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Seasonal profiles of leaf ascorbic acid content and redox state in ozone-sensitive wildflowers

Lookup NU author(s): Professor Howard Neufeld, Emeritus Professor Alan Davison

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Abstract

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.


Publication metadata

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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