title: Functional diversification of the potato R2R3 MYB anthocyanin activators AN1, MYBA1, and MYB113 and their interaction with basic helix-loop-helix cofactors.
abstract: In potato (Solanum tuberosum L.), R2R3 MYBs are involved in the regulation of anthocyanin biosynthesis. We examined sequences of these MYBs in cultivated potatoes, which are more complex than diploid potato due to ploidy and heterozygosity. We found amino acid variants in the C-terminus of the MYB StAN1, termed R0, R1, and R3, due to the presence of a repeated 10-amino acid motif. These variant MYBs showed some expression in both white and pigmented tubers. We found several new alleles or gene family members of R2R3 MYBs,StMYBA1 and StMYB113, which were also expressed in white potato tubers. From functional analysis in tobacco, we showed that the presence of a C-terminal 10-amino acid motif is optimal for activating anthocyanin accumulation. Engineering a motif back into a MYB lacking this sequence enhanced its activating ability. Versions of StMYBA1 and StMYB113 can also activate anthocyanin accumulation in tobacco leaves, with the exception of StMYB113-3, which has a partial R2R3 domain. We isolated five family members of potato StbHLH1, and one StJAF13, to test their ability to interact with MYB variants. The results showed that two alleles of StbHLH1 from white skin and red skin are non-functional, while three other StbHLH1s have different co-regulating abilities, and need to be activated by StJAF13. Combined with expression analysis in potato tuber, results suggest that StbHLH1 and StJAF13a re key co-regulators of anthocyanin biosynthesis, while the transcripts of MYB variants StAN1,StMYBA1, and StMYB113 are well expressed, even in the absence of pigmentation.
authors.affiliation: Gansu Key Laboratory of Crop Improvement and Germplasm Enhancement, Gansu Agricultural University, Lanzhou 730070, China.
authors.forename: Yuhui
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Plant & Food Research Mt Albert, Private Bag 92169, Auckland Mail Centre, Auckland 1142, New Zealand.
authors.forename: Kui
authors.initials: K
authors.lastname: Lin-Wang
authors.affiliation: Plant & Food Research Mt Albert, Private Bag 92169, Auckland Mail Centre, Auckland 1142, New Zealand.
authors.forename: Richard V
authors.initials: RV
authors.lastname: Espley
authors.affiliation: Gansu Key Laboratory of Crop Improvement and Germplasm Enhancement, Gansu Agricultural University, Lanzhou 730070, China College of Life Science and Technology, Gansu Agricultural University, Lanzhou 730070, China.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.affiliation: Gansu Key Laboratory of Crop Improvement and Germplasm Enhancement, Gansu Agricultural University, Lanzhou 730070, China College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China.
authors.forename: Hongyu
authors.initials: H
authors.lastname: Yang
authors.affiliation: Gansu Key Laboratory of Crop Improvement and Germplasm Enhancement, Gansu Agricultural University, Lanzhou 730070, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Yu
authors.affiliation: Plant & Food Research Mt Albert, Private Bag 92169, Auckland Mail Centre, Auckland 1142, New Zealand.
authors.forename: Andrew
authors.initials: A
authors.lastname: Dare
authors.affiliation: Plant & Food Research Mt Albert, Private Bag 92169, Auckland Mail Centre, Auckland 1142, New Zealand.
authors.forename: Erika
authors.initials: E
authors.lastname: Varkonyi-Gasic
authors.affiliation: College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Gansu Key Laboratory of Crop Improvement and Germplasm Enhancement, Gansu Agricultural University, Lanzhou 730070, China College of Horticulture, Gansu Agricultural University, Lanzhou 730070, China zhangjunlian77@163.com andrew.allan@plantandfood.co.nz.
authors.forename: Junlian
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Gansu Key Laboratory of Crop Improvement and Germplasm Enhancement, Gansu Agricultural University, Lanzhou 730070, China.
authors.forename: Di
authors.initials: D
authors.lastname: Wang
authors.affiliation: Plant & Food Research Mt Albert, Private Bag 92169, Auckland Mail Centre, Auckland 1142, New Zealand School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand zhangjunlian77@163.com andrew.allan@plantandfood.co.nz.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Allan
mesh_terms: D000595:Amino Acid Sequence; D000872:Anthocyanins / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D010802:Phylogeny; D010858:Pigmentation / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D035281:Plant Tubers / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D016415:Sequence Alignment; D011198:Solanum tuberosum / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics
chemical_list: D000872:Anthocyanins; D051792:Basic Helix-Loop-Helix Proteins; D010940:Plant Proteins; D012333:RNA, Messenger
keywords: Anthocyanin; MYB transcription factors; cofactors; diversification; interaction; potato.