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Lookup NU author(s): Professor Howard Neufeld, Emeritus Professor Alan Davison
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Cutleaf coneflower (Rudbeckia laciniata L.), crown-beard (Verbesina occidentalis Walt.), and tall milkweed (Asclepias exaltata L.) are wildflower species native to Great Smoky Mountains National Park (U.S.A.). Natural populations of each species were analyzed for leaf ascorbic acid (AA) and dehydroascorbic acid (DHA) to assess the role of ascorbate in protecting the plants from ozone stress. Tall milkweed contained greater quantities of AA (7-10 μmol g-1 fresh weight) than crown-beard (2-4 μmol g-1 fresh weight) or cutleaf coneflower (0.5-2 μmol g-1 fresh weight). DHA was elevated in crown-beard and cutleaf coneflower relative to tall milkweed suggesting a diminished capacity for converting DHA into AA. Tall milkweed accumulated AA in the leaf apoplast (30-100 nmol g-1 fresh weight) with individuals expressing ozone foliar injury symptoms late in the season having less apoplast AA. In contrast, AA was not present in the leaf apoplast of either crown-beard or cutleaf coneflower. Unidentified antioxidant compounds were present in the leaf apoplast of all three species. Overall, distinct differences in antioxidant metabolism were found in the wildflower species that corresponded with differences in ozone sensitivity.
Author(s): Burkey KO, Neufeld HS, Souza L, Chappelka AH, Davison AW
Publication type: Article
Publication status: Published
Journal: Environmental Pollution
Year: 2006
Volume: 143
Issue: 3
Pages: 427-434
ISSN (print): 0269-7491
ISSN (electronic): 1873-6424
Publisher: Pergamon
URL: http://dx.doi.org/10.1016/j.envpol.2005.12.009
DOI: 10.1016/j.envpol.2005.12.009
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