Plant surface lipid barriers: biosynthesis, regulation and protective functions

植物有特殊的基于脂质的屏障，在控制水分运动、养分吸收和气体交换方面发挥关键作用。这些表面脂类还提供了对各种环境应激的保护，如干旱和病原体攻击。植物气生表面覆盖着角质层，角质层主要由聚合脂(角质)和相关的蜡质组成。同样，Suberin是一种脂质-酚类异多聚体屏障，存在于各种外部和内部组织的细胞壁中，包括根内胚层和成熟的周皮(如块茎皮肤和树皮)。因此，植物角质层和角质化的周皮形成了地球上最大的生物界面，提供了与周围环境(通常是敌意的)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受控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学和生化方法相结合的方法来研究植物表面脂肪的产生，主要是在模式植物拟南芥中。具体地说，在接下来的五年里，我的研究团队将：(1)确定控制Suberin沉积的Myb转录因子家族的特征；(2)发现对产生完全功能的Suberin屏障至关重要的其他酶、转运体或调节器；(3)深入了解Suberin及其相关蜡质在极端胁迫期间保护植物的机制；以及(4)评估表面组织产生的挥发性脂肪酸和甲基酮在保护昆虫和病原体方面的潜在作用。 我们的总体目标是获得关于表面脂屏障的合成和生态生理功能的基础知识，其应用目的是为发展耐逆作物提供信息和工具。考虑到不断变化的气候条件目前限制了包括加拿大在内的世界大片地区的农业生产，提高作物的抗旱性尤其具有吸引力。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病害造成的损失的一项重要战略。此外，植物表面脂肪含有丰富的脂肪醇、烷基酯和含氧脂肪酸，这些都是有商业价值的化学品。对植物表面脂肪生物合成的详细了解对于充分利用这种可再生化学资源的潜力至关重要，例如通过油籽作物和微生物的代谢工程。在接下来的5年里，这项研究计划将为9名研究生(5名博士，4名硕士)和20-25名本科生提供脂类生物化学、遗传解剖、分子生物技术和植物逆境生理学方面的高级培训。

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.