Transcription Factors Evolve Faster Than Their Structural Gene Targets in the Flavonoid Pigment Pathway.
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Authors
Walker, Joseph F
Ng, Julienne
Deanna, Rocío
Dunbar-Wallis, Amy
Backes, Alice
Pezzi, Pedro H
Palchetti, M Virginia
Robertson, Holly M
Monaghan, Andrew
de Freitas, Loreta Brandão
Barboza, Gloria E
Publication Date
2022-03-02Journal Title
Mol Biol Evol
ISSN
0737-4038
Publisher
Oxford University Press (OUP)
Volume
39
Issue
3
Type
Article
This Version
VoR
Physical Medium
Print-Electronic
Metadata
Show full item recordCitation
Wheeler, L. C., Walker, J. F., Ng, J., Deanna, R., Dunbar-Wallis, A., Backes, A., Pezzi, P. H., et al. (2022). Transcription Factors Evolve Faster Than Their Structural Gene Targets in the Flavonoid Pigment Pathway.. Mol Biol Evol, 39 (3) https://doi.org/10.1093/molbev/msac044
Abstract
Dissecting the relationship between gene function and substitution rates is key to understanding genome-wide patterns of molecular evolution. Biochemical pathways provide powerful systems for investigating this relationship because the functional role of each gene is often well characterized. Here, we investigate the evolution of the flavonoid pigment pathway in the colorful Petunieae clade of the tomato family (Solanaceae). This pathway is broadly conserved in plants, both in terms of its structural elements and its MYB, basic helix-loop-helix, and WD40 transcriptional regulators, and its function has been extensively studied, particularly in model species of petunia. We built a phylotranscriptomic data set for 69 species of Petunieae to infer patterns of molecular evolution across pathway genes and across lineages. We found that transcription factors exhibit faster rates of molecular evolution (dN/dS) than their targets, with the highly specialized MYB genes evolving fastest. Using the largest comparative data set to date, we recovered little support for the hypothesis that upstream enzymes evolve slower than those occupying more downstream positions, although expression levels do predict molecular evolutionary rates. Although shifts in floral pigmentation were only weakly related to changes affecting coding regions, we found a strong relationship with the presence/absence patterns of MYB transcripts. Intensely pigmented species express all three main MYB anthocyanin activators in petals, whereas pale or white species express few or none. Our findings reinforce the notion that pathway regulators have a dynamic history, involving higher rates of molecular evolution than structural components, along with frequent changes in expression during color transitions.
Keywords
MYB, Petunieae, Solanaceae, anthocyanins, flower color, molecular evolution, phylogenomics, transcription factors
Sponsorship
Gatsby Charitable Foundation Fellowship
Identifiers
External DOI: https://doi.org/10.1093/molbev/msac044
This record's URL: https://www.repository.cam.ac.uk/handle/1810/335032
Rights
Attribution-NonCommercial 4.0 International
Licence URL: https://creativecommons.org/licenses/by-nc/4.0/
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