Formation, physical structure and biological function of plant wax compounds

干旱每年在加拿大和国外的许多农业部门造成严重损失。因此，为了养活面临全球气候变化的日益增长的人口，迫切需要具有更好耐旱性的作物品系。目前的作物品种遭受干燥和炎热的条件，主要是因为它们通过在广阔的空中表面过度蒸腾而失去水分。相比之下，许多野生植物物种都有密封的皮肤，以最大限度地减少蒸腾作用，使它们能够在稀树草原甚至沙漠中生长。为了防止水分流失，植物(和人类)的皮肤都涂上了含有所有物种相似化合物的蜡混合物。然而，尽管有这些相似之处，许多野生植物的蜡涂层具有远远优于我们目前作物的密封性能，这表明我们作物的蜡质成分相对较小的变化可能会极大地提高它们的抗旱性。*在操纵植物蜡成分方面进行了大量研究，但到目前为止对蜡性能的影响有限。首先，即使是含蜡量大幅增加的植物品系也只略微加强了蒸腾作用的控制，这表明表现更多地取决于蜡质成分而不是数量。然而，那些试图通过改变成分来增强屏障的研究也取得了有限的成功，可能是因为相对较少的化学信息和实验工具。所有以前的努力都局限于具有相似分子结构的所有物种共有的蜡类化合物。相反，决定蜡结构的关键化合物必须在选定的物种中确定，它们对蒸腾控制的影响取决于浓度和条件(温度)。在这个项目中，我们建议调查特殊的蜡化合物的影响，因为它们的突出结构，可能对蜡的密封性能有很大的影响。计划中的实验建立在我的实验室最近的进展的基础上，在那里我们已经开发了所有必要的工具来研究不同物种叶片衬里的复杂蜡混合物的化学成分、物理结构和生物功能。特别是，我们已经确定了许多蜡类化合物(酮)在其长碳链上有扭曲，扰乱了蜡混合物的分子堆积。我们现在将研究这些酮的形成，它们对蜡混合物的物理结构的影响，以及它们对抗旱性的影响。为此，将对拟南芥、小麦和其他含有蜡酮的物种的天然蜡质进行比较，并将选定的蜡质化合物混合在人工混合物中，以测试它们的效果。*这项研究工作将由研究生和本科生进行，他们将在他们的项目中获得重要的经验，使用最先进的工具以及未来在工业、政府或学术界就业所需的软技能。**

Droughts cause severe losses in many agronomy sectors in Canada and abroad every year. Therefore, to feed a growing population facing global climate change, crop lines with improved drought tolerance are urgently needed. Current crop varieties suffer from dry, hot conditions mainly because they loose water through excessive transpiration across their vast aerial surfaces. In contrast, many wild plant species have skins sealed to minimize transpiration, allowing them to grow in savannas or even deserts. To prevent water loss, the skins of plants (and humans) are coated with wax mixtures comprising similar compounds in all species. However, despite these similarities, the wax coatings of many wild plants have sealing properties far superior to our current crops, suggesting that relatively small changes in the wax composition of our crops may greatly improve their drought tolerance. ******Much research has gone into manipulating plant wax compositions, but with limited effects on wax performance so far. Firstly, even plant lines with drastically increased overall wax amounts had only modestly enhanced transpiration control, suggesting that performance depends more on wax composition than quantity. However, also those studies attempting to enhance the barrier by changing composition had limited success, likely because relatively little chemical information and experimental tools were available. All previous efforts were restricted to wax compounds common to all species, with similar molecular structures. Instead, key compounds determining wax structure must be identified in select species, and their effect on transpiration control quantified depending on concentrations and conditions (temperature).******In this project, we propose to investigate the effect of special wax compounds that, due to their outstanding structures, likely have strong effects on the sealing properties of the wax. The planned experiments build on recent progress in my lab, where we have developed all the necessary tools to investigate the chemical composition, physical structure, and biological function of complex wax mixtures lining the leaves of diverse species. In particular, we have identified many wax compounds (ketones) with kinks in their long carbon chains that disturb the molecular packing of the wax mixture. We will now study the formation of these ketones, their effects on the physical structure of the wax mixtures, and their impact on drought tolerance. To this end, the native waxes of Arabidopsis, wheat and other species containing wax ketones will be compared, and select wax compounds will be combined in artificial mixtures to test their effects. ******This research work will be performed by graduate and undergraduate students, who will gain important experience in their projects using state-of-the-art instruments along with soft skills needed for future employment in industry, government or academia.**