title: Failure to launch: the self-regulating Md-MYB10 R6 gene from apple is active in flowers but not leaves of Petunia.
abstract: The Md - MYB10 R6 gene from apple is capable of self-regulating in heterologous host species and enhancing anthocyanin pigmentation, but the activity of MYB10 is dependent on endogenous protein partners. Coloured foliage due to anthocyanin pigments (bronze/red/black) is an attractive trait that is often lacking in many bedding, ornamental and horticultural plants. Apples (Malus × domestica) containing an allelic variant of the anthocyanin regulator, Md-MYB10 R6 , are highly pigmented throughout the plant, due to autoregulation by MYB10 upon its own promoter. We investigated whether Md-MYB10 R6 from apple is capable of functioning within the heterologous host Petunia hybrida to generate plants with novel pigmentation patterns. The Md-MYB10 R6 transgene (MYB10-R6 pro :MYB10:MYB10 term ) activated anthocyanin synthesis when transiently expressed in Antirrhinum rosea (dorsea) petals and petunia leaf discs. Stable transgenic petunias containing Md-MYB10 R6 lacked foliar pigmentation but had coloured flowers, complementing the an2 phenotype of 'Mitchell' petunia. The absence of foliar pigmentation was due to the failure of the Md-MYB10 R6 gene to self-activate in vegetative tissues, suggesting that additional protein partners are required for Md-MYB10 to activate target genes in this heterologous system. In petunia flowers, where endogenous components including MYB-bHLH-WDR (MBW) proteins were present, expression of the Md-MYB10 R6 promoter was initiated, allowing auto-regulation to occur and activating anthocyanin production. Md-MYB10 is capable of operating within the petunia MBW gene regulation network that controls the expression of the anthocyanin biosynthesis genes, AN1 (bHLH) and MYBx (R3-MYB repressor) in petals.
authors.affiliation: The New Zealand Institute for Plant and Food Research Limited, Private Bag 11600, Palmerston North, 4442, New Zealand.
authors.forename: Murray R
authors.initials: MR
authors.lastname: Boase
authors.affiliation: The New Zealand Institute for Plant and Food Research Limited, Private Bag 92169 Auckland Mail Centre, Auckland, 1142, New Zealand.
authors.forename: Cyril
authors.initials: C
authors.lastname: Brendolise
authors.affiliation: The New Zealand Institute for Plant and Food Research Limited, Private Bag 11600, Palmerston North, 4442, New Zealand.
authors.forename: Lei
authors.initials: L
authors.lastname: Wang
authors.affiliation: The New Zealand Institute for Plant and Food Research Limited, Private Bag 11600, Palmerston North, 4442, New Zealand.
authors.forename: Hahn
authors.initials: H
authors.lastname: Ngo
authors.affiliation: The New Zealand Institute for Plant and Food Research Limited, Private Bag 92169 Auckland Mail Centre, Auckland, 1142, New Zealand.
authors.forename: Richard V
authors.initials: RV
authors.lastname: Espley
authors.affiliation: The New Zealand Institute for Plant and Food Research Limited, Private Bag 92169 Auckland Mail Centre, Auckland, 1142, New Zealand.|Biochemistry Department, University of Otago, Dunedin, New Zealand.|Centre for Tropical Crops and Biocommodities, Queensland University of Technology (QUT), Brisbane, Australia.
authors.forename: Roger P
authors.initials: RP
authors.lastname: Hellens
authors.affiliation: The New Zealand Institute for Plant and Food Research Limited, Private Bag 11600, Palmerston North, 4442, New Zealand.
authors.forename: Kathy E
authors.initials: KE
authors.lastname: Schwinn
authors.affiliation: The New Zealand Institute for Plant and Food Research Limited, Private Bag 11600, Palmerston North, 4442, New Zealand.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Davies
authors.affiliation: The New Zealand Institute for Plant and Food Research Limited, Private Bag 11600, Palmerston North, 4442, New Zealand. nick.albert@plantandfood.co.nz.
authors.forename: Nick W
authors.identifier: http://orcid.org/0000-0002-8579-529X
authors.initials: NW
authors.lastname: Albert
mesh_terms: D035264:Flowers / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D032306:Petunia / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*
chemical_list: D010940:Plant Proteins
keywords: Anthocyanin; BHLH; Flavonoid; MYB; Petunia; WDR