ASSAY OF THE ACTIVITY OF SUPPLEMENTARY DNA IN LOLIUM

Inbreeding species of Lolium have about 40 per cent more nuclear DNA than the outbreeding species. Even so inbreeders may be readily hybridised with outbreeders to produce viable F1’s which, in many cases, are fertile, producing F2 progenies on intercrossing or backcross progenies when crossed with the parents.Recombination between and within chromosomes at meiosis in the F1 results in the quantitative segregation of DNA to the nuclei of gametes and of F2 and backcross progenies. An assay of the effects of the DNA variation among these progenies showed no influence of DNA amount upon the expression of 19 phenotypic characters, ranging from early seedling growth to flowering. There was, however, a very slight reduction from expectation in the mean DNA amount of backcross and F2 progenies. Apart from this slight effect on viability, either of gametes or of zygotes with high nuclear DNA content, our assay shows that the supplementary DNA fraction which distinguishes outbreeding from inbreeding species has, at most, surprisingly little effect upon the growth and development of the Lolium hybrids. © 1979 The Genetical Society of Great Britain.