Molecular evolution of the plant R regulatory gene family.
Anthocyanin pigmentation patterns in different plant species are controlled in part by members of the myc-like R regulatory gene family. We have examined the molecular evolution of this gene family in seven plant species. Three regions of the R protein show sequence conservation between monocot and dicot R genes. These regions encode the basic helix-loop-helix domain, as well as conserved N-terminal and C-terminal domains; mean replacement rates for these conserved regions are 1.02 x 10(-9) nonsynonymous nucleotide substitutions per site per year. More than one-half of the protein, however, is diverging rapidly, with nonsynonymous substitution rates of 4.08 x 10(-9) substitutions per site per year. Detailed analysis of R homologs within the grasses (Poaceae) confirm that these variable regions are indeed evolving faster than the flanking conserved domains. Both nucleotide substitutions and small insertion/deletions contribute to the diversification of the variable regions within these regulatory genes. These results demonstrate that large tracts of sequence in these regulatory loci are evolving at a fairly rapid rate.
Department of Botany, University of Georgia, Athens 30602.
M D
MD
Purugganan
S R
SR
Wessler
D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D017931:DNA Primers; D017343:Genes, Plant; D005809:Genes, Regulator; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D006109:Poaceae / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers