GENETIC VARIATION IN TRITICUM AFFECTING THE LEVEL OF CHROMOSOME PAIRING IN INTERGENERIC HYBRIDS

Abstract

Genetic differences which affect the extent of homoeologous chromosome pairing in intergeneric hybrids have been demonstrated between varieties of Triticum aestivum. Each of seven varieties of Triticum was crossed with the same strain of Aegilops variabilis. Significant differences in chiasma frequencies between varieties were found. Varieties Eureka, Gamut and Chinese Spring constitute one group with a relatively low chiasma frequency and varieties A. R. Falcon, Federation and Poso constitute a distinct second group with a relatively high chiasma frequency. The variety Bearded Yalta is intermediate to the two groups. Thus, this genetic variation appears to be common among varieties of Triticum. Presumably this variation does not become subject to natural selection as long as chromosome pairing in the parental varieties remains strictly homologous.