title: ASL/LBD phylogeny suggests that genetic mechanisms of root initiation downstream of auxin are distinct in lycophytes and euphyllophytes.
abstract: Paleobotanical studies suggest that roots evolved at least twice independently during land plant diversification, once in lycophytes and once in euphyllophytes. Auxin promotes postembryonic root initiation in both groups but from different cell types. In several euphyllophytes, such as Arabidopsis, rice, and maize, AS2/LOB-domain (ASL/LBD) proteins act directly downstream of auxin and are conserved elements necessary for root initiation. It is currently unknown whether similar or different genetic mechanisms act downstream of auxin for root initiation in lycophytes and euphyllophytes. We searched for ASL/LBD proteins in genome sequences spanning the tree of life to retrace their evolutionary history. We performed a phylogenetic analysis of ASL/LBD proteins and mapped the functions of all characterized ASL/LBD onto the phylogenetic trees. We identified a clade specifically associated with root development, which includes no lycophyte sequence. This points toward the existence of distinct genetic mechanisms downstream of auxin for root initiation in lycophytes and euphyllophytes.
authors.affiliation: Université Montpellier 2, UMR 1098 Développement et Amélioration des Plantes, Place Eugène Bataillon, Montpellier, France. ync21@cam.ac.uk
authors.forename: Yoan
authors.initials: Y
authors.lastname: Coudert
authors.forename: Anne
authors.initials: A
authors.lastname: Dievart
authors.forename: Gaetan
authors.initials: G
authors.lastname: Droc
authors.forename: Pascal
authors.initials: P
authors.lastname: Gantet
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D019068:Bryopsida / Q000235:genetics / Q000254:growth & development; D017124:Conserved Sequence; D019143:Evolution, Molecular; D007210:Indoleacetic Acids / Q000378:metabolism*; D012275:Oryza / Q000235:genetics / Q000254:growth & development; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D018517:Plant Roots / Q000235:genetics* / Q000254:growth & development; D017434:Protein Structure, Tertiary; D027843:Vitis / Q000235:genetics / Q000254:growth & development
chemical_list: D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins