DISSERTATION RESEARCH: Investigating life history and environmental drivers structuring host-associated assemblages of mycorrhizal and endophytic fungi in subalpine tree islands

在DNA测序技术取得最新进展之前，科学家们永远无法想象与每一种植物和动物个体相关的巨大微生物多样性。所有的高等生物都是微生物的家园，而不是独立的个体生物，它们是各种各样的微小细菌和真菌的聚集地。从我们的嘴到植物的叶子，独特的微生物群落在高等生物的功能中起着重要的作用。本研究的重点是了解与植物叶片相关的真菌（叶面内生菌）和与树木根系相关的有益真菌（外生菌根真菌）的群落结构驱动机制。该研究通过揭示真菌多样性，有助于改善树木健康，生态系统稳定性和对气候变化的适应能力，具有广泛的社会影响。本研究的重点树种之一白皮松是亚高山环境中重要的生态系统功能基础树种。白皮松受到水疱锈病、山松甲虫和气候变化的严重威胁。众所周知，叶面内生菌可以提高树木对气候变化引起的疾病和温度波动的抵抗力。因此，揭示与这些树木相关的叶面内生菌的多样性有可能导致对这种濒危树种有益的处理。此外，该项目还具有很强的教育和推广成分。参与拟议工作的学生将获得实地工作和尖端DNA测序方法的经验。尽管真菌是植物群落组成和生态系统功能的重要驱动因素，但人们对这些真菌的基本生物学或多样性模式知之甚少。该项目将尖端的下一代测序技术应用于位于约塞米蒂国家公园的孤立松树，以回答有关这些真菌的群落结构，多样性和基本生物学的重要问题。在这里，一个简单的寄主岛环境被用来测试传播距离、寄主类型、环境（寄主生理、土壤化学和季节）对两种寄主依赖性真菌群落结构的影响。本文的主要目的是比较生态位组装和散布组装在宿主相关真菌的两个功能行会中的相对影响。

Prior to recent advances in DNA sequencing technologies, scientists could never have imagined the vast microbial diversity associated with each individual plant and animal. Rather than individual discrete organisms, all higher organisms are home to diverse consortia of microscopic bacteria and fungi, called microbes. From our mouths to plants' leaves, unique communities of microorganisms play important roles in higher organisms'ability to function. This research focuses on understanding the mechanisms driving the community structure of the fungi associated with the leaves of plants (foliar endophytes) and beneficial fungi associated with the roots of trees (ectomycorrhizal fungi). This research has broad ranging societal impacts by uncovering fungal diversity that can be helpful to improving tree health, ecosystem stability, and resilience to climate change. One of the focal trees in this study, the white bark pine, is a foundation species central to ecosystem function in subalpine environments. White bark pine trees are highly threatened by a combination of blister rust, mountain pine beetles, and climate change. Foliar endophytes are known to improve the resistance of trees to both disease and temperature fluctuations caused by climate change. Thus, uncovering the diversity of foliar endophytes associated with these trees has the potential to lead to beneficial treatments for this endangered tree species. In addition, this project also has strong educational and outreach components. Students involved in the proposed work will gain experience with fieldwork and cutting edge DNA sequencing methods. Despite being incredibly important drivers of plant community composition and ecosystem function, little is known about the basic biology or patterns of diversity of these fungi. This project applies cutting edge next generation sequencing technologies to isolated pine trees located in Yosemite National Park to answer important questions about the community structure, diversity, and basic biology of these fungi. Here a simple host-island setting is used to test for the effect of dispersal distance, host type, environment (host physiology, soil chemistry & season), on community structure in two host-dependent guilds of fungi. The main aim of this proposal is to compare the relative effects of niche versus dispersal assembly in two functional guilds of host-associated fungi.