Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/1998
Publication Date: N/A
Interpretive Summary: Barley yellow dwarf virus (BYDV) causes the most damaging virus disease of oats. The terms tolerant and sensitive have been used to describe the host plant responses to infection by BYDV. BYDV invades and replicates in the tissues of both tolerant and sensitive oat lines, but tolerant lines do not develop severe disease symptoms. No single major resistance or tolerance gene to BYDV infection has been identified in oat. However, high levels of tolerance to BYDV infection have been identified in oat that results from the interaction of two to four genes. Once high levels of multiple gene tolerance have been developed in germplasm lines, it can be difficult to move all of the genes for the tolerance into new cultivars for field use. This is especially true for BYDV tolerance where it is necessary to inoculate plants by infesting them with aphids harboring BYDV to evaluate the levels of tolerance expressed by each plant line. In this study, we used molecular techniques and specially derived oat populations to identify and map DNA markers related to BYDV tolerance in cultivated oat. The identification of molecular markers for these genes will greatly increase the efficiency of moving all of the gene for tolerance to BYDV from germplasm lines into new cultivars. This information also will lead to a better understanding of how multiple genes interact to produce virus tolerant plants, and will be helpful to public and private researchers who are working toward improved tolerance of small grain crops to BYDV.
Technical Abstract: Molecular markers were identified in oat that are linked to chromosomal loci conditioning tolerance to barley yellow dwarf virus (BYDV) infection. Two oat lines, Clintland64 (BYDV-sensitive) and IL86-5698 (BYDV-tolerant), were used to produce three pairs of near-isogenic (NILs) and a population of recombinant inbred lines (RILs). Markers for tolerance loci were identified using amplified fragment length polymorphism (AFLP) analysis. DNA samples from the NILs and the parents were digested with EcoRI and MseI and amplified with 80 different combinations of selective primers. Six markers were identified that cosegregated with tolerance and sensitivity in all three pairs of NILs. Based on the segregation of the banding patterns in the NILs, a subset of 26 primer combinations were chosen for analysis in 62 lines of the Clintland64 x IL86-5698 RIL population. The contributions to BYDV tolerance of loci were estimated using two years of BYDV field data and segregation of the markers in the Clintland64 x IL86-5698 RIL population. Among 290 bands scored, 35 markers showed a significant contribution to tolerance (P <= 0.01) in a population of 62 RILs. Markers that cosegregated with tolerance in the NILs contributed as high as 42% of the tolerance. Fiftyfive markers associated with BYDV tolerance were separated into five linkage groups using 126 RILs and placed on the hexaploid oat RFLP map by analyzing the segregation of the AFLP markers in the Kanota x Ogle RIL population. Using interval analysis, three major quantitative trait loci were associated significantly with BYDV tolerance and accounted for 58% of the variation in BYDV tolerance in multi-marker regression analysis.