Phospholipase D (PLD)– and phospholipase C (PLC)/diacylglycerol kinase (DGK)–coupled pathways produce phosphatidic acid (PA), which is an important signal transduction process in animal and plant cells. DGK is the second largest PA-generating factor after PLD in both biotic and abiotic stress responses, which could phosphorylate diacylglycerol (DG) to form PA. Here, we assessed the biological role of MpDGK2, a DGK gene isolated from Malus prunifolia that is upregulated by water deficit, oxidation, or exogenous abscisic acid. Its heterotopic expression is helpful to improve the drought resistance of transgenic Arabidopsis thaliana. Changes in electrolyte leakage, chlorophyll concentration, and malondialdehyde accumulation showed a positive response. MpDGK2 had effect on stomatal closure under water withholding condition. In addition, under stress conditions, MpDGK2 significantly regulates the accumulation of hydrogen peroxide (H2O2), which is manifested in the fluctuation of H2O2 concentration and the change of antioxidant enzyme activity. In summary, these results indicate that MpDGK2 affects the growth and tolerance of Arabidopsis under drought stress. Part of its function may be due to its effects on stomatal behavior and reactive oxygen species accumulation, thereby improving drought tolerance.

中文翻译：

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MpDGK2，一种来自苹果属的新型二酰基甘油激酶，赋予转基因拟南芥干旱胁迫耐受性

磷脂酶 D (PLD) 和磷脂酶 C (PLC)/二酰甘油激酶 (DGK) 偶联途径产生磷脂酸 (PA)，这是动植物细胞中重要的信号转导过程。DGK 是生物和非生物胁迫反应中仅次于 PLD 的第二大 PA 生成因子，可将二酰基甘油 (DG) 磷酸化以形成 PA。在这里，我们评估了 MpDGK2 的生物学作用，MpDGK2 是一种从苹果树中分离的 DGK 基因，该基因因缺水、氧化或外源性脱落酸而上调。其异位表达有助于提高转基因拟南芥的抗旱性。电解质泄漏、叶绿素浓度和丙二醛积累的变化显示出积极的反应。MpDGK2在截水条件下对气孔关闭有影响。此外，在胁迫条件下，MpDGK2显着调节过氧化氢（H2O2）的积累，表现为H2O2浓度的波动和抗氧化酶活性的变化。总之，这些结果表明 MpDGK2 影响干旱胁迫下拟南芥的生长和耐受性。它的部分功能可能是由于它对气孔行为和活性氧积累的影响，从而提高了耐旱性。