RUI: Water In, Air Out: Mechanisms of Xylem Embolism Repair in Seed Plants

维管植物通过高度专业化的水力系统木质部将水从根输送到叶。大多数时候，该系统中的水处于大气压以下或负压下，这就有可能通过泄漏将空气吸入导电细胞，形成气泡。这些被称为木质部栓塞的气泡会阻碍植物体内的水分运输，严重时可导致根、枝或整株植物死亡。在许多植物中，即使在轻微的干旱压力下，栓塞也会形成，甚至经常是每天。许多植物物种已经被发现有能力从木质部中去除气泡，并在木质部仍在负压下输送水分时向传导细胞中补充水分。其他物种似乎无法在负压下修复栓塞。该项目的目的是测试从禾草到针叶树等种子植物物种的栓塞修复，将研究结果与木质部的解剖特征联系起来，并测试这些物种用于去除空气和补充液压系统的细胞机制。这项研究旨在测试关于水传导细胞再填充的其他假设，这可能涉及被动的物理过程，也可能涉及与水传导细胞相关的活细胞施加的主动渗透力。研究的一些植物物种是经济上重要的作物、园艺和木材物种，因此，对栓塞修复机制的深入了解将有助于更好地了解这些植物的耐旱性，并将对农业、园艺和林业产生潜在影响，最直接的是可持续灌溉管理实践。该项目将继续让本科生和研究生积极参与研究，包括大量来自代表性不足群体的学生。该研究将与比利时和德国的研究实验室进行国际合作，并将包括国际学生和工作人员交流，这将使所有三个合作实验室的学生和研究人员接触到新的想法和经验。

Vascular plants transport water from roots to leaves in a highly specialized hydraulic system, the xylem. Most of the time, water in this system is under sub-atmospheric or negative pressure, which creates the possibility that air can be sucked into the conducting cells through leaks, forming air bubbles. These air bubbles, which are called xylem embolisms, can impede water transport in plants, in severe cases leading to death of roots, branches, or whole plants. In many plants, embolisms form even under mild drought stress, frequently even daily. Many plant species have been found to have the ability to remove air bubbles from the xylem and refill the conducting cells with water even while the xylem is still transporting water under negative pressure. Other species appear to be unable to repair embolism under negative pressure. The aims of this project are to test for embolism repair in seed plant species ranging from a grass to conifer trees, relate the findings to anatomical traits of the xylem, and test for cellular mechanisms used by these species to remove air and refill the hydraulic system. The research is designed to test alternative hypotheses regarding the refilling of water-conducting cells, which could involve either passive, physical processes or active, osmotic forces exerted by living cells that are associated with water-conducting cells. Several of the plant species studied are economically important crop, horticultural, and timber species, therefore insights into mechanisms of embolism repair will lead to a better understanding of drought tolerance in these plants and will have potential implications for agriculture, horticulture, and forestry, most directly for sustainable irrigation management practices. The project will continue ongoing and active involvement of undergraduate and graduate students in research, including a large number of students from underrepresented groups. The research will be done in an international collaboration with research labs in Belgium and Germany and will include international student and staff exchanges, which will expose students and researchers in all three collaborating labs to new ideas and experiences.