title: The beet Y locus encodes an anthocyanin MYB-like protein that activates the betalain red pigment pathway.
abstract: Nearly all flowering plants produce red/violet anthocyanin pigments. Caryophyllales is the only order containing families that replace anthocyanins with unrelated red and yellow betalain pigments. Close biological correlation of pigmentation patterns suggested that betalains might be regulated by a conserved anthocyanin-regulating transcription factor complex consisting of a MYB, a bHLH and a WD repeat-containing protein (the MBW complex). Here we show that a previously uncharacterized anthocyanin MYB-like protein, Beta vulgaris MYB1 (BvMYB1), regulates the betalain pathway in beets. Silencing BvMYB1 downregulates betalain biosynthetic genes and pigmentation, and overexpressing BvMYB1 upregulates them. However, unlike anthocyanin MYBs, BvMYB1 will not interact with bHLH members of heterologous anthocyanin MBW complexes because of identified nonconserved residues. BvMYB1 resides at the historic beet pigment-patterning locus, Y, required for red-fleshed beets. We show that Y and y express different levels of BvMYB1 transcripts. The co-option of a transcription factor regulating anthocyanin biosynthesis would be an important evolutionary event allowing betalains to largely functionally replace anthocyanins.
authors.affiliation: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA.
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Hatlestad
authors.affiliation: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA.
authors.forename: Neda A
authors.initials: NA
authors.lastname: Akhavan
authors.affiliation: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA.
authors.forename: Rasika M
authors.initials: RM
authors.lastname: Sunnadeniya
authors.affiliation: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA.
authors.forename: Lee
authors.initials: L
authors.lastname: Elam
authors.affiliation: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Cargile
authors.affiliation: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA.
authors.forename: Austin
authors.initials: A
authors.lastname: Hembd
authors.affiliation: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA.
authors.forename: Antonio
authors.initials: A
authors.lastname: Gonzalez
authors.affiliation: US Department of Agriculture-Agricultural Research Service, Sugarbeet and Bean Research Unit, Department of Crop and Soil Sciences, Michigan State University, East Lansing, Michigan, USA.
authors.forename: J Mitchell
authors.initials: JM
authors.lastname: McGrath
authors.affiliation: Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, Texas, USA.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Lloyd
mesh_terms: D060054:Agrobacterium / Q000235:genetics; D000595:Amino Acid Sequence; D000872:Anthocyanins / Q000096:biosynthesis; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D027461:Beta vulgaris / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D050858:Betalains / Q000096:biosynthesis*; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D020868:Gene Silencing; D017343:Genes, Plant; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D010858:Pigmentation / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000096:biosynthesis; D018749:RNA, Plant / Q000096:biosynthesis; D016415:Sequence Alignment; D017385:Sequence Homology; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D014170:Transformation, Genetic
chemical_list: D000872:Anthocyanins; D051792:Basic Helix-Loop-Helix Proteins; D050858:Betalains; D046912:Multiprotein Complexes; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D014157:Transcription Factors