title: Divergence in Enzymatic Activities in the Soybean GST Supergene Family Provides New Insight into the Evolutionary Dynamics of Whole-Genome Duplicates.
abstract: Whole-genome duplication (WGD), or polyploidy, is a major force in plant genome evolution. A duplicate of all genes is present in the genome immediately following a WGD event. However, the evolutionary mechanisms responsible for the loss of, or retention and subsequent functional divergence of polyploidy-derived duplicates remain largely unknown. In this study we reconstructed the evolutionary history of the glutathione S-transferase (GST) gene family from the soybean genome, and identified 72 GST duplicated gene pairs formed by a recent Glycine-specific WGD event occurring approximately 13 Ma. We found that 72% of duplicated GST gene pairs experienced gene losses or pseudogenization, whereas 28% of GST gene pairs have been retained in the soybean genome. The GST pseudogenes were under relaxed selective constraints, whereas functional GSTs were subject to strong purifying selection. Plant GST genes play important roles in stress tolerance and detoxification metabolism. By examining the gene expression responses to abiotic stresses and enzymatic properties of the ancestral and current proteins, we found that polyploidy-derived GST duplicates show the divergence in enzymatic activities. Through site-directed mutagenesis of ancestral proteins, this study revealed that nonsynonymous substitutions of key amino acid sites play an important role in the divergence of enzymatic functions of polyploidy-derived GST duplicates. These findings provide new insights into the evolutionary and functional dynamics of polyploidy-derived duplicate genes.
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, China University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Hai-Jing
authors.initials: HJ
authors.lastname: Liu
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, China.
authors.forename: Zhen-Xin
authors.initials: ZX
authors.lastname: Tang
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, China.
authors.forename: Xue-Min
authors.initials: XM
authors.lastname: Han
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, China.
authors.forename: Zhi-Ling
authors.initials: ZL
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
authors.forename: Fu-Min
authors.initials: FM
authors.lastname: Zhang
authors.affiliation: College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, China.
authors.forename: Hai-Ling
authors.initials: HL
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, China yanjing.liu@ibcas.ac.cn qingyin.zeng@ibcas.ac.cn.
authors.forename: Yan-Jing
authors.initials: YJ
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, China University of Chinese Academy of Sciences, Beijing, China yanjing.liu@ibcas.ac.cn qingyin.zeng@ibcas.ac.cn.
authors.forename: Qing-Yin
authors.initials: QY
authors.lastname: Zeng
mesh_terms: D005075:Biological Evolution; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant; D020131:Genes, Duplicate; D017343:Genes, Plant; D014644:Genetic Variation; D018745:Genome, Plant; D005982:Glutathione Transferase / Q000235:genetics* / Q000378:metabolism; D008957:Models, Genetic; D016297:Mutagenesis, Site-Directed; D010802:Phylogeny; D011123:Polyploidy; D013025:Glycine max / Q000201:enzymology* / Q000235:genetics*
chemical_list: D005982:Glutathione Transferase
keywords: enzyme activity; functional divergence; gene and genome duplication; gene family; glutathione S-transferase