The arabidopsis WAVE/SCAR protein BRICK1 associates with cell edges and plasmodesmata.

Plasmodesmata 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 plasmodesmatal 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 A. thaliana 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 plasmodesmatal callose stain aniline blue, further supporting BRK1's association with Plasmodesmata. Together, these findings suggest that the WAVE/SCAR complex participates in plasmodesmatal regulation by promoting ARP2/3-dependent actin filament branching at plasmodesmata, complementing the role of linear actin stabilization by formins.