title: The invention of WUS-like stem cell-promoting functions in plants predates leptosporangiate ferns.
abstract: The growth of land plants depends on stem cell-containing meristems which show major differences in their architecture from basal to higher plant species. In Arabidopsis, the stem cell niches in the shoot and root meristems are promoted by WUSCHEL (WUS) and WOX5, respectively. Both genes are members of a non-ancestral clade of the WUS-related homeobox (WOX) gene family, which is absent in extant bryophytes and lycophytes. Our analyses of five fern species suggest that a single WUS orthologue was present in the last common ancestor (LCA) of leptosporangiate ferns and seed plants. In the extant fern Ceratopteris richardii, the WUS pro-orthologue marks the pluripotent cell fate of immediate descendants of the root apical initial, so-called merophytes, which undergo a series of stereotypic cell divisions and give rise to all cell types of the root except the root cap. The invention of a WUS-like function within the WOX gene family in an ancestor of leptosporangiate ferns and seed plants and its amplification and sub-functionalisation to different stem cell niches might relate to the success of seed plants, especially angiosperms.
authors.affiliation: Institute of Developmental Biology, University of Cologne, Cologne Biocenter, Cologne, Germany.
authors.forename: Judith
authors.initials: J
authors.lastname: Nardmann
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Werr
mesh_terms: D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000235:genetics; D019143:Evolution, Molecular; D029624:Ferns / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000145:classification / Q000235:genetics*; D017403:In Situ Hybridization; D018519:Meristem / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D059828:Plant Cells / Q000378:metabolism*; D063245:Plant Development; D010940:Plant Proteins / Q000145:classification / Q000235:genetics*; D018517:Plant Roots / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D018547:Plant Stems / Q000166:cytology / Q000235:genetics / Q000254:growth & development; D010944:Plants / Q000145:classification / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D055153:Stem Cell Niche / Q000235:genetics; D013234:Stem Cells / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D010940:Plant Proteins; C116421:WUSCHEL protein, Arabidopsis
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