Dissertation Research: Characterization of Foliar Fungal Endophyte Communities of Sequoia sempervirens and Investigation of their Symbiotic Relationship

红杉(加利福尼亚州沿海的红杉)是众所周知的世界上最高的树，有些个体高达115米。最近的研究发现了一种独特的生理适应，使这些树能够应对从根系统向树冠上部树枝输送水分的压力。当地下水储存在漫长、干燥的夏季耗尽时，在季节性雾事件期间，半夏水能够吸收凝结在树叶表面的水。据推测，生长在半枝莲叶片上和叶片内的真菌群落有助于叶片吸收水分。这项拟议的研究将首先使用分子条形码对红杉树不同部分和沿海森林不同地区的叶真菌群落进行采样和表征。温室实验中的稳定同位素标记雾将被用来确定叶面真菌的存在是否增加了树木通过叶子吸收水分的能力，如果是这样的话，与半枝莲相关的哪些真菌群落在帮助水分吸收方面是最有效的。最后，C13标记的二氧化碳将被用来追踪碳(以糖的形式)从宿主到真菌的可能转移，暗示了树木与其所栖息的真菌群落之间的共生关系。这项研究将有助于表征加州沿海红杉的微生物群，这是一种重要的经济和生态关键物种。了解真菌群落在维持红杉树生长方面的作用将对可持续林业实践产生重要影响，特别是在夏季变得更加干燥以及通过雾吸收树叶可能在森林健康方面发挥越来越重要的作用的情况下。这项研究还证明了真菌在生态系统动力学中可以发挥的重要积极作用。这项研究将被纳入K-12学生的三个动手课程计划，说明他们周围自然环境中隐藏的、微观的多样性和复杂的物种相互作用。这些课程计划将被纳入美国国家科学基金会资助的GK-12计划“探索加州生物多样性”，并用于在加州公立学区伯克利的两所中学举行的“教授疯狂科学”课外计划。这项支助还将导致完成一名女科学家的博士论文，并培训两名研究实验室和计算技术的本科生学徒，以研究真菌多样性和群落生态学。

Sequoia sempervirens (California's coastal redwood) is well known as the tallest tree in the world, with some individuals reaching 115 meters tall. Recent research has uncovered a unique physiological adaptation that allows these trees to deal with the stress of transporting water from the root system to upper branches of the canopy. When ground water stores are depleted during the long, dry summers, S. sempervirens is able to absorb water that condenses on its leaf surfaces during seasonal fog events. It is hypothesized that a community of fungi living on and within the leaves of S. sempervirens aid in the foliar absorption of water. The proposed research will first sample and characterize the foliar fungal community present in different parts of the redwood trees and from different areas of the coastal forests using molecular 'barcoding'. Stable isotope-labeled fog in glasshouse experiments will be used to determine if the presence of foliar fungi increases the tree?s ability to absorb water through its foliage, and if so which fungal communities found in association with S. sempervirens are the most effective at aiding water absorption. Finally, C13-labeled carbon dioxide will be used to track the possible transfer of carbon (in the form of sugars) from the host to the fungi, suggesting a symbiotic relationship between the tree and the fungal community it harbors.This research will help to characterize the microbiome of the california coastal redwood, an economically and ecologically important keystone species. Understanding the role of the fungal community in sustaining redwood trees will have important consequences for sustainable forestry practices, especially as drier summers become more common and foliar uptake via fog may play an increasingly important role in forest health. This research additionally demonstrates the important positive role that fungi can play in ecosystem dynamics. This research will be incorporated into three hands-on lesson plans for K-12 students that illustrate the hidden, microscopic diversity and complex species interactions in the natural environment around them. These lesson plans will be incorporated into the NSF funded GK-12 program "Exploring California Biodiversity" and utilized in the "Teaching MadScience" after school program held at two Middle Schools in the Berkeley, CA Public School District. The support will also result in the completion of a doctoral dissertation by a female scientist and the training of two undergraduate research apprentices in laboratory and computational techniques for studying fungal diversity and community ecology.