Chloroplast membranes with their unique lipid composition are crucial for photosynthesis. Maintenance of the chloroplast membranes requires finely tuned lipid anabolic and catabolic reactions. Despite the presence of a large number of predicted lipid-degrading enzymes in the chloroplasts, their biological functions remain largely unknown. Recently, we described PLASTID LIPASE1 (PLIP1), a plastid phospholipase A1 that contributes to seed oil biosynthesis. The Arabidopsis thaliana genome encodes two putative PLIP1 paralogs, which we designated PLIP2 and PLIP3. PLIP2 and PLIP3 are also present in the chloroplasts, but likely with different subplastid locations. In vitro analysis indicated that both are glycerolipid A1 lipases. In vivo, PLIP2 prefers monogalactosyldiacylglycerol as substrate and PLIP3 phosphatidylglycerol. Overexpression of PLIP2 or PLIP3 severely reduced plant growth and led to accumulation of the bioactive form of jasmonate and related oxylipins. Genetically blocking jasmonate perception restored the growth of the PLIP2/3-overexpressing plants. The expression of PLIP2 and PLIP3, but not PLIP1, was induced by abscisic acid (ABA), and plip1 plip2 plip3 triple mutants exhibited compromised oxylipin biosynthesis in response to ABA. The plip triple mutants also showed hypersensitivity to ABA. We propose that PLIP2 and PLIP3 provide a mechanistic link between ABA-mediated abiotic stress responses and oxylipin signaling.
具有独特脂质成分的叶绿体膜对于光合作用至关重要。叶绿体膜的维护需要精细调节脂质合成代谢和分解代谢反应。尽管在叶绿体中存在大量预测的脂质降解酶,但其
生物学功能仍基本未知。最近,我们描述了P
LASTID LIPA
SE1(PLIP1),这是一种有助于种子油
生物合成的叶绿体
磷脂酶A1。拟南芥
基因组编码两种假定的PLIP1同源物,我们分别命名为PLIP2和PLIP3。PLIP2和PLIP3也存在于叶绿体中,但可能位于不同的亚叶绿体位置。体外分析表明,两者都是
甘油脂A1脂酶。在体内,PLIP2更喜欢单半
乳糖二酰基
甘油作为底物,而PLIP3更喜欢
磷脂酰
甘油。PLIP2或PLIP3的过度表达会严重抑制植物生长,并导致
茉莉酸和相关的氧脂素的
生物活性形式积累。通过
基因阻断
茉莉酸感知,恢复了PLIP2/3过度表达植物的生长。
脱落酸(ABA)诱导PLIP2和PLIP3的表达,但PLIP1的表达不受影响,而plip1 plip2 plip3三重突变体在响应ABA时表现出氧脂素
生物合成受损。plip三重突变体还对ABA表现出超敏反应。我们提出,