| An attempt to induce tetraploids with AABB from Japanese
wheat varieties with AABBDD I. NISHIYAMA Faculty of Agriculture, Kyoto University, Kyoto, Japan This paper is a preliminary note on the analysis of genome differentiation in Japanese common wheat varieties having the genome formula AABBDD. Two wheat varieties, Shinchunaga and Igachikugo, were crossed with pollen of Triticum polonicum having AABB. In 1952 the pentaploid F1 hybrids were grown and their progenies especially those having 14 bivalents were raised in the successive generations through self-pollination. In some cases the hybrid derivatives were backcrossed with the common wheat parent and their backcrossed progenies showing 14 bivalents were grown in the subsequent generations. In addition to the chromosome number the hybrid derivatives were selected on the basis of their morphology, and only plants which were less like T.polonicum were growon in the next generation. In 1959-60 the characteristics of hybrid derivatives with 14 bivalents were investigated in comparison with those of their parents, and the following can be said. (1) Out of 21 characters investigated 8-14 seem to have been derived from the common wheat, 7-13 from T. polonicum or a part of them probably from AB genomes of the common wheat, and 0-1 is common with both parents. (2) Most of tetraploid derivatives from the cross where Shinchunaga was used as one of the parents, showed a high sterility. (3) Chromosome configurations at meiosis in tetraploid derivatives were usually quite normal, but 1IV + 12II were observed in backcross F1 hybrids between T. polonicum and one tetraploid line from the original hybrid lgachikugo x T. polonicum. (4) Dwarf or rosette-type plants were found in a progeny of the original hybrid, Igachikugo x T. polonicum, and they behaved as simple recessive Mendelian characters. (5) The author never found any tetraploid derivatives which were similar to T. dicoccoides. This fact suggests that T. dicoccoides was not the ancestral plant of Japanese common wheats. |