivars (Triticum aestivum L.) were used. The experimental design was split-plot in RCBD with three replications, applying zinc oxide levels to the whole plot and the split plots. Leaf samples were taken for analysis before anthesis, at anthesis, and after anthesis. Application of Zn increased soluble sugars. However, the free amino acids were higher under irrigation, reached the maximum at anthesis, and decreased sharply after 2 weeks from anthesis. The ranking of cultivars for the three metabolites differed according to plant stage, reflecting the response to Zn and years. Correlations between metabolites according to Zn were positive. The findings suggest the potential of foliar application of Zn to alleviate drought stress. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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14 pages, 2481 KiB

Open AccessArticle

Identification of Potential Pathways of Morella cerifera Seedlings in Response to Alkali Stress via Transcriptomic Analysis

by Yun Jiao, Rang-Jin Xie and Hui-Min Jia

Plants 2022, 11(8), 1053; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11081053 - 12 Apr 2022

Cited by 1 | Viewed by 1593

Abstract

Alkali stress, a type of abiotic stress, severely inhibits plant growth. Only a few studies have investigated the mechanism underlying the transcriptional-level response of Morella cerifera to saline-alkali stress. Based on RNA-seq technology, gene expression differences in the fibrous roots of M. cerifera seedlings exposed to low- and high-concentration alkali stress (LAS and HAS, respectively) were investigated, and the corresponding 1312 and 1532 alkali stress-responsive genes were identified, respectively. According to gene set enrichment analysis, 65 gene sets were significantly enriched. Of these, 24 gene sets were shared by both treatment groups. LAS and HAS treatment groups exhibited 9 (all downregulated) and 32 (23 downregulated) unique gene sets, respectively. The differential gene sets mainly included those involved in trehalose biosynthesis and metabolism, phospholipid translocation, and lignin catabolism. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that M. cerifera seedlings were specifically enriched in stilbenoid, diarylheptanoid, and gingerol biosynthesis; phenylalanine, tyrosine, and tryptophan biosynthesis; and sesquiterpenoid and triterpenoid biosynthesis. Moreover, the related genes involved in hormone signaling pathways and transcription factors were determined through a localization analysis of core abiotic stress pathways. These genes and their molecular mechanisms will be the focus of future research. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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15 pages, 5131 KiB

Open AccessEditor’s ChoiceArticle

Genome-Wide Identification, Expression Pattern and Sequence Variation Analysis of SnRK Family Genes in Barley

by Jiangyan Xiong, Danyi Chen, Tingting Su, Qiufang Shen, Dezhi Wu and Guoping Zhang

Plants 2022, 11(7), 975; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11070975 - 03 Apr 2022

Cited by 3 | Viewed by 2402

Abstract

Sucrose non-fermenting 1 (SNF1)-related protein kinase (SnRK) is a large family of protein kinases that play a significant role in plant stress responses. Although intensive studies have been conducted on SnRK members in some crops, little is known about the SnRK in barley. Using phylogenetic and conserved motif analyses, we discovered 46 SnRK members scattered across barley’s 7 chromosomes and classified them into 3 sub-families. The gene structures of HvSnRKs showed the divergence among three subfamilies. Gene duplication and synteny analyses on the genomes of barley and rice revealed the evolutionary features of HvSnRKs. The promoter regions of HvSnRK family genes contained many ABRE, MBS and LTR elements responding to abiotic stresses, and their expression patterns varied with different plant tissues and abiotic stresses. HvSnRKs could interact with the components of ABA signaling pathway to respond to abiotic stress. Moreover, the haplotypes of HvSnRK2.5 closely associated with drought tolerance were detected in a barley core collection. The current results could be helpful for further exploration of the HvSnRK genes responding to abiotic stress tolerance in barley. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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8 pages, 1261 KiB

Open AccessCommunication

Low Salt Treatment Results in Plant Growth Enhancement in Tomato Seedlings

by Paola Rivera, Cristian Moya and José A. O’Brien

Plants 2022, 11(6), 807; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11060807 - 18 Mar 2022

Cited by 6 | Viewed by 2195

Abstract

Climate change together with excessive fertilization and poor water quality can affect soil quality and salinization. In plants, high salinity causes osmotic stress, ionic toxicity, and oxidative stress. Consequently, salt stress limits plant development, growth, productivity, and yield. Tomatoes are a very common agricultural product, and some cultivars can partially tolerate salinity. However, most studies are focused on salt excess, which does not necessarily extrapolate on how plants develop in soils with low concentrations of salts. Thus, this study characterizes plant growth and the development of different salt concentrations from 25 to 200 mM in Solanum lycopersicum cv. Moneymaker. Tomato seedlings grown in Murashige and Skoog medium supplied with different NaCl concentrations (0, 25, 50, 75, 100, 125, 150, 175, and 200 mM) showed that low salt concentrations (25 and 50 mM) have a positive impact on lateral root development. This was further observed in physiological parameters such as shoot length, primary root length, and proliferation of lateral roots versus controls. Interestingly, no significant changes in Na⁺ concentration were observed in 25 mM NaCl in roots or shoots versus controls. Overall, our results suggest that non-toxic salt concentrations can have a positive impact on plant development. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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17 pages, 5280 KiB

