Bacterial Inhabitants of Eastern Hemlock (Tsuga canadensis) Rhizospheres: Links to Plant Survival and Sustainability

 SUMMARY of Activities and Results (# 200 words; Lay Language): All plants require microbial partners in soil for nutrient exchange via their roots. Fungi and bacteria play extremely important roles in providing water, phosphorous, nitrogen, and sulfur among other things that plants depend upon for growth and reproduction. The Hemlock Woolly Adelgid threatens forest stability in Great Smoky Mountains National Park by killing and weakening stands of Eastern Hemlock. Examination of microbial communities inhabiting hemlock rhizospheres will help us determine which species are most important to the health of the plant and microbial stocks could be kept in case hemlock reforestation is necessary. This project describes species of bacteria that are the most common in hemlock roots systems – environments that have never been explored in this way. Two methods were used to assess  bacteria diversity; one used culturing techniques while the other relied on DNA sequenced directly from the environment. The results show that two major groups of bacteria (Actinobacteria and Alphaproteobacteria) that include nitrogen-fixing species were found to be very common in hemlock roots and may be aiding the trees in nutrient acquisition. Overall, 214 bacterial species were found, many of which are unknown to science and could be unique to  hemlock ecosystems.