Using Physcomitrella patens to Reconstruct the Role of EVE1 in the Evolution of Land Plants

A key innovation that directly preceded the evolution of the angiosperms was the development of vessel elements. In most instances this cell type allows for more efficient water conductivity through the plant stem. Recently we discovered the ENLARGED VESSEL ELEMENTS 1 (EVE1) gene in Populus trichocarpa. EVE1 overexpression in Populus led to increased vessel area as well as greater height growth and survival compared to wild-type at high temperature. Curiously, putative EVE1 orthologs have been detected in the genomes of the sister group to the land plants (streptophyte algae), and are maintained in genomes from species across the plant kingdom, including plants like mosses that lack any vasculature. Currently we are using the moss Physcomitrella patens to understand the developmental and physiological role of EVE1 orthologs across the land plants, in particular the role of EVE1 in species that do not contain vessel elements. We are currently overexpressing both the P. thrichocarpa EVE1 and an endogenous EVE1 in P. patens, and we plan to suppress the three P. patens EVE1 homologs using antisense-mediated gene silencing. Using a gene targeting strategy adapted for P. patens, we hope to reconstruct the role of EVE1 in the evolution of land plants.