Kushnir, U., School of Agriculture and Forestry, University of Melbourne, Parkville, 3052, Victoria, Australia
Halloran, G.M., School of Agriculture and Forestry, University of Melbourne, Parkville, 3052, Victoria, Australia

Comparisons were made of levels of chromosome pairing in pentaploid hybrids between normal and ph1b-and ph2-mutant forms of Triticum aestivum ssp. vulgare cv. Chinese Spring each crossed with Triticum kotschyi and T. turgidum var. dicoccoides. Higher levels of multivalent formation in the ph1b-kotschyi, compared with the ph1b-dicoccoides pentaploid was attributed mainly to the absence of allelic buffering, by the Ph1 allele, in the Kotschyi pentaploid and its presence in the dicoccoides pentaploid. The higher level of homoeologous pairing in the ph2-dicoccoides pentaploid compared with that of kotschyi was believed to be due to differential levels of homoe-and non-homoallelic buffering in the two pentaploids. The high level of homoeologous pairing caused by the ph2-mutant in the dicoccoides pentaploid indicates a potential use of pairing promoters, free of homoallelic buffering, as a means of increasing thelevel of homoeologous pairing in wheat and in certain of its hybrids with alien species. © 1982 Dr W. Junk Publishers.