A conserved signaling module controls tip growth in liverwort and Arabidopsis (Curr. Biol).
Plants have evolved with rooting cells to anchor them to the land and uptake nutrients efficiently. Growth of root hairs in seed plants or rhizoids in early diverging plants both rely on tip growth, which requires a coordination of wall loosening and deposition of wall materials with cell expansion in order to maintain cell wall integrity. Previous studies in Arabidopsis identified that this process depends on two malectin-like receptor kinases (MLRs) acting upstream of a PTI-like kinase. Here, Westermann et al. found that the MLR and PTI1-like signaling module is conserved between M. polymorpha and A. thaliana. MpMRI can replace the function of AtMRI to maintain cell wall integrity during pollen tube and root hair growth. This study proposes a homologous genetic mechanism regulating in the development of analogous structures of land plants. It also suggests that such an ancient common feature was probably shared by most lineages of land plants. (Summary by Nanxun Qin) Curr. Biol. 10.1016/j.cub.2019.09.069