DISSERTATION RESEARCH: Mechanisms of host preference in the ectomycorrhizal symbiosis

尽管互利互动在许多自然系统中很重要，但仍不清楚为什么有些系统涉及高度专业化的合作伙伴，而另一些系统则不涉及。这个项目调查了不同程度的特异性是如何在一种特定类型的共生中进化和发挥作用的--一种真菌和许多温带森林植物之间的互惠关系。这项研究将把一种真菌与多个遥远的寄主植物结合起来，以研究这种真菌在与不同物种的植物相互作用时如何改变其共生行为。这项实验将深入了解这种重要的互惠关系中的共生植物-微生物交流，并将允许与病原体中的类似系统进行比较。这项研究将使用RNA测序来确定外生菌根真菌Thelephora terrestris中通用宿主偏好的遗传基础。将在微型宇宙中建立来自4个科的6个植物物种，并将其接种到黄花树的孢子上。在共生成熟时，将用碳-13和氮-15标记微型宇宙，并将采集植物、真菌和共生组织进行同位素分析和RNA测序。转录数据将与植物和真菌资源分配的稳定同位素浓缩测量相结合，并在不同的植物-真菌组合中进行比较。在跟踪资源分配的同时，测量共生组织中的基因表达将揭示哪些基因与改善共生性能有关，从而在基因转录、生理功能和互惠作用的稳定性之间提供强大的联系。

Although mutually beneficial interactions are important in many natural systems, it remains unclear why some involve highly specialized partners, while others do not. This project investigates how different degrees of specificity have evolved and function in a particular type of symbiosis - a mutualistic relationship between a fungus and many temperate forest plants. This research will combine a fungus with multiple, distantly related host plants to investigate how the fungus alters its symbiotic behavior when interacting with different species of plants. This experiment will generate insight into symbiotic plant-microbe communication in this important mutualism, and will allow for comparison to similar systems in pathogens. Outreach to science enrichment programs for urban youth in San Francisco will also occur.This study will use RNA sequencing to determine the genetic basis of generalist host preference in the ectomycorrhizal fungus Thelephora terrestris. Six plant species from four families will be established in microcosms and inoculated with spores from Thelephora terrestris. At symbiotic maturity, microcosms will be labeled with carbon-13 and nitrogen-15 and plant, fungal, and symbiotic tissues will be harvested for isotope analysis and RNA sequencing. Transcriptional data will be combined with stable isotope enrichment measurements of plant and fungal resource allocation and compared across different plant-fungus combinations. Measuring gene expression in symbiotic tissues while simultaneously tracking resource allocation will reveal which genes are associated with improved symbiotic performance, providing a powerful link between gene transcription, physiological function, and the stability of mutualistic interactions.