IDENTIFICATION OF QUANTITATIVE LOCI FOR TOLERANCE TO BARLEY YELLOW DWARF VIRUS IN OAT

Molecular markers linked to quantitative trait loci conditioning toler ance to barley yellow dwarf virus (BYDV) were identified in oat (Avena sativa) using amplified fragment length polymorphism (AFLP) analysis. Near-isogenic and recombinant inbred lines (NILs and Ws, respectively ) derived from a cross of Clintland64 (BYDV-sensitive) and IL86-5698 ( BYDV-tolerant) were evaluated for their responses to an Illinois isola te of the PAV strain of BYDV. Individual markers identified in the ana lysis of the NILs explained up to 35% of the variability seen in the t olerance response. Single-point analysis of the marker data from the R IL population identified 24 markers in three linkage groups that were associated with tolerance to BYDV infection at P less than or equal to 0.001. These markers defined three major loci, A, C, and E, that were contributed by the tolerant parent (IL86-5698) and explained 35.0, 20 .6, and 17.0% of the variability, respectively. Three minor loci (G, H -1, and R) were identified at P less than or equal to 0.01. These loci were contributed by the sensitive parent (Clintland64) and explained 5.8, 5.6, and 5.6% of the variability respectively. Interval analysis showed that only the loci A, C, and E are associated significantly wit h BYDV tolerance at log of the likelihood ratio greater than or equal to 3.0. These loci explained about 50% total of the variation in BYDV tolerance in multimarker regression analysis in both years. The BYDV t olerance loci A, C, E, and R were mapped to hexaploid oat restriction fragment length polymorphism linkage groups 2, 8, 36, and 5, respectiv ely, by analyzing the segregation of the AFLP markers in the Kanota x Ogle RIL population.