Topic Editors

Dr. Attila L. Ádám
Plant Protection Institute, Centre for Agricultural Research, 1022 Budapest, H-1525, P.O. Box 102, Hungary
Department of Pathophysiology, Plant Protection Institute, Centre for Agricultural Research, ELKH, H-1022 Budapest, H-1525 P.O. Box 102, Hungary

Mechanisms of Resistance to Plant Diseases

Abstract submission deadline
closed (1 February 2022)
Manuscript submission deadline
closed (15 February 2022)
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Topic Information

Dear Colleagues,

This Special Issue will focus on molecular, biochemical, and morphological aspects of disease resistance mechanisms during plant–pathogen interactions, including defenses to viruses, phytoplasmas, bacteria, fungi, oomycetes, and double infections. Other novel approaches to the characterization of plant–pathogen interactions and descriptions of newly discovered plant–pathogen complexes are also appreciated.

The main topics of interest are listed below:

  • Resistance mechanisms to phytoplasmas—an emerging area of research, including the role of vector organisms;
  • Signal transduction during induction of acquired resistance (immunity) in plants;
  • Reactive oxygen species and antioxidants as components of plant resistance to pathogens;
  • Identification of resistance mechanisms in newly discovered plant–pathogen interactions;
  • New ways to control phytophthora diseases—a group of plant pathogens with emerging significance;
  • RNA interference (RNAi) processes during plant disease resistance.

Dr. Attila L. Ádám
Dr. Lorant Király
Topic Editors

Keywords

  • acquired resistance (immunity)
  • defense-related signal transduction
  • reactive oxygen species
  • antioxidants
  • RNA interference (RNAi)
  • emerging plant pathogens (phytophthora, phytoplasma, and other species)
  • plant hormone mediated resistance

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Plants
plants
4.5 5.4 2012 15.3 Days CHF 2700
Microorganisms
microorganisms
4.5 6.4 2013 15.1 Days CHF 2700

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Published Papers (19 papers)

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15 pages, 4512 KiB  
Article
Less Virulent Leptosphaeria biglobosa Immunizes the Canola Plant to Resist Highly Virulent L. maculans, the Blackleg Pathogen
by Kaluhannadige Rasanie Eranka Padmathilake and Wannakuwattewaduge Gerard Dilantha Fernando
Plants 2022, 11(7), 996; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11070996 - 06 Apr 2022
Cited by 4 | Viewed by 1758
Abstract
Leptosphaeria biglobosa is a less virulent Leptosphaeria spp. that causes blackleg disease in canola. Previous studies from our lab have shown that inoculation with the less virulent L. biglobosa can boost the resistance of canola plants against the highly virulent L. maculans. [...] Read more.
Leptosphaeria biglobosa is a less virulent Leptosphaeria spp. that causes blackleg disease in canola. Previous studies from our lab have shown that inoculation with the less virulent L. biglobosa can boost the resistance of canola plants against the highly virulent L. maculans. The objective of this study was to confirm the effectiveness of L. biglobosa as a biocontrol agent against L. maculans utilizing morphology, fluorescence microscopy, gene quantification, and transcriptomic analysis. The in planta development of two Leptosphaeria species inoculated at different time points was assessed using fluorescent protein-tagged isolates which are GFP-tagged L. maculans and DsRed-tagged L. biglobosa. The growth inhibition of L. maculans by pre-and co-inoculated L. biglobosa was supported by no lesion development on cotyledons and no or weak fluorescence protein-tagged mycelia under the confocal microscope. The host defense-related genes, WRKY33, PR1, APX6, and CHI, were upregulated in L. biglobosa inoculated Westar cotyledons compared to L. maculans inoculated cotyledons. The quantification of each pathogen through qPCR assay and gene expressions analysis on host defense-related genes by RT-qPCR confirmed the potential of L. biglobosa “brassicae’ in the management of the blackleg disease pathogen, L. maculans ‘brassicae’, in canola. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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18 pages, 4651 KiB  
Article
Genome-Wide Identification and Characterisation of Cytokinin-O-Glucosyltransferase (CGT) Genes of Rice Specific to Potential Pathogens
by Wadzani Palnam Dauda, Veerubommu Shanmugam, Aditya Tyagi, Amolkumar U. Solanke, Vishesh Kumar, Subbaiyan Gopala Krishnan, Bishnu Maya Bashyal and Rashmi Aggarwal
Plants 2022, 11(7), 917; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11070917 - 29 Mar 2022
Cited by 5 | Viewed by 2164
Abstract
Cytokinin glucosyltransferases (CGTs) are key enzymes of plants for regulating the level and function of cytokinins. In a genomic identification of rice CGTs, 41 genes with the plant secondary product glycosyltransferases (PSPG) motif of 44-amino-acid consensus sequence characteristic of plant uridine diphosphate (UDP)-glycosyltransferases [...] Read more.
