Genetic and molecular analysis of bacterial wilt resistance in chilli (Capsicum annuum L.)
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Date
2019
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Department of Vegetable science, OUAT, Bhubaneswar
Abstract
The present investigation entitled “Genetic and molecular analysis of bacterial wilt resistance in chilli (Capsicum annuum L.)” was carried out at Central Horticultural Experiment Station (ICAR-IIHR), Aiginia, Bhubaneswar, Odisha during the period of 2017-2019 with the objectives of studying the gene effects contributing for important fruit traits, yield and its component traits, inheritance of bacterial wilt disease resistance and to identify molecular markers that are associated with bacterial wilt resistance in chilli. Populations were developed using the bacterial wilt highly resistant accession IIHR-B-HP-130 and highly susceptible accession CM334. The six generation (P1, P2, F1, F2, B1 and B2) populations were artificially challenged with highly virulent Bhubaneswar isolate of Ralstonia solanacearum and screened by planting in sick plot. The segregation pattern of 130 (susceptible): 81 (resistant) showed good fit for the digenic ratio of 9:7 indicating the bacterial wilt resistance in IIHR-B-HP-130 x CM334 cross is governed by two recessive genes (bwr1 and bwr2) with complementary gene action. The high frequency of resistant plants in B1 population indicated that other minor genes also confer to resistance. Parental polymorphism survey using 150 SSR markers found that seven SSRs were polymorphic which extended to bulk segregant analysis, where in none showed polymorphism. Publicly available Bw1 QTL linked SSR marker (CAMS 451) was got validated in parents and also showed polymorphism in BSA, indicating its role in bacterial wilt resistance. The same set of six generation populations were evaluated under field conditions during late Rabi, 2018 and generation mean analysis was carried out. All the traits (fruit length, fruit width, pedicel length, average fruit weight, fruit shape index, fresh and dry yield per plant) except number of fruits per plant and dry recovery percentage were controlled by both additive and non-additive gene action. Only non-additive gene action was observed for number of fruits per plant and dry recovery percentage. And for all the traits, duplicate type of non-allelic interaction, high heritability coupled with low genetic advance was observed. This implies single seed descent method to cumulate all the desirable alleles and excluding selection in early generations will be the best strategy to improve the fruit traits including yield in this population.
Description
Th-5737
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