P-369 - Investigate the role of Actin in plant immunity

Actin is one of the most abundant proteins in living organisms, undergoing a multifaceted life cycle that includes nucleation, elongation, capping, subunit dehydration, uncapping, severing, depolymerization, and monomer diffusion. Each stage relies on distinct actin‐interacting proteins to maintain proper filament dynamics. Such actin rearrangements underpin critical aspects of plant physiology—ranging from seed germination and pollen tube formation to responses against various abiotic (e.g., alkaline pH, heat) and biotic (e.g., pathogens) stresses. The understanding of Actin in plant immunity has primarily been built by examining actin-related proteins responsible for the dynamic recycling and reorganization of actin filaments. These proteins, which function in various aspects of cytoskeletal remodeling, play pivotal roles in processes ranging from vesicular trafficking to cell division. Our laboratory identified one mutant in actin dynamics from Arabidopsis thaliana (mac1). Our data indicate that MAC1 may serve as a negative regulator in PTI signaling by examining responses in ROS activation, MAPK activation, gene expression, stomatal immunity, and susceptibility against Pseudomonas syringae pv. tomato DC3000. In addition, our results indicate that mac1 bifurcates PTI signaling upon different PAMP perceptions, thereby highlighting an unexplored receptor-specific immune regulation angle.