A protein complex required for polar growth of rhizobial infection threads

The colonization of many legumes by their rhizobial symbionts occurs through infection threads crossing the cells, which are initially formed in root hairs. The authors of this article show that a protein complex located notably at the tip of the growing thread is required for the polar growth of this infection compartment in the root hairs.

This complex comprises the VAPYRIN and VAPYRIN-LIKE proteins, stabilized by an E3 ligase called LUMPY INFECTION (LIN), as well as a subunit of the exocyst complex (involved in the transport of vesicles). Thus, two symbiotic proteins, VAPYRIN and LIN, orchestrate the polar growth of rhizobial infection threads, in connection with the cell machinery for secretion and with the nucleus.