Gametocidal genes in wheat and its relatives. III. Chromosome location and effects of two Aegilops speltoides-derived gametocidal genes in common wheat

A new gametocidal gene was found in a common wheat cultivar Chinese Spring carrying the cytoplasm of Aegilops speltoides strain KU 5725 (Plant Germplasm Institute, Kyoto University). Monosomic analysis revealed that this gene and a previously known gametocidal gene Gc1, both derived from Ae. speltoides, are located on chromosome 2B. The two genes appear to be allelic and so have been designated as Gc1a (previous gene) and Gc1b (present gene). The two genes differ in their ability to induce hybrid dysgenesis in wheat: Gc1a causes endosperm degeneration and chromosome aberrations, whereas Gc1b results in abnormal seed lacking the shoot primodium. No correlation between embryo or endosperm degeneration and chromosome breakage was observed.Key words: wheat, Aegilops speltoides, gametocidal gene, hybrid dysgenesis, chromosome breakage.