Association mapping for barley traits related to organic farming

Summary

In context of a larger project dealing with the traits of barley that are related to organic farming (BAR-OF), we performed an association mapping in order to dertermine the genetic loci linked with the respective traits. In two subsequent years (2002 and 2003), we used field results from 96 barley lines and varieties, partially overlapping between the years. The lines/varieties were grown on three Dansih locations (Flakkebjerg, Foulum and Jyndevad). For Foulum and Flakkebjerg, we observed both fields grown under organic and conventional regime; for Jyndevad only fields cultivated under organic conditions were ecploited. Neither in the organic nor in the conventional fields; diseases were controlled chemically. In the resulting five environments per year, deseases (powdery mildew, leaf rust, scald and net blotch), morphology related traits (stem lengh, ear braking, stem breaking and lodging), development related traits (time of heading and time of ripening) and yield related traits (kernel yiedl, kernel weight, kernel density, kernel size, starch and protein content) were observed. for the marker study, we used 65 polymorphic microsatellite markers distributed over all seven barley chromosomes. In the association analysis we applied a GLM analysis in the software TASSE and accepted only association with an error probability lower than 10-5. Beside for ear breaking, we found significant associations for each of the traits observed and always on more than one chromosome. The major part of the associations differed from 2002 to 2003. For the disease resistances and the kernel weight, we observed a relative high stability of the associated marker loci over the years, even so the barley lines on the field experiments differed partially from one year to the other. Surprisingly, we fond the best stability of association comparing the two years for the trait "kernel yield". Further analysis, especially in relation to G x E interaction and the influence of organic/conventional conditions will be published in an upcoming paper.