Development of an efficient method for assessing resistance to the net type of net blotch (Pyrenophora teres f. teres) in winter barley and mapping of quantitative trait loci for resistance

摘要

Breeding for resistance against Pyrenophora teres f. teres in barley is difficult due to the high virulence diversity of the pathogen and the fact that in field trials a simultaneous infection with Rhynchosporium commune, Puccinia hordei or Blumeria graminis f. sp. hordei often takes place. To avoid this, a so-called "summer hill trial" was developed in which winter barley is sown at the beginning of August at optimum conditions for P. teres infection. These trials allowed an unequivocal scoring of P. teres resistance. Using this approach, strong correlations of the results obtained in 3 years at two locations were observed and heritability was estimated at h (2) = 0.80 for the doubled haploid (DH) population Uschi x HHOR3073 and h (2) = 0.62 for (Post x Viresa) x HHOR9484. In parallel, genetic maps based on DArT, SSR and SNP markers were constructed, comprising 705.7 cM for the DH population Uschi x HHOR3073 and 1,035.8 cM for (Post x Viresa) x HHOR9484. In the population Uschi x HHOR3073, one quantitative trait locus (QTL) was detected on each of chromosomes 2H and 3H and two on chromosome 5H, explaining between 9.4 and 19.0 % of the phenotypic variance. In the population (Post x Viresa) x HHOR9484, three QTL were detected on chromosome 5H and one on chromosome 7H, explaining between 12.6 and 34.7 % of the phenotypic variance. These results show that the new summer hill trial design is best suited to obtain reliable phenotypic data for P. teres resistance under field conditions, as on the one hand already known QTL were confirmed and on the other hand new QTL were detected.