'Plant Breeding: Sustaining the Future' Abstracts of the XVIth EUCARPIA Congress, Edinburgh, Scotland, 10-14 September 2001 TOWARDS MAP-BASED CLONING OF Rph7.g USING RICE-BARLEY COLINEARITY S. BRUNNER, B. KELLER, C. FEUILLET  Institute of Plant Biology, University of Zurich, 8008 Zurich, Switzerland

Leaf rust, a fungal foliar disease caused by Puccinia hordei G. Otth. is becoming important in barley growing areas. So far, 16 race specific resistance genes (Rph genes) have been described. Rph7 is one of the four genes which are still effective against leaf rust. We have constructed a linkage map and found RFLP markers closely linked to the Rph7.g resistance gene on chromosome 3HS. An STS marker was developed from the receptor-like kinase gene Hv3Lrk that maps at 3.2 cM from Rph7.g. This marker represents a useful tool for marker-assisted selection. The genetical interval around the Rph7.g locus was further narrowed down to 0.53 cM using excellent colinearity between rice chromosome 1S and barley chromosome 3HS. Cosegregating markers were used to screen the Morex BAC library of barley. A physical barley BAC contig was then established at the Rph7.g locus. We are currently analyzing this chromosomal region in barley.