Junxiu Hou, Ping Lu, Xuan Cui, Liangfeng Luo, Qing Pan, Jiejie Li
Host actin remodeling is critical for plant defense against pathogen infection, yet its specific functions remain to be fully explored. This study characterizes the role of the actin cytoskeleton in regulating mitochondrial dynamics to enhance plant defense. We demonstrate that the perception of the bacterial flagellin epitope induces excessive mitochondrial elongation, which facilitates the exchange of mitochondrial components for the functional recovery of damaged mitochondria. This elongation also promotes ATP and mitochondrial ROS production. The formation of elongated mitochondria largely depends on actin bundles in the cortical array. The contribution of actin bundles involves providing structural support for mitochondrial fusion and preventing already elongated mitochondria from undergoing fission. We further identified the interaction between the actin-regulating protein MDP25 and the mitochondrial outer membrane protein VDAC3 in actin remodeling and mediating actin-mitochondria interaction essential for mitochondrial fusion and elongation. Collectively, this study presents a mechanistic model for actin-dependent mitochondrial elongation and its significance for plant immunity.