The dynamic cell wall of plant fibers

植物纤维的动态细胞壁

• 批准号: RGPIN-2014-03596
• 负责人: Deyholos, Michael
• 金额: $ 2.48万
• 依托单位: University of British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=649188
• 关键词: dynamic; cell; wall; plant; fibers

The cell wall is one of the most important determinants of plant structure, and also influences many physiological processes including stress and disease resistance, and contributes to the economic value of food, feed, paper, timber, textiles, biofuels and other industrial materials. The cell wall is a dynamic structure, the synthesis and maintenance of which requires activity of thousands of genes, including many related to a complex polymer known as pectin. The function of most genes expressed during cell wall development genes remains unclear. This is true especially for the specialized G-type (gelatinous type) cell walls produced by cells with high tensile strength, such as tension wood and some types of phloem fibers (e.g. bast fibers of flax (linseed, Linum usitatissimum)). Better understanding of the process of fiber development and G-type cell wall deposition will answer basic questions that are relevant to many species of plants and that will also improve understanding of cell wall biogenesis in general. Because our research is being conducted in a major Canadian crop, the outcomes will have direct economic relevance as well.**My laboratory has developed extensive genetic and genomic resources for flax, including a whole genome sequence assembly, gene expression profiles, and now a unique reverse genetics population in an elite linseed variety. This population was created using standard chemical mutagenesis, and is therefore not transgenic. Many individuals from this mutant population have now had the gene-rich regions of their genomes sequenced. This has produced a catalog of indexed mutations that allows us to rapidly isolate mutants of almost any gene of interest. This collection is therefore a unique and powerful resource that will allow us to conduct basic research to discover the function of cell wall related genes while simultaneously developing novel genotypes with industrial relevance. **I propose to use our indexed mutant population to investigate the role of pectin remodeling enzymes (pectin methylesterases and their associated inhibitors (PME/PMEIs), pectin acetylesterases (PAEs), pectate lyases (PLs), and polygalacturonases (PGs)) in fiber and cell wall development. These each represent medium to large gene families, and we have already identified strong, fiber specific candidates within some of these families. Although each of these types of enzymes is hypothesized to affect G-type cell wall development (based on gene expression studies and models of wall development), their functions in this context have not been investigated genetically or in living plants. Moreover, the activity of these enzymes is expected to greatly influence fiber extractability, which is a key limitation on Canadian flax utilization. **We will conduct detailed phenotypic analysis of mutants of pectin-modifying genes of flax using a range of techniques and methods already established in my laboratory, including: (i) comparative genomics and phylogenetics; (ii) microscopy (transmitted light, immunohistochemistry, TEM); (iii) biochemistry (GC/MS, enzyme assays) and spectroscopy (FTIR); (iv) micromechanical testing. With collaborators we will also measure crystallinity, and microfibrilar angle. The outcomes will include novel germplasm that can be immediately transferred to collaborating breeding programs to convert the straw of Canadian linseed from an undesirable waste product to a valuable feedstock in support of nascent industries (e.g. composite materials manufacturing). Most importantly, we will significantly increase understanding of the ways in which plant cell walls can dynamically alter their chemical and physical properties through enzymatic remodelling of pectin.

细胞壁是植物结构最重要的决定因素之一，也影响许多生理过程，包括胁迫和抗病性，并有助于食品，饲料，纸张，木材，纺织品，生物燃料和其他工业材料的经济价值。 细胞壁是一种动态结构，其合成和维持需要数千个基因的活性，其中包括许多与称为果胶的复杂聚合物有关的基因。 细胞壁发育过程中表达的大多数基因的功能仍不清楚。 这对于由具有高抗张强度的细胞产生的特化G型（凝胶型）细胞壁尤其如此，例如抗张木材和某些类型的韧皮纤维（例如亚麻（linseed，Linum usitatissimum）的韧皮纤维）。 更好地了解纤维发育和G型细胞壁沉积的过程将回答与许多植物物种相关的基本问题，也将提高对细胞壁生物发生的理解。 由于我们的研究是在加拿大的一种主要作物中进行的，因此研究结果也将具有直接的经济意义。我的实验室开发了广泛的亚麻遗传和基因组资源，包括全基因组序列组装，基因表达谱，现在在一个精英亚麻籽品种独特的反向遗传种群。 该群体使用标准化学诱变产生，因此不是转基因的。来自这个突变群体的许多个体现在已经对其基因组中基因丰富的区域进行了测序。 这产生了一个索引突变目录，使我们能够快速分离几乎任何感兴趣的基因的突变体。因此，这个集合是一个独特而强大的资源，将使我们能够进行基础研究，发现细胞壁相关基因的功能，同时开发具有工业相关性的新基因型。** 我建议使用我们索引的突变群体来研究果胶重塑酶（果胶甲基酯酶及其相关抑制剂（PME/PMEIs）、果胶乙酰酯酶（PAEs）、果胶酸裂解酶（PL）和多聚半乳糖醛酸酶（PG））在纤维和细胞壁发育中的作用。 这些每个代表中型到大型基因家族，我们已经确定了强大的，纤维特异性的候选人在这些家庭中的一些。 虽然这些类型的酶中的每一种都被假设影响G型细胞壁发育（基于基因表达研究和细胞壁发育模型），但它们在这种情况下的功能尚未在遗传学或活植物中进行研究。此外，预计这些酶的活性会极大地影响纤维的可提取性，这是加拿大亚麻利用的关键限制。 ** 我们将使用我的实验室已经建立的一系列技术和方法对亚麻果胶修饰基因的突变体进行详细的表型分析，包括：（i）比较基因组学和遗传学;（ii）显微镜（透射光，免疫组织化学，TEM）;（iii）生物化学（GC/MS，酶测定）和光谱学（FTIR）;（iv）微机械测试。 与合作者，我们还将测量结晶度和微纤丝角。 成果将包括新的种质，这些种质可以立即转移到合作育种计划中，将加拿大亚麻籽的稻草从不受欢迎的废品转化为有价值的原料，以支持新兴产业（例如复合材料制造）。 最重要的是，我们将显着增加了解的方式，植物细胞壁可以动态地改变其化学和物理性质，通过酶重塑果胶。