CHARACTERIZATION OF TOMATO TRANSGENIC EVENTS CARRYING Remusatia vivipara LECTIN AND Sclerotium rolfsii LECTIN GENES AND THEIR EVALUATION FOR THE NATURE OF RESISTANCE TO ROOT KNOT NEMATODE, WHITEFLY AND LEAFHOPPER
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Date
2014-09
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University of Agricultural Sciences, Dharwad
Abstract
Eight events each for transgenic tomato carrying Remusatia vivipara lectin (rvl1) and Sclerotium rolfsii lectin (srl1) genes were employed for this study. All sixteen events showed 3:1 transgene segregation in T1. The copy number was also confirmed by Southern hybridization. TAIL-PCR for five events each for rvl1 and srl1 showed different sites of integration. Specific activity of the lectin expressed among the homozygous (T3) plants ranged from 0.18 × 102 to 0.40 × 102 units and 0.18 × 102 to 0.76 × 102 units for RVL1 and SRL1, respectively. Bioassay with second stage juvenile of root knot nematode (Meloidogyne incognita) showed 10 to 40% reduction in gall formation among the transgenics over non-transgenics. RVL1 (50) and SRL1 (7) showed the lowest number of galls. Transgenics showed reduced egg hatching, delayed development of M. incognita and reduced giant cell formation compared to non-transgenics.
The transgenic plants were more tolerant to whitefly (Bemisia tabaci) and leafhopper (Amrasca bigutulla bigutulla) than the control plants under no-choice and free-choice conditions. RVL1 (50) and SRL1 (7) showed the highest whitefly nymphal mortality of 66.67% and 75.00%, respectively compared to non-transgenics (15.17%) under no-choice condition. They also showed less plant damage score compared to non-transgenics under free-choice condition. SRL1 (7) showed less plant damage score and higher leafhopper nymphal mortality (60%) as compared to non-transgenics (16.67%). Insecticidal activity of the lectins was assayed using artificial media containing 0.1% (w/v) lectins, where RVL1 and SRL1 showed the highest whitefly mortality of 33.33% and 46.11%, respectively after 36 h of insect release. Similarly, RVL1 and SRL1 exhibited a maximum mortality of 36.93 and 48.04%, respectively for leafhoppers after 30 h of insect release. This study demonstrated the potential of rvl1 and srl1 for development of transgenics to confer broad spectrum resistance against phytophagous pests.
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