Plant surface lipid barriers: biosynthesis, regulation and protective functions

植物具有专门的脂质屏障，在控制水分运动、营养吸收和气体交换方面发挥关键作用。这些表面脂质还提供对各种环境胁迫如干旱和病原体攻击的保护。植物气生表面覆盖有角质层，角质层主要由聚合脂质（角质）和相关的蜡组成。同样，木栓质是在各种外部和内部组织的细胞壁中发现的脂质-酚类杂聚物屏障，包括根内皮层和成熟的周皮（例如块茎皮和树皮）。因此，植物表皮和栓化的外表皮形成了地球上最大的生物界面，提供了与周围环境（通常是敌对环境）的第一个接触点。我的NSERC发现研究计划的长期目标是了解植物表面脂质屏障的调节生物合成以及它们发挥保护功能的机制。我的研究小组正在使用遗传和生物化学方法相结合的方法来研究植物表面脂质的产生，主要是在模式植物拟南芥中。具体而言，在未来五年内，我的研究团队将：（1）表征控制木栓质沉积调节的Myb转录因子家族，（2）揭示对于产生全功能木栓质屏障重要的其它酶、转运蛋白或调节剂，（3）提供对木栓质及其相关蜡在极端胁迫时期保护植物的机制的了解，和（4）评估表面组织产生的挥发性脂肪酸和甲基酮在保护免受昆虫和病原体侵害中的潜在作用。* 我们的总体目标是获得关于表面脂质屏障的合成和生态生理功能的基础知识，其应用目的是为耐胁迫作物的开发提供信息和工具。考虑到不断变化的气候条件目前正在限制包括加拿大在内的世界大片地区的农业生产，提高作物耐旱性特别有吸引力。加强作物对病原体和害虫的自然防御也是我们努力减少作物因疾病而损失的一项重要战略。此外，植物表面脂质富含脂肪醇、烷基酯和含氧脂肪酸，它们是具有商业价值的化学品。植物表面脂质生物合成的详细知识对于充分利用这种可再生化学资源至关重要，例如通过油料作物和微生物的代谢工程。在接下来的5年里，该研究计划将为9名研究生（5名博士，4名硕士）和20-25名本科生提供脂质生物化学，遗传解剖，分子生物技术和植物胁迫生理学领域的高级培训。*** ******

Plants have specialized lipid-based barriers that play critical roles in controlling water movement, nutrient uptake, and gas exchange. These surface lipids also provide protection against various environmental stresses such as drought and pathogen attack. Plant aerial surfaces are coated with cuticle, which is composed mostly of polymerized lipids (cutin) and associated waxes. Likewise, suberin is a lipid-phenolic heteropolymeric barrier found in the cell walls of various external and internal tissues, including root endodermis and mature periderms (e.g. tuber skins and tree bark). As such, plant cuticles and suberized periderms form the largest biological interfaces on the planet, providing first points of contact with the surrounding, often hostile, environment. The long-term goal of my NSERC Discovery research program is to understand the regulated biosynthesis of plant surface lipid barriers and the mechanisms by which they exert their protective functions.****My research group is using a combination of genetic and biochemical approaches to study plant surface lipid production, largely in the model plant Arabidopsis thaliana. Specifically, over the next five years, my research team will: (1) characterize a family of Myb transcription factors that control the regulation of suberin deposition, (2) uncover additional enzymes, transporters or regulators that are important for producing a fully functional suberin barrier, (3) provide insights into the mechanisms by which suberin and its associated waxes protect plants under periods of extreme stress, and (4) assess the potential roles of volatile fatty acids and methylketones produced by surface tissues in protection against insects and pathogens. ***Our overall goal is to gain fundamental knowledge regarding the synthesis and eco-physiological functions of surface lipid barriers, with the applied aim of providing information and tools for the development of stress tolerant crops. The improvement of crop drought tolerance is particularly attractive considering changing climate conditions are currently limiting agricultural production in large areas of the world, including Canada. Enhancing the natural defences of crops towards pathogens and pests is also an important strategy in our efforts to reduce crop losses to disease. In addition, plant surface lipids are rich in fatty alcohols, alkyl esters and oxygenated fatty acids, which are commercially valuable chemicals. Detailed knowledge of plant surface lipid biosynthesis is critical for harnessing this renewable chemical resource to its full potential, for example through the metabolic engineering of oilseed crops and microbes. Over the next 5 years, this research program will provide advanced training to 9 graduate (5 PhD, 4 MSc) and 20-25 undergraduate students in the areas of lipid biochemistry, genetic dissection, molecular biotechnology, and plant stress physiology.*** *** ******