Hybrid dysgenesis in common wheat caused by gametocidal genes

Abstract

When gametocidal agents (gametocidal genes or chromosomes) derived from four Aegilops species, Ae. speltoides, Ae. sharonensis, Ae. longissima and Ae. triuncialis, are present in a hetero- or hemizygous state in wheat, they cause a syndrome characterized by male and female sterility, seed shriveling, chromosome breakage and mutation. However, the characteristics of the syndrome differ among the agents. Gametocidal gene, Gc1, originally from Ae, speltoides, induces sterility, seed shriveling and mutation in the F₁ generation. In this case, seed shriveling is accentuated by low temperature, about 5 to 11 hrs after the pollination. Gametocidal chromosomes, 4S^sh of Ae. sharonesis and 4S¹ of Ae. longissima, cause high rates of mutation and chromosome aberration in addition to sterility, although they do not induce seed shriveling. Chromosome 3C of Ae. triuncialis induces only sterility in the F₁, though chromosome breakage and mutation are induced in the B₁1generation in the presence of its suppressor, Igc1 (from a common wheat cultivar Norin 26). The syndromes caused in wheat by these gametocidal agents are compared to hybrid dysgenesis observed in Drosophila melanogaster.