PRASANNA KUMAR, M. K.KAVYA, N.2023-01-162023-01-162022-12-27Th-13463https://krishikosh.egranth.ac.in/handle/1/5810192385Rice sheath blight caused by necrotrophic fungi Rhizoctonia solani is an economically significant disease posing major constraints in rice production, worldwide. In addition to the lack of resistant rice cultivars, knowledge regarding the infection strategy of the pathogen is fragmented. In this study, we used in silico approach to analyze the complete genome of R. solani isolate RS24 to find and describe novel cell death effectors. We found eight new effector proteins, RS107_1 to RS107_8, of which the protein metacaspase (RS107_6) was characterized. According to the results of the localization investigations, they are exclusively secreted in host cytoplasm. These proteins’ function, reactivity and stability were evaluated through domain prediction, physiochemical characterization and secondary structure prediction using bioinformatics tools. The 3D structures were predicted and verified. Effector proteins interact with rice genes implicated in early defense mechanism events with highest affinity, according to molecular docking studies. Interestingly, RS107_6 interacted with serine/threonine protein kinases involved in signal relay mechanism upon pathogen attack, which was further validated by MD simulation analysis. Gene cloning, expression, purification and characterization of RS107_6 protein of 906 bp which encodes a polypeptide of 301 amino acids with a molecular weight of 33.12 kDa was also carried out. The presence of endosymbiotic bacteria was investigated and reported two bacteria related to members of the genus Brevundimonas and Sphingomonas. Fluorescence microscopy, DNA analysis and metagenome studies supported the bacteria’s intracellular localization. Conclusively, this discovery will open up avenues for understanding the molecular mechanisms of R. solani pathogenesisEnglishThesis