Cytokinin glucosyltransferases (CGTs) are key enzymes of plants for regulating the level and function of cytokinins. In a genomic identification of rice CGTs, 41 genes with the plant secondary product glycosyltransferases (PSPG) motif of 44-amino-acid consensus sequence characteristic of plant uridine diphosphate (UDP)-glycosyltransferases (UGTs) were identified. In-silico physicochemical characterisation revealed that, though the CGTs belong to the same subfamily, they display varying molecular weights, ranging from 19.6 kDa to 59.7 kDa. The proteins were primarily acidic (87.8%) and hydrophilic (58.6%) and were observed to be distributed in the plastids (16), plasma membrane (13), mitochondria (5), and cytosol (4). Phylogenetic analysis of the CGTs revealed that their evolutionary relatedness ranged from 70–100%, and they aligned themselves into two major clusters. In a comprehensive analysis of the available transcriptomics data of rice samples representing different growth stages only the CGT, Os04g25440.1 was significantly expressed at the vegetative stage, whereas 16 other genes were highly expressed only at the reproductive growth stage. On the contrary, six genes, LOC_Os07g30610.1, LOC_Os04g25440.1, LOC_Os07g30620.1, LOC_Os04g25490.1, LOC_Os04g37820.1, and LOC_Os04g25800.1, were significantly upregulated in rice plants inoculated with Rhizoctonia solani (RS), Xoo (Xanthomonas oryzae pv. oryzae) and Mor (Magnaporthe oryzae). In a qRT-PCR analysis of rice sheath tissue susceptible to Rhizoctonia solani, Mor, and Xoo pathogens, compared to the sterile distilled water control, at 24 h post-infection only two genes displayed significant upregulation in response to all the three pathogens: LOC_Os07g30620.1 and LOC_Os04g25820.1. On the other hand, the expression of genes LOC_Os07g30610.1, LOC_Os04g25440, LOC_Os04g25490, and LOC_Os04g25800 were observed to be pathogen-specific. These genes were identified as the candidate-responsive CGT genes and could serve as potential susceptibility genes for facilitating pathogen infection. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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18 pages, 3333 KiB  
Article
Near-Isogenic Barley Lines Show Enhanced Susceptibility to Powdery Mildew Infection Following High-Temperature Stress
by Judit Kolozsváriné Nagy, Ildikó Schwarczinger, Lóránt Király, Renáta Bacsó, Attila L. Ádám and András Künstler
Plants 2022, 11(7), 903; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11070903 - 28 Mar 2022
Cited by 3 | Viewed by 1985
Abstract
Barley cultivation is adversely affected by high-temperature stress, which may modulate plant defense responses to pathogens such as barley powdery mildew (Blumeria graminis f. sp. hordei, Bgh). Earlier research focused mainly on the influence of short-term heat stress (heat shock) of barley [...] Read more.
Barley cultivation is adversely affected by high-temperature stress, which may modulate plant defense responses to pathogens such as barley powdery mildew (Blumeria graminis f. sp. hordei, Bgh). Earlier research focused mainly on the influence of short-term heat stress (heat shock) of barley on Bgh infection. In this study, our aim was to investigate the effects of both short- and long-term heat stress (35 °C from 30 s to 5 days) on Bgh infection in the barley cultivar Ingrid and its near-isogenic lines containing different powdery mildew resistance genes (Mla12, Mlg, and mlo5) by analyzing symptom severity and Bgh biomass with RT-qPCR. The expression of selected barley defense genes (BAX inhibitor-1, Pathogenesis- related protein-1b, Respiratory burst oxidase homologue F2, and Heat shock protein 90-1) was also monitored in plants previously exposed to heat stress followed by inoculation with Bgh. We demonstrated that pre-exposure to short- and long-term heat stress negatively affects the resistance of all resistant lines manifested by the appearance of powdery mildew symptoms and increased Bgh biomass. Furthermore, prolonged heat stress (48 and 120 h) enhanced both Bgh symptoms and biomass in susceptible wild-type Ingrid. Heat stress suppressed and delayed early defense gene activation in resistant lines, which is a possible reason why resistant barley became partially susceptible to Bgh. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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22 pages, 6724 KiB  
Article
Genome-Wide Identification and Expression Analysis of SNARE Genes in Brassica napus
by Jing Xu, Xu Zhao, Jiandong Bao, Yanan Shan, Mengjiao Zhang, Yanan Shen, Yakubu Saddeeq Abubakar, Guodong Lu, Zonghua Wang and Airong Wang
Plants 2022, 11(5), 711; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11050711 - 07 Mar 2022
Cited by 4 | Viewed by 2426
Abstract
SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) are central components that drive membrane fusion events during exocytosis and endocytosis and play important roles in different biological processes of plants. In this study, we identified 237 genes encoding SNARE family proteins in B. [...] Read more.
SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) are central components that drive membrane fusion events during exocytosis and endocytosis and play important roles in different biological processes of plants. In this study, we identified 237 genes encoding SNARE family proteins in B. napus in silico at the whole-genome level. Phylogenetic analysis showed that BnaSNAREs could be classified into five groups (Q (a-, b-, c-, bc-) and R) like other plant SNAREs and clustered into twenty-five subclades. The gene structure and protein domain of each subclade were found to be highly conserved. In many subclades, BnaSNAREs are significantly expanded compared with the orthologous genes in Arabidopsis thaliana. BnaSNARE genes are expressed differentially in the leaves and roots of B. napus. RNA-seq data and RT-qPCR proved that some of the BnaSNAREs are involved in the plant response to S. sclerotiorum infection as well as treatments with toxin oxalic acid (OA) (a virulence factor often secreted by S. sclerotiorum) or abscisic acid (ABA), methyl jasmonate (MeJA), and salicylic acid (SA), which individually promote resistance to S. sclerotiorum. Moreover, the interacted proteins of BnaSNAREs contain some defense response-related proteins, which increases the evidence that BnaSNAREs are involved in plant immunity. We also found the co-expression of BnaSYP121/2s, BnaSNAPs, and BnaVAMP722/3s in B. napus due to S. sclerotiorum infection as well as the probable interaction among them. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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15 pages, 4854 KiB  
Article
Host–Pathogen Interactions in Leaf Petioles of Common Ash and Manchurian Ash Infected with Hymenoscyphus fraxineus
by Lene R. Nielsen, Nina E. Nagy, Sara Piqueras, Chatchai Kosawang, Lisbeth G. Thygesen and Ari M. Hietala
Microorganisms 2022, 10(2), 375; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms10020375 - 05 Feb 2022
Cited by 2 | Viewed by 1952
Abstract
Some common ash trees (Fraxinus excelsior) show tolerance towards shoot dieback caused by the invasive ascomycete Hymenoscyphus fraxineus. Leaf petioles are considered to serve as a pathogen colonization route to the shoots. We compared four common ash clones with variation [...] Read more.
Some common ash trees (Fraxinus excelsior) show tolerance towards shoot dieback caused by the invasive ascomycete Hymenoscyphus fraxineus. Leaf petioles are considered to serve as a pathogen colonization route to the shoots. We compared four common ash clones with variation in disease tolerance, and included the native host, Manchurian ash (Fraxinus mandshurica), as a reference. Tissue colonization, following rachis inoculation by H. fraxineus, was monitored by histochemical observations and a quantitative polymerase chain reaction (qPCR) assay specific to H. fraxineus. Axial spread of the pathogen towards the petiole base occurred primarily within the phloem and parenchyma, tissues rich in starch in healthy petioles. In inoculated petioles, a high content of phenolics surrounded the hyphae, presumably a host defense response. There was a relationship between field performance and susceptibility to leaf infection in three of the four studied common ash clones, i.e., good field performance was associated with a low petiole colonization level and vice versa. Low susceptibility to leaf infection may counteract leaf-to-shoot spread of the pathogen in common ash, but the limited number of clones studied warrants caution and a larger study. The Manchurian ash clone had the highest petiole colonization level, which may suggest that this native host has evolved additional mechanisms to avoid shoot infection. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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14 pages, 1764 KiB  
Article
Differences in Gene Expression of Pear Selections Showing Leaf Curling or Leaf Reddening Symptoms Due to Pear Decline Phytoplasma
by Mina Kaviani, Paul H. Goodwin and David M. Hunter
Plants 2022, 11(3), 427; https://0-doi-org.brum.beds.ac.uk/10.3390/plants11030427 - 04 Feb 2022
Cited by 2 | Viewed by 1871
Abstract
While host gene expression has been related to symptoms associated with different phytoplasma diseases, it is unknown why some phytoplasmas are associated with different symptoms in genotypes of the same plant species. Pear tree selections showed symptoms of either leaf reddening (selection 8824-1) [...] Read more.
While host gene expression has been related to symptoms associated with different phytoplasma diseases, it is unknown why some phytoplasmas are associated with different symptoms in genotypes of the same plant species. Pear tree selections showed symptoms of either leaf reddening (selection 8824-1) or leaf curling (selection 9328-1) associated with pear decline (PD) phytoplasma presence. PD populations were similar in leaves and shoots of the two selections, but in the roots, populations were significantly lower in selection 8824-1 than in 9328-1, indicating greater resistance. For host carbohydrate metabolism gene expression in PD-infected tissues, significant up-regulation in selection 8824-1 was observed for a sucrose synthase gene in leaves and an acid invertase gene in leaves and roots. These features have been associated with localized higher sugar levels in phytoplasma-infected tissues, and thus may be related to leaf reddening. For host stress/defense response gene expression in PD-infected tissues, significant up-regulation of a phenylalanine ammonia lyase gene was observed in PD-infected shoots of both selections; however, up-regulation of alcohol dehydrogenase gene in shoots, a chitinase gene in all tissues and a phloem protein 2 gene in roots was only observed for selection 8824-1. These changes indicate greater triggered innate immunity in roots associated with lower PD populations and leaf reddening. Leaf reddening may be related to changes in gene expression associated with increased sugar levels in leaves and stronger immune responses in several tissues, while leaf curling may be due to water stress resulting from dysfunctional root associated with higher PD populations in the roots. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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13 pages, 1711 KiB  
Article
Bacillus nematocida B16 Enhanced the Rhizosphere Colonization of Pochonia chlamydosporia ZK7 and Controlled the Efficacy of the Root-Knot Nematode Meloidogyne incognita
by Tingting Bo, Chuixu Kong, Shunxing Zou, Minghe Mo and Yajun Liu
Microorganisms 2022, 10(2), 218; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms10020218 - 20 Jan 2022
Cited by 5 | Viewed by 1848
Abstract
Pochonia chlamydosporia is widely applied in many countries as a biocontrol fungus against parasitic nematodes in plants. In a field experiment, the combined use of Bacillus nematocida B16 increased the biocontrol efficiency of P. chlamydosporia ZK7 against Meloidogyne incognita. Further study indicated [...] Read more.
