RAPID: From microbes to new tropical forests: an experimental test of fungal specialization on host tree genotypes in the context of a reforestation experiment

土壤真菌被认为是建立热带树木幼苗的最重要因素之一。致病性土壤真菌可以导致幼苗死亡，而其他土壤真菌与幼苗形成有益的共生关系，可以通过获取土壤中的关键营养物质来帮助幼苗茁壮成长。该项目的目标是更好地了解真菌在重新造林项目中促进幼苗生长和维持树种多样性的背景。成年树之间的亲缘关系将是这项工作的一个特别重点，假设幼苗种植在与自己基因差异更大的成年树附近时，将与更多有益的真菌相互作用。该项目将在厄瓜多尔进行，这是一个物种丰富的地区，森林砍伐日益受到威胁，而森林砍伐向大气中释放碳。相比之下，重新造林为许多濒危物种创造了碳汇和栖息地。这项关于幼苗与真菌相互作用的研究可以帮助设计重新造林工作。更广泛的影响还包括培养一名在美国的博士后助理和研究生。该项目提供了一种新颖的多物种测试，通过选择更常见的基因型和支持罕见基因型的生存，病原土壤真菌的种内特化促进并维持了植物物种内的遗传多样性。同时，该研究还探讨了土壤真菌群落是否以及在什么情况下对幼苗有积极影响。为此，该团队将在厄瓜多尔的一个大规模植树造林项目中实施一项荫蔽屋实验。研究设计允许评估幼苗的表现，作为一个函数，一个给定的幼苗母树是如何相关的树在其土壤中种植的幼苗。该设计允许对16种不同树种进行36个种内两两比较，每个重复8个，并使用无菌接种物进行对照。树木的遗传亲缘性和真菌群落组成和功能的概况将通过高通量测序进行评估。这项工作有望为土壤真菌在物种内专业化发生的程度提供新的数据；同种母树遗传相似性预测土壤真菌对幼苗性能影响的大小和方向的程度；以及土壤和根真菌群落的特定组合如何影响幼苗的表现。这些发现有望促进我们对控制热带树木多样性的生态和微观进化因素的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Soil fungi are thought to be one of the most important factors for establishment of tropical tree seedlings. Pathogenic soil fungi can cause seedlings to die while other soil fungi form beneficial symbiosis with seedlings that can help them thrive by obtaining key nutrients in the soil. The goal of this project is to better understand the contexts in which fungi promote seedling growth and maintain tree species diversity, in the context of a reforestation project. Degree of relatedness between adult trees will be a particular focus of this work, with the hypothesis that seedlings will interact with more beneficial fungi when they are planted near adult trees that are more genetically different from themselves. This project will take place in Ecuador, in a species-rich region that is increasingly threatened with deforestation, which releases carbon into the atmosphere. Reforestation, in contrast, creates a sink for carbon and habitat for many endangered species. This research on seedling-fungal interactions can aid in designing reforestation efforts. The broader impacts further include training a U.S. based post-doctoral associate and graduate student.This project provides a novel, multi-species test of the idea that, by selecting against more common genotypes and favoring survival of rarer genotypes, within-species specialization by pathogenic soil fungi promotes and maintains genetic diversity within plant species. At the same time, the research also explores whether and in what contexts soil fungal communities have positive impacts on seedlings. To do so, the team will implement a shade house experiment made possible by a large-scale reforestation project in Ecuador. The study design allows an assessment of seedling performance as a function of how related a given seedling’s maternal tree is to the conspecific tree in whose soil the seedling is planted. The design allows 36 within-species pairwise comparisons with 8 replicates each, for each of 16 different tree species, as well as controls with sterilized inoculum. Genetic relatedness of trees and profiles of fungal community composition and function will be assessed via high-throughput sequencing. This work is expected to provide novel data on the extent to which within-species specialization by soil fungi occurs; the degree to which genetic similarity between conspecific maternal trees predicts magnitude and direction of soil fungal impacts on seedling performance; and how specific combinations of soil and root fungal communities impact seedling performance. These findings are expected to advance our understanding of the ecological and microevolutionary factors that control the diversity of tropical treesThis award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.