Vol. 11, Issue 5 (2022)

Author(s):
NA Delvadiya, DR Mehta and AK Nandha

Abstract:
Grain size is an important agronomic trait that influences the grain yield and milling quality of wheat. In this paper, the experimental material comprised of P₁, P₂, F₁, F₂ and F_2:3 generations of wheat cross GW-11 X GW-322 for grain size and related traits respectively to fulfill the objective of linkage and QTL mapping in bread wheat. Out of 200 SSR markers screened for parental polymorphism for grain size and related traits, about 23% of SSR markers showed good polymorphism between two parental lines. Out of 46 tests for calculated chi-square, 42 test markers do not deviate significantly from expected ratios revealing that observed data are in agreement with expected ratio of 1:2:1. The linkage map was constructed using software IciMapping v.4.1 and Recombination frequencies were converted into map distance using Kosambi’s mapping function. The markers were grouped with minimum logarithm of the odds (LOD) of 3.0 with walking speed was set at 1.0 cM. Seven linkage groups with a total map length of 77.31 cM were constructed using data from 46 SSR marker loci for 74 F₂ plants which ranged from minimum of 2.74 cM (LG2) to maximum of 26.89 cM (LG3). Genotypic data of F₂ and phenotypic data of on 74 F_2:3 lines were analyzed for identification of the main effect QTLs using the software ICIM-ADD mapping in QTL IciMappingV4.1. A linkage map of grain size and related traits output data file was used for the construction of QTL mapping. A total six QTL had been identified for grain size and related traits, one each for 100-grain weight; number of grain per the main spike (NGPMS); grain yield per plant (GYPP); number of effective tillers per plant (NETPP) and two QTLs for grain weight per the main spike (GWPMS) and could be used for marker assisted selection after validation.