Figure 2.

The regulatory role of PI4P in the salt stress response of plants. PI4P level is induced by salt stress. PI binds PM H⁺-ATPase and inhibits its activity under normal conditions without salt stress; however, under salt stress condition, PI4P derived from PI stimulates SOS1 activity and excludes excess Na⁺ from plant cells; PI4P also mediates the internalization of CESA3 and KORRIGAN1 from the plasma membrane, which may participate in salt stress response through the regulation of cellulose synthesis; PI4P at the plasma membrane generates an electrostatic field, which may interact with PINOID, BKI1, MAKRs, and PUB13, and participate in salt stress response. PI, phosphatidylinositol; PI4P, PI 4-phosphate; PS, phosphatidylserine; PM: plasma membrane; SOS1, salt overly sensitive 1; BKI1, BRI1 kinase inhibitor 1; MAKRs, membrane associated kinase regulators; PUB13: PLANT U-BOX13; BR, brassinosteroid; SA, salicylic acid.