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首页> 外文学位 >Cell wall composition regulates cell shape and growth behaviour in pollen tubes.
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Cell wall composition regulates cell shape and growth behaviour in pollen tubes.

机译：细胞壁成分调节花粉管中的细胞形状和生长行为。

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摘要

One of the most important features characterizing plant cells and differentiating them from animal cells is the cell wall that surrounds them. The cell wall plays a critical role in providing protection to the protoplast; it acts as a filtering mechanism and is the location of many biochemical reactions implicated in the regulation of the cell metabolism and the mechanical properties of the cell. The local stiffness, extensibility, plasticity and elasticity of the different cell wall components determine the shape and geometry of the cell during differentiation and morphogenesis. The goal of my thesis is to understand the role played by the different cell wall components in shaping the plant cell and controlling its growth behaviour. To achieve this goal, I studied the pollen tube, or male gametophyte, as a cellular model system. The pollen tube is a cellular protuberance formed by the pollen grain upon its contact with the stigma. Its main purpose is to deliver the sperm cells to the female gametophyte to ensure double fertilization. The pollen tube is a tip-growing cell characterized by its simple cell wall composition and by the fact that it is the fastest growing cell of the plant kingdom. This makes it the ideal model to study the effects of drugs, mutations or stresses on cellular growth behaviour, metabolism and cell wall mechanics. The pollen tube cell wall consists mainly of proteins and three major polysaccharidic components: pectins, cellulose and callose. To understand the role played by these components in regulating pollen tube growth, I investigated the effects of mutations, enzymatic treatments, hyper-gravity and omni-directional gravity on the pollen tube cell wall. Using mathematical modeling combined with molecular biology and high-resolution electron and fluorescent microscopy I was able to show that the regulation of pectin chemistry is required for the regulation of the growth rate and pollen tube shape and that cellulose is crucial for determining the pollen tube diameter in the sup-apical region. Moreover, I investigated the role of the pectate lyases, a group of pectin digesting enzymes expressed during pollen tube development, and I showed that this enzyme activity is required for the initiation of pollen germination. More importantly, I directly showed for the first time that the pollen tube secretes cell wall loosening enzymes to facilitate its penetration through the style.
机译：表征植物细胞并将它们与动物细胞区分开的最重要特征之一是围绕它们的细胞壁。细胞壁在提供对原生质体的保护中起着至关重要的作用。它起着过滤机制的作用，并且是许多生化反应的场所，涉及细胞代谢和细胞机械特性的调节。不同细胞壁成分的局部刚度，可延展性，可塑性和弹性决定了分化和形态发生过程中细胞的形状和几何形状。本文的目的是了解不同细胞壁成分在塑造植物细胞和控制其生长行为中所起的作用。为了实现这个目标，我研究了花粉管或雄配子体作为细胞模型系统。花粉管是由花粉粒与柱头接触而形成的细胞突起。其主要目的是将精子细胞传递给雌配子体，以确保双受精。花粉管是一种顶端生长的细胞，其特征在于其简单的细胞壁组成以及其是植物界中生长最快的细胞这一事实。这使其成为研究药物，突变或应激对细胞生长行为，新陈代谢和细胞壁力学的影响的理想模型。花粉管细胞壁主要由蛋白质和三种主要的多糖成分组成：果胶，纤维素和call质。为了了解这些成分在调节花粉管生长中所起的作用，我研究了突变，酶处理，超重力和全向重力对花粉管细胞壁的影响。通过将数学模型与分子生物学，高分辨率电子显微镜和荧光显微镜相结合，我能够证明果胶化学的调节是调节生长速率和花粉管形状所必需的，而纤维素对于确定花粉管直径至关重要在心尖区。此外，我研究了果胶酸裂解酶的作用，果胶酸裂解酶是在花粉管发育过程中表达的一组果胶消化酶，并且我证明了这种酶的活性是启动花粉萌发所必需的。更重要的是，我第一次直接证明花粉管分泌细胞壁松弛酶，以促进其通过花粉的穿透。

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  • 作者

    Chebli, Youssef.;

  • 作者单位

    Universite de Montreal (Canada).;

  • 授予单位 Universite de Montreal (Canada).;
  • 学科 Biology Cell.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 371 p.
  • 总页数 371
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 肿瘤学;
  • 关键词

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