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，脂质屏障包含由羟基脂肪酸衍生的聚酯的核心结构：角质层和木质素。角质层和蜡质构成了覆盖植物空气初级表面的角质层。木栓素见于树皮的软木细胞壁、块茎皮、种皮和根周皮。这些天然防御可以保护植物免受病原体、盐度和干旱的侵害。尽管脂质聚酯对所有农业和林业物种的生存和性能至关重要，但我们对其生物合成和结构的理解仍存在关键的未知因素。本基金申请中的研究将(1)增强我们对木质素和角质素的生物合成和结构的理解，(2)利用一种新的系统——茄属植物的湿柱头来定义脂质聚酯合成的酶学。将采用多学科方法。拟南芥、杨树和马铃薯的突变体将用于解决聚酯结构的问题。生物化学方法将利用烟草柱头的发育，柱头会产生一种富含羟基脂肪酸聚合物的渗出物，与角质层不同，这种聚合物可溶于有机溶剂，在实验中更容易分析。基因组方法将涉及烟草柱头发育的转录组分析。候选基因将通过基因沉默和基因过表达在烟草和矮牵牛花柱头测试。这项研究计划的一个长期目标是操纵植物聚酯的组成，以改善理想的农艺作物性状，包括抵抗生物和气候压力，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，而茄科包括主要的作物物种，如西红柿和土豆。除了对农业生产的潜在影响外，这项工作还涉及重要的工业产品，聚酯及其单体，ω -羟基脂肪酸。了解柱头聚酯组装可能会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一个团队的一部分，在这个团队中，化学和分子遗传学方法将在同一个实验室中同时进行，通常在同一个工作台上进行。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.