Articles written in Journal of Genetics
Volume 97 Issue 1 March 2018 pp 25-33 RESEARCH ARTICLE
Okra’s (Abelmoschus esculentus (L.) Moench) commercial cultivation is threatened in the tropics due to high incidence of yellow vein mosaic virus (YVMV) disease. Okra geneticists across the world tried to understand the inheritance pattern of YVMV disease tolerance without much success. Therefore, the inheritance pattern of YVMV disease in okra was revisited by employing sixgenerations (P₁, P₂, F₁, F₂, BC₁ and BC₂) of four selected crosses (one tolerant × tolerant, two tolerant × susceptible and one susceptible × susceptible) using two tolerant (BCO-1 and Lal Bhendi) and two susceptible (Japanese Jhar Bhendi and PAN 2127) genotypes. Qualitative genetic analysis was done on the basis of segregation pattern of tolerant and susceptible plants in F₂ andbackcross generations of all the four crosses. It revealed that a single dominant gene along with some minor factors governed the disease tolerant trait in both the tolerant parents used. However, it was observed that genes governing disease tolerance identified in both the tolerant variety used was different. It could be concluded that the gene governing YVMV disease tolerance in okra wasgenotype specific. Further, duplicate gene action as evident from an approximate ratio of 15 : 1 (tolerant : susceptible) in the F₂ population in the cross of two tolerant varieties gave a scope of increasing the tolerance level of the hybrid plants when both the tolerant genes are brought together.However, generationmean analysis revealed involvement of both additive and nonadditive effects in the inheritance of disease tolerance. Thus, the present study confirms that a complicated genetic inheritance pattern is involved in the disease tolerance against YVMV trait. The major tolerance genes could be transferred to other okra varieties, but the tolerance breaking virus strains might not allow them to achieve tolerance in stable condition. Therefore, accumulation of additional genes may be needed for a sustainable tolerance phenotype in okra.
Volume 99 All articles Published: 19 June 2020 Article ID 0056 RESEARCH ARTICLE
Development of mutants and their effective utilization to incorporate desirable traits in tomato would be a sound improvement strategy to develop so called ‘smart’ tomato variety of the coming century. Initially we developed three induced mutants from two varieties, ‘Patharkuchi’, a local adapted cultivar and an introduced variety ‘Berika’, and then three crosses (Berika 9 P Mut-5, Berika 9 P Mut-11, Patharkuchi 9 B Mut-1) were made to involve in these two varieties and their respective mutants. Six generations (P1, P2, F1, F2, BC1 and BC2) of three crosses were utilized to study the genetic control of yield and quality traits, and to study the genetic basis of formation of dark green fruit. The nature and magnitude of gene action controlling the inheritance of 27 quantitative traits differed from one cross to another and from one trait to another, mostly conditioned by nonadditive gene action and duplicate epistasis. The prevalence of duplicate epistasisin three crosses for most of the traits revealed that the pace of progress through conventional selection process would be hindered as this kind of epistasis might result in decreased variation in F2 and subsequent generations. Recurrent selection in biparental progenies would be helpful for exploiting this type of nonallelic interaction through generation of high frequency of desirable recombination and concentration of genes having cumulative effects in the population. We also observed complex genetic behaviour of some of the traits revealing significant epistatic components. Inheritance study of ‘dark green fruit’ (
Volume 99 All articles Published: 5 November 2020 Article ID 0084 RESEARCH ARTICLE
Okra production in eastern India at present is severely threatened by whitefly-mediated okra enation leaf curl disease(OELCuD). Identification of resistant genotype and understanding the genetic control and biochemical relationship of OELCuD resistanceare prerequisite for developing an effective breeding strategy. This study was conducted employing six populations (P1, P2, F1, F2, BC1 andBC2) of two selected (resistant x susceptible (RxS)) crosses. Associationship between severity of OELCuD and biochemical parametersof parents and hybrids at preflowering and flowering stages was studied. Segregation pattern of the genotypes in F2 generation showingOELCuD reaction of two crosses suggested that two duplicate recessive genes was operative for resistance to OELCuD. Generation meananalysis revealed involvement of both additive and nonadditive effects in the inheritance of disease resistance. Hence, postponement ofselection in later generations or intermating among the selected segregates followed by one or two generations of selfing to break theundesirable linkage and allow the accumulation of favourable alleles could be suggested for the development of stable resistant genotypeagainst this disease. Higher peroxidase activity and total phenol content in leaf emerged as reliable biochemical markers for early selectionof genotype resistant to OELCuD.
Volume 100, 2021
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