Developmentally distinct MYB genes encode functionally equivalent proteins in Arabidopsis.
The duplication and divergence of developmental control genes is thought to have driven morphological diversification during the evolution of multicellular organisms. To examine the molecular basis of this process, we analyzed the functional relationship between two paralogous MYB transcription factor genes, WEREWOLF (WER) and GLABROUS1 (GL1), in Arabidopsis. The WER and GL1 genes specify distinct cell types and exhibit non-overlapping expression patterns during Arabidopsis development. Nevertheless, reciprocal complementation experiments with a series of gene fusions showed that WER and GL1 encode functionally equivalent proteins, and their unique roles in plant development are entirely due to differences in their cis-regulatory sequences. Similar experiments with a distantly related MYB gene (MYB2) showed that its product cannot functionally substitute for WER or GL1. Furthermore, an analysis of the WER and GL1 proteins shows that conserved sequences correspond to specific functional domains. These results provide new insights into the evolution of the MYB gene family in Arabidopsis, and, more generally, they demonstrate that novel developmental gene function may arise solely by the modification of cis-regulatory sequences.
Lee
M M
MM
Department of Biology, University of Michigan, Ann Arbor, Michigan 48109, USA.
Schiefelbein
J
J
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins / Q000235:genetics*; D017343:Genes, Plant; D020570:Genes, myb; D005816:Genetic Complementation Test; D018546:Hypocotyl / Q000166:cytology; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics*; D018517:Plant Roots / Q000166:cytology; D015800:Protozoan Proteins; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics; D015533:Transcriptional Activation
D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; C112737:MYB2 protein, Dictyostelium discoideum; D010940:Plant Proteins; D015800:Protozoan Proteins; D014157:Transcription Factors; C402111:WER protein, Arabidopsis; C071556:GL1 protein, Arabidopsis