Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAE, F-69342, Lyon, France.
Limagrain, Limagrain Field Seeds, Research Centre, Gerzat, France.
J Cell Biol. 2021 Oct 4;220(10). doi: 10.1083/jcb.202010077. Epub 2021 Jul 29.
Phospholipases cleave phospholipids, major membrane constituents. They are thus essential for many developmental processes, including male gamete development. In flowering plants, mutation of phospholipase NOT-LIKE-DAD (NLD, also known as MTL or ZmPLA1) leads to peculiar defects in sexual reproduction, notably the induction of maternal haploid embryos. Contrary to previous reports, NLD does not localize to cytosol and plasma membrane of sperm cells but to the pollen endo-plasma membrane (endo-PM), a specific membrane derived from the PM of the pollen vegetative cell that encircles the two sperm cells. After pollen tube burst, NLD localizes at the apical region of the egg apparatus. Pharmacological approaches coupled with targeted mutagenesis revealed that lipid anchoring together with electrostatic interactions are involved in the attachment of NLD to this atypical endo-PM. Membrane surface-charge and lipid biosensors indicated that phosphatidylinositol-4,5-bisphosphate is enriched in the endo-PM, uncovering a unique example of how membrane electrostatic properties can define a specific polar domain (i.e., endo-PM), which is critical for plant reproduction and gamete formation.
磷脂酶可切割磷脂，而磷脂是主要的膜组成部分。因此，它们对许多发育过程至关重要，包括雄性配子体的发育。在开花植物中，磷脂酶 NOT-LIKE-DAD（NLD，也称为 MTL 或 ZmPLA1）的突变会导致有性生殖中出现特殊缺陷，特别是诱导母性单倍体胚胎的形成。与之前的报道相反，NLD 并不定位于精子细胞的细胞质和质膜，而是定位于花粉内质膜（endo-PM）。endo-PM 是一种源自花粉营养细胞质膜的特殊膜，它包围着两个精子细胞。花粉管爆裂后，NLD 定位于卵器的顶端区域。药理学方法结合靶向诱变揭示了脂质锚定和静电相互作用参与了 NLD 与这种非典型内质膜的附着。膜表面电荷和脂质生物传感器表明，磷脂酰肌醇-4,5-二磷酸在内质膜中富集，揭示了一种独特的例子，即膜静电特性如何定义特定的极性区域（即内质膜），这对植物繁殖和配子体形成至关重要。
