The SYP123-VAMP727 SNARE Complex Is Involved in the Delivery of Inner Cell Wall Components to the Root Hair Shank in Arabidopsis

The study investigated the mechanism of deposition of inner cell wall materials in the shank of Arabidopsis root hairs, a process less understood compared to the secretion at the root hair apex. The researchers found that the Qa-SNARE protein SYP123 localizes to the subapical zone and shank of elongating root hairs and is involved in their elongation. They discovered that SYP123's plasma membrane localization is affected by the production of phosphatidylinositol-3,5-bisphosphate (PtdIns(3,5)P2), and that SYP123 forms a SNARE complex with VAMP727. Mutants of syp123 and vamp727 showed reduced cell wall stiffness in the root hair shank due to impaired deposition of inner cell wall components. This indicates that the SYP123/VAMP727-mediated secretion pathway is crucial for the transport of inner cell wall components necessary for the hardening of the root hair shank.