Genetic analysis of mechanisms linking cell wall integrity with growth control in Arabidopsis

细胞壁物质是大多数植物中主要的碳水化合物成分。最近的研究已经确定了编码参与合成不同细胞壁成分的酶的基因，但细胞壁功能和组织的许多其他方面仍有待研究。我们最近的研究表明，一些编码糖合成酶的基因突变体在黑暗和淀粉水平升高的情况下表现出强烈的糖依赖性生长和发育表型。这些表型需要一种具有良好特征的蛋白质参与调节糖、激素和光反应。我们还发现细胞壁结构/组成的变化很可能是观察到的表型的原因。我们的目标是使用遗传筛选来定义该途径的其他成分，并与已知的糖反应途径建立联系。这项研究的结果将可能是第一次确定，植物细胞壁的组成和水平是根据碳水化合物的可用性而调节的。这些知识将提供资源如何分配给细胞壁合成的理解，也可能有助于设计将更多资源分配给细胞壁生物量的作物。了解植物细胞壁组成是如何被控制的是一个高度相关的目标，因为目前有可能将细胞壁材料转化为生物燃料和化学原料。该领域的一个主要研究目标是改变生物质作物的细胞壁组成，如速生柳、杨树和多年生草。几项研究表明，试图改变细胞壁成分会导致主要的，有些意想不到的细胞变化，如激活应激和防御反应。这些会导致细胞活性和细胞壁组成的不良变化。这些结果表明，试图改变细胞壁组成，例如调整细胞壁组成以更有效地降解，需要更多关于如何控制细胞壁组成的知识。本文所描述的工作将在模式植物拟南芥中增加这些知识。有关基因的知识可能最终被用于改造生物质作物的细胞壁控制，例如增加细胞壁多糖的水平。这些作物可以为燃料生产提供可持续和具有成本效益的来源，并通过更有效地利用全球碳循环来帮助缓解气候变化。

Cell wall materials represent the major carbohydrate component in most plants. Recent research has identified genes encoding enzymes involved in synthesising different cell wall components, but many other aspects of cell wall function and organisation remain to be investigated. We have recently shown that several mutants in genes encoding enzymes synthesising sugars destined for incorporation into cell wall polysaccharides exhibit strong sugar-dependent growth and developmental phenotypes in the dark and elevated starch levels. These phenotypes require a well characterised protein involved in regulating sugar, hormone and light responses. We also showed that changes in cell wall structure/composition are most likely responsible for the observed phenotypes. We aim to define other components of this pathway using genetic screens and establish links with known sugar- response pathways. The outcomes of this research will establish, possibly for the first time, that plant cell wall composition and levels are regulated in response to carbohydrate availability. This knowledge will provide an understanding of how resources are allocated to cell wall synthesis and may also help design crops that allocate more resources to cell wall biomass. Understanding how plant cell wall composition is controlled is a highly relevant objective at the moment because of the potential for converting cell wall material to biofuels and chemical feedstocks. A major research objective in this area is to alter cell wall composition in biomass crops such as rapidly growing willow, poplar and perennial grasses. Several studies show that attempts to alter cell wall composition lead to major, and somewhat unexpected, cellular changes such as activation of stress and defence responses. These then lead to undesirable changes in cell activity and cell wall composition. These results suggest that attempts to alter cell wall composition, for example to tailor cell wall composition for more efficient degradation, require a lot more knowledge about how the composition of the cell wall is controlled. The work described here will add to this knowledge in the model plant Arabidopsis. Knowledge of the genes involved might ultimately be used to engineer altered cell wall control in biomass crops, for example to increase levels of cell wall polysaccharides. These crops may provide sustainable and cost-effective sources for fuel production and help to ameliorate climate change by more effective use of the global carbon cycle.