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Temperature and nitrogen effects on regulators and products of the flavonoid pathway: experimental and kinetic model studies
Author(s) -
OLSEN KRISTINE M.,
SLIMESTAD RUNE,
LEA UNNI S.,
BREDE CATO,
LØVDAL TROND,
RUOFF PETER,
VERHEUL MICHEL,
LILLO CATHRINE
Publication year - 2009
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2008.01920.x
Subject(s) - flavonoid , chemistry , kaempferol , flavonols , quercetin , flavonoid biosynthesis , biochemistry , nitrogen , stereochemistry , organic chemistry , transcriptome , gene expression , gene , antioxidant
The flavonoid pathway is known to be up‐regulated by different environmental stress factors. Down‐regulation of the pathway is much less studied and is emphasized in the present work. Flavonoid accumulation was induced by exposing plants for 1 week to nitrogen depletion at 10 °C, giving high levels of anthocyanins and 3‐glucoside‐7‐rhamnosides, 3,7‐di‐rhamnosides and 3‐rutinoside‐7‐rhamnosides of kaempferol and quercetin. Flavonol accumulation as influenced by temperatures and nitrogen supply was not related to the glycosylation patterns but to the classification as quercetin and kaempferol. When nitrogen was re‐supplied, transcripts for main regulators of the pathway, PAP1/GL3 and PAP2/MYB12 , fell to less than 1 and 0.1% of initial values, respectively, during 24 h in the 15–30 °C temperature range. Anthocyanins showed a half‐life of approximately 1 d, while the degradation of flavonols was much slower. Interestingly, the initial fluxes of anthocyanin and flavonol degradations were found to be temperature‐independent. A kinetic model for the flavonoid pathway was constructed. In order to get the observed concentration‐temperature profiles as well as the temperature compensation in the flavonoid degradation flux, the model predicts that the flavonoid pathway shows an increased temperature sensitivity at the end of the pathway, where the up‐regulation by PAP/GL3 has been found to be largest.