Formation, physical structure and biological function of plant wax compounds

干旱每年给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，迫切需要耐旱性更好的作物品系。目前的农作物品种之所以遭受干旱、炎热的环境，主要是因为它们在广阔的空气表面上通过过度的蒸腾作用使水分流失。相比之下，许多野生植物物种的表皮都是密封的，以尽量减少蒸腾作用，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，所有物种的植物（和人类）的皮肤都涂上了含有类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的密封性能远远优于我们现在的作物，这表明我们的作物蜡成分的相对较小的变化可能会大大提高它们的耐旱性。******许多研究都是为了操纵植物蜡的成分，但迄今为止对蜡的性能影响有限。首先，即使是蜡质总量大幅增加的植物品系，其蒸腾控制能力也只有适度增强，这表明其性能更多地取决于蜡质的组成而不是数量。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，可能是因为化学信息和实验工具相对较少。以前所有的努力都局限于所有物种共有的蜡化合物，具有相似的分子结构。相反，决定蜡结构的关键化合物必须在选定的物种中确定，并根据浓度和条件（温度）对其对蒸腾控制的影响进行量化。******在这个项目中，我们建议研究特殊蜡化合物的影响，由于其杰出的结构，可能对蜡的密封性能有很强的影响。计划中的实验建立在我的实验室最近的进展基础上，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子上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化合物（酮），它们的长碳链上有扭结，扰乱了蜡混合物的分子包装。我们现在将研究这些酮的形成，它们对蜡混合物物理结构的影响，以及它们对耐旱性的影响。为此，将比较拟南芥、小麦和其他含有蜡酮的物种的原生蜡，并将精选的蜡化合物组合在人工混合物中，以测试其效果。******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使用最先进仪器的重要经验，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.**