title: Decipher the ancestry of the plant-specific LBD gene family.
abstract: Lateral Organ Boundaries Domain (LBD) genes arise from charophyte algae and evolve essential functions in land plants in regulating organ development and secondary metabolism. Although diverse plant species have been investigated to construct the phylogeny of LBD gene family, a detailed and reliable ancestry that characterizes their evolutionary patterns has not been revealed.
  
  
  
  We develop an improved bioinformatic method that allows robust detection of 431 LBD genes in 11 high-quality land plant genomes. Phylogenetic analysis classifies the LBD genes into six subfamilies which support the existence of 7 ancient gene lineages. Phylogenetic relationship and gene collinearity are combined to retrace 11 ancestor genes for seed plants and 18 ancestor genes for angiosperms, which improves the resolution of LBD gene ancestry. The ancient gene lineages are strictly preserved in current plant genomes, including the previously controversial class IB gene in Selaginella moellendorphii, suggesting extreme reluctance of LBD genes to be lost during evolution. Meanwhile, whole-genome and dispersed gene duplications substantially expand LBD gene family in angiosperms, and elaborate functions of LBD genes through frequent expression pattern change and protein sequence variation.
  
  
  
  Through phylogenetic and gene collinearity analyses, we retrace the landscape of LBD gene ancestry which lays foundation for elucidating evolutionary diversification of LBD genes in land plants.
authors.affiliation: Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
authors.forename: Yimeng
authors.initials: Y
authors.lastname: Kong
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Xu
authors.affiliation: Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
authors.forename: Xinyun
authors.initials: X
authors.lastname: Jing
authors.affiliation: Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
authors.forename: Longxian
authors.initials: L
authors.lastname: Chen
authors.affiliation: National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China. lgli@sibs.ac.cn.
authors.forename: Laigeng
authors.initials: L
authors.lastname: Li
authors.affiliation: Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China. lixuan@sippe.ac.cn.
authors.forename: Xuan
authors.initials: X
authors.lastname: Li
mesh_terms: D016000:Cluster Analysis; D019143:Evolution, Molecular; D020440:Gene Duplication; D020869:Gene Expression Profiling; D017343:Genes, Plant; D019684:Magnoliopsida / Q000145:classification / Q000235:genetics; D005810:Multigene Family; D010802:Phylogeny; D010944:Plants / Q000145:classification / Q000235:genetics*
keywords: Evolution; LBD gene family; Land plant; Phylogenetic analysis