Seasonal profiles of leaf ascorbic acid content and redox state in ozone-sensitive wildflowers
Burkey KO, Neufeld HS, Souza L, Chappelka AH, Davison AW. 2006. Seasonal profiles of leaf ascorbic acid content and redox state in ozone-sensitive wildflowers. Environmental Pollution. 143:427-434
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 (7e10 mmol g 1 fresh weight) than crown-beard (2e4 mmol g 1 fresh weight) or cutleaf coneflower (0.5e2 mmol 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 (30e100 nmol g 1 fresh weight) with individuals expressing ozone foliar injury symptoms late in the season having less apoplast AA. In contrast, AAwas 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.
- Type
- Journal Article
- Authors
- Burkey, Kent; Neufeld, Howard; Souza, Lara; Chappelka, Arthur; Davison, Alan
- Units
- ARD , GRSM
- Keywords
- AIRBIB, Antioxidant capacity, APHN, Appalachian Highlands Network, ARD_Park-Air-Info_Collection, Ascorbic acid, Foliar Injury, Great Smoky Mountains National Park, GRSM, GRSM-00030, GRSM-00269, Native Plants, Ozone, SER, Southeast Region