| Genomes of 6x species of Aegilops*
H. KIHARA, K. YAMASHITA and M. TANAKA National Institute of Genetics, Misima and Kyoto University, Kyoto, Japan Aegilops crassa According to Eig (1929), the species Ae.crassa is known to be distributed through Palestine, Syria, Iraq, Iran, Afghanistan and Turkestan in U.S.S.R., but the respective geographical distributions of the 4x and 6x forms have not been established as yet. In our collection however, one strain from Iraq proved to be 4x, while one from Tashkent in Trukestan (U.S.S.R.) was 6x. In addition to these, it has also been found that among the materials collected by our expedition to the Karakoram and Hindukush in 1955, all the strains from lran are 4x while in the northern stretch of the Hindukush Range in Afghanistan, namely in Pulikhumri and Maimana, 6x forms grow mixed together with the 4x. There were noticed significant ecological and morphological differences between Afghan and Iranian strains, namely the Iranian is recumbent and has narrow and dark green leaves, while the Afghan is erect and has broad and light green leaves. Near Kandahar, Afghanistan, a new awnless 4x form was collected. Morphological analyses have been carried on for the comparison of the 4x and 6x forms. The characteristics represented by M genome are apparent in the 4x form and the characteristics by D genome are seen in the 6x form. From these facts, it can be said that the third genome involved in the 6x form is supposed to be D. We have further evidences, which will be discussed here. An amphiploid was obtained by colchicine method from the cross between Ae. crassa 4x (DMcr) and Ae. squarrosa (D). Accordingly its genome constitution is DDMcr. The amphidiploid resembles the 6x species of Ae. crassa and the chromosome pairing of the plant is good (average number of bivalents per cell is 20.57), and its fertility is nearly normal. This plant was crossed to the 6x forms for the purpose of genome analysis. F1 hybrids showed rather good chromosome pairing in average, namely, up to about 19 pairs, and the fertility was rather high, namelr the pollen fertility was 68.8% and seed fertility was 90%. Based on thcse data it is clear that the parents in this cross have closely related genomes. The 4x form of Ae. crassa would have bcen originated somewhere in and around Asia Minor. Where will be the home of the 6x form of Ae. crassa ? From the fact that both 4x and 6x forms were found in a mixture in the northern stretch of the Hindukush Range in Afghanistan, it can be said that the 6x form was originated there from the cross between the 4x form of Ae. crassa (DMcr) and Ae.squarrosa (D) distributed there forming a wide simple popuiation. According to the communication of Dr. Kuckuck his 6x material of Ae. crassa was found solely in Khorasan, the north-eastern part of Iran. |
| * This paper was read by K. Yamashita at the 10th International Genetics Congress in Montreal, 1958. |
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