Proper Nacl Alleviates Osmotic Stress in Lycium Ruthenicum

Lycium ruthenicum is a salt-accumulating xerophytic species with excellent adaptability to adverse environments. Previous studies showed that a certain amount of NaCl resulted in promoting plant growth. To investigate the mechanism of Na + to plant growth and the effect of drought stress, the growth, photosynthesis, water status and K + , Na + transport related genes were subjected to different NaCl treatments and osmotic stress in the presence or absence of additional NaCl were assessed. Compared to the control, 50 mM NaCl strongly boosted the fresh weight, dry weight and relative growth rate of L. ruthenicum , and significantly increased the concentration of Na + , the K + concentration in roots and stems remained stable, while which in leaves increased significantly. Furthermore, the addition of 50 mM NaCl sharply up-regulated the expression of LrSOS1 in roots, LrNHX and LrVP1 in leaves, LrHKT1 down-regulated in roots, it’s the reason why a high quantity of Na + was accumulated in leaves under 50 mM NaCl. LrAKT1 up-regulated in roots, LrSKOR decreased first and then increased in roots, whereas LrSKOR in leaves remained stable and slightly up-regulated, thereby absorb a large amount of K + by LrAKT1 and transport it to the leaf through LrSKOR. Moreover, external NaCl apparently alleviated the inhibition of osmotic stress in plant growth. Compared with the drought treatment, the addition of 50 mM NaCl significantly increased the Na + and K + content in roots, stems and leaves of L. ruthenicum , resulted in a decrease in proline content and no significant change in soluble sugar content, it is speculated that NaCl treatment could significantly improve the Na + , K + concentration, thus enhance the osmotic regulation ability of plants, and then improve the photosynthesis and water status of L. ruthenicum .