Decoding drought tolerance

大型生物体的健康取决于其循环系统或血管系统的正常功能。心血管疾病常常危害人类健康，植物也是如此。植物的健康取决于维管组织在植物体内分配水、营养物质和糖的能力。重要的是，植物的运输过程容易受到干旱和霜冻等环境因素的影响。这两种因素都能触发木质部导管中空气栓塞的形成，这将使叶片的水分供应更加困难。由于木质部阻塞，叶片将减少气体交换，在更严重的情况下，这将导致枯死和死亡。不利的环境条件也可能减少韧皮部中的糖运输。干旱是影响植物维管功能的主要因素。它是最复杂的，可以说是最限制植物生长的压力因素，在世界范围内，在农田和森林一样。此外，干旱往往与火灾和虫害的爆发有关。尽管干旱在林业和农业中的重要性，但我们仍然缺乏对植物如何应对干旱的一些基本了解。近年来，由于干旱引起的森林树木枯死的报道越来越多，人们对树木枯死的确切机制提出了疑问。***我的研究计划的长期目标是了解干旱对血管功能的多重影响，并探索物种和基因型在如何应对缺水方面的差异。我研究的短期目标是：(1)研究整个植物的水力传导动力学；(2)分析树木年轮中干旱和昆虫落叶的独特细胞特征；(3)量化不同气候区白云杉幼苗抗旱性的遗传变异；(4)探讨干旱对植物韧皮部发育和功能的影响。随着全球温度和降水制度的不断变化，有必要培养下一代科学家来推进干旱生理学领域。该计划将培养2名博士、2名硕士和5名本科生。从这项研究中获得的知识将使我们能够选择并最终设计出具有耐旱性和生长特性的植物，这些植物将适应其生长环境中当前和未来的挑战。

The health of larger organisms depends on the proper function of their circulatory or vascular systems. Human health is often compromised by cardiovascular diseases, and the same is true for plants. Plant health depends on the ability of the vascular tissue to distribute water, nutrients, and sugar across the plant body. Importantly, transport processes in plants are susceptible to environmental factors such as drought and frost. Both of these factors can trigger the formation of air embolism in xylem conduits, and this will make the supply of water to leaves more difficult. As a result of xylem blockage, leaves will reduce gas exchange, and in more severe cases this will be followed by dieback and mortality. Adverse environmental conditions are likely to also reduce sugar transport in the phloem.***Drought is the main factor that compromises vascular function in plants. It is the most complex and arguably the most limiting stress factor for plant growth worldwide, in agricultural fields and forests alike. In addition, drought is often associated with fire and insect outbreaks. Despite the importance of drought in forestry and agriculture, we still lack some basic understanding of how plants cope with drought. This topic has recently received much attention among tree physiologists, as accumulating reports of drought-induced forest tree dieback have raised questions about the exact mechanism of tree dieback.***The long-term goals of my research program are to understand the multiple effects of drought on vascular function and to explore how species and genotypes differ in how they cope with water shortage. The short-term objectives of my research are to: (1) Study the dynamics of whole-plant hydraulic conductance; (2) Analyze the unique cellular signatures of drought and insect defoliation in tree rings; (3) Quantify genetic variation of drought tolerance in white spruce seedlings from different climate regions; and (4) Explore how drought impacts the development and putative function of phloem.***As global temperatures and precipitation regimes continue to change, there is a need for training the next generation of scientists to advance the field of drought physiology. The proposed research program will train 2 Ph.D., 2 M.Sc., and 5 undergraduate students. The knowledge gained from this research will allow us to select and eventually engineer plants with drought tolerance and growth characteristics that will match current and future challenges in their growing environment.