Pochonia chlamydosporia is widely applied in many countries as a biocontrol fungus against parasitic nematodes in plants. In a field experiment, the combined use of Bacillus nematocida B16 increased the biocontrol efficiency of P. chlamydosporia ZK7 against Meloidogyne incognita. Further study indicated that the colonization of P. chlamydosporia ZK7 in the rhizosphere soil and the roots of tomatoes was significantly higher in the combined use group than in the control group. Gas chromatography was conducted to determine the effects of signaling substances. Five compounds, hexanal, (E)-2-hexenal, furfural, benzaldehyde, and 2-nonanone, were found to be highly altered in the volatile compounds produced in the soil under the combined application. The changes in benzaldehyde and 2-nonanone were the main factors that resulted in an increase in the colonization of fungi P. chlamydosporia ZK7 in the tomato roots. Furfural was the main volatile substance that affected the colonization of fungi P. chlamydosporia ZK7 in the soil. The combined use of B. nematocida B16 and P. chlamydosporia ZK7 altered the volatile ranges and resulted in increased colonization of biocontrol fungi and improved biocontrol efficiency against nematodes. This combined model could be used to promote the ability of biocontrol fungi to control root-knot nematodes. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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19 pages, 3787 KiB  
Article
Seaweed Extract-Stimulated Priming in Arabidopsis thaliana and Solanum lycopersicum
by Md Tohidul Islam, Tony Arioli and David M. Cahill
Plants 2021, 10(11), 2476; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10112476 - 16 Nov 2021
Cited by 10 | Viewed by 2180
Abstract
Plant priming is an induced physiological state where plants are protected from biotic and abiotic stresses. Whether seaweed extracts promote priming is largely unknown as is the mechanism by which priming may occur. In this study, we examined the effect of a seaweed [...] Read more.
Plant priming is an induced physiological state where plants are protected from biotic and abiotic stresses. Whether seaweed extracts promote priming is largely unknown as is the mechanism by which priming may occur. In this study, we examined the effect of a seaweed extract (SWE) on two distinct stages of plant priming (priming phase and post-challenge primed state) by characterising (i) plant gene expression responses using qRT-PCR and (ii) signal transduction responses by evaluating reactive oxygen species (ROS) production. The SWE is made from the brown algae Ascophyllum nodosum and Durvillaea potatorum. The priming phase was examined using both Arabidopsis thaliana and Solanum lycopersicum. At this stage, the SWE up-regulated key priming-related genes, such as those related to systemic acquired resistance (SAR) and activated the production of ROS. These responses were found to be temporal (lasting 3 days). The post-challenge primed state was examined using A. thaliana challenged with a root pathogen. Similarly, defence response-related genes, such as PR1 and NPR1, were up-regulated and ROS production was activated (lasting 5 days). This study found that SWE induces plant priming-like responses by (i) up-regulating genes associated with plant defence responses and (ii) increasing production of ROS associated with signalling responses. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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18 pages, 2756 KiB  
Review
Development and Adoption of Genetically Engineered Plants for Virus Resistance: Advances, Opportunities and Challenges
by Prakash M. Niraula and Vincent N. Fondong
Plants 2021, 10(11), 2339; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10112339 - 29 Oct 2021
Cited by 9 | Viewed by 6084
Abstract
Plant viruses cause yield losses to crops of agronomic and economic significance and are a challenge to the achievement of global food security. Although conventional plant breeding has played an important role in managing plant viral diseases, it will unlikely meet the challenges [...] Read more.
Plant viruses cause yield losses to crops of agronomic and economic significance and are a challenge to the achievement of global food security. Although conventional plant breeding has played an important role in managing plant viral diseases, it will unlikely meet the challenges posed by the frequent emergence of novel and more virulent viral species or viral strains. Hence there is an urgent need to seek alternative strategies of virus control that can be more readily deployed to contain viral diseases. The discovery in the late 1980s that viral genes can be introduced into plants to engineer resistance to the cognate virus provided a new avenue for virus disease control. Subsequent advances in genomics and biotechnology have led to the refinement and expansion of genetic engineering (GE) strategies in crop improvement. Importantly, many of the drawbacks of conventional breeding, such as long lead times, inability or difficulty to cross fertilize, loss of desirable plant traits, are overcome by GE. Unfortunately, public skepticism towards genetically modified (GM) crops and other factors have dampened the early promise of GE efforts. These concerns are principally about the possible negative effects of transgenes to humans and animals, as well as to the environment. However, with regards to engineering for virus resistance, these risks are overstated given that most virus resistance engineering strategies involve transfer of viral genes or genomic segments to plants. These viral genomes are found in infected plant cells and have not been associated with any adverse effects in humans or animals. Thus, integrating antiviral genes of virus origin into plant genomes is hardly unnatural as suggested by GM crop skeptics. Moreover, advances in deep sequencing have resulted in the sequencing of large numbers of plant genomes and the revelation of widespread endogenization of viral genomes into plant genomes. This has raised the possibility that viral genome endogenization is part of an antiviral defense mechanism deployed by the plant during its evolutionary past. Thus, GM crops engineered for viral resistance would likely be acceptable to the public if regulatory policies were product-based (the North America regulatory model), as opposed to process-based. This review discusses some of the benefits to be gained from adopting GE for virus resistance, as well as the challenges that must be overcome to leverage this technology. Furthermore, regulatory policies impacting virus-resistant GM crops and some success cases of virus-resistant GM crops approved so far for cultivation are discussed. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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19 pages, 4220 KiB  
Article
Transcriptomic Analysis Reveals Candidate Genes Responding Maize Gray Leaf Spot Caused by Cercospora zeina
by Wenzhu He, Yonghui Zhu, Yifeng Leng, Lin Yang, Biao Zhang, Junpin Yang, Xiao Zhang, Hai Lan, Haitao Tang, Jie Chen, Shibin Gao, Jun Tan, Jiwei Kang, Luchang Deng, Yan Li, Yuanyuan He, Tingzhao Rong and Moju Cao
Plants 2021, 10(11), 2257; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10112257 - 22 Oct 2021
Cited by 8 | Viewed by 2701
Abstract
Gray leaf spot (GLS), caused by the fungal pathogen Cercospora zeina (C. zeina), is one of the most destructive soil-borne diseases in maize (Zea mays L.), and severely reduces maize production in Southwest China. However, the mechanism of resistance to [...] Read more.
