We have located links that may give you full text access.
Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Relaxed constraint and evolutionary rate variation between basic helix-loop-helix floral anthocyanin regulators in Ipomoea.
Molecular Biology and Evolution 2007 December
Regulatory genes are believed to play a large role in morphological diversification and are often characterized by elevated rates of evolution. Whether this rapid evolution is primarily due to adaptive differentiation or relaxed selective constraint remains an open question. We attempted to distinguish between these alternative outcomes in 2 transcription factors known to regulate the expression of anthocyanin pigmentation genes in flowers. We cloned the full-length coding region from 2 basic helix-loop-helix transcription factors from several species of Ipomoea with diverse flower colors and determined the selective forces operating on them. In both genes, rapidly evolving sites and indel mutations are clustered in nonbinding domains, but the extent of rate acceleration in these domains is reduced relative to most previously characterized plant transcription factors. Moreover, codon models of substitution rates and models evaluating the magnitude of change to physical amino acid properties demonstrate little evidence for adaptive evolution and suggest that elevated nonsynonymous substitution rates in these domains represent relaxed selective constraint. Although both genes show qualitatively similar patterns, their rates of evolution differ significantly due to an increased rate of nonsynonymous substitutions in the nonbinding domains in one copy, suggesting substantial differences in functional constraint on each gene. In general, these results provide additional evidence demonstrating that decreased constraint as opposed to positive selection is largely responsible for the frequently observed pattern of rapid evolution in particular domains of plant transcription factors. More specifically, they suggest that most of the amino acid substitutions are neutral and do not implicate a role for natural selection on these regulatory genes in the diversification of flower color in Ipomoea.
Full text links
Related Resources
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app
All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.
By using this service, you agree to our terms of use and privacy policy.
Your Privacy Choices
You can now claim free CME credits for this literature searchClaim now
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app