Of the estimated 1.5 million fungal species on earth, only about 74,000 species have been formally described. Current knowledge of the biology of most of the described fungal species is poor. Estimates of global fungal diversity often hinge on the number of unique fungal species thought to be associated with individual plant species. However, if fungi that live in association with plants are sensitive to genetic differences among individuals within plant species, then there may be much more hidden fungal diversity. It is therefore important to increase survey efforts, and to examine the potential for fungal communities to differ among genetically different individual plants. This study focuses on variation in fungal communities among genetically different individuals within narrowleaf cottonwoods using an experimental forest in which multiple clones of an individual are planted in the same environment. This project will add to previous findings in two major ways. First, it compares the diversity estimates of fungi using culturing techniques with diversity estimates based on direct examination of fungal DNA. Second, the study will estimate the amount of fungal tissue in individual plants by measuring the fungal steroid, ergosterol.

Broader Impacts: There are several ways in which a broader impact will be ensured for this research. First, it will be presented at the Flagstaff Festival of Science (FFS) 2011. The FFS is a 10-day event that promotes science to people of all ages. Participants will view endophytic fungal cultures using microscopy and handle locally collected sporocarps from a variety of fungi. Second, findings from this research will be disseminated to regional groups through the cottonwood ecology group's Research Notes for Land Managers periodical. This publication is distributed to nearly 20 groups, including government agencies, non-profit land conservation groups, and environmental education centers. Third, this research will also facilitate the training of undergraduate lab volunteers in culturing and molecular methods. Fourth, results will be presented to the scientific community at regional and national meetings, and published in peer-reviewed journals.

Project Report

All plants have fungi living within them, termed endophytes. Some of these fungi may be beneficial and others harmful, however very little is understood about their diversity, functions and distributions. The goal of this project was to broaden our understanding of how different types of trees influence the quantity of fungi, and the fungal species, in their stems. Cottonwood trees are extremely important in streamside habitats around the northern hemisphere, and are also economically imporant. Thousands of dependent species, from insects to fungi and birds, depend on cottonwoods for food and habitat. Some cottonwood species hybridize with other cottonwood species, and unique organisms often live in association with these hybrids. This is because hybrid trees can have unique traits that some organisms are partial to. However, endophyte preferences for hybrid cottonwoods in natural habitats has been minimally investigated. For this project, twigs were collected from fremont cottonwoods, narrowleaf cottonwoods and their natural hybrids, to understand how these three tree types differentially influenced their endophyte communities. Fungi were isolated from twigs placed on nutrient agar petridishes. Additionally, DNA was extracted directly from twigs and then the fungal sequences of DNA in the extract were read with a genome analyzer. This allowed us to understand which fungi were living in which tree type. We also used biochemical methods to estimate the total quantity of fungi in twigs. The final data for this project has been obtained. The goal now is to analyze and publish the data in a scientific journal. Over the course of the project, three undergraduates were provided their first research experiences. Undoubtedly, these experiences helped shape their decisions in where to take their careers after they finished college. Importantly, a graduating PhD student needs to find a postdoctoral research position, which is a stepping stone on the path to a final faculty job. This DDIG award not only looks very attractive on a resume but also provided additional training with unique methods and data that the awardee did not preveously have. The grant really suceeded in helping a PhD student move to the next step in their career, which that student is very grateful for.

National Science Foundation (NSF)
Division of Environmental Biology (DEB)
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Alan James Tessier
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Northern Arizona University
United States
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