title: Effect of the temperature and the exclusion of UVB radiation on the phenolics and iridoids in Menyanthes trifoliata L. leaves in the subarctic.
abstract: The long-term effects of UVB exclusion and temperature on the methanol extractable (ME) phenolics (flavonoids, phenolic acids) and iridoids of Menyanthes trifoliata L. (Mt) leaves were studied in northern Finland (68 degrees N) using wooden frames covered with filters for UVB exclusion (polyester filter), control (cellulose acetate filter) and ambient (no filter) conditions. Analysis of ambient plots showed no effect of the daily mean temperature (2sigma = 1.58 degrees C) on the leaf ME compound content and composition, but minimum temperatures decreased the flavonol content. UVB exclusion did not affect the total ME compound content but significantly decreased the proportion of flavonols concomitantly with an increase in iridoids. Due to its high iridoid content, Mt appears as an interesting model plant for studying the iridoid biosynthesis and its regulation under stress conditions.
authors.affiliation: Arctic Centre, University of Lapland, POB 122, FI-96101 Rovaniemi, Finland.
authors.forename: Françoise
authors.initials: F
authors.lastname: Martz
authors.forename: Minna
authors.initials: M
authors.lastname: Turunen
authors.forename: Riitta
authors.initials: R
authors.lastname: Julkunen-Tiitto
authors.forename: Kaisa
authors.initials: K
authors.lastname: Lakkala
authors.forename: Marja-Liisa
authors.initials: ML
authors.lastname: Sutinen
mesh_terms: D039823:Iridoids / Q000032:analysis* / Q000378:metabolism; D019684:Magnoliopsida / Q000737:chemistry* / Q000378:metabolism / Q000528:radiation effects*; D010636:Phenols / Q000032:analysis* / Q000378:metabolism; D010936:Plant Extracts / Q000032:analysis* / Q000378:metabolism; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D039823:Iridoids; D010636:Phenols; D010936:Plant Extracts