High resolution map around the vrs1 locus controlling two- and six-rowed spike in barley, Hordeum vulgare

The vrs1 (formerly nu) locus in the long arm of chromosome 2H controls late ral spikelet development in barley. The vrs1 locus was mapped by backcross- derived lines that consisted of 373 BC7F1 plants and 278 BC6F2 plants. The linkage study indicated that MWG801, CMNA-38/700, cMWG699, vrs1 and MWG865 exist in the order listed, with map distances of 3.1, 0.4, 0.1, and 0.9 cen timorgans (cM), respectively. Recombination in female and male meiocytes sh owed no significant difference within this region. In a neighboring region between MWG865 and MWG503, the recombination frequency was higher in female than male meiocytes in one mapping population. The combined linkage data o btained from this study were compared with published data, and genotype-spe cific suppression of crossing-over was not evident in the vrs1 region.