scholarly journals Loss of function of a DMR6 ortholog in tomato confers broad-spectrum disease resistance

2021 ◽  
Vol 118 (27) ◽  
pp. e2026152118
Author(s):  
Daniela Paula de Toledo Thomazella ◽  
Kyungyong Seong ◽  
Rebecca Mackelprang ◽  
Douglas Dahlbeck ◽  
Yu Geng ◽  
...  

Plant diseases are among the major causes of crop yield losses around the world. To confer disease resistance, conventional breeding relies on the deployment of single resistance (R) genes. However, this strategy has been easily overcome by constantly evolving pathogens. Disabling susceptibility (S) genes is a promising alternative to R genes in breeding programs, as it usually offers durable and broad-spectrum disease resistance. In Arabidopsis, the S gene DMR6 (AtDMR6) encodes an enzyme identified as a susceptibility factor to bacterial and oomycete pathogens. Here, we present a model-to-crop translational work in which we characterize two AtDMR6 orthologs in tomato, SlDMR6-1 and SlDMR6-2. We show that SlDMR6-1, but not SlDMR6-2, is up-regulated by pathogen infection. In agreement, Sldmr6-1 mutants display enhanced resistance against different classes of pathogens, such as bacteria, oomycete, and fungi. Notably, disease resistance correlates with increased salicylic acid (SA) levels and transcriptional activation of immune responses. Furthermore, we demonstrate that SlDMR6-1 and SlDMR6-2 display SA-5 hydroxylase activity, thus contributing to the elucidation of the enzymatic function of DMR6. We then propose that SlDMR6 duplication in tomato resulted in subsequent subfunctionalization, in which SlDMR6-2 specialized in balancing SA levels in flowers/fruits, while SlDMR6-1 conserved the ability to fine-tune SA levels during pathogen infection of the plant vegetative tissues. Overall, this work not only corroborates a mechanism underlying SA homeostasis in plants, but also presents a promising strategy for engineering broad-spectrum and durable disease resistance in crops.

2021 ◽  
Author(s):  
Beatriz Val Torregrosa ◽  
Mireia Bundo ◽  
Tzyy Jen Chiou ◽  
Victor Flors ◽  
Blanca San Segundo

Background: Phosphorus is an important macronutrient required for plant growth and development. It is absorbed through the roots in the form of inorganic phosphate (Pi). To cope with Pi limitation, plants have evolved an array of adaptive mechanisms to facilitate Pi acquisition and protect them from stress caused by Pi starvation. The NITROGEN LIMITATION ADAPTION (NLA) gene plays a key role in the regulation of phosphate starvation responses (PSR), its expression being regulated by the microRNA miR827. Stress caused by Pi limiting conditions might also affect the plant response to pathogen infection. However, cross-talk between phosphate signaling pathways and immune responses remains unclear. Results: In this study, we investigated whether NLA plays a role in Arabidopsis immunity. We show that loss-of-function of NLA and MIR827 overexpression causes an increase in phosphate (Pi) content which results in resistance to infection by the fungal pathogen Plectosphaerella cucumerina. The nla mutant plants accumulated callose in their leaves, a response that is also observed in wild-type plants that have been treated with high Pi. We also show that pathogen infection and treatment with fungal elicitors is accompanied by transcriptional activation of MIR827 and down-regulation of NLA. Upon pathogen challenge, nla plants exhibited higher levels of the phytoalexin camalexin compared to wild type plants. Camalexin level also increases in wild type plants treated with high Pi. Furthermore, the nla mutant plants accumulated salicylic acid (SA) and jasmonic acid (JA) in the absence of pathogen infection whose levels further increased upon pathogen. Conclusions: This study shows that NLA acts as a negative regulator of Arabidopsis immunity. Overaccumulation of Pi in nla plants positively affects resistance to infection by fungal pathogens. This piece of information reinforces the idea of signaling convergence between Pi and immune responses for the regulation of disease resistance in Arabidopsis.


