The effect of ph mutations on homoeolgous pairing in hybrids of wheat with Triticum longissimum.

Homoeologous pairing at metaphase-I was analyzed in wild-type, ph2b, and ph1b hybrids of wheat and a low-pairing type of T. longissimum in order to study the effect of ph mutations on the pairing of T. longissimum chromosomes with wheat chromosomes. Chromosomes of both species, and their arms, were identified by C-banding. The three types of hybrids, with low-, intermediate-, and high-pairing levels, respectively, exhibited a very similar pairing pattern which was characterized by the existence of two types, A-D and B-S(1), of preferential pairing. These results confirm that the S(1) genome of T. longissimum is closely related to the B genome of wheat. The possible use of ph1b and ph2b mutations in the transfer to wheat of genes from related species is discussed.