title: Positive selection and functional divergence of R2R3-MYB paralogous genes expressed in inflorescence buds of Scutellaria species (Labiatae).
abstract: Anthocyanin is the main pigment forming floral diversity. Several transcription factors that regulate the expression of anthocyanin biosynthetic genes belong to the R2R3-MYB family. Here we examined the transcriptomes of inflorescence buds of Scutellaria species (skullcaps), identified the expression R2R3-MYBs, and detected the genetic signatures of positive selection for adaptive divergence across the rapidly evolving skullcaps. In the inflorescence buds, seven R2R3-MYBs were identified. MYB11 and MYB16 were detected to be positively selected. The signature of positive selection on MYB genes indicated that species diversification could be affected by transcriptional regulation, rather than at the translational level. When comparing among the background lineages of Arabidopsis, tomato, rice, and Amborella, heterogeneous evolutionary rates were detected among MYB paralogs, especially between MYB13 and MYB19. Significantly different evolutionary rates were also evidenced by type-I functional divergence between MYB13 and MYB19, and the accelerated evolutionary rates in MYB19, implied the acquisition of novel functions. Another paralogous pair, MYB2/7 and MYB11, revealed significant radical amino acid changes, indicating divergence in the regulation of different anthocyanin-biosynthetic enzymes. Our findings not only showed that Scutellaria R2R3-MYBs are functionally divergent and positively selected, but also indicated the adaptive relevance of regulatory genes in floral diversification.
authors.affiliation: Department of Life Science, National Taiwan Normal University, 88, Ting-Chow Rd., Sec. 4, Taipei 116, Taiwan. 80243011s@ntnu.edu.tw.
authors.forename: Bing-Hong
authors.initials: BH
authors.lastname: Huang
authors.affiliation: Laboratory of Computational Molecular Biology, College of Life Sciences, Beijing Normal University, Beijing 100875, China. pangerli@bnu.edu.cn.
authors.forename: Erli
authors.initials: E
authors.lastname: Pang
authors.affiliation: Department of Biological Science and Technology, National Pingtung University of Science and Technology, 1, Shuefu Rd., Neipu, Pingtung 912, Taiwan. m10118029@mail.npust.edu.tw.
authors.forename: Yi-Wen
authors.initials: YW
authors.lastname: Chen
authors.affiliation: Laboratory of Computational Molecular Biology, College of Life Sciences, Beijing Normal University, Beijing 100875, China. hfcao@mail.bnu.edu.cn.
authors.forename: Huifen
authors.initials: H
authors.lastname: Cao
authors.affiliation: School of Life Science and Engineering, Chongqing Three Gorges University, Chongqing 404001, China. ruanyu2@163.com.|The College of Forestry, Beijing Forestry University, Beijing 100083, China. ruanyu2@163.com.
authors.forename: Yu
authors.initials: Y
authors.lastname: Ruan
authors.affiliation: Department of Life Science, National Taiwan Normal University, 88, Ting-Chow Rd., Sec. 4, Taipei 116, Taiwan. pcliao@ntnu.edu.tw.
authors.forename: Pei-Chun
authors.initials: PC
authors.lastname: Liao
mesh_terms: D000595:Amino Acid Sequence; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D056626:Inflorescence / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D031363:Scutellaria / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D012641:Selection, Genetic; D016415:Sequence Alignment; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D014157:Transcription Factors