Genetic analyses of BYDV-tolerance in barley (Hordeum vulgare L.)

Barley yellow dwarf luteovirus (BYDV) is an important plant pathogen and causes the most important virus disease of barley world-wide. In order to obtain information about the mode of inheritance of tolerance to BYDV-PAV, three DH populations were tested for variation in yield, plant height, and yield components. Measurements were gathered on both non-infected plants and plants of the same DH line artificially inoculated with BYDV-PAV hearing aphids in pot and field experiments for 3 years at two locations. For all traits, a continuous variation was observed suggesting a quantitative mode of inheritance for tolerance against BYDV-PAV. Two QTL for relative grain yield per plant after BYDV infection have been identified in the population 'Post' x 'Vixen' which explain nearly 47 % of the phenotypic variance. One QTL on the long arm of chromosome 2HL with the positive allele derived from 'Post' was detected in the DH-population 'Post' x 'Nixe' in exactly the same marker interval. Besides this, the importance of the Ryd2 gene for the level of tolerance was estimated in two populations, giving hint that these regions on chromosome 2H and 3H are of special importance for tolerance against the BYDV-PAV isolate used in these studies. Markers flanking these regions can be efficiently used for pre-selection of BYDV-tolerant genotypes. On a longer turn, these markers serve as starting points for the isolation of relevant genes and analysis of their function.