EXPLORING THE BIOSYNTHESIS OF PLANT FATTY ACID-BASED POLYMERS

植物与环境的相互作用始于它们的表面。植物表面被脂质屏障覆盖，这种屏障含有从羟基脂肪酸中提取的聚酯的核心结构：角质和Suberin。角质和蜡质形成覆盖植物气生初级表面的角质层。Suberin存在于树皮、块茎皮、种皮和根周皮的软木细胞壁上。这些天然防御系统保护植物免受病原体、盐分和干旱的侵袭。尽管脂肪聚酯对所有农林物种的生存和表现都是至关重要的，但在我们对其生物合成和结构的了解中仍有一些关键的未知因素。在这项拨款申请中提出的研究将(1)加强我们对大豆油素和角质的生物合成和结构的了解，以及(2)使用一种新的系统-茄科植物的湿柱头-定义脂肪聚酯合成的酶学。将使用多学科方法。拟南芥、杨树和马铃薯突变体将被用来解决关于聚酯结构的问题。生化方法将使用烟草的发育中的柱头，它会产生一种富含羟基脂肪酸聚合物的渗出物，与角质不同，这种聚合物可溶于有机溶剂，在实验上更容易分析。基因组学方法将涉及对发育中的烟草柱头进行转录组分析。候选基因将通过基因沉默和烟草和矮牵牛柱头中的基因过度表达来测试。这项研究计划的一个长期目标是操纵植物聚酯的组成，以改善理想的作物农艺性状，包括抵抗生物和气候胁迫，改变种子休眠，提高种子活力。拟南芥的研究适用于近亲，如油菜科，而茄科包括主要作物物种，如番茄和马铃薯。除了对农业生产的潜在影响外，拟议的工作还涉及重要的工业产品、聚酯及其单体--欧米伽-羟基脂肪酸。了解柱头聚酯组装可能导致在植物或微生物发酵系统中更丰富地生产这些材料的方法。在这个项目中接受培训的研究生、本科生和博士后将成为团队工作的一部分，在这个团队中，化学和分子遗传学方法将在同一实验室并排进行，而且通常是在同一张长凳上进行。拟议的研究将提供植物分子生物技术和分析化学方面的尖端HQP培训。

The interactions of plants with the environment begin at their surface. Plant surfaces are covered by lipid barriers that contain a core structure of polyesters derived from hydroxy fatty acids: cutin and suberin. Cutin and waxes form the cuticle that covers the aerial primary surfaces of plants. Suberin is found on cork cell walls of tree bark, tuber skin, seed coats, and root periderm. These natural defenses protect plants against pathogens, salinity, and drought. Although lipid polyesters are critical to the subsistence and performance of all agricultural and forestry species, there are key unknowns in our understanding of their biosynthesis and structure. Research proposed in this grant application will (1) enhance our understanding of the biosynthesis and structure of suberin and cutin, and (2) define the enzymology of lipid polyester synthesis using a novel system, the wet stigmas of Solanaceous species. Multidisciplinary approaches will be used. Arabidopsis, poplar and potato mutants will be employed to address questions on polyester structure. Biochemical approaches will use developing stigmas of tobacco, which produce an exudate rich in hydroxy fatty acid polymers that, unlike cutin, are soluble in organic solvents and experimentally easier to analyze. Genomic approaches will involve transcriptome analysis of developing tobacco stigmas. Candidate genes will be tested by gene silencing and by gene overexpression in tobacco and petunia stigmas. One long-term goal of this research program is to manipulate the composition of plant polyesters to improve desirable agronomic crop traits, including resistance to biotic and climatic stresses, modification of seed dormancy, and improvement of seed viability. Research in Arabidopsis is applicable to close relatives such as canola, whereas the Solanaceae family includes major crop species, for example tomato and potato. In addition to its potential impact on agricultural production, the work proposed involves important industrial products, polyesters and their monomers, omega-hydroxy fatty acids. Understanding stigma polyester assembly may lead to ways of producing these materials more abundantly in plants or in microbial fermentation systems. Graduate and undergraduate students and postdocs trained in this project will be part of a team effort where chemical and molecular genetic approaches take place side-by-side in the same laboratory and often at the same bench. The proposed research will provide cutting-edge HQP training in plant molecular biotechnology and analytical chemistry.