Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/2003
Publication Date: 1/1/2004
Citation: Vales, M.I., Capettini, F., Corey, A., Chen, X., Hayes, P.M., Mather, D., Mundt, C., Richardson, K., Sandoval-Islas, S., Schoen, C.C. 2004. Effect of population size in the estimation of barley stripe rust qtl. Plant and Animal Genome Abstracts. p. 479.
Technical Abstract: Population size is an important issue in quantitative trait loci (QTL) detection. The limited population sizes used in many of the reported QTL detection experiments may have led to underestimation of QTL number, overestimation of QTL effects, and a failure to quantify QTL interactions. We generated a large barley doubled haploid mapping population (n=409), derived from the F1 of BCD47 and Baronesse, to assess the effect of population size on the estimation of QTL for a major disease in barley, barley stripe rust (BSR), caused by Puccinia striiformis f.sp. hordei. BCD47 was developed by marker-assisted pyramiding of BSR resistance alleles at QTL on chromosomes 4H and 5H. Baronesse is the most widely grown variety in the Pacific Northwest and it is susceptible to BSR. Genetic resistance to BSR can be qualitatively or quantitatively inherited. The use of qualitative sources of resistance alone is risky because there is evidence that pathogen virulence can evolve more quickly than plant breeders can deploy single resistance genes in new varieties. Quantitative resistance, alone or in combination with qualitative resistance, is in general more durable and is a key consideration in disease resistance breeding. We have identified QTL on chromosomes 3H, 4H, 5H and 6H where the resistant parent contributed resistance alleles, and QTL on chromosomes 2H, 5H and 7H where the susceptible parent contributed favorable alleles. We demonstrated that the number of QTL detected increased as the population size increased and that small population sizes overestimate the percentage of variance explained by the QTL.