Homology of chromosome II of Chinese Spring with a chromosome of Triticum monococcum

KOZO NISHIKAWA

Faculty of Agriculture, Gifu University, Gifu, Japan

OKAMOTO (1962) assigned fourteen chromosomes (formerly I-XIV) of Chinese Spring, a variety of Triticum aestivum, to the A and B genomes. Recently, CHAPMAN and RILEY (1966) confirmed OKAMOTO's assignment except for two chromosomes (II and XIII) belonging to the homoeologous group 2.

The present author crossed T. monococcum var. vulgare (Early) as pollen parent to a 29-chromosome plant derived from Chinese Spring-durum (LD 222) hybrid that was marked with telo II right ; the 29-chrosome plant had thirteen normal and one heteromorphic bivalent and one univalent that is presumably 2D. Out of nine F₁'s cytologically checked, only one was found to be the desired hybrid carrying the telocentric chromosome in addition to the 20 normal chromosomes of A and B genomes and one D genome chromosome. Chromosome pairing in the hybrid is summarized in the table below.

Mean pairing was such as could be expected in a durum-monococcum hybrid. The telocentric for chromosome II participated in pairing in more than 80 per cent of PMC's. The homologous partner of the telocentric seems to be one of the T. monococcum chromosomes because the extra D genome chromosome paired only very rarely with the telocentric and its homologue, forming a trivalent in the 29 chromosome parent. The present result is consistent with that of CHAPMAN and RILEY, indicating that chromosome II should be assigned to A genome.

Chromosome pairing at MI in the hybrid between T. durum telocentric for chromosome II right and T. monococcum vulgare :

(Received June 26, 1967)