title: Multiple repeats of a promoter segment causes transcription factor autoregulation in red apples.
abstract: Mutations in the genes encoding for either the biosynthetic or transcriptional regulation of the anthocyanin pathway have been linked to color phenotypes. Generally, this is a loss of function resulting in a reduction or a change in the distribution of anthocyanin. Here, we describe a rearrangement in the upstream regulatory region of the gene encoding an apple (Malus x domestica) anthocyanin-regulating transcription factor, MYB10. We show that this modification is responsible for increasing the level of anthocyanin throughout the plant to produce a striking phenotype that includes red foliage and red fruit flesh. This rearrangement is a series of multiple repeats, forming a minisatellite-like structure that comprises five direct tandem repeats of a 23-bp sequence. This MYB10 rearrangement is present in all the red foliage apple varieties and species tested but in none of the white fleshed varieties. Transient assays demonstrated that the 23-bp sequence motif is a target of the MYB10 protein itself, and the number of repeat units correlates with an increase in transactivation by MYB10 protein. We show that the repeat motif is capable of binding MYB10 protein in electrophoretic mobility shift assays. Taken together, these results indicate that an allelic rearrangement in the promoter of MYB10 has generated an autoregulatory locus, and this autoregulation is sufficient to account for the increase in MYB10 transcript levels and subsequent ectopic accumulation of anthocyanins throughout the plant.
authors.affiliation: New Zealand Institute for Plant and Food Research Limited, Mt Albert Research Centre, Auckland 1025, New Zealand.
authors.forename: Richard V
authors.initials: RV
authors.lastname: Espley
authors.forename: Cyril
authors.initials: C
authors.lastname: Brendolise
authors.forename: David
authors.initials: D
authors.lastname: Chagné
authors.forename: Sumathi
authors.initials: S
authors.lastname: Kutty-Amma
authors.forename: Sol
authors.initials: S
authors.lastname: Green
authors.forename: Richard
authors.initials: R
authors.lastname: Volz
authors.forename: Jo
authors.initials: J
authors.lastname: Putterill
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Schouten
authors.forename: Susan E
authors.initials: SE
authors.lastname: Gardiner
authors.forename: Roger P
authors.initials: RP
authors.lastname: Hellens
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Allan
mesh_terms: D000483:Alleles; D000872:Anthocyanins / Q000096:biosynthesis; D001483:Base Sequence; D016386:Chromosome Walking; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D027845:Malus / Q000235:genetics* / Q000378:metabolism; D018598:Minisatellite Repeats; D008969:Molecular Sequence Data; D010858:Pigmentation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000378:metabolism; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA; D014026:Nicotiana / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000872:Anthocyanins; D018744:DNA, Plant; D010940:Plant Proteins; D014157:Transcription Factors