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。人类健康经常受到心血管疾病的危害，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分、营养物质和糖分的能力。重要的是，植物的运输过程很容易受到干旱和霜冻等环境因素的影响。这两个因素都会在木质部导管中引发气栓形成，这将使叶片的水分供应更加困难。由于木质部堵塞，叶片会减少气体交换，在更严重的情况下，这将导致枯萎和死亡。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。无论是在农业领域还是在森林中，它都是世界范围内植物生长最复杂、也可以说是最有限的压力因素。此外，干旱往往与火灾和虫害爆发联系在一起。尽管干旱在林业和农业中很重要，但我们仍然缺乏对植物如何应对干旱的基本了解。这个话题最近在树木生理学家中引起了很大的关注，因为越来越多的关于干旱引起的森林树木死亡的报道提出了关于树木死亡的确切机制的问题。*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，并探索物种和基因在如何应对缺水方面的差异。我研究的短期目标是：(1)研究全植物导水率的动态；(2)分析树木年轮干旱和昆虫落叶的独特细胞特征；(3)量化来自不同气候地区的白云杉幼苗抗旱性的遗传变异；(4)探索干旱如何影响韧皮部的发育和可能的功能。*随着全球气温和降水制度的持续变化，有必要培训下一代科学家，以促进干旱生理学领域的发展。拟议的研究计划将培养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抗旱性和生长特性的植物，以匹配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.