Utilization of Hordeum vulgare subsp. spontaneum for improvement of disease resistance in cultivated barley.

Abstract

As a result of extensive inbreeding within small populations, cultivated barley (Hordeum vulgare subsp. vulgare) has come to have a narrow genetic base, especially with regard to disease resistance. Wild barley (Hordeum vulgare subsp. spontaneum) is known to be a diverse source of novel alleles for introgression of disease resistance into cultivated barley. Two wild barley accessions collected in Israel, Damon 11-11 and Shechem 12-32, were found to carry resistance to several economically important diseases. Two doubled haploid mapping populations were created from crosses between these two accessions and the two-rowed malting quality standard cultivar Harrington. A new set of wild barley-derived Diversity Arrays Technology (DArT) markers were developed and combined with the previously developed cultivated-derived barley markers to create a ‘comprehensive’ barley DArT array capable of more robust genotyping of both wild and cultivated barley germplasm. This array was utilized to genotype the Damon/Harrington (D/H) and Shechem/Harrington (S/H) populations and to create genetic linkage maps of these two populations as well as a synthetic map of the barley genome containing 3,542 markers. The D/H and S/H populations were phenotyped for resistance to seven economically important diseases, including powdery mildew, stem rust, stripe rust, leaf rust, net blotch, spot blotch, and Septoria speckled leaf blotch. Additionally, several aspects of heading date, inflorescence and leaf characteristics, plant height, and yield were assessed and all traits were subjected to quantitative trait loci (QTL) analyses. Significant QTL were detected for all traits. Identification of markertrait associations for loci controlling both disease resistance and morphological and agronomical traits should help limit linkage drag by allowing for simultaneous selection for and against desirable and undesirable alleles, respectively. These marker-trait associations will be utilized for implementing marker-assisted selection to introgress and maintain favorable alleles into elite breeding germplasm..