COMPARATIVE RFLP MAPPING OF TRITICUM-MONOCOCCUM GENES-CONTROLLING VERNALIZATION REQUIREMENT

The adaptability of Triticum aestivum to a large range of environments is partially due to genetic differences in sensitivity to vernalizati on. The most potent gene reducing the vernalization requirement in hex aploid wheat is Vrn-A1. An orthologous vernalization gene, designated Vrn-A(m)1, was mapped in the diploid wheat Triticum monococcum between RFLP markers Xwg908 and Xabg702 on the long arm of chromosome 5A(m)L. The orthology of VrnA(m)1 with Vrn-A1 (5A wheat, originally Vrn1), Vr n-D1 (5D wheat, originally Vrn3), Vrn-R1 (5R rye, originally Sp1) and Vrn-H1 (5H barley, originally Sh2) was shown by mapping RFLP markers l inked to these vernalization genes on the T. monococcum linkage map. A second vernalization gene, designated Vrn-A(m)2, was found in the dis tal region of chromosome 5A(m)L within a segment translocated from hom oeologous group 4. This gene is completely linked to RFLP marker Xbcd1 402 and located between the same RFLP markers (X beta-Amy-1 and Xmwg61 6) as the Vrn-H2 (originally Sh) locus in Hordeum vulgare.