Molecular genetics and biochemistry of plant cell wall biosynthesis

植物的一个决定性特征是存在细胞壁，它包围着所有的植物细胞，对它们的功能是必不可少的。它们通过确定细胞形状来控制植物的生长和形状，但也起着特殊的作用，如水分运输，为茎等器官提供刚性，以及保护植物表面的细胞不受环境的影响。具有导水和结构功能的壁沉积在茎和根的维管和纤维系统的细胞中，由于它们沉积在初级壁之后，因此被称为“次生壁”。次生壁可能很大，占许多植物的大部分生物量，特别是树木(木材主要由次生壁组成)。由于这种生物质代表着大量化学能的可再生积累，这些化学能通过光合作用从太阳能中获得，这些材料不仅用于结构目的，而且作为非化石燃料衍生能源的来源，引起了人们的浓厚兴趣。次生细胞壁是复杂的复合结构，包含三种主要聚合物，碳水化合物聚合物纤维素和半纤维素，以及木质素，一种基于酚环的高度交联的聚合物。这些聚合物的相对丰度和结构对木材和纤维的性质及其商业用途有很大影响。次生壁聚合物的合成过程以及这一过程是如何在基因水平上调节的，目前仍不清楚。我们将使用两个系统，模式小型植物拟南芥和快速生长的杨树，来研究次生细胞壁生物合成和沉积的调节，重点是细胞调节回路中的基因和蛋白质，该回路似乎根据植物可用的资源微调次生细胞壁沉降量。我们还将研究覆盖花粉粒的细胞壁的性质和生物合成。花粉壁主要由一种名为孢粉蛋白的聚合物组成，这是自然界最坚韧和最耐用的基质之一。对孢粉蛋白的结构和沉积知之甚少。我们将使用遗传学、生物化学和先进的成像技术来解决这些问题，提供对这种重要生物材料的新理解。

A defining characteristic of plants is the presence of cell walls, which surround all plant cells and are essential for their functions. They control plant growth and shape by determining the cell shape, but also serve specialized roles such water transport, providing rigidity to organs such as stems, and protection from the environment to cells at plant surfaces. Walls with water-conducting and structural functions are deposited in the cells of stem and root vascular and fibre systems, and are termed "secondary walls" since they are deposited after primary walls. Secondary walls can be massive and account for the bulk of the biomass of many plants, especially trees (wood is composed mostly of secondary walls). Since this biomass represents the renewable accumulation of enormous amounts of chemical energy, derived from solar energy via photosynthesis, there is intense interest in these materials not only for structural purposes, but also as a source of non-fossil fuel-derived energy. Secondary cell walls are complex composite structures, containing three major polymers, the carbohydrate polymers cellulose and hemi-cellulose, and lignin, a heavily cross-linked polymer based on phenolic rings. The relative abundance and structures of these polymers has a large impact on wood and fibre properties and their commercial uses. The processes by which secondary wall polymers are synthesized and how this process regulated at the genetic level is still not well understood. We will use two systems, the model small plant Arabidopsis and fast growing poplar trees, to investigate the regulation of secondary cell wall biosynthesis and deposition, focusing on the genes and proteins in a cellular regulatory circuit that appears to fine-tune amount of secondary cell wall deposition according to resources available to the plant. We will also investigate the properties and biosynthesis of the cell wall that coats pollen grains. Pollen walls consist mostly of a polymer called sporopollenin, one of nature's toughest and most durable matrices. Relatively little is known sporopollenin structure and deposition. We will use genetics, biochemistry and advanced imaging technology to address these questions, providing new understanding of this important biological material.