Université Montpellier 2, UMR 1098 Développement et Amélioration des Plantes, Place Eugène Bataillon, Montpellier, France.
Mol Biol Evol. 2013 Mar;30(3):569-72. doi: 10.1093/molbev/mss250. Epub 2012 Oct 30.
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.
古植物学研究表明，在陆生植物多样化过程中，根至少独立进化了两次，一次在石松类植物中，一次在真叶植物中。生长素促进了这两组植物的胚胎后根起始，但起始的细胞类型不同。在一些真叶植物中，如拟南芥、水稻和玉米，AS2/LOB 结构域（ASL/LBD）蛋白直接作用于生长素下游，是根起始所必需的保守元件。目前还不清楚在石松类植物和真叶植物中，生长素是否通过类似或不同的遗传机制来促进根起始。我们在跨越生命之树的基因组序列中搜索 ASL/LBD 蛋白，以追溯它们的进化历史。我们对 ASL/LBD 蛋白进行了系统发育分析，并将所有已鉴定的 ASL/LBD 功能映射到系统发育树上。我们鉴定出一个专门与根发育相关的分支，其中不包括石松类植物的序列。这表明在石松类植物和真叶植物中，生长素下游的根起始存在不同的遗传机制。
