Figure 2

Ion transporters and their molecular regulation mechanism in plants

Faiçal Brini* and Walid Saibi

Published: 25 May, 2021 | Volume 5 - Issue 2 | Pages: 028-043

jpsp-aid1058-g002

Figure 2:

Schematic representation showing key plasma and tonoplast membrane transporters, channels and pumps mediating Na+ and K+ homeostasis in plants under salt stress. Na+ ions enter the cells via Non-Selective Cation Channels (NSCCs) and possibly via other cation transporters (symplast flow) and through the cell wall and intercellular spaces (apoplast flow). The Na+/H+ antiporter SOS1 extrudes Na+ at the root soil interface, thus reducing the Na+ net influx of Na+. At the xylem parenchyma cells, HKT1-like proteins retrieve Na+ from the xylem sap, thereby restricting the amount of Na+ reaching the photosynthetic tissues. To translocate Na+ back to the root, ions unloaded from xylem may be transported into phloem via additional HKT1-like protein. In addition, HKT1-like proteins also load Na+ into shoot phloem, and then Na+ is transferred into roots via phloem, preventing Na+ accumulation in shoots. SOS1, localized in the xylem parenchyma cells, is also suggested to mediate Na+ efflux from xylem vessels under high salinity. Incoming Na+, in root and shoots, is stored in the large central vacuole by tonoplast-localized NHX exchangers. Plasma membrane (PM) H+-ATPase (P-ATPase), PM H+-PPase (PM-PPase), tonoplast H+-ATPase (V-ATPase) and tonoplast H+-PPase (V-PPase) generate electrochemical potential gradient for secondary active transport. 

Read Full Article HTML DOI: 10.29328/journal.jpsp.1001058 Cite this Article Read Full Article PDF

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