Genome Size And Fruit Colour Variation In Dasypyrum Villosum

R Obermayer and J Greilhuber

Institute of Botany, University of Vienna, Rennweg 14, A-1030 Vienna, Austria
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    .Dasypyrum villosum (Poaceae) is a diploid Mediterranean grass (2n = 14) exhibiting a modificatory intra-individual fruit colour variation. It is more than surprising that, according to Cremonini et al. (1994) (1), seedlings from yellow caryopses are 1.24- to 1.28-fold higher in genome size than those from brown caryopses. Here we present the results from a re-investigation of this "plastic genome" problem.

    We investigated 29 accessions. Caryopses within spikes and accessions showed a continuum in colour from yellow to dark brown. Therefore, three categories were sorted out; yellow, medium brown and dark brown. Nuclear DNA contents of 186 young plants were measured with PI flow cytometry. The internal standard was Pisum sativum.

    T-tests for paired samples turned out non-significantly, e.g., among 17 accessions in which plants from yellow and dark brown caryopses could be compared, ratios of "yellow versus dark brown" varied between 0.97 and 1.02 (n.s., p = 0.212). However, a moderate variation was found in C-values between accessions up to 1.075-fold and between individuals up to 1.118-fold. C-values of plants from yellow and brown caryopses were correlated at a population level, indicating that the differences between populations are more than random noise (p = 0.001).

    Genome size variation within Dasypyrum is not correlated with the origin of the plants from yellow or brown caryopses, in contrast to a previous report.

    1. Cremonini R, Colonna N, Stefani A, Galasso I, Pignone D. (1994). Heredity 72: 365-373.