title: Leaf phenolic compounds in red clover (Trifolium pratense L.) induced by exposure to moderately elevated ozone.
abstract: Red clover (Trifolium pratense L.), an important feed crop in many parts of the world, is exposed to elevated ozone over large areas. Plants can limit ozone-induced damages by various defence mechanisms. In this work, changes in the concentrations of antioxidant phenolic compounds induced by slightly elevated levels of ozone were determined in red clover leaves by high-performance liquid chromatography and mass spectrometry. 31 different phenolics were identified and the most abundant isoflavones and flavonoids were biochanin A glycoside malonate (G-M), formononetin-G-M and quercetin-G-M. Elevated ozone (mean 32.4 ppb) increased the total phenolic content of leaves and also had minor effects on the concentrations of individual compounds. Elevated ozone increased the net photosynthesis rate of red clover leaves before visible injuries by 21-23%. This study thus suggests that the concentrations of phenolics in red clover leaves change in response to slightly elevated ozone levels.
authors.affiliation: University of Kuopio, Department of Biosciences, Institute of Applied Biotechnology, Box 1627, 70211 Kuopio, Finland.
authors.forename: Niina M M
authors.initials: NM
authors.lastname: Saviranta
authors.forename: Riitta
authors.initials: R
authors.lastname: Julkunen-Tiitto
authors.forename: Elina
authors.initials: E
authors.lastname: Oksanen
authors.forename: Reijo O
authors.initials: RO
authors.lastname: Karjalainen
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D000704:Analysis of Variance; D002851:Chromatography, High Pressure Liquid; D013058:Mass Spectrometry; D015394:Molecular Structure; D010126:Ozone / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D010636:Phenols / Q000032:analysis* / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000737:chemistry*; D029921:Trifolium / Q000737:chemistry*
chemical_list: D000393:Air Pollutants; D010636:Phenols; D010126:Ozone