磷脂酸PA与GhHOX蛋白互作的分子机制及其在棉纤维发育和品质形成中的作用

At present, the molecular mechanisms of cotton fiber cell initiation and development are largely unclear. Our previous study confirmed that GhHOX3 and GhHOX4 were expressed at high level at the times of cotton fiber differentiation and initiation, and phosphatidic acid (PA )was identified to regulate AtGL2 which are GhHOX homologous protein in Arabidopsis. No research was reported on the molecular mechanism of interaction between PA and GhHOX3 and GhHOX4 that affect cotton fiber development.we speculate a possible molecular mechanism of cotton fiber development based on our previous research results . The binding of GhHOX3 and GhHOX4 to the signaling lipid PA depended on intracellular PH.GhHOX3 and GhHOX4 is sequestered on the endoplasmic reticulum(ER),resulting in both proteins function loss. the change of intracellular PH results in the rapid depletion of PA,release of GhHOX3 and GhHOX4 from ER, and translocation of GhHOX3 and GhHOX4 to the nucleus. This affects the cotton fiber development. We use lipid overlay assay, liposomal assay and PA bead IP to research the mechanism of the interaction between PA and GhHOX3 ,GhHOX4 in vitro, Arabidopsis and cotton, and analyze how interaction of PA and GhHOX3,GhHOX4 impacts the quality of cotton fiber in overexpress ,RNAi transgenic cotton.This research will provide new evidence and strategy to understand the initiation and development of cotton fiber cells.

棉花是我国重要的经济作物，阐明棉纤维细胞发育的分子机制对于改良棉纤维品质具有重要意义。我们在前期工作中发现GhHOX3和GhHOX4参与了棉纤维发育，并在拟南芥中确证了磷脂酸PA和GhHOX同源蛋白GL2的互作，而PA作为脂信号分子调控GhHOX蛋白影响棉纤维发育和品质性状的形成尚未见研究报道。基于此，我们推测GhHOX3/4蛋白与PA结合，定位在内质网上，使之不能进入核内发挥转录功能，影响棉纤维发育，调控纤维品质形成。本项目拟选择体外、拟南芥和棉花三种体系研究PA与GhHOX3/4蛋白互作的分子机制及其影响棉纤维发育和品质的调控途径。采用lipid overlay 、脂质体蛋白结合实验及PA bead免疫共沉淀等技术，阐明PA与GhHOX3/4蛋白互作的分子机制；通过超量表达、RNAi和离体胚珠培养等方法，解析其分子机制及其在棉纤维发育品质形成中的调控作用，揭示棉纤维发育的分子遗传基础。