Gray leaf spot (GLS), caused by the fungal pathogen Cercospora zeina (C. zeina), is one of the most destructive soil-borne diseases in maize (Zea mays L.), and severely reduces maize production in Southwest China. However, the mechanism of resistance to GLS is not clear and few resistant alleles have been identified. Two maize inbred lines, which were shown to be resistant (R6) and susceptible (S8) to GLS, were injected by C. zeina spore suspensions. Transcriptome analysis was carried out with leaf tissue at 0, 6, 24, 144, and 240 h after inoculation. Compared with 0 h of inoculation, a total of 667 and 419 stable common differentially expressed genes (DEGs) were found in the resistant and susceptible lines across the four timepoints, respectively. The DEGs were usually enriched in ‘response to stimulus’ and ‘response to stress’ in GO term analysis, and ‘plant–pathogen interaction’, ‘MAPK signaling pathways’, and ‘plant hormone signal transduction’ pathways, which were related to maize’s response to GLS, were enriched in KEGG analysis. Weighted-Genes Co-expression Network Analysis (WGCNA) identified two modules, while twenty hub genes identified from these indicated that plant hormone signaling, calcium signaling pathways, and transcription factors played a central role in GLS sensing and response. Combing DEGs and QTL mapping, five genes were identified as the consensus genes for the resistance of GLS. Two genes, were both putative Leucine-rich repeat protein kinase family proteins, specifically expressed in R6. In summary, our results can provide resources for gene mining and exploring the mechanism of resistance to GLS in maize. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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15 pages, 3468 KiB  
Article
Alleviation of Chlorpyrifos Toxicity in Maize (Zea mays L.) by Reducing Its Uptake and Oxidative Stress in Response to Soil-Applied Compost and Biochar Amendments
by Humera Aziz, Ghulam Murtaza, Muhammad Hamzah Saleem, Shafaqat Ali, Muhammad Rizwan, Umair Riaz, Abdullah Niaz, Muyassar H. Abualreesh and Aishah Alatawi
Plants 2021, 10(10), 2170; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10102170 - 14 Oct 2021
Cited by 13 | Viewed by 2020
Abstract
Chlorpyrifos (CP) is a pesticide used extensively in agricultural crops. Residual CP has been found in a variety of soils, vegetables and fruits indicating a serious danger to humans. Therefore, it is necessary to restrict its entry into agricultural products for food safety. [...] Read more.
Chlorpyrifos (CP) is a pesticide used extensively in agricultural crops. Residual CP has been found in a variety of soils, vegetables and fruits indicating a serious danger to humans. Therefore, it is necessary to restrict its entry into agricultural products for food safety. A wire-house pot experiment was conducted with maize plants in biochar- and compost-amended soil (at 0.25% and 0.50%, respectively, in weight-by-weight composition) contaminated with 100 and 200 mg kg−1 of CP, respectively. Results indicated toxicity at both CP levels (with 84% growth reduction) at CP 200 mg kg−1. However, application of compost and biochar at the 0.50% level improved the fresh weight (2.8- and 4-fold, respectively). Stimulated superoxide dismutase (SOD) and peroxidase (POX) activities and depressed catalase (CAT) activity were recorded in response to CP contamination and were significantly recovered by the amendments. Both amendments significantly decreased the CP phytoavailability. With biochar, 91% and 76% reduction in the CP concentration in maize shoots and with compost 72% and 68% reduction was recorded, at a 0.50% level in 100 and 200 mg kg−1 contaminated treatments respectively. Compost accelerated the CP degradation in postharvest soil. Therefore, biochar and compost amendments can effectively be used to decrease CP entry in agricultural produce by reducing its phytoavailability. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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15 pages, 40096 KiB  
Article
Virulence of Rigidoporus microporus Isolates Causing White Root Rot Disease on Rubber Trees (Hevea brasiliensis) in Malaysia
by Wen Ze Go, Kit Ling Chin, Paik San H’ng, Mui Yun Wong, Chuah Abdullah Luqman, Arthy Surendran, Geok Hun Tan, Chuan Li Lee, Pui San Khoo and Wai Jern Kong
Plants 2021, 10(10), 2123; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10102123 - 07 Oct 2021
Cited by 14 | Viewed by 3300
Abstract
Latex production from Hevea brasiliensis rubber tree is the second most important commodity in Malaysia, but this industry is threatened by the white root rot disease (WRD) caused by Rigidoporus microporus that leads to considerable latex yield loss and tree death. This study [...] Read more.
