The actin-related protein2/3 complex regulates mitochondrial-associated calcium signaling during salt stress in Arabidopsis.

摘要

Microfilament and Ca2+ dynamics play important roles in stress signaling in plants. Through genetic screening of Arabidopsis thaliana mutants that are defective in stress-induced increases in cytosolic Ca2+ ([Ca2+]_cyt), we identified Actin-Related Protein2 (Arp2) as a regulator of [Ca2+]_cyt in response to salt stress. Plants lacking Arp2 or other proteins in the Arp2/3 complex exhibited enhanced salt-induced increases in [Ca2+]_cyt, decreased mitochondria movement, and hypersensitivity to salt. In addition, mitochondria aggregated, the mitochondrial permeability transition pore opened, and mitochondrial membrane potential Psi m was impaired in the arp2 mutant, and these changes were associated with salt-induced cell death. When opening of the enhanced mitochondrial permeability transition pore was blocked or increases in [Ca2+]_cyt were prevented, the salt-sensitive phenotype of the arp2 mutant was partially rescued. These results indicate that the Arp2/3 complex regulates mitochondrial-dependent Ca2+ signaling in response to salt stress.