Two types of gametocidal chromosome of Aegilops sharonensis and Ae. longissima.

Certain chromosomes of Aegilops sharonensis (2n=14, S1S1) and Ae. longissima (2n=14, S1S1), wild species related to wheat (Triticum), have been known to be retained selectively in durum and common wheats by their gametocidal action that is exerted exclusively on gametes lacking the Aegilops chromosome. Three of such gametocidal chromosomes from Ae. sharonensis and two from Ae. longissima, collected from different sources, were studied on their cytological features, homoeology, and interrelation. One of the Ae. sharonensis and one of the Ae. longissima chromosomes had similar N-banding patterns, which resembled that of wheat chromosome 2B, and were homoeologous to the group 2 wheat chromosomes. The other gametocidal chromosomes, which had been proved or speculated to be in homoelogous group 4, had N-banding patterns relatively similar to wheat chromosome 4A; the two Ae. sharonensis chromosomes could not be distinguished by the N-banding. In double monosomic additions of common wheat with the gametocidal chromosomes of the same homoeology, gametes carrying either or both of the alien chromosome became fertile, and in those with non-homoeologous gametocidal chromosomes, only the gametes carrying the alien chromosome of homoeologous group 4 were functional. Thus, it became clear that there were two types of gametocidal chromosomes each in Ae. sharonensis and Ae. longissima.