title: Leaf extracellular ascorbate in relation to O(3) tolerance of two soybean cultivars.
abstract: Soybean [Glycine max (L.) Merr.] cultivars Essex and Forrest that exhibit differences in ozone (O(3)) sensitivity were used in greenhouse experiments to investigate the role of leaf extracellular antioxidants in O(3) injury responses. Charcoal-filtered air and elevated O(3) conditions were used to assess genetic, leaf age, and O(3) effects. In both cultivars, the extracellular ascorbate pool consisted of 80-98% dehydroascorbic acid, the oxidized form of ascorbic acid (AA) that is not an antioxidant. For all combinations of genotype and O(3) treatments, extracellular AA levels were low (1-30nmolg(-1) FW) and represented 3-30% of the total antioxidant capacity. Total extracellular antioxidant capacity was twofold greater in Essex compared with Forrest, consistent with greater O(3) tolerance of Essex. The results suggest that extracellular antioxidant metabolites in addition to ascorbate contribute to detoxification of O(3) in soybean leaves and possibly affect plant sensitivity to O(3) injury.
authors: USDA-ARS Plant Science Research Unit and Department of Crop Science, North Carolina State University, 3127 Ligon Street, Raleigh, NC 27607, USA.
authors: Fang-Yi
authors: FY
authors: Cheng
authors: Kent O
authors: KO
authors: Burkey
authors: J Michael
authors: JM
authors: Robinson
authors: Fitzgerald L
authors: FL
authors: Booker
mesh_terms: D000383:Agriculture; D000393:Air Pollutants / Q000633:toxicity*; D000975:Antioxidants / Q000032:analysis; D001205:Ascorbic Acid / Q000032:analysis; D003683:Dehydroascorbic Acid / Q000032:analysis; D004463:Ecology; D010126:Ozone / Q000633:toxicity*; D010788:Photosynthesis; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism*; D013025:Glycine max / Q000378:metabolism*; D013045:Species Specificity; D014815:Vitamins / Q000032:analysis
chemical_list: D000393:Air Pollutants; D000975:Antioxidants; D014815:Vitamins; D010126:Ozone; D001205:Ascorbic Acid; D003683:Dehydroascorbic Acid