Maintaining ion homeostasis, especially a low Na+/K+ ratio in cytoplasm, is essential for plants growth and development, particularly under salt stress. Salt Overly Sensitive (SOS) pathway is an important salt excretion mechanism that helps plants to reduce Na+ accumulation in cells through the sequential work of SOS3-SOS2-SOS1.
Previous studies have intensively elucidated the function and mechanism of the three key SOS components. But overexpression of SOS1, SOS2 and/or SOS3 cannot significantly increase plant salt tolerance, suggesting that additional key factor of SOS pathway has not been identified.
Recently, a research team led by Prof. XIE Qi from the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences revealed how an ESCRT-I component VPS23A confers plant salt tolerance through strengthening the function of SOS module, and the possible strategy to apply SOS module in improving plant salt tolerance.
In this study, the researchers found VPS23A positively regulates plant salt response. VPS23A promotes the process of re-distribution of SOS2 to the plasma membrane and enhances SOS2/SOS3 complex affinity, and then activates the antiporter activity of SOS1 to reduce Na+ accumulation in plant cells.
Genetic evidence demonstrated that salt tolerance achieved by the overexpression of SOS2 and SOS3 depends on VPS23A. Based on the knowledge, an engineered membrane-bound SOS2 greatly increased plants salt tolerance. These findings revealed that VPS23A sustains salt tolerance by strengthening the SOS module.
"This discovery not only broadens our knowledge on the mechanism of SOS-mediated salt tolerance, but also provides important guides for cultivating salt-tolerant crops based on SOS pathway in the future," said Prof. XIE.
This study entitled "ESCRT-I component VPS23A sustains salt tolerance by strengthening the SOS module in Arabidopsis" has been published online in Molecular Plant on May 18, 2020.
This research is supported by the National Key R&D Program of China, the National Natural Science Foundation of China and the Transgenic Research Projects.