Abstract:
The development of winter 6-row malting barley varieties is an objective of the OSU program. The program's winter germplasm is quite susceptible to Barley Yellow Dwarf Virus (BYDV). The program recently released the spring 2-row variety Orca, which carries the Yd2 gene for BYDV resistance. The objective of this project was to transfer the Yd2 gene from Orca to the winter varieties Strider and Kold. A molecular marker tightly linked to the Yd2 locus was used to facilitate the introgression of this gene from the spring to the winter ger nplasm pool In 1998, six-row plants were selected in F2 populations derived from crosses of Orca x Kold and Orca x Spider. DNA was extracted from these plants for genotyping with the molecular marker YLM, which is tightly linked to the Yd2 locus on the long arm of chromosome 3 (311). In order to encourage natural infection by BYDV-infected aphids, the F3 families tracing to selected F2 plants were planted one month before the usual planting date in the fall of 1998. Unusually low temperatures in December 1998 led to significant winter injury, leading to the loss of approximately 70% of the F3 families in each of the two populations. Phenotype data (visual rating of BYDV symptoms on F2 plants and F3 families, and visual rating of winter survival in F3 families) and genotype data (allelic structure of each F2 plant at the YLM locus) were collected to determine the genotype of the F3 phenotypic selections and to assess the utility of the marker locus as tools for rapidly introgressing target alleles from spring to winter germplasm.
