Studies on the production of amphidploid as the source of resistance to leaf-rust of wheats : V. Cytogenetic studies on the F₁ hybrids and the amphidiploids, Triticum Timopheeve Zhuk. × Aegilops umbellulata Zhuk.

Abstract

With an aim to obtain a good source of resistance to leaf-rust of wheats, the amphidiploid of T. Tiopheevi Zhuk, and Ae. umbellulata Zhuk. wassynthesized by treating thc F₁ seed with O.05% colchicine. In the root-tip cells of the F₁ plant, 21 somatic chromosomes were confirmed, which correspone to the sum of the reduced numbers of their parents, and in those of amphidiploids 42 chromnosomes were clearly counted corresponding to the multiple number of chromosomes of the F₁ plant. The modal meiotic configuration of the F₁ hybrid is 1_II+19_I, followed closely by 21_I. Two to four bivalents were observed also. The modal meiotic configuration of the amphidiploids was 21_II, but 20_II +2_I was also encountered rather frequently. The spikes of the new amphidiploid were similar to those of T. Timopheevi, but in the manner of disarticulation of spikes they showed "umbrella-type" dominantly like Ae. umbellulta. The grains were large and firmly adherent to the glumes. They were immune from many races of Puccinia triticia and crossed quite readily not only with the cultivated varieties within uulgare group but also with other species in Dinkel series. Therefore, they are expected to be the useful breeding material as a source of resistance to leaf-rust of wheats.