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IPY: A Community Genomics Investigation of Fungal Adaptation to Cold
Fungi survive, reproduce, and carry out diverse biogeochemical transformations in arctic soils that are extremely cold, often dry, and mostly snow covered. Clearly, these fungi are adapted to extremes of cold and dark. Yet our knowledge of the identities and activities of these cold-adapted fungi is negligible. We propose to carry out a large-scale community genomics analysis of fungi in the Arctic to provide insights into the diversity, metabolism, and seasonal dynamics of cold-adapted fungi. Our goal is to better understand fungal adaptation to cold. We argue that the necessary first steps to achieving this aim are to determine 1) which species actually occur in the coldest climates, and 2) which species are metabolically active at the coldest temperatures.
While focused on adaptation, our project will also inform ecosystem ecology. Polar regions provide significant ecosystem services to society, including climate regulation. The ongoing changesin polar regions, which are often more rapid and of larger magnitude than in lower latitudes, arehaving uncertain effects on ecosystem services, particularly positive and negative feedbacks to globalwarming. Two key, interrelated uncertainties are 1) how vegetation patterns will change, and how these changes will feed back to climate, and 2) how soil carbon pools will change with changing patterns of permafrost, soil temperatures and vegetation cover. Mycorrhizal fungi strongly influence plant growth and community structure through their roles as ubiquitous symbionts of arctic plants. Decomposer fungi strongly influence rates and patterns of respiratory carbon release to the atmosphere, as well as mineralization and immobilization of the limiting nutrients nitrogen and phosphorus. Hence, soil-dwelling fungi are central players in both vegetation change and carbon dynamics, and therefore, in our uncertainties about climate change and the future of polar regions.
We have three specific objectives in the research proposed here:
1) To reveal which fungal species are most adapted to extreme arctic environmental conditions by characterizing the changes in fungal communities along three latitudinal gradients (NAAT, Eurasia, Spitsbergen) using high-throughput, DNA-based clone-library sequencing.
2) To test whether predicted changes in climate will select for more southerly or northerly fungal communities using reciprocal soil warming and cooling experiments and clone-library sequencing at the Toolik Lake and Bonanza Creek Long Term Ecological Research (LTER) sites.
3) To characterize the components of the fungal communities that are metabolically active in both summer and winter using our newly developed RNA-based library sequencing method.
The intellectual merits of the proposal lie in our use of genomics-enabled technologies combined with analysis of fungal activity in extreme soil environments. These technologies will a) provide one of the most thorough analyses of fungal diversity to date, b) improve the ecological inference possible through clone-library sequencing using a tagging method recently developed by our group, and c) give the first insights into the metabolic activities of individual fungal species through the application of our new rapid-turnover RNA-typing method. By identifying the most cold-adapted fungi, our project will set the stage for myriad follow-on research projects investigating the physiological and biochemical phenotypes of these species. These investigations will invigorate fields ranging from ecosystem ecology to molecular evolution to protein biochemistry. Three additional aspects of the proposal exemplify its IPY relevance. First, by revealing which species and guilds of fungi are most active in different habitats, in different seasons, and under different temperature regimes, our work will unveil novel insights into process underling winter respiration and nutrient cycling in the Arctic. We pay particular attention to winter processes and sampling, which have too long been ignored. Second, our study is pan-Arctic and international, both in geographic extent and in the collaborating consortium of US, Russian, and UK scientists. Third, this will be the first in-depth molecular study of microbial diversity along any arctic climate gradient. Our project will have broader impacts on education, ecosystem services and biotechnology. At the local level, we will engage in outreach endeavors to acquaint elementary school students with fungi and their ecology in a new Camp Habitat module. The project will also support graduate education and scientific exchange among multiple countries. At the regional and global levels, our research will contribute to a better understanding of winter respiration and CO2 feedbacks to climate change, a key issue in ecosystem services to society. Finally, there is considerable biotechnological potential for the cold-active enzymes that will be discovered upon identification of novel winteractive fungi.
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