Myosin XI-1 mediates salt tolerance through a Na+ transport pathway in Arabidopsis

Salt stress significantly affects plant growth and productivity; therefore, it is important to understand the molecular mechanisms underlying salt tolerance. Myosin XI, a primary driver of intracellular trafficking and organelle movement in plant cells, has recently been implicated in abiotic stress responses. However, their specific roles in salt tolerance remain unclear. In this study, we demonstrate that the expression of Arabidopsis myosin XI isoforms AtXI-K, AtXI-2, and AtXI-1 is induced under salt stress. Notably, both the triple mutant (3ko) and the single atxi-1 mutant showed enhanced salt tolerance. Contrastingly, the salt tolerance of atxi-k, atxi-2, and the double mutant (2ko) lines was similar to that of the wild-type (WT) plants, indicating a specific role of AtXI-1 in salt tolerance. Moreover, the atxi-1 plants accumulated less Na+ and maintained higher chlorophyll and proline contents under salt stress compared to the WT plants. However, reduced seed germination in 3ko under salt stress suggests a stage-specific tolerance mechanism. Hence, AtXI-1 significantly regulates adaptation to salt stress, potentially through the Na+ homeostasis. These findings suggest functional diversification among myosin XI isoforms and provide valuable insights into myosin XI-mediated stress responses, identifying potential targets for enhancing crop resilience to salinity.