Collaborative Research: Seed-fungal interactions: uncovering functional specificity and primary symbionts as key drivers of tropical tree recruitment

微生物是所有陆地生物群系中植物种群大小、密度和多样性的关键决定因素。在物种丰富的热带森林中，真菌和真菌样生物介导植物种群动态和群落结构。大多数植物真菌动力学的研究都集中在幼苗和树苗上，很少考虑种子。然而，种子的存活是为下一代招募个体的关键的第一步。本研究旨在验证种子期植物与真菌的有益和拮抗相互作用对热带树木招募的重要假设。这些研究人员将提供来自美国和拉丁美洲的包容性、跨学科的研究培训和指导。领导团队将确保所有学员、学生和博士后将受益于他们所在机构和巴拿马史密森尼热带研究所丰富的科学社区，包括专业成长、网络、合作和参与史密森尼热带研究所的包容、多样性、公平和准入倡议的机会。此外，调查人员将启动基于课程的本科研究模块，并在巴拿马继续一个长期的本科实地课程。最后，该团队将在地区、国家（美国、巴拿马）和国际环境中为学生和公众做双语演讲，并通过主办种子生态学IX（两年一次的国际会议）展示他们的研究成果，该会议将于2024年在巴拿马举行。了解影响热带森林生物多样性的过程在全球范围内是很重要的。真菌病原体是热带地区死亡的主要来源，对了解热带树木种群大小、密度、繁殖成功率以及最终的物种多样性至关重要。通过结合种子防御和真菌共生的研究，该项目将揭示热带森林中树木补充的潜在关键但隐藏的驱动因素。本研究将(1)使用两种新方法（非靶向代谢组学和诱导防御试验）来了解种子化学如何影响真菌感染的易感性、致病性和相应的真菌反应；(2)超越局部地理尺度，探索自然环境和母体基因型如何在景观尺度上影响巴拿马运河流域真菌群落组成和寄主易感性；(3)结合实验室和实地方法来验证低多样性微生物系统中的优先效应将强烈影响植物-微生物相互作用结果的假设（称为初级共生假设）；(4)支持在美国及其他地区开展多样化的培训、推广和教育活动。总的来说，这些因素将有助于解决内在因素（种子防御）和外在偶然性（额外的微生物伙伴，不同的环境条件，植物的可变遗传背景），这些因素决定了热带地区种子-真菌相互作用的结果。因此，该项目将阐明真菌如何影响植物招募，并与植物从种子再生的各种野生和农业生态系统相关。该项目包括在南佛罗里达大学、伊利诺伊大学、犹他州立大学和亚利桑那大学对本科生、研究生和博士后进行研究培训。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。

Microbes are key determinants of plant population size, density, and diversity in all terrestrial biomes. In species-rich tropical forests, fungi and fungus-like organisms mediate plant population dynamics and community structure. Most studies of plant-fungal dynamics have focused on seedlings and saplings, with little consideration of seeds. Yet, the survival of seeds is a critical first step to the recruitment of individuals to the next generation. This research aims to test the hypothesis that beneficial and antagonistic plant-fungal interactions at the seed stage are important to tropical tree recruitment. The researchers will provide inclusive, cross-disciplinary research training and mentorship from the US and Latin America. The leadership team will ensure that all trainees, students, and postdoctoral associates, will benefit from the rich scientific community of their institutions and the Smithsonian Tropical Research Institute in Panama, including opportunities for professional growth, networking, collaboration, and participation in the Inclusion, Diversity, Equity and Access initiative at the Smithsonian Tropical Research Institute. In addition, the investigators will initiate course-based undergraduate research modules and continue a long-standing undergraduate field course in Panama. Finally, the team will give bilingual presentations for students and the public in regional, national (US, Panama), and international settings, and showcase their research by hosting Seed Ecology IX, a biennial international meeting, in Panama in 2024.Understanding the processes that influence tropical forest biodiversity is important at a global scale. Fungal pathogens are major sources of mortality in the tropics and essential to understanding tropical tree population size, density, reproductive success, and ultimately, species diversity. By combining the study of seed defenses and fungal symbioses, the project will uncover the potentially crucial but hidden drivers of tree recruitment in tropical forests. This research will (1) use two novel approaches (untargeted metabolomics and assays of inducible defenses) to understand how seed chemistry influences susceptibility to fungal infection, pathogenicity, and corresponding fungal responses; (2) move beyond local geographical scales to explore how the physical environment and maternal genotype influence fungal community composition and host susceptibility at a landscape scale, spanning the Panama Canal watershed; (3) combine lab and field approaches to test the hypothesis that priority effects in low diversity microbial systems will strongly influence the outcome of plant-microbial interactions (known as the primary symbiont hypothesis); and (4) support diverse training, outreach, and educational activities in the US and beyond. Collectively these elements will contribute to resolving the intrinsic factors (seed defenses) and extrinsic contingencies (additional microbial partners, different environmental conditions, variable genetic background of plants), that determine the outcome of seed-fungal interactions in the tropics. Thus, this project will elucidate how fungi influence plant recruitment, with relevance to diverse wild- and agro-ecosystems where plants regenerate from seeds. The project includes research training at the undergraduate, graduate student and postdoctoral levels at the University of South Florida, University of Illinois, Utah State University and University of Arizona.This 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.