title: Flavonols accumulate asymmetrically and affect auxin transport in Arabidopsis.
abstract: Flavonoids represent a class of secondary metabolites with diverse functions in plants including ultraviolet protection, pathogen defense, and interspecies communication. They are also known as modulators of signaling processes in plant and animal systems and therefore are considered to have beneficial effects as nutraceuticals. The rol1-2 (for repressor of lrx1) mutation of Arabidopsis (Arabidopsis thaliana) induces aberrant accumulation of flavonols and a cell-growth phenotype in the shoot. The hyponastic cotyledons, aberrant shape of pavement cells, and deformed trichomes in rol1-2 mutants are suppressed by blocking flavonoid biosynthesis, suggesting that the altered flavonol accumulation in these plants induces the shoot phenotype. Indeed, the identification of several transparent testa, myb, and fls1 (for flavonol synthase1) alleles in a rol1-2 suppressor screen provides genetic evidence that flavonols interfere with shoot development in rol1-2 seedlings. The increased accumulation of auxin in rol1-2 seedlings appears to be caused by a flavonol-induced modification of auxin transport. Quantification of auxin export from mesophyll protoplasts revealed that naphthalene-1-acetic acid but not indole-3-acetic acid transport is affected by the rol1-2 mutation. Inhibition of flavonol biosynthesis in rol1-2 fls1-3 restores naphthalene-1-acetic acid transport to wild-type levels, indicating a very specific mode of action of flavonols on the auxin transport machinery.
authors.affiliation: Institute of Plant Biology, University of Zurich, 8008 Zurich, Switzerland.
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Kuhn
authors.forename: Markus
authors.initials: M
authors.lastname: Geisler
authors.forename: Laurent
authors.initials: L
authors.lastname: Bigler
authors.forename: Christoph
authors.initials: C
authors.lastname: Ringli
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000166:cytology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D001692:Biological Transport; D053898:Biosynthetic Pathways; D048430:Cell Shape; D018548:Cotyledon / Q000166:cytology / Q000378:metabolism; D004058:Diffusion; D044948:Flavonols / Q000378:metabolism*; D005816:Genetic Complementation Test; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism*; D058503:Mesophyll Cells / Q000166:cytology / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D011523:Protoplasts / Q000166:cytology / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013489:Suppression, Genetic
chemical_list: D029681:Arabidopsis Proteins; D044948:Flavonols; D007210:Indoleacetic Acids; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins