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Published on: January 12, 2019
Evolutionary rate patterns of the Gibberellin pathway genes
Yan-hua Yang1, Fu-min Zhang, Song Ge
1State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, PR China. yanhuayang@126.com
BMC Evolutionary Biology
|August 20, 2009
Summary
Molecular evolution of gibberellin pathway genes in rice shows significant rate variation. Natural selection favors enzymes controlling pathway flux, with no evidence of positive selection driving evolution.
Area of Science:
- Molecular evolution
- Plant biochemistry
- Population genetics
Background:
- Understanding molecular evolutionary patterns in metabolic pathways reveals how natural selection shapes protein evolution in interacting systems.
- Previous research suggested upstream genes evolve slower than downstream genes, but the correlation between gene position and evolutionary rate remains unclear.
Purpose of the Study:
- To investigate evolutionary rates and patterns of core structural genes in the gibberellin (GA) biosynthetic pathway.
- To test hypotheses regarding gene position, evolutionary forces, and selection intensity within metabolic pathways.
Main Methods:
- Sequencing and characterization of 7 core gibberellin biosynthetic pathway genes from 8 rice tribe (Oryzeae) species.
- Analysis of synonymous and nonsynonymous substitution rates using branch and codon models.
Main Results:
- Significant rate heterogeneity was detected among the 7 GA pathway genes, primarily due to varying selection intensity, not mutation pressure.
- Contrary to previous hypotheses, downstream GA pathway genes did not show elevated rates; genes at branch points or catalyzing multiple steps evolved slowest due to strong purifying selection.
- No evidence of positive selection was found for any lineage or codon within the GA pathway genes.
Conclusions:
- Evolutionary rate heterogeneity in GA pathway genes is mainly driven by differential constraint relaxation, not positive selection.
- Findings support the pathway flux theory, indicating natural selection targets enzymes with the greatest control over metabolic fluxes.
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