Latex production from Hevea brasiliensis rubber tree is the second most important commodity in Malaysia, but this industry is threatened by the white root rot disease (WRD) caused by Rigidoporus microporus that leads to considerable latex yield loss and tree death. This study aimed to characterize and compare the virulence of five R. microporus isolates obtained from infected rubber trees located at different states in Malaysia. These isolates were subjected to morphological and molecular characterization for species confirmation and pathogenicity test for the determination of virulence level. BLAST search showed that the ITS sequences of all the pathogen isolates were 99% identical to R. microporus isolate SEG (accession number: MG199553) from Malaysia. The pathogenicity test of R. microporus isolates conducted in a nursery with 24 seedlings per isolate showed that isolate RL21 from Sarawak has developed the most severe above- and below-ground symptoms of WRD on the rubber clone RRIM600 as host. Six months after being infected with R. microporus, RL21 was evaluated with the highest average of disease severity index of 80.52% for above- and below-ground symptoms, followed by RL22 (68.65%), RL20 (66.04%), RL26 (54.38%), and RL25 (43.13%). The in vitro growth condition tests showed that isolate RL21 of R. microporus has optimum growth at 25–30 °C, with the preference of weakly acidic to neutral environments (pH 6–7). This study revealed that different virulence levels are possessed among different R. microporus isolates even though they were isolated from the same host species under the same climate region. Taken together, field evaluation through visual observation and laboratory assays have led to screening of the most virulent isolate. Determination of the most virulent isolate in the present study is vital and shall be taken into consideration for the selection of suitable pathogen isolate in the development of more effective control measures in combating tenacious R. microporus. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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20 pages, 4938 KiB  
Article
Metabolic Footprints of Burkholderia Sensu Lato Rhizosphere Bacteria Active against Maize Fusarium Pathogens
by Guadalupe C. Barrera-Galicia, Héctor A. Peniche-Pavía, Juan José Peña-Cabriales, Sergio A. Covarrubias, José A. Vera-Núñez and John P. Délano-Frier
Microorganisms 2021, 9(10), 2061; https://0-doi-org.brum.beds.ac.uk/10.3390/microorganisms9102061 - 29 Sep 2021
Cited by 5 | Viewed by 2324
Abstract
Consistent with their reported abundance in soils, several Burkholderia sensu lato strains were isolated from the rhizosphere of maize plants cultivated at different sites in central México. Comparative analysis of their 16S rRNA gene sequences permitted their separation into three distinctive clades, which [...] Read more.
Consistent with their reported abundance in soils, several Burkholderia sensu lato strains were isolated from the rhizosphere of maize plants cultivated at different sites in central México. Comparative analysis of their 16S rRNA gene sequences permitted their separation into three distinctive clades, which were further subdivided into six other clusters by their close resemblance to (1) Trinickia dinghuensis; (2) Paraburkholderia kirstenboschensis, P. graminis, P. dilworthii and P. rhynchosiae; (3) B. gladioli; (4) B. arboris; (5) B. contaminans, or (6) B. metallica representative species. Direct confrontation assays revealed that these strains inhibited the growth of pathogenic Fusarium oxysporum f. sp. radicis-lycopersici, and F. verticillioides within a roughly 3–55% inhibition range. The use of a DIESI-based non-targeted mass spectroscopy experimental strategy further indicated that this method is an option for rapid determination of the pathogen inhibitory capacity of Burkholderia sensu lato strains based solely on the analysis of their exometabolome. Furthermore, it showed that the highest anti-fungal activity observed in B. contaminans and B. arboris was associated with a distinctive abundance of certain m/z ions, some of which were identified as components of the ornbactin and pyochelin siderophores. These results highlight the chemical diversity of Burkholderia sensu lato bacteria and suggest that their capacity to inhibit the Fusarium-related infection of maize in suppressive soils is associated with siderophore synthesis. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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13 pages, 1258 KiB  
Article
Identification of Bacterial Wilt (Erwinia tracheiphila) Resistances in USDA Melon Collection
by Bimala Acharya, Lucas Mackasmiel, Ali Taheri, Christine A. Ondzighi-Assoume, Yiqun Weng and C. Korsi Dumenyo
Plants 2021, 10(9), 1972; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10091972 - 21 Sep 2021
Cited by 1 | Viewed by 3303
Abstract
Bacterial wilt (BW) caused by the Gram-negative bacterium, Erwinia tracheiphila (Et.), is an important disease in melon (Cucumis melo L.). BW-resistant commercial melon varieties are not widely available. There are also no effective pathogen-based disease management strategies as BW-infected plants ultimately die. [...] Read more.
