Browsing by Author "Rani, Mamta"

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    Evolution of pathogenicity-associated genes in Rhizoctonia solani AG1-IA by genome duplication and transposon-mediated gene function alterations
    (BioMed Central Ltd, 2023) Francis, Aleena; Ghosh, Srayan; Tyagi, Kriti; Prakasam, V.; Rani, Mamta; Singh, Nagendra Pratap; Pradhan, Amrita; Sundaram, R. M.; Priyanka, C.; Laha, G. S.; Kannan, C.; Prasad, M. S.; Chattopadhyay, Debasis; Jha, Gopaljee
    Background: Rhizoctonia solani is a polyphagous fungal pathogen that causes diseases in crops. The fungal strains are classified into anastomosis groups (AGs); however, genomic complexity, diversification into the AGs and the evolution of pathogenicity-associated genes remain poorly understood. Results: We report a recent whole-genome duplication and sequential segmental duplications in AG1-IA strains of R. solani. Transposable element (TE) clusters have caused loss of synteny in the duplicated blocks and introduced differential structural alterations in the functional domains of several pathogenicity-associated paralogous gene pairs. We demonstrate that the TE-mediated structural variations in a glycosyl hydrolase domain and a GMC oxidoreductase domain in two paralogous pairs affect the pathogenicity of R. solani. Furthermore, to investigate the association of TEs with the natural selection and evolution of pathogenicity, we sequenced the genomes of forty-two rice field isolates of R. solani AG1-IA. The genomic regions with high population mutation rates and with the lowest nucleotide diversity are enriched with TEs. Genetic diversity analysis predicted the genes that are most likely under diversifying and purifying selections. We present evidence that a smaller variant of a glucosamine phosphate N-acetyltransferase (GNAT) protein, predicted to be under purifying selection, and an LPMP_AA9 domain-containing protein, predicted to be under diversifying selection, are important for the successful pathogenesis of R. solani in rice as well as tomato. Conclusions: Our study has unravelled whole-genome duplication, TE-mediated neofunctionalization of genes and evolution of pathogenicity traits in R. solani AG1-IA. The pathogenicity-associated genes identified during the study can serve as novel targets for disease control.
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    Host gamma aminobutyric acid metabolic pathway is involved in resistance against Rhizoctonia solani
    (American Phytopathological Society, 2021) Rani, Mamta; Jha, Gopaljee
    Rhizoctonia solani is a highly destructive necrotrophic fungal pathogen having a diverse host range, including rice and tomato. Previously R. solani infection in rice has been found to cause large-scale readjustment in host primary metabolism and accumulation of various stress associated metabolites such as gamma aminobutyric acid (GABA). In this study, we report upregulation of GABA shunt genes during pathogenesis of R. solani in rice as well as tomato. The exogenous application of GABA provided partial resistance against R. solani infection in both the hosts. Further, using virus induced gene silencing (VIGS) approach, we knocked down the expression of some of the tomato genes involved in GABA biosynthesis (glutamate decarboxylase; GAD) and GABA catabolism (GABA-transaminase; GABA-T and succinic semialdehyde dehydrogenase; SSADH) to study their role in host defense against R. solani infection. The silencing of each of these genes was found to enhance disease susceptibility in tomato. Overall the results from gene expression analysis, exogenous chemical treatment and gene silencing studies suggest that GABA pathway plays a positive role in plant resistance against necrotrophic fungal pathogen R. solani.