Differential regulation of closely related R2R3‐MYB transcription factors controls flavonol accumulation in different parts of the Arabidopsis thaliana seedling

Abstract

SummaryThe genes MYB11, MYB12 and MYB111 share significant structural similarity and form subgroup 7 of the Arabidopsis thaliana R2R3-MYB gene family. To determine the regulatory potential of these three transcription factors, we used a combination of genetic, functional genomics and metabolite analysis approaches. MYB11, MYB12 and MYB111 show a high degree of functional similarity and display very similar target gene specificity for several genes of flavonoid biosynthesis, including CHALCONE SYNTHASE, CHALCONE ISOMERASE, FLAVANONE 3-HYDROXYLASE and FLAVONOL SYNTHASE1. Seedlings of the triple mutant myb11 myb12 myb111, which genetically lack a complete subgroup of R2R3-MYB genes, do not form flavonols while the accumulation of anthocyanins is not affected. In developing seedlings, MYB11, MYB12 and MYB111 act in an additive manner due to their differential spatial activity; MYB12 controls flavonol biosynthesis mainly in the root, while MYB111 controls flavonol biosynthesis primarily in cotyledons. We identified and confirmed additional target genes of the R2R3-MYB subgroup 7 factors, including the UDP-glycosyltransferases UGT91A1 and UGT84A1, and we demonstrate that the accumulation of distinct and structurally identified flavonol glycosides in seedlings correlates with the expression domains of the different R2R3-MYB factors. Therefore, we refer to these genes as PFG1-3 for 'PRODUCTION OF FLAVONOL GLYCOSIDES'.

Genetic and physical fine mapping of the novel brown midrib gene bm6 in maize (Zea mays L.) to a 180 kb region on chromosome 2

“…F3H is co-expressed with other flavonoid enzymes involved in anthocyanin biosynthesis and responsible for plant colorations (Han et al 2010). In Arabidopsis, genes in the anthocyanin biosynthesis pathway are co-regulated by MYB11 and MYB12 (Stracke et al 2007). Interestingly, the lignin biosynthesis genes are also co-regulated by MYB transcriptional factors (Zhao and Dixon 2011).…”

Metabolite profiling of Arabidopsis seedlings in response to exogenous sinalbin and sulfur deficiency

“…However, many of these secondary metabolites of Arabidopsis are as yet unidentified. Some metabolites were identified from a comprehensive analysis of mass fragmentation patterns and by comparison with published literature (Graham, 1998;Von Roepenack-Lahaye et al, 2004;Tohge et al, 2005;Kerhoas et al, 2006;Routaboul et al, 2006;Stobiecki et al, 2006;Besseau et al, 2007;Stracke et al, 2007). Additionally, compounds were identified by molecular weight determinations from protonated [M+H] + and deprotonated [MÀH] À molecular ions in the first order mass spectra and then MS/MS spectra where sufficient collision energy was applied to obtain maximum structural information.…”

“…Consequently, when the activity of enzymes of the competing branch pathway and downstream of UGT78D2 increased relative to UGT78D2 activity, the levels of the flavonol diglycosides (93, 95, 97) with a glucose attached at the 3-position were markedly reduced and the flavonol diglycosides (94, 96) with rhamnose attached at the 3-position and flavonol triglycosides with glucose attached at the 3-position were significantly increased in abundance. Under sulfur-deficient conditions, genes of the R2R3-MYB family of transcriptional factors, which participate in flavonol accumulation in the A. thaliana seedling (Nikiforova et al, 2003;Stracke et al, 2007), are especially upregulated and could account for the increases of these flavonol glycosides. However, flavonol diglycosides (93, 95, 97) with a glucose attached at the 3-position did not significantly increase in amount.…”

“…UV/VIS absorption spectra were taken in the range of 200-600 nm. Known metabolites were identified by their mass spectrometric fragmentation patterns and relevant data reported in the literature (Graham, 1998;von Roepenack-Lahaye et al, 2004;Tohge et al, 2005;Kerhoas et al, 2006;Routaboul et al, 2006;Besseau et al, 2007;Stracke et al, 2007). The secondary metabolites identified by LC-MS were quantified by integrating the peak areas monitored at 254 nm using the CSASS (Complex Sample Analysis Software System) software and by normalizing them to the fresh wt of the extracted plant material and the peak areas of the internal standard genistein.…”

Respuesta transcripcional de Populus a bifenilos policlorados: Aspectos aplicados a la fitorremediación

“…En plantas, algunos factores de transcripción MYB participan en la activación de genes de respuesta a estrés biótico (Hirayama y Shinozaki, 2010), tales como infección por patógenos (Vailleau et al, 2002); en la regulación del metabolismo primario y secundario, como el control de la acumulación de flavonoles (Stracke et al, 2007), biosíntesis de antocianinas (González et al, 2008), el desarrollo del polen (Preston et al, 2004), la biosíntesis de lignina (Newman et al, 2004;Zhou et al, 2009;Zhong et al, 2007Zhong et al, , 2008 y la apertura estomática (Liang et al, 2005), entre otras. Sin embargo también se ha encontrado su participación en mecanismos de respuesta a estrés abiótico (Alves et al, 2015;.…”