Dimensions US-China: Collaborative Research: Impacts of Heritable Plant-fungus Symbiosis on Phylogenetic, Genetic and Functional Diversity.

PROJECT SUMMARY Overview: Fully preserving the biological diversity in seeds of flowering plants (angiosperms) means preserving more than just plant germplasm, but also their seed-transmitted symbionts (seed-endophytes). By enhancing plant resistance to abiotic stresses, herbivores, and pathogens, fungal seed-endophytes facilitate host plant expansion into novel habitats and affect plant community diversity by altering competitive hierarchies among their hosts. Most currently known groups of fungal seed-endophytes are associated with extremely species-rich plant groups, suggesting that they may also impact angiosperm diversification. China is one of the world’s hotspots of angiosperm diversity, and the GBOWS seed collection in Kunming is an extraordinary resource that currently holds 37% of the angiosperm species of China. The project’s first objective entails a survey of GBOWS and other collections to examine possible roles of fungal seed-endophytes in promoting diversification across the angiosperm phylogeny. The second objective is to conduct population surveys to test the relationships of diverse seed-endophytes to genetic and functional diversity of their host plants based on both transcriptomic and morphometric trait data, as well as on phylogenetic diversity of the surrounding plant communities. To complement these broad-scale surveys, the third objective is to experimentally manipulate presence/absence and genetic diversity of fungal seed-endophytes of grasses and legumes in field plots to test their causal effects on functional diversity of their hosts and phylogenetic diversity of the broader plant community. This project will teach a multidisciplinary toolkit of molecular and ecological techniques to graduate students in China and the U.S. via regular exchanges between lab groups. In addition, the project will integrate field, classroom, and lab activities to help K-12 and undergraduate students discover layers of biological complexity and cooperation between microscopic and macroscopic organisms. Integration: Fungal seed-endophytes clearly have the potential to play a critical role in the fitness and population dynamics of their hosts based on examples illustrating their contributions to resource acquisition, stress tolerance, and herbivore deterrence. However, the potential exists that they have also helped shape the entire diversity of angiosperms as we know it. By conducting a systematic survey for seed-endophytes across the angiosperm phylogeny, we will elucidate their roles in expanding the phylogenetic diversity of angiosperms through heightened diversification as well as their functional diversity through niche expansion. We will then conduct range-wide surveys of focal host species to investigate the role that fungal seed-endophytes have played in constraining or expanding genetic and functional diversity within angiosperm species. Finally, we will use experimental manipulations of endophyte genetic diversity to causally determine the role fungal seed-endophytes play in the diversity not only of their own hosts, but also of the phylogenetic diversity of associated angiosperm communities. Intellectual Merit: The teams in both China and the U.S. bring expertise in plant and fungal ecology, molecular biology, and genomics. The project enhances ongoing U.S-China collaborations between these teams on diverse symbiotic systems. This research furthers understanding of the impacts diverse symbiotic associations can have on plant functional, genetic, and phylogenetic diversity, elucidating ecological functions of seed-endophytes that are relevant to both conservation and plant responses to global change. The objectives incorporate the very first survey to characterize seed-endophytes across the diversity of flowering plants with intensive population surveys and field experiments that integrate genomic, transcriptomic, and morphometric analyses of diverse focal species. Results will deliver insight into the impacts of fungal seed-endophytes on the dimensions of diversity of their host plants and the surrounding plant community. Broader Impacts: Multiple impacts include: 1) generating live and voucher specimens plus a global database that incorporates functional, genomic and phylogenetic diversity of angiosperms and their fungal seed-endophytes, 2) implementing novel teaching modules in programs specifically designed for K-12 students, including groups traditionally underrepresented in STEM, to engage them in field, lab and classroom activities that integrate disciplines as diverse as botany, mycology, taxonomy, ecology, chemistry, molecular biology and bioinformatics, and 3) facilitating regular exchange of graduate students between China and the U.S. in order to provide them with training in diverse ecological and molecular methodologies while helping them build international networks of future collaborators.