EAGER: Mycoplasma-related Endobacteria of Arbuscular Mycorrhizal Fungi: Life History and Evolutionary Genomics

该项目将研究MRE的生物学，并以类似的方式改变对生态系统功能的理解，就像认识AM真菌在植物生态学中的作用改变了对植物群落动态的理解一样。此外，如果MRE确实是肾小球菌的寄生虫，那么了解它们古老的无性真菌宿主如何应对寄生虫的压力将成为一个紧迫的问题。最后，确定驱动MRE种群动态的力量对于理解MRE及其支原体亲戚的基因组进化将是重要的。该项目为研究生、本科生和高中生提供机会，包括微生物学、分子遗传学和生物信息学方面的研究经验。本科生将通过微生物之友和敌人REU和康奈尔大学本科生物学办公室招募，高中生将通过BOCES招募。在PI指导的学生中，有一半以上来自科学界代表性不足的群体。PI与康奈尔大学学术多样性倡议办公室合作，为少数族裔本科生创造培训机会。本项目旨在了解新发现的丛枝菌根（AM）真菌（Glomeromycota门）支原体相关内菌（MRE）的生活史和进化基因组学。AM真菌及其内细菌是复杂共生关系的组成部分，也包括大多数陆生植物，可能是地球上最常见的多伙伴共生关系之一。AM真菌定植在陆地植物的根上，并协助吸收矿物质营养以换取植物同化的碳。因此，AM真菌在塑造陆地生态系统的结构和功能方面起着关键作用。虽然MRE的生物学在很大程度上是未知的，但它们分布在肾小球菌的所有主要谱系中，并且在其AM真菌宿主的个体中表现出大量的遗传变异性。这种模式与进化理论不一致，因为共生内共生体被预测在宿主内的基因是一致的。因此，假设MRE是寄生虫，它们的基因组表现出与寄生虫生活方式一致的特征。本项目将结合MRE的生态学和进化基因组学来阐明其在肾小球菌科中的作用。(1)评价MRE感染对宿主适应性的影响将揭示MRE是寄生还是共生。(2) MRE基因组的测序和从头组装将有助于推断MRE代谢特征。(3)阐明驱动MRE种群动态的力量将揭示MRE基因组进化的机制。

This project will investigate the biology of MRE and transform understanding of ecosystem functioning in similar ways as the recognition of the role of AM fungi in plant ecology transformed the understanding of plant community dynamics. Furthermore, if MRE are indeed parasites of Glomeromycota, then understanding how their ancient asexual fungal hosts dealt with parasite pressure will become a pressing issue of general interest. Finally, identifying forces that drive MRE population dynamics will be important for understanding genome evolution in MRE and their Mycoplasma relatives. The project includes opportunities for graduate, undergraduate, and high school students, including research experiences in microbiology, molecular genetics, and bioinformatics. Undergraduates will be recruited through the Microbial Friends & Foes REU and the Cornell Office of Undergraduate Biology, and high school students through BOCES. More than half of the students mentored by the PI have been from groups underrepresented in science. The PI works with the Cornell Office of Academic Diversity Initiatives to create training opportunities for minority undergraduates.The goal of this project is to understand the life history and evolutionary genomics of the newly discovered mycoplasma-related endobacteria (MRE) of arbuscular mycorrhizal (AM) fungi (phylum Glomeromycota). AM fungi and their endobacteria are components of a complex symbiotic association that also includes the majority of terrestrial plants, and may be one of the most common multi-partner symbioses on the planet. AM fungi colonize roots of land plants and assist in the uptake of mineral nutrients in exchange for plant-assimilated carbon. Thus, AM fungi are pivotal in shaping the structure and function of terrestrial ecosystems. While the biology of MRE is largely unknown, they are distributed in all major lineages of Glomeromycota and exhibit substantial genetic variability within individuals of their AM fungal hosts. This pattern is inconsistent with evolutionary theory in that mutualistic endosymbionts are predicted to be genetically uniform within a host. Consequently, it is hypothesized that MRE are parasites and that their genomes exhibit features consistent with a parasitic lifestyle. This project will integrate the ecology and evolutionary genomics of MRE to elucidate their role in the Glomeromycota. (1) An assessment of the effects of MRE infection on host fitness will reveal whether MRE are parasites or mutualists. (2) Sequencing and de novo assembly of MRE genomes will enable inferences about MRE metabolic features. (3) Elucidating forces that drive MRE population dynamics will reveal mechanisms responsible for MRE genome evolution.