Ambrose, C.; Chi, Z.

Plasmodesmata (PD) are specialized structures in plant cell walls that mediate intercellular communication by regulating the trafficking of molecules between adjacent cells. The actin cytoskeleton plays a pivotal role in controlling PD permeability, but the molecular mechanisms underlying this regulation remain unclear. Here, we report that BRK1, a component of the WAVE/SCAR complex involved in Arp2/3-mediated actin nucleation, localizes to PD and primary pit fields in Arabidopsis cotyledons, leaves, and hypocotyls. Using a BRK1-YFP reporter line, we detected BRK1 enrichment at cell edges and in primary pit fields, identified by regions of reduced propidium iodide staining. We also observed colocalization between BRK1-YFP and the PD callose stain aniline blue, further supporting BRK1s association with PD. Together, these findings suggest that the WAVE/SCAR complex participates in PD regulation by promoting ARP2/3-dependent actin filament branching at PD, complementing the role of linear actin stabilization by formins.