Open AccessArticle

NLP2-NR Module Associated NO Is Involved in Regulating Seed Germination in Rice under Salt Stress

by Yake Yi, Yaqiong Peng, Tao Song, Siqiong Lu, Zhenning Teng, Qin Zheng, Fankai Zhao, Shuan Meng, Bohang Liu, Yan Peng, Guanghui Chen, Jianhua Zhang and Nenghui Ye

Plants 2022, 11(6), 795; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11060795 - 17 Mar 2022

Cited by 14 | Viewed by 2520

Abstract

Salt stress has the most severe impact on plant growth and development, including seed germination. However, little is known about the mechanism of NR (nitrate reductase)-associated nitric oxide (NO) regulates salt tolerance during seed germination in rice. Herein, we shown that inhibition of seed germination by salt stress was significantly impaired by sodium nitroferricyanide (SNP), a NO donor. Then a triple mutant, nr1/nr2/nr3, was generated. Results shown that germination of triple mutants were delayed and were much more sensitive to salt stress than WT plant, which can be rescued by application of SNP. qPCR analysis revealed that expressions of abscisic acid (ABA) catabolism gene, OsABA8ox1, was suppressed in triple mutants under salt stress, resulting in an elevated ABA content. Similar to SNP, application of nitrate also rescued seed germination under salt stress, which, however, was blocked in the triple mutants. Further study revealed that a nitrate responsive transcript factor, OsNLP2, was induced by salt stress, which thus up-regulates the expression of OsNRs and NR activity, resulting in promoted salt tolerance during seed germination. In addition, nitrate-mediated salt tolerance was impaired in mutant of aba8ox1, a target gene for NLP2. Transient trans-activation assays further revealed NLP2 can significantly activate the expression of OsABA8ox1 and OsNR1, suggesting that NLP2 activates expression of ABA catabolism gene directly or indirectly via NR-associated NO. Taken together, our results demonstrate that NLP2-NR associated NO was involved in salt response by increasing ABA catabolism during seed germination and highlight the importance of NO for stress tolerance of plants. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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17 pages, 21066 KiB

Open AccessArticle

Comparative Transcriptomic Analysis Provides Novel Insights into the Blanched Stem of Oenanthe javanica

by Sunjeet Kumar, Xinfang Huang, Gaojie Li, Qun Ji, Kai Zhou, Guopeng Zhu, Weidong Ke, Hongwei Hou, Honglian Zhu and Jingjing Yang

Plants 2021, 10(11), 2484; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10112484 - 17 Nov 2021

Cited by 5 | Viewed by 1727

Abstract

In the agricultural field, blanching is a technique used to obtain tender, sweet, and delicious water dropwort stems by blocking sunlight. The physiological and nutritional parameters of blanched water dropwort have been previously investigated. However, the molecular mechanism of blanching remains unclear. In the present study, we investigated transcriptomic variations for different blanching periods in the stem of water dropwort (pre, mid, post-blanching, and control). The results showed that many genes in pathways, such as photosynthesis, carbon fixation, and phytohormone signal transduction as well as transcription factors (TFs) were significantly dysregulated. Blanched stems of water dropwort showed the higher number of downregulated genes in pathways, such as photosynthesis, antenna protein, carbon fixation in photosynthetic organisms, and porphyrin and chlorophyll metabolism, which ultimately affect the photosynthesis in water dropwort. The genes of hormone signal transduction pathways (ethylene, jasmonic acid, brassinosteroid, and indole-3-acetic acid) showed upregulation in the post-blanched water dropwort plants. Overall, a higher number of genes coding for TFs, such as ERF, BHLH, MYB, zinc-finger, bZIP, and WRKY were overexpressed in blanched samples in comparison with the control. These genes and pathways participate in inducing the length, developmental processes, pale color, and stress tolerance of the blanched stem. Overall, the genes responsive to blanching, which were identified in this study, provide an effective foundation for further studies on the molecular mechanisms of blanching and photosynthesis regulations in water dropwort and other species. Full article

(This article belongs to the Special Issue Physiological and Genetic Mechanisms of Abiotic Stress Tolerance in Crops)

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