Linkage Analysis of RFLP Markers and Quantitative Traits of Hexaploid Oat (Avena sativa L.)

Development of molecular markers has allowed researchers to construct linkage maps in many crop species and identify chromosomal regions with significant influence on traits. The objectives o fthis study were to develop a linkage map of hexaploid oat (Avena saliva L.) and to identify chromosomal regions, so called quantitative trait loci (QTLs), that are associated with seven traits. The populations were Cayuse X Froker (popl) and PI 539874 X Nodaway 70 (pop2). One hundred thirteen and 89 marker loci were used to construct linkage maps for pop 1 and pop2, respectively. Fresh tissue samples of F2 plants were used for RFLP analysis. Linkage analysis was conducted using MAPMAKER software (ver. 3.0) with a LOD (Log10 of likelihood ratio) score of 3.0. Marker loci for popl covered 802.4 cM of oat genome with an average of 9.2 cM per locus, and were arranged in 17 linkage groups. The map for pop2 consisted of 16 linkage groups with a total size of 706.9 cM and with an average of 11.1 cM per locus. Based on the common markers, overlapping of the two maps revealed 21 linkage groups. Due to smaller map sizes, however, it is uncertain whether these linkage groups represent the 21 haploid chromosome number of oat. For QTL analysis, F2:3 families of these populations were grown in three locations. Traits analyzed included heading date, plant height, tiller number, groat weight, hull weight, seed weight, and percent hull. Quantitative trait loci analysis was conducted using both one-way ANOV A and interval mapping with the data representing overall mean of years and locations, and individual location means. One-way ANOVA detected large number of QTLs as significant (P\u3c0.01) for all of the traits. Common markers were identified in both populations indicating the stability of the QTLs across populations. Notably, UMN361, ISU1146c, CDO341, and ISU2184 showed significant associations with heading date. These markers were also found to be linked to plant height indicating the presence of pleiotrophy. Interval mapping analysis revealed the QTLs with large effects. In pop 1, two QTLs for heading date and plant height, and one QTL for tiller number and seed weight were identified at least in two locations. In pop2, three QTLs for heading date and plant height, and one QTL for tiller number, groat weight, hull weight, and seed weight were identified at least in two locations. These results indicate the stability of the QTLs across locations. Markers found to be associated with the traits in this study offer an opportunity to oat breeders to implement marker-assisted selection. Mapping more markers onto these maps would allow better characterization of the QTLs and identification of new QTLs for the traits