MARKER-BASED ANALYSIS OF QUANTITATIVE TRAITS IN WINTER-WHEAT X TRITICUM-TAUSCHII POPULATIONS

Triticum tauschii (Coss.) Schmal. has become a commonly used genetic r esource for wheat improvement. Although genes controlling qualitative traits such as disease and insect resistances are generally targeted i n germplasm development programs, genes for quantitative traits may be introgressed along with the target genes. This study was designed to identify genomic regions associated with quantitative traits from hexa ploid/diploid wheat crosses. One hundred forty-seven BC2F1-derived fam ilies from crosses between elite common wheat (Triticum aestivum L.) l ines and T. tauschii were evaluated for yield, kernel weight, protein concentration, and kernel hardness in held experiments at two location s during 2 yr. Genotypes of these families were determined by testing with one protein, 25 restriction fragment length polymorphism probes, and eight random amplified polymorphic DNA (RAPD) markers. Two RAPD ma rkers were associated with consistent effects on grain yield. Three ma rkers were associated with kernel weight, accounting for 16% of the va riance among families. In addition, two loci associated with protein c oncentration and one locus associated with kernel hardness were identi fied, accounting for 29 and 9% of the variance among families for the respective traits. In most instances, quantitative trait Loci had rela tively small effects, and regression analysis of agronomic performance on proportion of marker alleles from T. tauschii showed that the majo rity of linked chromatin from the diploid species had no detectable ef fect on any trait. Based on these results and previous studies, T. tau schii can be considered a primary source of resistance genes for wheat improvement.