清华大学陈浩东团队发现，淀粉体沉积使LAZY再极化来实现植物的重力感应。2023年9月22日，《细胞》杂志在线发表了这项成果。
研究人员报告了重力刺激的重新定向会触发拟南芥根瘤细胞中基底极化的LAZY蛋白的丝裂原活化蛋白激酶（MAPK）信号介导的磷酸化。LAZY的磷酸化增加了它与淀粉体表面叶绿体外包膜（TOC）蛋白中几个转位子的相互作用，进而促进了LAZY蛋白在淀粉体上的富集。淀粉体沉积随后引导LAZY迁移到小柱细胞质膜的新下侧，LAZY在那里诱导不对称的生长素分布和根系差异生长。总之，这项研究为淀粉-平衡石假说提供了分子解释：细胞器运动触发分子极性形成。
据介绍，重力控制着植物的定向生长，一个多世纪前提出的经典淀粉-平衡石假说假定，特化细胞中的淀粉体沉积启动了重力感应，但其分子机制仍未定性。众所周知，LAZY蛋白是重力感知的关键调控因子，lazy突变体表现出显著的重力感知缺陷。
附：英文原文
Title: Amyloplast sedimentation repolarizes LAZYs to achieve gravity sensing in plants
Author: Jiayue Chen, Renbo Yu, Na Li, Zhaoguo Deng, Xinxin Zhang, Yaran Zhao, Chengfu Qu, Yanfang Yuan, Zhexian Pan, Yangyang Zhou, Kunlun Li, Jiajun Wang, Zhiren Chen, Xiaoyi Wang, Xiaolian Wang, Shu-Nan He, Juan Dong, Xing Wang Deng, Haodong Chen
Issue&Volume: 2023-09-22
Abstract: Gravity controls directional growth of plants, and the classical starch-statolithhypothesis proposed more than a century ago postulates that amyloplast sedimentationin specialized cells initiates gravity sensing, but the molecular mechanism remainsuncharacterized. The LAZY proteins are known as key regulators of gravitropism, andlazy mutants show striking gravitropic defects. Here, we report that gravistimulationby reorientation triggers mitogen-activated protein kinase (MAPK) signaling-mediatedphosphorylation of Arabidopsis LAZY proteins basally polarized in root columella cells. Phosphorylation of LAZYincreases its interaction with several translocons at the outer envelope membraneof chloroplasts (TOC) proteins on the surface of amyloplasts, facilitating enrichmentof LAZY proteins on amyloplasts. Amyloplast sedimentation subsequently guides LAZYto relocate to the new lower side of the plasma membrane in columella cells, whereLAZY induces asymmetrical auxin distribution and root differential growth. Together,this study provides a molecular interpretation for the starch-statolith hypothesis:the organelle-movement-triggered molecular polarity formation.
DOI: 10.1016/j.cell.2023.09.014
Source: https://www.cell.com/cell/fulltext/S0092-8674(23)01035-8