The phytohormone auxin is a major determinant and regulatory component important for plant development. Auxin transport between cells is mediated by a complex system of transporters such as AUX1/LAX, PIN, and ABCB proteins, and their localization and activity is thought to be influenced by phosphatases and kinases. Flavonols have been shown to alter auxin transport activity and changes in flavonol accumulation in the Arabidopsis thaliana rol1-2 mutant cause defects in auxin transport and seedling development. A new mutation in ROOTS CURL IN NPA 1 (RCN1), encoding a regulatory subunit of the phosphatase PP2A, was found to suppress the growth defects of rol1-2 without changing the flavonol content. rol1-2 rcn1-3 double mutants show wild type-like auxin transport activity while levels of free auxin are not affected by rcn1-3. In the rol1-2 mutant, PIN2 shows a flavonol-induced basal-to-apical shift in polar localization which is reversed in the rol1-2 rcn1-3 to basal localization. In vivo analysis of PINOID action, a kinase known to influence PIN protein localization in a PP2A-antagonistic manner, revealed a negative impact of flavonols on PINOID activity. Together, these data suggest that flavonols affect auxin transport by modifying the antagonistic kinase/phosphatase equilibrium.

• MeSH
• Arabidopsis účinky léků   genetika   metabolismus   MeSH
• flavonoidy farmakologie   MeSH
• glukosyltransferasy genetika   metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• mutace MeSH
• proteinfosfatasa 2 genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 3-hydroxyflavone MeSH Prohlížeč
• flavonoidy MeSH
• glukosyltransferasy MeSH
• kyseliny indoloctové MeSH
• PIN2 protein, Arabidopsis MeSH Prohlížeč
• proteinfosfatasa 2 MeSH
• proteiny huseníčku MeSH
• RCN1 protein, Arabidopsis MeSH Prohlížeč
• RHM1 protein, Arabidopsis MeSH Prohlížeč

The phenylpropanoid 3,4-(methylenedioxy)cinnamic acid (MDCA) is a plant-derived compound first extracted from roots of Asparagus officinalis and further characterized as an allelochemical. Later on, MDCA was identified as an efficient inhibitor of 4-COUMARATE-CoA LIGASE (4CL), a key enzyme of the general phenylpropanoid pathway. By blocking 4CL, MDCA affects the biosynthesis of many important metabolites, which might explain its phytotoxicity. To decipher the molecular basis of the allelochemical activity of MDCA, we evaluated the effect of this compound on Arabidopsis thaliana seedlings. Metabolic profiling revealed that MDCA is converted in planta into piperonylic acid (PA), an inhibitor of CINNAMATE-4-HYDROXYLASE (C4H), the enzyme directly upstream of 4CL. The inhibition of C4H was also reflected in the phenolic profile of MDCA-treated plants. Treatment of in vitro grown plants resulted in an inhibition of primary root growth and a proliferation of lateral and adventitious roots. These observed growth defects were not the consequence of lignin perturbation, but rather the result of disturbing auxin homeostasis. Based on DII-VENUS quantification and direct measurement of cellular auxin transport, we concluded that MDCA disturbs auxin gradients by interfering with auxin efflux. In addition, mass spectrometry was used to show that MDCA triggers auxin biosynthesis, conjugation, and catabolism. A similar shift in auxin homeostasis was found in the c4h mutant ref3-2, indicating that MDCA triggers a cross talk between the phenylpropanoid and auxin biosynthetic pathways independent from the observed auxin efflux inhibition. Altogether, our data provide, to our knowledge, a novel molecular explanation for the phytotoxic properties of MDCA.

• MeSH
• 4-monooxygenasa kyseliny skořicové antagonisté a inhibitory   metabolismus   MeSH
• Arabidopsis účinky léků   genetika   metabolismus   MeSH
• benzoáty metabolismus   farmakologie   MeSH
• biosyntetické dráhy účinky léků   MeSH
• cinnamáty chemie   metabolismus   farmakologie   MeSH
• fenylpropionáty chemie   metabolismus   farmakologie   MeSH
• geneticky modifikované rostliny MeSH
• hmotnostní spektrometrie MeSH
• homeostáza účinky léků   MeSH
• koenzym A-ligasy antagonisté a inhibitory   metabolismus   MeSH
• konfokální mikroskopie MeSH
• kořeny rostlin účinky léků   genetika   metabolismus   MeSH
• kyseliny indoloctové metabolismus   MeSH
• lignin biosyntéza   MeSH
• semenáček účinky léků   genetika   růst a vývoj   metabolismus   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• 4-coumarate-CoA ligase MeSH Prohlížeč
• 4-monooxygenasa kyseliny skořicové MeSH
• benzoáty MeSH
• cinnamáty MeSH
• cinnamic acid MeSH Prohlížeč
• fenylpropionáty MeSH
• koenzym A-ligasy MeSH
• kyseliny indoloctové MeSH
• lignin MeSH
• phenylpropanoid 3,4-(methylenedioxy)cinnamic acid MeSH Prohlížeč
• piperonylic acid MeSH Prohlížeč