Phosphatidic acid (PA) is a key phospholipid in glycerolipid metabolism and signaling. Diacylglycerol kinase (DGK) produces PA by phosphorylating diacylglycerol, a crucial step in PA metabolism. Although DGK activity is known to be involved in plant development and stress response, how specific DGK isoforms function in development and phospholipid metabolism remains elusive. Here, we showed that Arabidopsis (Arabidopsis thaliana) DGK2 and DGK4 are crucial for gametogenesis and biosynthesis of phosphatidylglycerol and phosphatidylinositol in the endoplasmic reticulum (ER). With comprehensive transcriptomic data of seven DGKs and genetic crossing, we found that dgk2-1/– dgk4-1/– plants were gametophyte lethal, although parental single homozygous plants were viable. The dgk2-1/+ dgk4-1/+ double heterozygote showed defective pollen tube growth and seed development because of nonviable mutant gametes. DGK2 and DGK4 were localized to the ER and were involved in PA production for pollen tube growth. Transgenic knockdown lines of DGK2 and DGK4 confirmed the gametophyte defect and also revealed defective leaf and root growth. Glycerolipid analysis in the knockdown lines showed that phosphatidylglycerol and phosphatidylinositol metabolism was affected differently in floral buds and leaves. These results suggest that DGK2 and DGK4 are essential during gametogenesis and are required for ER-localized phospholipid metabolism in vegetative and reproductive growth.

磷脂酸 (PA) 是甘油脂代谢和信号转导中的关键磷脂。二酰甘油激酶 (DGK) 通过磷酸化二酰甘油产生 PA，这是 PA 代谢的关键步骤。尽管已知 DGK 活性参与植物发育和胁迫反应，但特定的 DGK 亚型在发育和磷脂代谢中如何发挥作用仍不清楚。在这里，我们表明拟南芥（Arabidopsis thaliana）DGK2和DGK4对于配子发生以及内质网（ER）中磷脂酰甘油和磷脂酰肌醇的生物合成至关重要。通过七个DGK的全面转录组数据和遗传杂交，我们发现dgk2-1/– dgk4-1/–尽管亲本单纯合植物是可存活的，但植物的配子体是致死的。由于不能存活的突变配子， dgk2-1 /+ dgk4-1/+双杂合子表现出花粉管生长和种子发育缺陷。DGK2 和 DGK4 定位于 ER，参与花粉管生长的 PA 生产。DGK2和DGK4转基因敲除系证实了配子体缺陷，还揭示了叶子和根生长缺陷。敲低品系中的甘油脂分析表明，花芽和叶子中磷脂酰甘油和磷脂酰肌醇代谢受到不同的影响。这些结果表明 DGK2 和 DGK4 在配子发生过程中至关重要，并且是营养和生殖生长中内质网定位磷脂代谢所必需的。