Flavonoids redirect PIN mediated polar auxin fluxes during root gravitropic responses Journal Article

Author(s): Santelia, Diana; Henrichs, Sina; Vincenzetti, Vincent; Sauer, Michael; Bigler, Laurent; Klein, Markus B; Bailly, Aurélien; Lee, Yuree; Friml, Jiří; Geisler, Markus; Martinoia, Enrico
Article Title: Flavonoids redirect PIN mediated polar auxin fluxes during root gravitropic responses
Abstract: The rate, polarity, and symmetry of the flow of the plant hormone auxin are determined by the polar cellular localization of PIN-FORMED (PIN) auxin efflux carriers. Flavonoids, a class of secondary plant metabolites, have been suspected to modulate auxin transport and tropic responses. Nevertheless, the identity of specific flavonoid compounds involved and their molecular function and targets in vivo are essentially unknown. Here we show that the root elongation zone of agravitropic pin2/eir1/wav6/agr1 has an altered pattern and amount of flavonol glycosides. Application of nanomolar concentrations of flavonols to pin2 roots is sufficient to partially restore root gravitropism. By employing a quantitative cell biological approach, we demonstrate that flavonoids partially restore the formation of lateral auxin gradients in the absence of PIN2. Chemical complementation by flavonoids correlates with an asymmetric distribution of the PIN1 protein. pin2 complementation probably does not result from inhibition of auxin efflux, as supply of the auxin transport inhibitor N-1-naphthylphthalamic acid failed to restore pin2 gravitropism. We propose that flavonoids promote asymmetric PIN shifts during gravity stimulation, thus redirecting basipetal auxin streams necessary for root bending. © 2008 by The American Society for Biochemistry and Molecular Biology, Inc.
Keywords: plant roots; Carrier Proteins; Gravitropism; Arabidopsis; Arabidopsis Proteins; Indoleacetic Acids; Membrane Transport Proteins; Plant Growth Regulators; Flavonoids; Phthalimides
Journal Title: Journal of Biological Chemistry
Volume: 283
Issue 45
ISSN: 1083-351X
Publisher: American Society for Biochemistry and Molecular Biology  
Date Published: 2008-11-07
Start Page: 31218
End Page: 31226
DOI: 10.1074/jbc.M710122200
Open access: no