2019 ◽  
Vol 20 (22) ◽  
pp. 5523 ◽  
Author(s):  
Yasukazu Kanda ◽  
Hitoshi Nakagawa ◽  
Yoko Nishizawa ◽  
Takashi Kamakura ◽  
Masaki Mori

Plants activate their immune system through intracellular signaling pathways after perceiving microbe-associated molecular patterns (MAMPs). Receptor-like cytoplasmic kinases mediate the intracellular signaling downstream of pattern-recognition receptors. BROAD-SPECTRUM RESISTANCE 1 (BSR1), a rice (Oryza sativa) receptor-like cytoplasmic kinase subfamily-VII protein, contributes to chitin-triggered immune responses. It is valuable for agriculture because its overexpression confers strong disease resistance to fungal and bacterial pathogens. However, it remains unclear how overexpressed BSR1 reinforces plant immunity. Here we analyzed immune responses using rice suspension-cultured cells and sliced leaf blades overexpressing BSR1. BSR1 overexpression enhances MAMP-triggered production of hydrogen peroxide (H2O2) and transcriptional activation of the defense-related gene in cultured cells and leaf strips. Furthermore, the co-cultivation of leaves with conidia of the blast fungus revealed that BSR1 overexpression allowed host plants to produce detectable oxidative bursts against compatible pathogens. BSR1 was also involved in the immune responses triggered by peptidoglycan and lipopolysaccharide. Thus, we concluded that the hyperactivation of MAMP-triggered immune responses confers BSR1-mediated robust resistance to broad-spectrum pathogens.


2019 ◽  
Author(s):  
Eram Sultan ◽  
Kalpana Dalei ◽  
Prashant Singh ◽  
Binod Bihari Sahu

A plant species is infected by handful of pathogenic organism despite the fact that it is constantly exposed to innumerable pathogens. The chemical anti-bio agents exploited against these pathogens were harmful to environment and human health as well. So the only alternative way is to grow disease resistant varieties of crops by introducing resistant (R) genes. However, new pathogenic races evolve constantly and are notorious for their ability to withstand race specific resistance mediated by R-genes . Plants deploy robust, broad-spectrum and durable resistance mechanisms called nonhost resistance (NHR) against most pathogenic organisms. Such disease resistance mechanisms are nonspecific and effective against all nonhost or non-adaptive pathogens. The NHR defence response includes production of phytoalexins and other antimicrobial compounds, hypersensitive response by rapid localized cell death, deposition of callose and expression of pathogenesis related genes at the site of infection that restricts further growth of pathogen. Although NHR has immense potential to improve crop production in agriculture, very little is known about the mechanism of NHR and its genetic pathways at molecular level. Detail knowledge about the NHR genes from a nonhost plant and engineering the NHR gene into the host plant will be helpful in making broad-spectrum and durable disease resistant crops. In this mini review, we report the list of NHR genes and their function against various phytopathogens. We further report a method to identify or map putative NHR gene/s in Arabidopsis against soybean pathogen Phytophthora sojae nonhost with a goal to improve disease resistance in crop species.


Agronomy ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 134 ◽  
Author(s):  
Stefanie Ranf

Infestations of crop plants with pathogens pose a major threat to global food supply. Exploiting plant defense mechanisms to produce disease-resistant crop varieties is an important strategy to control plant diseases in modern plant breeding and can greatly reduce the application of agrochemicals. The discovery of different types of immune receptors and a detailed understanding of their activation and regulation mechanisms in the last decades has paved the way for the deployment of these central plant immune components for genetic plant disease management. This review will focus on a particular class of immune sensors, termed pattern recognition receptors (PRRs), that activate a defense program termed pattern-triggered immunity (PTI) and outline their potential to provide broad-spectrum and potentially durable disease resistance in various crop species—simply by providing plants with enhanced capacities to detect invaders and to rapidly launch their natural defense program.


2020 ◽  
Author(s):  
Ravindra Kumar Chandan ◽  
Rahul Kumar ◽  
Durga Madhab Swain ◽  
Srayan Ghosh ◽  
Prakash Kumar Bhagat ◽  
...  

