Light-induced expression of a MYB gene regulates anthocyanin biosynthesis in red apples.
Anthocyanins are secondary metabolites found in higher plants that contribute to the colors of flowers and fruits. In apples (Malus domestica Borkh.), several steps of the anthocyanin pathway are coordinately regulated, suggesting control by common transcription factors. A gene encoding an R2R3 MYB transcription factor was isolated from apple (cv Cripps' Pink) and designated MdMYB1. Analysis of the deduced amino acid sequence suggests that this gene encodes an ortholog of anthocyanin regulators in other plants. The expression of MdMYB1 in both Arabidopsis (Arabidopsis thaliana) plants and cultured grape cells induced the ectopic synthesis of anthocyanin. In the grape (Vitis vinifera) cells MdMYB1 stimulated transcription from the promoters of two apple genes encoding anthocyanin biosynthetic enzymes. In ripening apple fruit the transcription of MdMYB1 was correlated with anthocyanin synthesis in red skin sectors of fruit. When dark-grown fruit were exposed to sunlight, MdMYB1 transcript levels increased over several days, correlating with anthocyanin synthesis in the skin. MdMYB1 gene transcripts were more abundant in red skin apple cultivars compared to non-red skin cultivars. Several polymorphisms were identified in the promoter of MdMYB1. A derived cleaved amplified polymorphic sequence marker designed to one of these polymorphisms segregated with the inheritance of skin color in progeny from a cross of an unnamed red skin selection (a sibling of Cripps' Pink) and the non-red skin cultivar Golden Delicious. We conclude that MdMYB1 coordinately regulates genes in the anthocyanin pathway and the expression level of this regulator is the genetic basis for apple skin color.
Takos
Adam M
AM
Commonwealth Scientific and Industrial Research Organization, Plant Industry, Adelaide Laboratory, Waite Campus, Urrbrae, SA 5064, Australia.
Jaffé
Felix W
FW
Jacob
Steele R
SR
Bogs
Jochen
J
Robinson
Simon P
SP
Walker
Amanda R
AR
D000595:Amino Acid Sequence; D000872:Anthocyanins / Q000096:biosynthesis*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D003116:Color; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects*; D017343:Genes, Plant / Q000235:genetics*; D020570:Genes, myb / Q000235:genetics*; D008027:Light; D027845:Malus / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics; D030821:Plants, Genetically Modified
D000872:Anthocyanins; D010940:Plant Proteins