PROCEEDINGS: Index of Abstracts

PUTRESCINE: A MARKER OF STRESS IN RED SPRUCE TREES

Rakesh Minocha-1, Walter C. Shortle-1, Gregory B. Lawrence-2, Mark B. David-3, and Subhash C. Minocha-4

1-USDA Forest Service, Northeastern Forest Experiment Station, PO Box 640, Durham, NH 03824. 2-Research Hydrologist, US Geological Survey, 425 Jordan Rd., Troy, NY 12180. 3-University of Illinois, W-503 Turner Hall, 1102 S. Goodwin Ave., Urbana, IL 61801. 4-University of New Hampshire, Plant Biology Department, Durham, NH 03824.

Aluminum (Al) has been suggested to be an important stress factor in forest decline due to its mobilization in soil following atmospheric deposition of acidic pollutants. A major goal of our research is to develop physiological and biochemical markers of stress in trees using cell cultures and whole plants. Needles of red spruce (Picea rubens) collected from several sites in the northeastern United States and red spruce cells grown in suspension cultures were examined for polyamine and inorganic-ion content. The cells in culture were exposed to various concentrations of Al for different lengths of time. Exposure to Al increased putrescine biosynthesis and lowered the concentrations of cellular Ca, Mg, Mn, and K. No treatments were applied to the trees but some of the sites were known to be under "general environmental stress" as indicated by a large number of dead and dying red spruce trees. All of the sites, while differing in geochemistry, had a soil pH value below 4.0. Data collected from field studies enabled us to categorize these sites on the basis of cellular levels of putrescine and soil chemistry. Needles from trees growing on Ca-rich soils (organic horizon) with low exchangeable Al:Ca ratios had lower levels of putrescine than those from trees growing on Ca-poor soils with high Al:Ca ratios.