Preliminary Study On Rice Phospholipase Dα3 And ζ1 In Response To Salt Stress

Phospholipids are major components of cell membranes, which serve as barriers to protect cells from attack of adverse factors, and are also the sites of metabolism and signaling transduction. Phospholipase D (PLD) hydrolyzes membrane phospholipids to generate phosphatidic acid, a signal molecule and head group. The activation of PLD may functions as dual effects on both membrane remodeling and signaling transduction involved in various biological processes such as plant growth, development and stress responses. Rice genome contains 17 PLD genes, and their roles are less known. In this study, the T-DNA insertion mutants of rice PLD genes were isolated for the functional characterization. The result showed that PLDζ1 and PLDa3 are involved in salt stress response in a different manner. PLDζ1 plays a positive role in hyperosmotic stress such as salt and cold stresses. The loss of PLDζ1 resulted in hypersensitivity to salt and cold treatments, as shown by severer growth inhibition, less accumulations of proline and sugar in pldζ1 mutants than that of wildtype. It also showed that pldζ1 mutant plants accumulated more sodium and less potassium than WT under salt stress. By contrast, PLDa3 plays a negative role in response to salt stress. The loss of PLDa3 conferred plants more tolerance to salt stress. The plda3 mutant plants displayed delaying senescence with more chlorophyll content in leaves than that of WT. The lost transcription of PLDa3 resulted in less membrane degradation revealed by lower levels of MDA and ion conductivity in plda3 plants than in WT under salt stress. This suggests that reduced PLDa3 may inhibit membrane degradation under salt stress, resulting in enhanced resistant to salt stress.