MOLECULAR MAPPING OF WHEAT - MAJOR GENES AND REARRANGEMENTS IN HOMOEOLOGOUS GROUP-4, GROUP-5, AND GROUP-7

A molecular-marker linkage map of hexaploid wheat (Triticum aestivum L . em. Thell) provides a framework for integration with the classical g enetic map and a record of the chromosomal rearrangements involved in the evolution of this crop species. We have constructed restriction fr agment length polymorphism (RFLP) maps of the A-, B-, and D-genome chr omosomes of homoeologous groups 4, 5, and 7 of wheat using 114 F-7 lin es from a synthetic x cultivated wheat cross and clones from 10 DNA li braries. Chromosomal breakpoints for known ancestral reciprocal transl ocations involving these chromosomes and for a known pericentric inver sion on chromosome 4A were localized by linkage and aneuploid analysis . Known genes mapped include the major vernalization genes Vrn1 and Vr n3 on chromosome arms 5AL and 5DL, the red-coleoptile gene Rc1 on 7AS, and presumptively the leaf-rust (Puccinia recondita f.sp. tritici) re sistance gene Lr34 on 7DS and the kernel-hardness gene Ha on 5DS. RFLP markers previously obtained for powdery-mildew (Blumeria graminis f.s p. tritici) resistance genes Pm2 and Pm1 were localized on chromosome arms 5DS and 7AL.