Arabidopsis Seed Coats as a Model System for Molecular Genetic Analysis of Plant Cell Wall Biosynthesis and Modification

植物细胞壁通常由纤维素和半纤维素组成，嵌入一种叫做果胶的亲水性碳水化合物凝胶中。这些细胞壁成分相互作用，形成一种环境屏障，满足细胞在生长和分化过程中的需要。此外，细胞壁还提供了一种细胞外基质，相邻的细胞通过这种基质相互连接。因此，有关植物细胞壁结构的信息以及如何随着细胞的发育和适应环境的变化而改变它的信息是有价值的，并在农业和林业中有许多应用。我们研究了一种特殊的拟南芥种皮细胞类型，它可以产生大量的细胞壁多糖。无法正确合成这些多糖的突变体被鉴定出来，并用于分离编码细胞壁生物合成和修饰所需蛋白质的相应基因。然后，这些基因及其蛋白质产物可以被用作了解细胞壁结构和功能的工具。利用这种方法，我们建议研究如何：1.多糖可以被修饰以使细胞壁更紧密或更少，2.细胞靶向细胞壁的蛋白质，3.特定的细胞壁碳水化合物是细胞壁特性所必需的，4.细胞壁蛋白被降解，5.细胞壁在分子水平上被构造。我们相信，这些问题的答案将有助于我们理解和操纵细胞壁的物理性质，以影响植物的生长和发育。

Plant cell walls are typically composed of the polysaccharides cellulose and hemicellulose, embedded in a hydrophilic, carbohydrate gel called pectin. These cell wall components interact with one another to create an environmental barrier that meets the needs of the cell during growth and differentiation. In addition the wall provides an extracellular matrix through which adjacent cells are connected to each other. Consequently, information concerning plant cell wall structure and how it can be modified as cells develop and adapt to a changing environment is valuable and has many applications in agriculture and forestry. We study a specialized cell type of the Arabidopsis thaliana seed coat that makes large quantities of cell wall polysaccharides. Mutants unable to synthesize these polysaccharides correctly are identified and used to isolate the corresponding genes encoding proteins needed for cell wall biosynthesis and modification. These genes and their protein products can then be used as tools to understand cell wall structure and function. Using this approach we propose to study how: 1. polysaccharides can be modified to make the cell wall more or less cohesive, 2. cells target proteins to the cell wall, 3. specific cell-wall carbohydrates are required for cell wall properties, 4. Cell wall proteins are degraded, and 5. the cell wall is structured at the molecular level. We believe that answers to these questions will help us to understand and manipulate physical properties of the cell wall for the purposes of influencing plant growth and development.