DNA base composition heterogeneity in the grass genus Briza L.

Abstract

Intragenomic DNA base composition heterogeneity is determined for eight species of Briza L. (Poaceae). High-resolution first-derivative DNA denaturation profiles, recording base composition distribution, provide a "fingerprint" of a species genome. Differences in base composition between species may be explained by chromosome loss or recent sequence amplification events and correlate with relationships established by traditional biosystematic methods. The complex polyphasic profiles can be deconvoluted into a small number of Gaussian curves that accurately represent the complex profile. The physical basis of this representation is demonstrated by affinity chromatography of DNA fragments of at least 600 base pairs, which separates a number of components. Key words: Briza, DNA base composition, genome heterogeneity, grass systematics, thermal denaturation.