Bacterial wilt (BW) caused by the Gram-negative bacterium, Erwinia tracheiphila (Et.), is an important disease in melon (Cucumis melo L.). BW-resistant commercial melon varieties are not widely available. There are also no effective pathogen-based disease management strategies as BW-infected plants ultimately die. The purpose of this study is to identify BW-resistant melon accessions in the United States Department of Agriculture (USDA) collection. We tested 118 melon accessions in two inoculation trials under controlled environments. Four-week-old seedlings of test materials were mechanically inoculated with the fluorescently (GFP) labeled or unlabeled E. tracheiphila strain, Hca1-5N. We recorded the number of days to wilting of inoculated leaf (DWIL), days to wilting of whole plant (DWWP) and days to death of the plant (DDP). We identified four melon lines with high resistance to BW inoculation based on all three parameters. Fluorescent microscopy was used to visualize the host colonization dynamics of labeled bacteria from the point of inoculation into petioles, stem and roots in resistant and susceptible melon accessions, which provides an insight into possible mechanisms of BW resistance in melon. The resistant melon lines identified from this study could be valuable resistance sources for breeding of BW resistance as well as the study of cucurbit—E. tracheiphila interactions. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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11 pages, 939 KiB  
Article
Molecular and Enzymatic Characterization of Flavonoid 3′-Hydroxylase of Malus × domestica
by Julia Weissensteiner, Christian Molitor, Silvija Marinovic, Lisa Führer, Syed Waqas Hassan, Olly Sanny Hutabarat, Andreas Spornberger, Karl Stich, Johanna Hausjell, Oliver Spadiut, Christian Haselmair-Gosch and Heidi Halbwirth
Plants 2021, 10(9), 1956; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10091956 - 19 Sep 2021
Cited by 4 | Viewed by 2346
Abstract
Malus × domestica (apple) accumulates particularly high amounts of dihydrochalcones in various tissues, with phloridzin (phloretin 2′-O-glucoside) being prevalent, although small amounts of 3-hydroxyphloretin and 3-hydroxyphloridzin are also constitutively present. The latter was shown to correlate with increased disease resistance of [...] Read more.
Malus × domestica (apple) accumulates particularly high amounts of dihydrochalcones in various tissues, with phloridzin (phloretin 2′-O-glucoside) being prevalent, although small amounts of 3-hydroxyphloretin and 3-hydroxyphloridzin are also constitutively present. The latter was shown to correlate with increased disease resistance of transgenic M. × domestica plants. Two types of enzymes could be involved in 3-hydroxylation of dihydrochalcones: polyphenol oxidases or the flavonoid 3′-hydroxylase (F3′H), which catalyzes B-ring hydroxylation of flavonoids. We isolated two F3′H cDNA clones from apple leaves and tested recombinant Malus F3′Hs for their substrate specificity. From the two isolated cDNA clones, only F3′HII encoded a functionally active enzyme. In the F3′HI sequence, we identified two putatively relevant amino acids that were exchanged in comparison to that of a previously published F3′HI. Site directed mutagenesis, which exchanged an isoleucine into methionine in position 211 restored the functional activity, which is probably because it is located in an area involved in interaction with the substrate. In contrast to high activity with various flavonoid substrates, the recombinant enzymes did not accept phloretin under assay conditions, making an involvement in the dihydrochalcone biosynthesis unlikely. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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10 pages, 2822 KiB  
Article
Inheritance of Black Rot Resistance and Development of Molecular Marker Linked to Xcc Races 6 and 7 Resistance in Cabbage
by Jeong-Eui Hong, Khandker Shazia Afrin, Md Abdur Rahim, Hee-Jeong Jung and Ill-Sup Nou
Plants 2021, 10(9), 1940; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10091940 - 17 Sep 2021
Cited by 3 | Viewed by 2764
Abstract
Black rot, caused by Xanthomonas campestris pv. campestris (Xcc), produces V-shaped chlorotic lesions on the leaves of cabbage (Brassica oleracea var. capitata L.), causing darkened veins and drastically reducing yield and quality. Of the 11 Xcc races identified, races 1, [...] Read more.
Black rot, caused by Xanthomonas campestris pv. campestris (Xcc), produces V-shaped chlorotic lesions on the leaves of cabbage (Brassica oleracea var. capitata L.), causing darkened veins and drastically reducing yield and quality. Of the 11 Xcc races identified, races 1, 4, and 6 are predominant globally. In the present study, we aimed to develop a molecular marker linked to black rot resistance against Xcc races 6 and 7. Crossed between black rot-resistant (‘SCNU-C-3470’) and -susceptible (‘SCNU-C-3328’) lines obtained 186 F2 plants. Resistance to Xcc race 6 segregated in a 3:1 (susceptible:resistant) ratio in the F2 population, which is consistent with a monogenic recessive trait. Nucleotide-binding site (NBS) leucine rich repeat (LRR)-encoding resistance (R) genes play a crucial role in plant defenses to various pathogens. The candidate R gene (Bol031422) located on chromosome C08, previously reported by our research group, was cloned and sequenced in resistant and susceptible cabbage lines. The R gene Bol031422 consisted of a single exon with a 3 bp insertion/deletions (InDels), a 292 bp polymorphism (an insertion in the exon of the resistant line relative to the susceptible line) and several single nucleotide polymorphisms (SNPs). Here, we developed the InDel marker BR6-InDel to assess linkage between variation at Bol031422 and resistance to Xcc races 6 and 7. This marker will help cabbage breeders develop cabbage cultivars resistant to Xcc races 6 and 7. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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20 pages, 6056 KiB  
Article
Effects on Capsicum annuum Plants Colonized with Trichoderma atroviride P. Karst Strains Genetically Modified in Taswo1, a Gene Coding for a Protein with Expansin-like Activity
by Ricardo Sánchez-Cruz, Richa Mehta, Karina Atriztán-Hernández, Olivia Martínez-Villamil, María del Rayo Sánchez-Carbente, Ayixon Sánchez-Reyes, Verónica Lira-Ruan, Carlos Alberto González-Chávez, María Luisa Tabche-Barrera, Roberto Carlos Bárcenas-Rodríguez, Ramón Alberto Batista-García, Alfredo Herrera-Estrella, Edgar Balcázar-López and Jorge Luis Folch-Mallol
Plants 2021, 10(9), 1919; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10091919 - 15 Sep 2021
Cited by 7 | Viewed by 2469
Abstract
Here, we analyzed the effects on Capsicum annuum plants of Trichoderma atroviride P. Karst strains altered in the expression of SWOLLENIN (SWO1), a protein with amorphogenic activity on plant cell wall components. Strains of T. atroviride that overexpressed the Taswo1 gene were constructed [...] Read more.
