A phosphoinositide-specific phospholipase C pathway elicits stress-induced Ca2+ signals and confers salt tolerance to rice

• Published in: The New phytologist Vol. 214; no. 3; pp. 1172 - 1171
• Main Authors: Li, Li, Wang, Fawei, Yan, Peiwen, Jing, Wen, Zhang, Chunxia, Kudla, Jörg, Zhang, Wenhua
• Format: Journal Article
• Language: English
• Published: Lancaster New Phytologist Trust 01-05-2017; Wiley Subscription Services, Inc
• Subjects: Abiotic stress; Biological activity; Ca2+ signal; Calcium ions; Calcium signalling; Cytoplasm; Diglycerides; Inositol 1,4,5-trisphosphate receptors; Isoforms; Molecular chains; Molecular modelling; Oryza sativa; Phosphates; Phosphatidylinositol 4,5-diphosphate; phosphatidylinositol‐4‐phosphate; Phosphoinositides; Phospholipase; Phospholipase C; Physiological functions; Physiology; rice; Salt; salt response; Salt tolerance; Second messengers; Shoots; Signal transduction; Stress; Stresses
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.14426

In animal cells, phospholipase C (PLC) isoforms predominantly hydrolyze phosphatidylinositol-4,5-biphosphates [PtdIns(4,5)P2] into the second messengers diacylglycerol (DAG) and inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] to regulate diverse biological processes. By contrast, the molecular mechanisms and physiological significance of PLC signaling in plants still awaits full elucidation. Here, we identified a rice (Oryza sativa cv) PI-PLC, OsPLC1, which preferred to hydrolyze phosphatidylinositol-4-phosphate (PtdIns4P) and elicited stress-induced Ca2+ signals regulating salt tolerance.
Analysis by ion chromatography revealed that the concentration of PtdIns4P was c. 28 times of that of PtdIns(4,5)P2 in shoots. OsPLC1 not only converted PtdIns(4,5)P2 but also – and even more efficiently – converted PtdIns4P into DAG and Ins(1,4,5)P3
in vitro and in vivo.
Salt stress induced the recruitment of OsPLC1 from cytoplasm to plasma membrane, where it hydrolyzed PtdIns4P. The stress-induced Ca2+ signaling was dependent on OsPLC1, and the PLC-mediated Ca2+ signaling was essential for controlling Na+ accumulation in leaf blades, thus establishing whole plant salt tolerance.
Our work identifies a conversion pathway and physiological function for PtdIns4P pools in rice and reveals the connection between phosphoinositides and Ca2+ signals mediated by PLC during salt stress responses.