Molecular Mapping of Loci for Agronomic Traits on Chromosome 3A of Bread Wheat

Abstract

ABSTRACTChromosome 3A of bread wheat (Triticum aestivum L.) cultivar ‘Wichita’ (WI) was previously found to differ from that of ‘Cheyenne’ (CNN) for genes affecting a number of agronomically important traits such as grain yield (GYLD), kernel number spike−1 (KPS), 1000‐kernel weight (TKWT), spike number m−2 (SPSM), grain volume weight (GVWT), plant height (PHT), and anthesis date (influenced by Eps locus). This study was designed to map the Eps locus and to identify regions of chromosome 3A of wheat associated with agronomic traits. A population of 3A recombinant inbred chromosome lines (RICLs‐3A) was previously evaluated in replicated field trials. Thirteen RFLPs and one morphological marker locus, Eps, were used to develop a genetic linkage map and to identify QTLs associated with agronomic traits. Individual loci explained from 8.9 to 38.2% of the total phenotypic variation for the measured traits. The major locus Eps was mapped distal to an RFLP marker locus Xcdo549 on the short arm of chromosome 3A and explained 38.2% of the total phenotypic variation for PHT, and 17.4% for both KPS and TKWT. Additional QTLs for PHT, TKWT, and KPS were identified on the chromosome. A QTL for SPSM on the long arm of chromosome 3A was tightly linked to QTL for PHT and KPS. QTLs for GYLD were identified only in a few individual environments whereas no QTL was detected for GVWT. No epistasis was detected between markers associated with QTLs. The QTLs identified across environments were consistent in all or most environments, hence should be useful in future marker assisted selection programs for breeding wheat cultivars.