The homoeologous relationships of rye chromosomes 4R and 7R with wheat chromosomes

By means of rye chromosome CR from Imperial added to Chinese Spring wheat the alien substitutions 4A/CR, 4A/CR^S, 4B/CR, 4D/CR, 4D/CR^S, 7A/CR^L, 7B/CR, 7B/CR^L, 7D/CR and 7D/CR^L were isolated. Substitutions 4A/CR^S and 4D/CR^S had a better fertility and vegetative vigour than the corresponding substitutions with the complete chromosome CR. In substitutions the entire chromosome CR did not compensate for the absence of wheat chromosomes of group 7, whereas the substitutions 7A/CR^L, 7B/CR^L and 7D/CR^L were more fertile than the corresponding nullisomics 7A, 7B and 7D. It was shown that the short arm of CR is homoeologous to wheat telosomes 4A^α, 4B^L and 4D^S, whereas most of the long arm of CR is homoeologous to the wheat arms 7A^S, 7B^S and 7D^S. Rye chromosome CR is designated 4R. Only three substitutions with rye chromosome DR were produced. The fertility of substitutions 7A/DR and 7B/DR were considerably lower than that of nulli-7A and nulli-7B. The 4B/DR substitution was sterile. Rye chromosome DR is believed to be a double interchanged chromosome in comparison to the corresponding Secale montanum chromosomes. Rye chromosome DR is designated 7R. On the basis of substitution ability of CR and DR and several homoeologous gene loci on these chromosomes an evolutionary scheme for the derivation of the Secale cereale genome from Secale montanum is outlined.