Dissertation Research: Characterization of Foliar Fungal Endophyte Communities of Sequoia sempervirens and Investigation of their Symbiotic Relationship

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Sequoia sempervirens (California's coastal redwood) is well known as the tallest tree in the world, with some individuals reaching 115 meters tall. Recent research has uncovered a unique physiological adaptation that allows these trees to deal with the stress of transporting water from the root system to upper branches of the canopy. When ground water stores are depleted during the long, dry summers, S. sempervirens is able to absorb water that condenses on its leaf surfaces during seasonal fog events. It is hypothesized that a community of fungi living on and within the leaves of S. sempervirens aid in the foliar absorption of water. The proposed research will first sample and characterize the foliar fungal community present in different parts of the redwood trees and from different areas of the coastal forests using molecular 'barcoding'. Stable isotope-labeled fog in glasshouse experiments will be used to determine if the presence of foliar fungi increases the tree?s ability to absorb water through its foliage, and if so which fungal communities found in association with S. sempervirens are the most effective at aiding water absorption. Finally, C13-labeled carbon dioxide will be used to track the possible transfer of carbon (in the form of sugars) from the host to the fungi, suggesting a symbiotic relationship between the tree and the fungal community it harbors.This research will help to characterize the microbiome of the california coastal redwood, an economically and ecologically important keystone species. Understanding the role of the fungal community in sustaining redwood trees will have important consequences for sustainable forestry practices, especially as drier summers become more common and foliar uptake via fog may play an increasingly important role in forest health. This research additionally demonstrates the important positive role that fungi can play in ecosystem dynamics. This research will be incorporated into three hands-on lesson plans for K-12 students that illustrate the hidden, microscopic diversity and complex species interactions in the natural environment around them. These lesson plans will be incorporated into the NSF funded GK-12 program "Exploring California Biodiversity" and utilized in the "Teaching MadScience" after school program held at two Middle Schools in the Berkeley, CA Public School District. The support will also result in the completion of a doctoral dissertation by a female scientist and the training of two undergraduate research apprentices in laboratory and computational techniques for studying fungal diversity and community ecology.