Minimizing ergot infection in hybrid rye by a SMART breeding approach

Restoration of male fertility is currently the most favourable approach to minimize ergot infection in hybrid rye varieties. Novel gene-based STS markers proved to be efficient tools for marker assisted introgression of the restorer gene Rfp1 in hybrid rye varieties. In the present study, we were able to detect linkage of these markers to a second major restorer gene of the P cytoplasm, Rfp2, as well. Our analysis of Rfp2 revealed, that the expression of this major restorer gene is largely influenced by modifier genes. As an additional result, we identified microsatellite markers linked to minor restorer genes located on chromosomes 1R, 3R, 6R and 7R. Although the the SSR markers provide a significant progress in addressing these minor restorer genes, the complex genetics of male-fertility restoration based on Rfp2 increases the efforts of marker assisted introgression of this restorer gene in elite breeding lines. The observed linkage of the STS markers to Rfp2 as well as to Rfp1 and Rfc1 in a previous study supports the assumption, that the restorer genes identified on chromosome 4RL are either alleles of a single restorer gene or represent different linked genes located in this sub-genomic region. The gene-based markers on chromosome 4RL, together with a set of microsatellite markers dispersed throughout the entire rye genome, proved to be efficient tools to elucidate the genetics and to examine the value of restorer genes for practical hybrid rye breeding.