AbstractPlant diseases pose a serious threat to sustainable agriculture as controlling them in eco-friendly manner remains a challenge. In this study, we establish RAV1 as a master transcriptional regulator of defense genes in model plant Arabidopsis. The overexpression of AtRAV1 provided disease resistance against necrotrophic fungal pathogen (Rhizoctonia solani) infection in A. thaliana. The transgenic lines exhibited enhanced expression of several defense genes including mitogen associated protein kinases (MAPKs) and the amplitude of their expression was further enhanced upon pathogen infection. Conversely, the atrav1 mutant plants were unable to induce the expression of these defense genes and were highly susceptible to infection. Our data suggests that upon pathogen attack, AtRAV1 transcriptionally upregulate the expression of MAPKs (AtMPK3, AtMPK4 and AtMPK6) and AtMPK3 and AtMPK6 are essential for AtRAV1 mediated disease resistance. Further, we demonstrate that AtRAV1 is a phosphorylation target of AtMPK3 (but not AtMPK6) and the phospho-defective variants of AtRAV1 are unable to induce disease resistance in A. thaliana. Considering the presence of AtRAV1 orthologs in diverse plant species, we propose that they can be gainfully deployed to control economically important diseases. In deed we observe that overexpression of tomato ortholog of AtRAV1 (SlRAV1) provides broad spectrum disease resistance against bacterial (Ralstonia solanacearum), fungal (R. solani) and viral (Tomato leaf curl virus) infections in tomato.


2021 ◽  
Author(s):  
Xiao-Hong Hu ◽  
Jing Fan ◽  
Jin-Long Wu ◽  
Shuai Shen ◽  
Jia-Xue He ◽  
...  

Crops with broad-spectrum resistance (BSR) to diseases are highly desirable in agricultural production. Identification of BSR loci and dissection of the underlying mechanisms are fundamental for crop resistance breeding. Here, we describe the identification and characterization of a rice UMP1 allele, which confers race-nonspecific BSR against blast pathogen Magnaporthe oryzae. OsUMP1 encodes a proteasome maturation factor that contributes to 26S proteasome abundance and activity in rice. Modulation of OsUMP1 expression leads to proteome changes, particularly affects the amounts and activities of H2O2-degrading enzymes. Consequently, H2O2 accumulation and disease resistance are enhanced in OsUMP1-overexpressing rice but reduced in loss-of-function mutants. Elevation of OsUMP1 expression also promotes rice resistance to foliar pathogens Rhizoctonia solani and Xanthomonas oryzae pv. oryzae and a floral pathogen Ustilaginoidea virens without observable yield penalty. These results indicate a BSR pathway linking the proteasome machinery and H2O2 homeostasis, and provide a candidate gene for balancing BSR and yield traits in rice breeding.


2019 ◽  
Author(s):  
Eram Sultan ◽  
Kalpana Dalei ◽  
Prashant Singh ◽  
Binod Bihari Sahu

A plant species is infected by handful of pathogenic organism despite the fact that it is constantly exposed to innumerable pathogens. The chemical anti-bio agents exploited against these pathogens were harmful to environment and human health as well. So the only alternative way is to grow disease resistant varieties of crops by introducing resistant (R) genes. However, new pathogenic races evolve constantly and are notorious for their ability to withstand race specific resistance mediated by R-genes . Plants deploy robust, broad-spectrum and durable resistance mechanisms called nonhost resistance (NHR) against most pathogenic organisms. Such disease resistance mechanisms are nonspecific and effective against all nonhost or non-adaptive pathogens. The NHR defence response includes production of phytoalexins and other antimicrobial compounds, hypersensitive response by rapid localized cell death, deposition of callose and expression of pathogenesis related genes at the site of infection that restricts further growth of pathogen. Although NHR has immense potential to improve crop production in agriculture, very little is known about the mechanism of NHR and its genetic pathways at molecular level. Detail knowledge about the NHR genes from a nonhost plant and engineering the NHR gene into the host plant will be helpful in making broad-spectrum and durable disease resistant crops. In this mini review, we report the list of NHR genes and their function against various phytopathogens. We further report a method to identify or map putative NHR gene/s in Arabidopsis against soybean pathogen Phytophthora sojae nonhost with a goal to improve disease resistance in crop species.


