报告题目： Coordinated regulation  of Na⁺ extrusion and  long-distance transport in plant

报告时间：2024年01月22日（星期一）上午10:30  -12:00

地点：深圳大学丽湖校区守慧楼(A6)-501

主讲嘉宾：Dae-Jin  Yun (尹大珍)，Ph.D .  

Professor,  Department of Biomedical Science & Engineering, Konkuk University,  Korea

Member  of Korean Academy of Science and Technology

摘要：To  control net sodium (Na⁺)  uptake, Arabidopsis plants utilize the plasma membrane Na⁺/H⁺ antiporter  SOS1 that catalyzes Na⁺ efflux  at the root and promotes Na⁺ loading  into the xylem, and the channel-like HKT1;1 protein that mediates the reverse  flux of Na⁺ unloading  at the xylem. Together, these opposing transport systems govern the partition of  Na⁺ within  the plant, yet they must be finely co-regulated to prevent a futile cycle of  xylem loading and unloading. Here we show that the Arabidopsis SOS3 protein acts  as the molecular switch governing these Na⁺ fluxes  by favoring the recruitment of SOS1 to the plasma membrane and its subsequent  activation by the SOS2/SOS3 kinase complex under salt stress, while commanding  HKT1;1 protein degradation upon acute salt stress. SOS3 achieves this novel role  by direct and SOS2-independent binding to previously unrecognized functional  domains of SOS1 and HKT1;1. These results evidence that roots first retain  moderate amounts of salts to facilitate osmoregulation. When sodicity exceeds  the stress set point, activation of SOS3 switches the balance towards  Na⁺ export  out of the root via the xylem. Thus, SOS3 functionally links and co-regulates  the two major Na⁺ transport  systems operating in vascular plants controlling plant tolerance to  salinity.

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