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Research Interests of Participating Faculty
John Constable, Biology.
The research focus of the laboratory is the
physiological and biochemical response of plants to abiotic stresses
associated with climate change including altered CO2 concentration,
nitrogen deposition, diurnal thermal regimes and pollutants.
Response variables examined include photosynthetic and transpiration
rates, enzyme activities associated with nitrogen assimilation, and
patterns of nitrogen and carbon allocation and partitioning.
Ongoing research activities are currently funded
through the United States Department of Agriculture (USDA) and the
National Science Foundation (NSF). Research supported through the
USDA is investigating the response of the enzyme nitrate reductase
(NR) to elevated CO2 in perennial species of differing growth form.
This work involved field activities at three Free Air CO2 enrichment
sites to measure nitrate reductase activity in foliage and fine root
tissue. This is being followed by ongoing laboratory work at
California State University, Fresno assessing nitrate concentration,
total tissue nitrogen concentration, and concentration of soluble
sugars and starch to establish correlations with measured in situ NR
activity rates. Additional activities are being funded by NSF
through an equipment grant to purchase two controlled environment
growth chambers including complete control over gaseous CO2
concentration, humidity and illumination. This work will facilitate
the examination of the differential response of nitrate vs. ammonium
amended plants under elevated CO2 conditions. Unfunded work is
examining the influence of environmental conditions on the growth of
Mayapple and its influence on the tissue concentrations of
podophyllotoxin, an important precursor compound for the production
of the anticancer drugs etoposide and tenoposide. Funding is being
pursued for this work along with work examining how alterations in N
deposition and use affect the susceptibility of a tree species to an
invasive insect pest (collaborating with Dr. J.D. Lewis at Fordham
University).
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