• N. Rai

      Articles written in Journal of Genetics

    • Genetic analysis to identify good combiners for ToLCV resistance and yield components in tomato using interspecific hybridization

      Ramesh K. Singh N. Rai Major Singh S. N. Singh K. Srivastava

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      The interspecific hybridization for tomato leaf curl virus (ToLCV) resistance was carried out among 10 genetically diverse tomato genotypes (diversified by 50 SSR markers). Among the 10 parents, four susceptible cultivars of Solanum lycopersicum were crossed with six resistant wilds, such as S. pimpinellifolium, S. habrochaites, S. chemielewskii, S. ceraseforme, S. peruvianum and S. chilense in a line × tester mating design. All the 24 hybrids and their parents were grown in the field and glasshouse conditions to determine the general-combining abilities (GCA) and specific-combining abilities (SCA). The variances due to SCA and GCA showed both additive and nonadditive gene effects. Based on GCA estimates, EC-520061 and WIR-5032 were good general combiners while based on SCA estimates, PBC × EC-520061 and PBC × EC-521080 were best specific combiners for coefficient of infection and fruit yield per plant in both the environments. These lines could be selected and utilized in ToLCV resistance and high yield breeding programme for improving the traits.

    • Elucidation of diversity among F₁ hybrids to examine heterosis and genetic inheritance for horticultural traits and ToLCV resistance in tomato


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      Genetic diversity during prebreeding or postbreeding programme, is the key pillar to characterize the valuable traits and gene of interest.Whereas, superior or inferior heterotic performance of F₁ depend on the diverse nature of their pedigree. Therefore, the aim of this study was to see the diversity between the interspecific crosses and effect of heterosis, and inheritance for the morphological traits and ToLCV resistance. All the 24 F₁ interspecific crosses were classified into four clusters on the basis of morphological traitsas well as simple sequence repeat (SSR) markers. Among the F₁ hybrids, 23 were grouped into clusters II, III and IV with different phylogeny, while PBC×EC 521080 was individual with cluster I. On the basis of visual observation of fruit colour, deep red and green colours in the crosses of S. pimpinellifolium (EC 521080) and S. habrochaites (EC 520061) exhibited dominant effects. In context of heterosis breeding, the crosses which were made using Solanum pimpinellifolium (EC 521080), S. chmielewskii (EC 520049) and S.cerasiforme (EC 528372) were better for yield capacity and the crosses of S. habrochaites (EC 520061) exhibited low and negative heterosis for ToLCV resistance. The F₂ progenies were segregated in various Mendelian ratio as follows 3:1, 1:2:1, 1:3, 13:3, 15:1, 12:3:1 and 9:6:1 for ToLCV disease reaction of incidence, plant growth habit and fruit colour appearance, respectively. Therefore, these interspecific crosses can be utilized for developing high yield, impressive fruit colour combiners and resistant hybrids/varieties of tomato.

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