Identification of homoeologous regions in complex genomes using lambda genomic clones

Linkage groups containing genomic regions homoeologous to the region of the soybean genome that contains the Phytophthora a root and stem rot resistance locus Rps1 were identified using lambda genomic clones containing loci homoeologous to two loci linked to Rps1: A071-1, a locus with homology to a gene of unknown function and sle3, a member of a multi-gene family that encodes a soybean late embryogenic protein of the group I LEA type. The homoeologous regions were identified by detecting linkage conservation between A071, sle and tightly linked low copy loci derived from the lambda clones. Both previously reported and new homoeologous relationships between linkage group N and linkage groups D1, G, J and L were detected by this method as compared to standard restriction fragment length polymorphism (RFLP) mapping. Information on sequence conservation in the regions surrounding homoeologous loci and on the distribution of repetitive sequences surrounding homoeologous soybean genes was also obtained. These results demonstrate that genomic clones of homoeologous loci can identify and provide molecular information on homoeologous genomic regions in species for which multiple mapping populations are unavailable and genetic polymorphism is low. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.