Here, we analyzed the effects on Capsicum annuum plants of Trichoderma atroviride P. Karst strains altered in the expression of SWOLLENIN (SWO1), a protein with amorphogenic activity on plant cell wall components. Strains of T. atroviride that overexpressed the Taswo1 gene were constructed as well as deletion mutants. A novel, cheap and accurate method for assessing root colonization was developed. Colonization assays showed that the Taswo1 overexpressing strains invaded the host root better than the WT, resulting in a stronger plant growth-promoting effect. The expression of plant defense marker genes for both the systemic acquired resistance and induced systemic resistance pathways was enhanced in plants inoculated with Taswo1 overexpressing strains, while inoculation with deletion mutant strains resulted in a similar level of expression to that observed upon inoculation with the wild-type strain. Response to pathogen infection was also enhanced in the plants inoculated with the Taswo1 overexpressing strains, and surprisingly, an intermediate level of protection was achieved with the mutant strains. Tolerance to abiotic stresses was also higher in plants inoculated with the Taswo1 overexpressing strains but was similar in plants inoculated with the wild-type or the mutant strains. Compatible osmolyte production in drought conditions was studied. This study may contribute to improving Trichoderma biocontrol and biofertilization abilities. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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12 pages, 2389 KiB  
Commentary
Genomic Variation and Diversification in Begomovirus Genome in Implication to Host and Vector Adaptation
by Deepti Nigam
Plants 2021, 10(8), 1706; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10081706 - 19 Aug 2021
Cited by 16 | Viewed by 3244
Abstract
Begomoviruses (family Geminiviridae, genus Begomovirus) are DNA viruses transmitted in a circulative, persistent manner by the whitefly Bemisia tabaci (Gennadius). As revealed by their wide host range (more than 420 plant species), worldwide distribution, and effective vector transmission, begomoviruses are highly [...] Read more.
Begomoviruses (family Geminiviridae, genus Begomovirus) are DNA viruses transmitted in a circulative, persistent manner by the whitefly Bemisia tabaci (Gennadius). As revealed by their wide host range (more than 420 plant species), worldwide distribution, and effective vector transmission, begomoviruses are highly adaptive. Still, the genetic factors that facilitate their adaptation to a diverse array of hosts and vectors remain poorly understood. Mutations in the virus genome may confer a selective advantage for essential functions, such as transmission, replication, evading host responses, and movement within the host. Therefore, genetic variation is vital to virus evolution and, in response to selection pressure, is demonstrated as the emergence of new strains and species adapted to diverse hosts or with unique pathogenicity. The combination of variation and selection forms a genetic imprint on the genome. This review focuses on factors that contribute to the evolution of Begomovirus and their global spread, for which an unforeseen diversity and dispersal has been recognized and continues to expand. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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14 pages, 10591 KiB  
Article
Transcriptomic Reprograming of Xanthomonas campestris pv. campestris after Treatment with Hydrolytic Products Derived from Glucosinolates
by Pari Madloo, Margarita Lema, Victor Manuel Rodríguez and Pilar Soengas
Plants 2021, 10(8), 1656; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10081656 - 11 Aug 2021
Cited by 3 | Viewed by 2201
Abstract
The bacterium Xanthomonas campestris pv. campestris (Xcc) causes black rot disease in Brassica crops. Glucosinolates are known to be part of the defence system of Brassica crops against Xcc infection. They are activated upon pathogen attack by myrosinase enzymes. Their hydrolytic [...] Read more.
The bacterium Xanthomonas campestris pv. campestris (Xcc) causes black rot disease in Brassica crops. Glucosinolates are known to be part of the defence system of Brassica crops against Xcc infection. They are activated upon pathogen attack by myrosinase enzymes. Their hydrolytic products (GHPs) inhibit the growth of Xcc in vitro. However, the mechanisms underlying this inhibition and the way Xcc can overcome it are not well understood. We studied the transcriptomic reprogramming of Xcc after being supplemented with two chemically different GHPs, one aliphatic isothiocyanate (allyl-ITC) and one indole (indol-3-carbinol), by RNA-seq. Based on our results, the arrest in Xcc growth is related to the need to stop cell division to repair damaged DNA and cell envelope components. Otherwise, GHPs modify energy metabolism by inhibiting aerobic respiration and increasing the synthesis of glycogen. Xcc induces detoxification mechanisms such as the antioxidant defence system and the multidrug efflux system to cope with the toxic effects driven by GHPs. This is the first time that the transcriptomic reprogramming of a plant pathogenic bacterium treated with GHPs has been studied. This information will allow a better understanding of the interaction of a plant pathogen mediated by GSLs. Full article
(This article belongs to the Topic Mechanisms of Resistance to Plant Diseases)
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