Understanding xylem refilling: Molecular and biophysical perspectives

植物，特别是树木，每天都将大量的水从土壤中转移到大气中，而不使用任何移动部件。 对于成熟的橡树来说，这可能是每天200加仑的水。 这种运输在张力下发生，因此容易受到气穴的影响，导致栓塞（用空气填充木质部导管），这是造成水力连续性丧失的原因。 这种在树干中的水分运输能力的损失可能导致光合能力的显著损失，甚至植物死亡。植物如何处理这种明显的内在弱点，并保持水柱完整，仍然是理解运输过程的主要问题。 目前的一个假设是，植物不能避免栓塞的发生，而是进化出重新填充空血管和恢复运输能力的能力，在积极蒸腾。 本研究的目的是整合遗传、生化、形态和生理过程，分析植物在张力下栓塞再填充过程中的生物活性。 从多个实验中产生的数据将用于通知系统水平的方法，包括定量和定性分析以及理论建模，以了解环境应力下栓塞形成和再填充的动力学和控制。 解决这种栓塞/再填充过程将填补知识的重大空白，并为未来研究植物水关系，植物生物技术和自我修复装置的生物模拟以应对气候变化的挑战开辟新的途径。 将解剖学与生理学联系起来也将为更好地理解早期植物进化的进化轨迹提供基础，这些早期植物进化使这些以前的水生生物能够成功地入侵陆地栖息地。将利用外联活动，包括公开讲座和在网上传播新方法和新规程，以扩大受众范围。拟议的研究项目还将支持博士后研究员的职业发展，并通过暑期就业机会激发本科生对植物生物学的兴趣。

Plants and especially trees move a significant volume of water every day from the soil to the atmosphere without employing any moving parts. In the case of the mature oak tree, this could be as much as 200 gallons of water a day. This transport happens under tension and thus it is vulnerable to cavitation resulting in embolism (filling of xylem vessels with air) that is responsible for the loss of hydraulic continuity. Such loss of water transport capacity in tree stems could lead to significant loss of photosynthetic capacity or even plant death. How plants deal with this apparent intrinsic weakness and keep the water column intact remains the major question in the understanding of the transport process. One of the current hypotheses is that plants cannot avoid occurrence of embolism but instead evolved the ability to refill empty vessels and restore the transport capacity during active transpiration. The goal of this proposal is to analyze plant biological activity during embolism refilling under tension by integrating genetic, biochemical, morphological and physiological processes. The data generated from multiple experiments will be used to inform a systems level approach including quantitative and qualitative analysis as well as theoretical modeling to understand the dynamics and control of embolism formation and refilling under environmental stress. Resolving this embolism/refilling process would fill a major gap in knowledge and open new avenues for future research in plant water relations, plant biotechnology, and bio-mimicking of self healing devices to deal with challenges of climate change. Linking anatomy with physiology will also provide a foundation for better understanding the evolutionary trajectories of early plant evolution that allowed these formerly aquatic organisms to succeed in their quest to invade terrestrial habitats. Outreach activities, including public lectures and web dissemination of new methods and protocols, will be used to reach a broader audience. The proposed research project will also support the career development of a postdoctoral fellow and stimulate interest in plant biology among undergraduate students via summer employment opportunities.