title: Functionally Similar WRKY Proteins Regulate Vacuolar Acidification in Petunia and Hair Development in Arabidopsis.
abstract: The WD40 proteins ANTHOCYANIN11 (AN11) from petunia (Petunia hybrida) and TRANSPARENT TESTA GLABRA1 (TTG1) from Arabidopsis thaliana and associated basic helix-loop-helix (bHLH) and MYB transcription factors activate a variety of differentiation processes. In petunia petals, AN11 and the bHLH protein AN1 activate, together with the MYB protein AN2, anthocyanin biosynthesis and, together with the MYB protein PH4, distinct genes, such as PH1 and PH5, that acidify the vacuole. To understand how AN1 and AN11 activate anthocyanin biosynthetic and PH genes independently, we isolated PH3. We found that PH3 is a target gene of the AN11-AN1-PH4 complex and encodes a WRKY protein that can bind to AN11 and is required, in a feed-forward loop, together with AN11-AN1-PH4 for transcription of PH5. PH3 is highly similar to TTG2, which regulates hair development, tannin accumulation, and mucilage production in Arabidopsis. Like PH3, TTG2 can bind to petunia AN11 and the Arabidopsis homolog TTG1, complement ph3 in petunia, and reactivate the PH3 target gene PH5. Our findings show that the specificity of WD40-bHLH-MYB complexes is in part determined by interacting proteins, such as PH3 and TTG2, and reveal an unanticipated similarity in the regulatory circuitry that controls petunia vacuolar acidification and Arabidopsis hair development.
authors.affiliation: Department of Molecular and Cell Biology, VU University, 1071 HK Amsterdam, The Netherlands.
authors.forename: Walter
authors.identifier: http://orcid.org/0000-0001-8310-9068
authors.initials: W
authors.lastname: Verweij
authors.affiliation: Department of Molecular and Cell Biology, VU University, 1071 HK Amsterdam, The Netherlands Swammerdam Institute for Life Sciences, University of Amsterdam, 1012 WX Amsterdam, The Netherlands.
authors.forename: Cornelis E
authors.identifier: http://orcid.org/0000-0001-8012-2291
authors.initials: CE
authors.lastname: Spelt
authors.affiliation: Department of Molecular and Cell Biology, VU University, 1071 HK Amsterdam, The Netherlands Swammerdam Institute for Life Sciences, University of Amsterdam, 1012 WX Amsterdam, The Netherlands.
authors.forename: Mattijs
authors.identifier: http://orcid.org/0000-0002-0488-4873
authors.initials: M
authors.lastname: Bliek
authors.affiliation: Department of Molecular and Cell Biology, VU University, 1071 HK Amsterdam, The Netherlands.
authors.forename: Michel
authors.initials: M
authors.lastname: de Vries
authors.affiliation: Department of Molecular and Cell Biology, VU University, 1071 HK Amsterdam, The Netherlands.
authors.forename: Niek
authors.identifier: http://orcid.org/0000-0001-7441-5995
authors.initials: N
authors.lastname: Wit
authors.affiliation: Department of Molecular and Cell Biology, VU University, 1071 HK Amsterdam, The Netherlands.
authors.forename: Marianna
authors.identifier: http://orcid.org/0000-0002-6537-9926
authors.initials: M
authors.lastname: Faraco
authors.affiliation: Department of Molecular and Cell Biology, VU University, 1071 HK Amsterdam, The Netherlands Swammerdam Institute for Life Sciences, University of Amsterdam, 1012 WX Amsterdam, The Netherlands ronald.koes@uva.nl.
authors.forename: Ronald
authors.identifier: http://orcid.org/0000-0003-3793-5072
authors.initials: R
authors.lastname: Koes
authors.affiliation: Department of Molecular and Cell Biology, VU University, 1071 HK Amsterdam, The Netherlands Swammerdam Institute for Life Sciences, University of Amsterdam, 1012 WX Amsterdam, The Netherlands.
authors.forename: Francesca M
authors.identifier: http://orcid.org/0000-0001-8040-4061
authors.initials: FM
authors.lastname: Quattrocchio
mesh_terms: D000872:Anthocyanins / Q000378:metabolism*; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D035264:Flowers / Q000166:cytology / Q000235:genetics / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D053263:Gene Regulatory Networks; D006706:Homeostasis; D006863:Hydrogen-Ion Concentration; D032306:Petunia / Q000166:cytology / Q000235:genetics* / Q000502:physiology; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified; D014617:Vacuoles / Q000378:metabolism
chemical_list: D000872:Anthocyanins; D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D010940:Plant Proteins; C106652:AN11 protein, Petunia x hybrida; C121067:TTG1 protein, Arabidopsis