title: CPC, a single-repeat R3 MYB, is a negative regulator of anthocyanin biosynthesis in Arabidopsis.
abstract: Single-repeat R3 MYB transcription factors like CPC (CAPRICE) are known to play roles in developmental processes such as root hair differentiation and trichome initiation. However, none of the six Arabidopsis single-repeat R3 MYB members has been reported to regulate flavonoid biosynthesis. We show here that CPC is a negative regulator of anthocyanin biosynthesis. In the process of using CPC to test GAL4-dependent driver lines, we observed a repression of anthocyanin synthesis upon GAL4-mediated CPC overexpression. We demonstrated that this is not due to an increase in nutrient uptake because of more root hairs. Rather, CPC expression level tightly controls anthocyanin accumulation. Microarray analysis on the whole genome showed that, of 37 000 features tested, 85 genes are repressed greater than three-fold by CPC overexpression. Of these 85, seven are late anthocyanin biosynthesis genes. Also, anthocyanin synthesis genes were shown to be down-regulated in 35S::CPC overexpression plants. Transient expression results suggest that CPC competes with the R2R3-MYB transcription factor PAP1/2, which is an activator of anthocyanin biosynthesis genes. This report adds anthocyanin biosynthesis to the set of programs that are under CPC control, indicating that this regulator is not only for developmental programs (e.g. root hairs, trichomes), but can influence anthocyanin pigment synthesis.
authors.affiliation: Department of Biology, Washington University, St Louis, MO 63130, USA.
authors.forename: Hui-Fen
authors.initials: HF
authors.lastname: Zhu
authors.affiliation: Department of Biology, Washington University, St Louis, MO 63130, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Fitzsimmons
authors.affiliation: Department of Biology, Washington University, St Louis, MO 63130, USA.
authors.forename: Abha
authors.initials: A
authors.lastname: Khandelwal
authors.affiliation: Department of Biology, Washington University, St Louis, MO 63130, USA. Electronic address: kranz@biology.wustl.edu.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Kranz
mesh_terms: D000595:Amino Acid Sequence; D000872:Anthocyanins / Q000096:biosynthesis*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology; D008954:Models, Biological; D008969:Molecular Sequence Data; D000073718:Pancreatitis-Associated Proteins; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D020598:Proto-Oncogene Proteins c-myb / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
chemical_list: D000872:Anthocyanins; D029681:Arabidopsis Proteins; C511989:CPC protein, Arabidopsis; D000073718:Pancreatitis-Associated Proteins; D020598:Proto-Oncogene Proteins c-myb; C000612141:REG3A protein, human