Publications of NIPGR Scientists

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Subject: search.filters.subject.Necrotrophs

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    RAV1 family members function as transcriptional regulators and play a positive role in plant disease resistance
    (John Wiley & Sons, 2023) Chandan, Ravindra Kumar; Kumar, Rahul; Swain, Durga Madhab; Ghosh, Srayan; Bhagat, Prakash Kumar; Patel, Sunita; Bagler, Ganesh; Sinha, Alok Krishna; Jha, Gopaljee
    Phytopathogens pose a severe threat to agriculture and strengthening plant defense response is an important strategy for disease control. Here, we report that AtRAV1, an AP2 and B3 domain-containing transcription factor is required for basal plant defense in Arabidopsis thaliana. The atrav1 mutant lines demonstrate hyper-susceptibility against fungal pathogens (Rhizoctonia solani and Botrytis cinerea) while AtRAV1 overexpressing (OE) lines exhibit disease resistance against them. Enhanced expression of various defense genes and activation of MAP kinases (AtMPK3 and AtMPK6) are observed in the R. solani infected OE lines, but not in the atrav1 mutant plants. In-vitro phosphorylation assay suggests AtRAV1 to be a novel phosphorylation target of AtMPK3. The bimolecular fluorescence complementation and yeast two-hybrid assay support physical interactions between AtRAV1 and AtMPK3. Overexpression of the native as well as phospho-mimic but not the phospho-defective variant of AtRAV1 impart disease resistance in the atrav1 mutant A. thaliana lines. On the other hand, overexpression of AtRAV1 fails to impart disease resistance in the atmpk3 mutant. These analyses emphasize that AtMPK3-mediated phosphorylation of AtRAV1 is important for the elaboration of defense response in A. thaliana. Considering that RAV1 homologs are conserved in diverse plant species, we propose that they can be gainfully deployed to impart disease resistance in agriculturally important crop plants. Indeed, overexpression of SlRAV1 (a member of the RAV1 family) imparts disease tolerance against not only fungal (R. solani and B. cinerea) but also against bacterial (Ralstonia solanacearum) pathogens in tomato, while silencing of the gene enhances disease susceptibility.
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    Fungal effectors, the double edge sword of phytopathogens
    (Springer Nature Publishing AG, 2021) Pradhan, Amrita; Ghosh, Srayan; Sahoo, Debashis; Jha, Gopaljee
    Phyto-pathogenic fungi can cause huge damage to crop production. During millions of years of coexistence, fungi have evolved diverse life-style to obtain nutrients from the host and to colonize upon them. They deploy various proteinaceous as well as non-proteinaceous secreted molecules commonly referred as efectors to sabotage host machinery during the infection process. The efectors are important virulence determinants of pathogenic fungi and play important role in successful pathogenesis, predominantly by avoiding host-surveillance system. However, besides being important for pathogenesis, the fungal efectors end-up being recognized by the resistant cultivars of the host, which mount a strong immune response to ward-of pathogens. Various recent studies involving diferent pathosystem have revealed the virulence/avirulence functions of fungal efectors and their involvement in governing the outcome of host–pathogen interactions. However, the efectors and their cognate resistance gene in the host remain elusive for several economically important fungal pathogens. In this review, using examples from some of the biotrophic, hemi-biotrophic and necrotrophic pathogens, we elaborate the double-edged functions of fungal efectors. We emphasize that knowledge of efector functions can be helpful in efective management of fungal diseases in crop plants.
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    Identification and functional analysis of AG1-IA specific genes of Rhizoctonia solani
    (Springer, 2014) Ghosh, Srayan; Gupta, Santosh Kumar; Jha, Gopaljee
    Rhizoctonia solani is an important necrotrophic fungal pathogen which causes disease on diverse plant species. It has been classified into 14 genetically distinct anastomosis groups (AGs), however, very little is known about their genomic diversity. AG1-IA causes sheath blight disease in rice and controlling this disease remains a challenge for sustainable rice cultivation. Recently the draft genome sequences of AG1-IA (rice isolate) and AG1-IB (lettuce isolate) had become publicly available. In this study, using comparative genomics, we report identification of 3,942 R. solani genes that are uniquely present in AG1-IA. Many of these genes encode important biological, molecular functions and exhibit dynamic expression during in-planta growth of the pathogen in rice. Based upon sequence similarity with genes that are required for plant and human/zoonotic diseases, we identified several putative virulence/pathogenicity determinants amongst AG1-IA specific genes. While studying the expression of 19 randomly selected genes, we identified three genes highly up-regulated during in-planta growth. The detailed in silico characterization of these genes and extent of their up-regulation in different rice genotypes, having variable degree of disease susceptibility, suggests their importance in rice-Rhizoctonia interactions. In summary, the present study reports identification, functional characterization of AG1-IA specific genes and predicts important virulence determinants that might enable the pathogen to grow inside hostile plant environment. Further characterization of these genes would shed useful insights about the pathogenicity mechanism of AG1-IA on rice.