On the location of the asynaptic gene in wheats¹⁾

Tokuhiko MAKINO

Faculty of Agriculture, Tottori University, Tottori, Japan

In several previous studies it was found that the same asynaptic gene as of Chinese Spring of bread wheat (OKAMOTO 1957) is located on each chromosome 5B of two cultivars of bread wheat, Holdfast (RILEY and CHAPMAN 1958, 1960) and Poso (DRISCOLL and QUINN 1968), and of one of durum wheat, Stewart (MOCHIZUKI and KAWATA 1968).

F₁ plants between monosomic 5B F₁s of five Japanese cultivars with Chinese Spring and an inbred rye, strain 10, were grown at 15 to 28C in the greenhouse and PMC's of them were cytologically examined. The results of an observation on the meiotic chromosome associations of 27- and 28-chromosome hybrids (Table 1) show that each chromosome 5B of five Japanese cultivars has the same 5B effect as of Chinese Spring.

Out of five Japanese cultivars examined, only one cultivar, Asozairai, has a major reciprocal translocation concerning with chromosome 5B in relation to Chinese Spring (unpublished). By the meiotic observation of chromosome associations in the F₁ plants between monosomic 5A, 5B and 5D of Chinese Spring and Asozairai it is suggested that the translocated segment of chromosome 5B of Asozairai is larger than that of Poso and that there is one more minor translocation of defficiency-duplication type in addition to the reciprocal one between those two cultivars (Table 2).

It is, therefore, quite probable that the asynaptic gene is basically located on chromosome 5B of both emmer and common wheat, but on the proximal part of the long arm.

Literature cited

DRISCOLL, C. J. and C. J. QUINN 1968. Wheat-alien hybrids involving a chromosome 5B translocation. Can.J.Genet.Cytol. 10 : 217-220.

MOCHIZUKI, A. and H. KAWATA 1968. Meiotic behaviour of a nulli-5B haploid of durum wheat. Japan. J. Breeding 18 (suppl. 2) : 63-64.

OKAMOTO, M. 1957. Asynaptic effect of chromosome V. Wheat Inform. Service 5 : 6.

RILEY, R. and V. CHAPMAN 1958. Genetic control of the cytologically diploid behaviour of hexaploid wheat. Nature 182 : 713-715.

(Received March 3, 1970)