| Chromosome pairing in hybrids between Aegilops sharonensis
and some species of Aegilops and Triticum By Masatake TANAKA Lab. Genet., Kyoto Univ., Kyoto Chromosome pairing and fertility of the hybrids are listed in Table 1. In Ae. sharonensis x Ae. longissima and the reciprocal hybrid, the chromosome pairing was the regular of the investigated combinations. However, one tetravalent was found in every PMC, and rarely one univalent. The pollen- and seed-fertility were practically normal: 81.3-87.1% and 81.8-86.0%, respectively. The outer glumes of Ae. sharonensis are awned but those of Ae. longissima are not. The hybrids are awnless. The F2 segregated in awnless : awned in the proportion of 38:12. In the backcrosses the segregatidn was 29:0 in F1 x Ae.longissima, and 12:9 in F1 x Ae. sharonensis. In the hybrid Ae. sharonensis x Ae. bicornis the chromosome pairing was fairly regular but a few univalents were found. Pollen- and seed-fertility were high. But the plants were dwarf-like and weak. In the hybrid Ae. Aucheri x Ae. sharonensis and its reciprocal more univalents were found than in the hybrid between the latter and other species of S-group. Pollen fertility was very low (3.5%) and no seed, even from open pollination, was obtained. The plants were semi-dwarfs. These results suggest that the genome of Ae. sharonensis is homologous to that of Ae. longissima (S1-genome), except for one translocation. Accordingly, from the view point of genome analysis, Ae. sharonensis may be considered to be a variety of Ae. longissima. According to EIG (1929), Ae. sharonensis is closely related to Triticum. Unpublished data of the present writer and MATSUBAYASHI indicate that Ae. longissima and Ae. sharonensis have, some morphological characteristics of the B-genome of Emmer- and Dinkel-wheats. However, the chromosome pairing in the hybrids of Ae. sharonensis with T. monococcum and T.turgidum is so incomplete that S1-genome cannot be homologous to B-genome. |