Molecular evolution and phylogenetic application of DMC1.

The protein encoded by the single-copy nuclear gene DMC1 belongs to the recA-like group of proteins involved in meiosis. Partial nucleotide sequence, spanning exon 10 to exon 15, was used to test the applicability of the gene to phylogenetic studies in higher plants and used to assess its molecular evolution. The sequences produced from the Triticeae (Poaceae) show that most of the variation is confined to the introns. If a wider taxon sampling is used, alignment problems may be predicted. Comparisons including four complete coding sequences from GenBank reveal that the exons are more than twice as variable as rbcL, but easy to align, and hence may be valuable at higher taxonomic levels. Substitution rates are variable within the Triticeae, though local subclades show rate constancy. The relationships between exon variation and predicted protein structure are briefly discussed. In general, none of the observed nucleotide substitutions can be predicted to cause major structural or functional changes.