Molecular Genetic Analysis of Cell Polarity in the Maize Leaf Epidermis

在所有其他真核生物和原核生物中，植物发育过程中形态和功能的多样化取决于细胞极性。相对而言，从分子角度来看，我们对细胞如何将极化信号转化为局部细胞骨架组件，从而指导其他细胞成分或细胞生长机制的极化知之甚少。在美国国家科学基金会的支持下，采用遗传学方法分析了玉米叶表皮细胞极化的机制，重点研究了表皮细胞极化生长和分裂所需的三个Brick （Brk）基因。在此基础上，提出了进一步提高我们对植物细胞极性的理解的研究，具体目标如下：1。将采取互补的方法来定位BRK1蛋白在极化附属母细胞和扩大的表皮铺路细胞中。2. 将采用互补的方法来鉴定候选BRK1相互作用蛋白，并研究它们与BRK1的体内相互作用。3. 如Brk基因所示，两个Pangloss （Pan）基因促进辅助母细胞的极化，但不是极化细胞扩增所必需的。Pan基因的功能及其与Brk基因的关系将通过单突变体和双突变体的表型分析进一步阐明。4. 为了更全面地了解玉米叶表皮细胞是如何极化的，我们将克隆一个额外的表皮细胞极性基因（Pan1、Brk2或Brk3），并通过转座子标记进行分子表征。细胞极性在所有真核生物和原核生物发育中的核心重要性，以及BRK1（可能包括所有3个Brk基因发挥作用的整个途径）在真核生物中是保守的这一事实，增强了所提出工作的智力价值。因此，我们的发现很可能会在植物细胞生物学的界限之外产生影响。所提出的工作的更广泛影响将主要是参与研究的年轻科学家的教育和培训，包括一名博士后，一名博士生和一系列本科生。

0212724SmithAs in all other eukaryotes and prokaryotes, diversification of form and function during plant development depends on cell polarity. Relatively little is known in molecular terms about how cells translate polarizing cues into localized cytoskeletal assemblies that direct the polarization of other cell components or of the cell growth machinery. With the support of a prior NSF award, a genetic approach was taken to analyze mechanisms by which maize leaf epidermal cells become polarized, focusing on three Brick (Brk) genes required for the polarized growth and division of epidermal cells. Building on this work, studies are proposed here to further advance our understanding of plant cell polarity, with the following specific objectives: 1. Complementary approaches will be taken to localize BRK1 protein in polarizing subsidiary mother cells and expanding epidermal pavement cells. 2. Complementary approaches will be taken to identify candidate BRK1-interacting proteins and investigate their in vivo interactions with BRK1. 3. As shown for the Brk genes, two Pangloss (Pan) genes promote the polarization of subsidiary mother cells, but are not required for polarized cell expansion. The functions of Pan genes and how they relate to those of Brk genes will be further elucidated through phenotypic analysis of single and double mutants. 4. To help build a bigger picture of how maize leaf epidermal cells become polarized, one additional epidermal cell polarity gene (Pan1, Brk2, or Brk3) will be cloned and molecularly characterized by means of transposon tagging. The intellectual merit of the work proposed is augmented by the central importance of cell polarity in the development of all eukaryotes and prokaryotes, and the fact that BRK1 (and probably the entire pathway in which all 3 Brk genes were shown to function) is conserved among eukaryotes. Therefore, our findings will most likely have an impact outside the boundaries of plant cell biology. The broader impact of the work proposed will mainly be the education and training of young scientists participating in the research, including one postdoc, one Ph.D. student, and a series of undergraduates.