Barley [Hordeum vulgare] EST markers enhance map saturation and QTL mapping in diploid wheat [Triticum aestivum]

A linkage map was constructed using PCR-based markers developed from barley expressed sequence tags (ESTs) for recombinant inbred (RI) lines (Fsub(10)) derived from a cross between Triticum monococcum L. strain KT3-5 and T. boeoticum Boiss, strain KT1-1. Among the primer sets of 2,695 barley ESTs, 242 EST markers were integrated into the frame of a previously constructed diploid wheat linkage map with 96 RFLP markers. The total map length comprising barley EST, previously mapped RFLP and morphological markers was 1,038.1 cM, and the average distance between two adjacent loci was 3.1 cM. The linkage map showed saturation with the barley EST markers by covering extended telomeric regions and increasing the resolution compared with the previous RFLP map. Order of barley ESTs on the diploid wheat linkage map mostly showed a collinearity to that on the barley linkage map constructed previously, although the long arms of the homoeologous linkage groups 4 and 5 showed structural changes between diploid wheat and barley. Phenotypes of nine quantitative traits were scored for the diploid wheat RI lines and their parents. Composite interval mapping enabled to detect 24 quantitative trait loci for the traits. Thus, barley ESTs could become powerful tools to reveal homoeologous relationships between barley and wheat chromosomes, and valuable resources to develop genetic markers for wheat genomes.