title: Kaempferol 3-O-rhamnoside-7-O-rhamnoside is an endogenous flavonol inhibitor of polar auxin transport in Arabidopsis shoots.
abstract: Polar auxin transport (PAT) plays key roles in the regulation of plant growth and development. Flavonoids have been implicated in the inhibition of PAT. However, the active flavonoid derivative(s) involved in this process in vivo has not yet been identified. Here, we provide evidence that a specific flavonol bis-glycoside is correlated with shorter plant stature and reduced PAT. Specific flavonoid-biosynthetic or flavonoid-glycosylating steps were genetically blocked in Arabidopsis thaliana. The differential flavonol patterns established were analyzed by high-performance liquid chromatography (HPLC) and related to altered plant stature. PAT was monitored in stem segments using a radioactive [(3)H]-indole-3-acetic acid tracer. The flavonoid 3-O-glucosyltransferase mutant ugt78d2 exhibited a dwarf stature in addition to its altered flavonol glycoside pattern. This was accompanied by reduced PAT in ugt78d2 shoots. The ugt78d2-dependent growth defects were flavonoid dependent, as they were rescued by genetic blocking of flavonoid biosynthesis. Phenotypic and metabolic analyses of a series of mutants defective at various steps of flavonoid formation narrowed down the potentially active moiety to kaempferol 3-O-rhamnoside-7-O-rhamnoside. Moreover, the level of this compound was negatively correlated with basipetal auxin transport. These results indicate that kaempferol 3-O-rhamnoside-7-O-rhamnoside acts as an endogenous PAT inhibitor in Arabidopsis shoots.
authors.affiliation: Institute of Biochemical Plant Pathology, Helmholtz Zentrum München, 85764, Neuherberg, Germany.
authors.forename: Ruohe
authors.initials: R
authors.lastname: Yin
authors.affiliation: Institute of Biochemical Plant Pathology, Helmholtz Zentrum München, 85764, Neuherberg, Germany.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Han
authors.affiliation: Institute of Biochemical Plant Pathology, Helmholtz Zentrum München, 85764, Neuherberg, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Heller
authors.affiliation: Research Unit Environmental Simulation, Helmholtz Zentrum München, 85764, Neuherberg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Albert
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague 6, Czech Republic.
authors.forename: Petre I
authors.initials: PI
authors.lastname: Dobrev
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Prague 6, Czech Republic.
authors.forename: Eva
authors.initials: E
authors.lastname: Zažímalová
authors.affiliation: Institute of Biochemical Plant Pathology, Helmholtz Zentrum München, 85764, Neuherberg, Germany.
authors.forename: Anton R
authors.initials: AR
authors.lastname: Schäffner
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D001692:Biological Transport; D007210:Indoleacetic Acids / Q000378:metabolism*; D044949:Kaempferols / Q000378:metabolism / Q000502:physiology*; D010641:Phenotype; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism
chemical_list: D007210:Indoleacetic Acids; D044949:Kaempferols
keywords: Arabidopsis thaliana; flavonol biosynthesis; flavonol glycoside; flavonol glycosyltransferases; plant growth; polar auxin transport