SARADA JAYALAKSHMI DEVI, RSUNIL KUMAR, M2018-05-162018-05-162016http://krishikosh.egranth.ac.in/handle/1/5810046319D5347Tobacco streak virus (TSV) belongs to the genus Ilarvirus of family Bromoviridae and its virions were characterized by quasi-isometric particles measuring about 27 – 35 nm in diameter. TSV was found to be a serious production constraint in several field and horticultural crops. A study was undertaken to characterize and develop suitable management strategies against TSV. Survey conducted during Kharif 2014-15 and 2015-16 in Andhra Pradesh and Karnataka revealed disease incidence of 9-28 per cent in groundnut, 6-18 per cent in sunflower and 5-22 per cent in cucumber. TSV infected samples collected from groundnut (GNAP7), sunflower (SFAP17), cucumber (CUKA13) and parthenium (PHAP15) was maintained on cowpea for biological and molecular characterization. TSV isolates (GNAP7. SFAP17, CUKA13 and PHAP15) maintained on cowpea were cross inoculated on five popularly grown cultivars of groundnut (JL-24, K-6, Prasuna, K-9, Kadiri harithandra), sunflower (KBSH-44, DRSH1, NDSH-1012, Mordent, Sunbred-275) and cucumber (Long green, Swarna poorna, Swarna ageti, Swarna sheetal, Pusa uday). Incubation period required for the initiation of local and systemic symptoms varied among different hosts and cultivars. Local symptoms of veinal necrosis, leaf yellowing and wilting, petiole necrosis, chlorotic spot, tip necrosis and systemic symptoms of mosaic, wilting, necrotic streaks on stem, bud necrosis, axillary shoot proliferation were observed in different hosts and cultivars. Out of 23 plant species tested against TSV by sap inoculation, 14 plant species were susceptible to TSV, which included Beta vulgaris, Abelmoschus esculentus, Cicer arietinum, Solanum melongena, Ricinus communis, Phaseolus vulgaris, Gerbera jamesonii, Macrotyloma uniflorum, Vigna unguiculata ssp. unguiculata, Tagetus erecta, Allium cepa, Phaseolus coccineus, Solanum lycopersicum and Vigna unguiculata ssp. sesquipedalis. Complete genome sequence of TSV isolates, groundnut (GNAP7), sunflower (SFAP17), cucumber (CUKA13) and parthenium (PHAP15) was done and submitted to Genbank, NCBI and showed high level of diversity at nucleotide and amino acid level. Phylogenetic analysis of RNA1, RNA2 and RNA3 genes revealed that TSV isolates under present study (Groundnut, Sunflower, Cucumber and Parthenium) clustered into one group along with other Indian TSV isolates. A total of eleven recombination events in RNA1, eight recombination events in RNA2 and six recombination events in RNA3 were identified. The motif distribution and secondary structures (α helix, β strand and coiled region) in replicase protein, RNA dependent RNA polymerase protein, movement protein and coat protein of groundnut, sunflower, cucumber and parthenium isolates showed high level of variability among TSV isolates. For quick diagnosis of TSV, various molecular diagnostic techniques like IC-RT-PCR, RT-LAMP and IC-RT-LAMP were standardized. Cucumber fruits from sap inoculated plants and from naturally infected plants (fruits collected from cucumber plants with parthenium as border crops) were collected and found positive for TSV in immature seeds. Among different treatments or modules used to study Integrated Disease Management (IDM) of TSV in groundnut during Kharif 2014-15 and 2015-16, Treatment 3 (T3) (improved practice) (Border crop (4 rows of Jowar) + seed rate @ 200 kg ha-1 + seed treatment with Imidacloprid, Gaucho 600 FS @ 2 ml kg-1 seed and Mancozeb @ 3 g kg-1 seed + spraying of Thiocloprid 480 SC @ 150 ml ha-1 at 20 DAS followed by Acetamiprid 20 SP @ 100 g ha-1 at 35 DAS.) was found to be effective with lowest PSND disease incidence and thrips damage at 7 and 14 days after 1st and 2nd spraying and with more yield parameters followed by Treatment 2 (T2) (recommended practice) (Border crop with Jowar, 4 rows around the field + Seed rate @ 200 kg ha-1 + Seed treatment with Imidacloprid 600 FS @ 2 ml kg-1 seed and Mancozeb @ 3 g kg-1 seed + foliar spray of Dimethoate @ 2 ml l-1 of water at 20 days after sowing) which were significantly different from each other.en-USnullThesis