SARADA JAYALAKSHMI DEVI, RPRASAD, KURAKU2020-02-242020-02-242019http://krishikosh.egranth.ac.in/handle/1/5810143464D5871Survey was carried out for disease incidence of leaf curl and stem necrosis during rabi 2018-19 in three blackgram growing districts of A.P. The mean disease incidence ranged from 4.10-6.26 %. The disease was successfully transmitted onto cowpea and back to blackgram from cowpea by mechanical inoculations. It produce typical local lesions and veinal necrosis on cowpea and leaf curling, necrosis of petiole, buds, leaves and other parts on blackgram. Total RNA was isolated and amplified by RT-PCR with GBNV/ TSV primers. An amplicon of 800bp was obtained with GBNV but not with TSV primers. About 800bp product was purified, sequenced and determined its length as 831 nucleotides and codes for 276 amino acids. The sequence homology studies with other GBNV isolates from data base shared 93-100 % and 94.5% to 100% sequence identity with GBNV at the nucleotide and amino acid levels, respectively. Phylogenetic tree was generated by comparing with 20 other reported Tospoviruses at nucleotide level by neighbour joining method and present isolate formed unique cluster with GBNV isolates. Among 21 genotypes screened by artificial inoculations, 5 genotypes (NDUK-15-222, TU-40, OBG-32, GKB-3, KPU-12-213) were found disease free, 2 genotypes (TBG-130, VBG-12-111-1) were found resistant, 4 genotypes (GBG-1, TBG-129, LBG-20, IPU-2-43) were found moderate resistance, 6 genotypes (LBG-645, LBG-623, TBG-104, SRI, LBG-787, TUTIMINUMU) were found susceptible, 4 genotypes (LBG-752, LBG-685, PU-31, BUTTAMINUMU) were found highly susceptible.en-USnullThesis