Department of Biology, University of Oxford, South Parks Road, Oxford OX1 3RB, UK; Gregor Mendel Institute of Molecular Plant Biology (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Dr. Bohr-Gasse 3, Vienna 1030, Austria.
Department of Biology, University of Oxford, South Parks Road, Oxford OX1 3RB, UK; Gregor Mendel Institute of Molecular Plant Biology (GMI), Austrian Academy of Sciences, Vienna BioCenter (VBC), Dr. Bohr-Gasse 3, Vienna 1030, Austria.
Curr Biol. 2023 Jul 24;33(14):2897-2911.e6. doi: 10.1016/j.cub.2023.06.015. Epub 2023 Jun 28.
Cell polarity-broadly defined as the asymmetric distribution of cellular activities and subcellular components within a cell-determines the geometry of cell growth and division during development. RHO GTPase proteins regulate the establishment of cell polarity and are conserved among eukaryotes. RHO of plant (ROP) proteins are a subgroup of RHO GTPases that are required for cellular morphogenesis in plants. However, how ROP proteins modulate the geometry of cell growth and division during the morphogenesis of plant tissues and organs is not well understood. To investigate how ROP proteins function during tissue development and organogenesis, we characterized the function of the single-copy ROP gene of the liverwort Marchantia polymorpha (MpROP). M. polymorpha develops morphologically complex three-dimensional tissues and organs exemplified by air chambers and gemmae, respectively. Mprop loss-of-function mutants form defective air chambers and gemmae, indicating ROP function is required for tissue development and organogenesis. During air chamber and gemma development in wild type, the MpROP protein is enriched to sites of polarized growth at the cell surface and accumulates at the expanding cell plate of dividing cells. Consistent with these observations, polarized cell growth is lost and cell divisions are misoriented in Mprop mutants. We propose that ROP regulates both polarized cell growth and cell division orientation in a coordinated manner to orchestrate tissue development and organogenesis in land plants.
细胞极性——广义上是指细胞内的细胞活动和亚细胞成分的不对称分布——决定了细胞在发育过程中的生长和分裂的几何形状。RHO GTPase 蛋白调节细胞极性的建立，并在真核生物中保守。植物 RHO（ROP）蛋白是 RHO GTPase 蛋白的一个亚群，对于植物细胞形态发生是必需的。然而，ROP 蛋白如何调节植物组织和器官形态发生过程中细胞生长和分裂的几何形状还不是很清楚。为了研究 ROP 蛋白在组织发育和器官发生过程中的功能，我们对苔藓植物 Marchantia polymorpha（MpROP）的单拷贝 ROP 基因的功能进行了表征。M. polymorpha 发育出形态复杂的三维组织和器官，分别以气囊和芽基为代表。Mprop 功能丧失突变体形成有缺陷的气囊和芽基，表明 ROP 功能是组织发育和器官发生所必需的。在野生型气囊和芽基的发育过程中，MpROP 蛋白富集到细胞表面的极化生长部位，并积累在分裂细胞的扩展细胞板上。与这些观察结果一致，在 Mprop 突变体中，极化细胞生长丧失，细胞分裂定向错误。我们提出 ROP 以协调的方式调节极化细胞生长和细胞分裂方向，以协调陆地植物的组织发育和器官发生。
