RESEARCH ARTICLE Variable Nitrogen Fixation in Wild Populus Sharon L. Doty1*, Andrew W. Sher1¤, Neil D. Fleck1, Mahsa Khorasani1, Roger E. Bumgarner2, Zareen Khan1, Andrew W. K. Ko1, Soo-Hyung Kim1, Thomas H. DeLuca1 1 School of Environmental and Forest Sciences, College of the Environment, University of Washington, Seattle, Washington, United States of America, 2 Department of Microbiology, University of Washington, Seattle, Washington, United States of America ¤ Current address: Department of Biology, University of California San Diego, La Jolla, California, United States of America *
[email protected] a11111 Abstract The microbiome of plants is diverse, and like that of animals, is important for overall health and nutrient acquisition. In legumes and actinorhizal plants, a portion of essential nitrogen (N) is obtained through symbiosis with nodule-inhabiting, N2-fixing microorganisms. How- ever, a variety of non-nodulating plant species can also thrive in natural, low-N settings. OPEN ACCESS Some of these species may rely on endophytes, microorganisms that live within plants, to Citation: Doty SL, Sher AW, Fleck ND, Khorasani M, fix N2 gas into usable forms. Here we report the first direct evidence of N2 fixation in the Bumgarner RE, Khan Z, et al. (2016) Variable early successional wild tree, Populus trichocarpa, a non-leguminous tree, from its native Nitrogen Fixation in Wild Populus. PLoS ONE 11(5): riparian habitat. In order to measure N fixation, surface-sterilized cuttings of wild poplar e0155979. doi:10.1371/journal.pone.0155979 2 15 were assayed using both N2 incorporation and the commonly used acetylene reduction Editor: Benedicte Riber Albrectsen, Umeå Plant assay.