Disease resistance genes in a doubled haploid population of two-rowed barley segregating for malting quality attributes

Abstract

Malting barley (Hordeum vulgare L.) improvement involves selection for many quality traits, but the search for and deployment of resistance genes has continued to be an equally important endeavour. As an aid to phenotypic selection in breeding programs, gene mapping can serve to characterise genes known to exist in elite breeding lines. In the present study, 180 doubled haploid lines derived from the cross of VB9524/ND11231*12 were screened for disease resistance under field and greenhouse conditions. Quantitative trait locus (QTL) mapping and classical genetic linkage approaches were used to identify and map QTLs for resistance to powdery mildew (Blumeria graminis f.sp. hordei), net form of net blotch (Pyrenophora teres f. teres) and stem rust (Puccinia graminis f.sp. tritici). The analyses offered a comparison between QTL mapping and traditional genetic linkage analysis. Both approaches identified a QTL for powdery mildew resistance on chromosome 1H, which mapped to the approximate genomic location of the Mla6 gene. Similarly, both methods identified a major QTL for resistance to net form of net blotch on chromosome 6H and for stem rust resistance on chromosome 7H. The QTL for stem rust resistance on 7H mapped to the approximate location of the Rpg1 gene. Classical linkage analysis identified the 3 QTLs with major effects, but was unable to detect 3 other loci with minor effects.