Christa Schwintzer
Professor Emerita of Botany
Research Topic:
Biology of Frankia, a nitrogen-fixing actinomycete, and physiological plant ecology with emphasis on nitrogen fixing and wetland plants
Research Program:
My main research interests lie at the interface between physiology of plants and the kinds of environments in which they occur. Topics that are of special interest to me include the physiological ecology of actinorhizal nitrogen-fixing plants, physiological ecology of peatland plants, plant energy budgets, and physiological ecology of seed germination.
Most of my current work concerns the physiology and ecology of actinorhizal plants. These plants are woody dicots that form nitrogen-fixing root nodules with Frankia, an actinomycete. They are found in 23 genera in 8 families and include alders (Alnus spp.), sweet gale (Myrica gale), bayberry (Myrica pensylvanica), and sweet fern (Comptonia peregrina). Actinorhizal plants commonly grow vigorously in nitrogen-poor soils where most plants grow only poorly or not at all. Such soils include raw mineral soils, sandy soils found on glacial outwash plains and along shores, and wet soils along streams and shores and in swamps and peatlands.
Presently we are examining the role that hemoglobin plays in Frankia including its localization within the cell and its interaction with oxygen. In addition we are examining the conditions needed for seedling establishment in common Maine actinorhizal plants.
Publications:
Coats, V., C.R. Schwintzer, and J.D. Tjepkema. 2009. Truncated hemoglobins in Frankia CcI3: effects of nitrogen source, oxygen concentration, and nitric oxide. Canadian Journal of Microbiology 55: 867-873.
Schultz, H.S., R. Manley, W. Halteman, M.S. Erich, C.R. Schwintzer, and C. Stubbs. 2007. Effects of kaolin particle film on viburnum leaf beetle during container production of Viburnum dentatum under different levels of nitrogen fertilization. Journal of Environmental Horticulture 25: 4-8.
Silvester, W.B., R.H. Berg, C.R. Schwintzer, and J.D. Tjepkema. 2005. Oxygen responses, hemoglobin, and the structure and function of vesicles. In: K. Pawlowski (ed.), Actinorhizal Symbioses. Kluwer Academic Publishers.
Schwintzer, C.R. and J.D. Tjepkema. 2005. Effect of oxygen concentration on growth and hemoglobin production in Frankia. Symbiosis 39: 77-82.
Tjepkema, J.D., Cashon, R.E., Beckwith, J., and Schwintzer, C.R. 2002. Hemoglobin in Frankia, a nitrogen-fixing actinomycete. Applied and Environmental Microbiology 68: 2629-2631.
Schwintzer, C.R. and Tjepkema, J.D. 2001. Effect of elevated carbon dioxide in the root atmosphere on nitrogenase activity in three actinorhizal plants. Canadian Journal of Botany 79: 1010-1018.
Tjepkema, J.D., Schwintzer, C.R., Burris, R.H., Johnson, G.V., and Silvester, W.B. 2000. Natural abundance of 15N in actinorhizal plants and nodules. Plant and Soil 219: 285-289.
Dow, M.A. and Schwintzer, C.R. 1999. Seed germination, seedling emergence, and seed bank ecology of sweet-fern (Comptonia peregrina (L.) Coult.). Canadian Journal of Botany 77: 1378-1386.
Barkmann, J. and Schwintzer, C.R. 1998. Rapid N2 Fixation in Pines? – Results of a Maine Field Study. Ecology 79: 1453-1457.
Hurd, T.M. and Schwintzer, C.R. 1997. Formation of cluster roots and mycorrhizal status of Comptonia peregrina and Myrica pensylvanica in Maine, U.S.A. Physiologia Plantarum 99: 680-689.
Schwintzer, C.R. and Tjepkema, J.D. 1997. Field nodules of Alnus incana ssp. rugosa and Myrica gale exhibit pronounced acetylene-induced declines in nitrogenase activity. Canadian Journal of Botany 75: 1415-1423.
Bartsch, I. and Schwintzer, C.R. 1994. Growth of Chamaedaphne calyculata at two peatland sites in relation to nutrient availability. Wetlands 14: 147-158.
Schwintzer, C.R. and J.D. Tjepkema. 1994. Factors affecting the acetylene-to-15N2 conversion ratio in root nodules of Myrica gale L. Plant Physiology 106: 1041-1047.
Schwintzer, Christa R. and John D. Tjepkema (eds). 1990. The Biology of Frankia and Actinorhizal Plants. Academic Press, New York, 389 pp.