Krishna Reddy, M.PAVITHRA, B. S.2018-03-122018-03-122016-12-27Th-11586http://krishikosh.egranth.ac.in/handle/1/5810041678Survey was conducted in different districts of Karnataka, Andhra Pradesh and Tamil Nadu indicated GBNV incidence of 3 to 21 per cent and the infected plants exhibited chlorotic and necrotic ringspot symptoms. The virus was transmitted mechanically and infects systemically to groundnut, beans, soybean, pea, watermelon, potato, marigold and local lesions on cowpea, tobacco, datura, petunia, chenopodium and sunhemp. The electron microscopic observation of virus infected chilli samples showed presence of spherical particles of 80-120 nm in diameter. In DAC-ELISA, the virus showed positive reaction to GBNV specific antisera. Using overlapping primers specific to GBNV, complete genome was amplified and sequenced for three isolates of GBNV. The S RNA has 3057 nt length with two ORFs (NSs and N gene) separated by intergenic region (IGR), the M RNA contains 4815 to 4817 nt in length with two ORFs (NSm and Gp) separated by IGR and the L RNA of 8911 nt has single ORF which codes for RNA dependent RNA polymerase. Among 102 germplasm screened, eight genotypes are highly resistant, eight genotypes are resistant, seven genotypes are moderately resistant. Using RGA primers specifically amplified a DNA fragment of 0.5kb from resistant chilli genotypes but not from susceptible genotypes. After cloning and sequencing, out of 81 clones, 60 clones showed 69.5 to 100 per cent similarities with known RGAs. Eighteen clones of Non TIR-NBS-LRR type of RGAs had similar homology with putative late blight resistance genes of Nicotiana tabacum, N. tomentosiformis, Solanum lycopersicom, S. pennelli, S. tuberosum and PVr9 potyvirus resistance protein. Twelve clones of TIR-NBSLRR type of RGAs had similar homology with TMV resistance protein N like gene of Capsicum annuum, Nicotiana tabacum, N. tomentosiformis, Solanum aculeatissimum, S. bulbocastanum, S. esculentum, S. pennelli and S. tuberosum. RGAs identified will be useful in marker-assisted breeding for GBNV resistance in chilli.ennullThesis