The Role Of Rice Phospholipase D?1 In Response To Salt Stress

Phospholipids are not only important components of cell membranes,but also are rich in sources for generating cellular messengers.Phospholipase D(PLD)hydrolyzes phospholipids to generate phosphatidic acid(PA),which acts as an important signaling molecule.Increasing evidence shows that PLD plays an important role in stress responses in Arabidopsis.Rice contains 17 PLD genes,and Rice PLDs are much more complicated than Arabidopsis.However,the role of rice PLD in stress response remains unclear.This study focuses on the functional characterization of rice PLD?l in response to salt stress.The PLD?1 transcript level was higher in leaves than in roots at the tillering and heading stages,and was induced by salt stress.PLD?1 was localized to the endoplasmic reticulum as visualized by PLD?1-GFP under laser confocal microscope.To analyze enzymatic properties,PLD?1 was cloned from rice and the protein was expressed in E.coli cells.The PLD?1 was activated by PIP2,and Ca2+ was not required for PLD?1 activity,but the millimolar concentration of Ca2+ inhibited PLD?1 activity.To explore the role of PLD?1 in growth and stress response,the PLD?1 mutant was isolated and the overexpression plants were generated.The mutant plants were more sensitive to salt stress with reduced plant height and biomass,and increased ionic leakage and Malondialdehyde content,whereas OE plants exhibited an opposite phenotype with enhancing salt stress tolerance.Loss of PLD?1 resulted in the transcriptional alteration of genes involved in sodium transporter,and conferred increased sodium content in plants under salt stress.The application of PA information inhibitor abolished the phenotype,suggesting that PA plays a role in salt stress.Lipid profiling showed that loss of PLD?1 resulted in the changes of lipids including PA.Moreover,PA binds to the SOS3 and ribosomal protein S6 kinase.The results suggest PLD?1-derived PA interacts with SOS3 and S6K1 to regulate sodium transport and plant growth to enhance salt stress tolerance.