title: Divergence and adaptive evolution of the gibberellin oxidase genes in plants.
abstract: BACKGROUND
  The important phytohormone gibberellins (GAs) play key roles in various developmental processes. GA oxidases (GAoxs) are critical enzymes in GA synthesis pathway, but their classification, evolutionary history and the forces driving the evolution of plant GAox genes remain poorly understood.
  
  
  RESULTS
  This study provides the first large-scale evolutionary analysis of GAox genes in plants by using an extensive whole-genome dataset of 41 species, representing green algae, bryophytes, pteridophyte, and seed plants. We defined eight subfamilies under the GAox family, namely C19-GA2ox, C20-GA2ox, GA20ox,GA3ox, GAox-A, GAox-B, GAox-C and GAox-D. Of these, subfamilies GAox-A, GAox-B, GAox-C and GAox-D are described for the first time. On the basis of phylogenetic analyses and characteristic motifs of GAox genes, we demonstrated a rapid expansion and functional divergence of the GAox genes during the diversification of land plants. We also detected the subfamily-specific motifs and potential sites of some GAox genes, which might have evolved under positive selection.
  
  
  CONCLUSIONS
  GAox genes originated very early-before the divergence of bryophytes and the vascular plants and the diversification of GAox genes is associated with the functional divergence and could be driven by positive selection. Our study not only provides information on the classification of GAox genes, but also facilitates the further functional characterization and analysis of GA oxidases.
authors.affiliation: College of Life Sciences, Peking University, Beijing, 100871, China. huangyuan@pku.edu.cn.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Huang
authors.affiliation: College of Life Sciences, Peking University, Beijing, 100871, China. wangxi2245@pku.edu.cn.
authors.forename: Xi
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China. gesong@ibcas.ac.cn.
authors.forename: Song
authors.initials: S
authors.lastname: Ge
authors.affiliation: College of Life Sciences, Peking University, Beijing, 100871, China. rao@pku.edu.cn.
authors.forename: Guang-Yuan
authors.initials: GY
authors.lastname: Rao
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019143:Evolution, Molecular; D017343:Genes, Plant; D005875:Gibberellins / Q000096:biosynthesis; D006899:Mixed Function Oxygenases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D010944:Plants / Q000145:classification / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D012639:Seeds / Q000235:genetics; D016415:Sequence Alignment
chemical_list: D005875:Gibberellins; D006899:Mixed Function Oxygenases