2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Yiming Wang ◽  
Soumeng Dong

AbstractBreeding of disease-resistant and high-yield crops is essential to meet the increasing food demand of the global population. However, the breeding of such crops remains a significant challenge for scientists and breeders. Two recent discoveries may help to overcome this challenge: the discovery of a novel molecular framework to fine-tune disease resistance and yields that includes epigenetic regulation of antagonistic immune receptors, and the discovery of a Ca2+ sensor-mediated immune repression network that enables the transfer of subspecies-specific and broad-spectrum disease resistance. These breakthroughs provide a promising roadmap for the future breeding of disease resistant crops.


2020 ◽  
Author(s):  
Md. Rafiqul Islam ◽  
Mohammad Rashed Hossain ◽  
Denison Michael Immanuel Jesse ◽  
Hee-Jeong Jung ◽  
Hoy-Taek Kim ◽  
...  

Abstract Background: Bacterial fruit blotch (BFB), a disease caused by Acidovorax citrulli, results in significant economic losses in melon. The causal QTLs and genes for resistance to this disease have yet to be identified. Resistance (R)-genes play vital roles in resistance to plant diseases. Since the complete genome sequence of melon is available and genome-wide identification of R-genes has been performed for this important crop, comprehensive expression profiling may lead to the identification of putative candidate genes that function in the response to BFB.Results: We identified melon accessions that are resistant and susceptible to BFB through repeated bioassays and characterized all 70 R-genes in melon, including their gene structures, chromosomal locations, domain organizations, motif distributions, and syntenic relationships. Several disease resistance-related domains were identified, including NBS, TIR, LRR, CC, RLK, and DUF domains, and the genes were categorized based on the domains of their encoded proteins. In addition, we profiled the expression patterns of the genes in melon accessions with contrasting levels of BFB resistance at 12 h, 1 d, 3 d, and 6 d after inoculation with A. citrulli. Six R-genes exhibited consistent expression patterns (MELO3C023441, MELO3C016529, MELO3C022157, MELO3C022146, MELO3C025518, and MELO3C004303), with higher expression levels in the resistant vs. susceptible accession. Conclusion: We identified six putative candidate R-genes against BFB in melon. Upon functional validation, these genes could be targeted for manipulation via breeding and biotechnological approaches to improve BFB resistance in melon in the future.


2020 ◽  
Author(s):  
Md. Rafiqul Islam ◽  
Mohammad Rashed Hossain ◽  
Denison Michael Immanuel Jesse ◽  
Hee-Jeong Jung ◽  
Hoy-Taek Kim ◽  
...  

Abstract Background Bacterial fruit blotch (BFB), a disease caused by Acidovorax citrulli , results in significant economic losses in melon. The causal QTLs and genes for resistance to this disease have yet to be identified. Resistance ( R )-genes play vital roles in resistance to plant diseases. Since the complete genome sequence of melon is available and genome-wide identification of R -genes has been performed for this important crop, comprehensive expression profiling may lead to the identification of putative candidate genes that function in the response to BFB. Results We identified melon accessions that are resistant and susceptible to BFB through repeated bioassays and characterized all 70 R -genes in melon, including their gene structures, chromosomal locations, domain organizations, motif distributions, and syntenic relationships. Several disease resistance-related domains were identified, including NBS, TIR, LRR, CC, RLK, and DUF domains, and the genes were categorized based on the domains of their encoded proteins. In addition, we profiled the expression patterns of the genes in melon accessions with contrasting levels of BFB resistance at 12 h, 1 d, 3 d, and 6 d after inoculation with A. citrulli via qRT-PCR. Six R -genes exhibited consistent expression patterns (MELO3C023441, MELO3C016529, MELO3C022157, MELO3C022146, MELO3C025518, and MELO3C004303), with higher expression levels in the resistant vs. susceptible accession. Conclusion We identified six putative candidate R -genes against BFB in melon. Upon functional validation, these genes could be targeted for manipulation via breeding and biotechnological approaches to improve BFB resistance in melon in the future.


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