An Evolutionarily Conserved Receptor-like Kinases Signaling Module Controls Cell Wall Integrity During Tip Growth.

Rooting cells and pollen tubes-key adaptative innovations that evolved during the colonization and subsequent radiation of plants on land-expand by tip growth. Tip growth relies on a tight coordination between the protoplast growth and the synthesis/remodeling of the external cell wall. In root hairs and pollen tubes of the seed plant Arabidopsis thaliana, cell wall integrity (CWI) mechanisms monitor this coordination through the Malectin-like receptor kinases (MLRs), such as AtANXUR1 and AtFERONIA, that act upstream of the AtMARIS PTI1-like kinase. Here, we show that rhizoid growth in the early diverging plant, Marchantia polymorpha, is also controlled by an MLR and PTI1-like signaling module. Rhizoids, root hairs, and pollen tubes respond similarly to disruption of MLR and PTI1-like encoding genes. Thus, the MLR and PTI1-like signaling module that controls CWI during tip growth is conserved between M. polymorpha and A. thaliana, suggesting that it was active in the common ancestor of land plants.