Light-Induced Expression of a MYB Gene Regulates Anthocyanin Biosynthesis in Red Apples

Abstract

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.

Gene Expression and Metabolite Profiling of Developing Highbush Blueberry Fruit Indicates Transcriptional Regulation of Flavonoid Metabolism and Activation of Abscisic Acid Metabolism

“…6). By contrast, VcMYBPA1 did not activate an anthocyanin pathway-specific promoter, a previously characterized anthocyanidin-3-O-glycosyltransferase MdF3GT promoter (Takos et al, 2006), which we had further validated by activation with the apple anthocyanin regulator MdMYB1 (A. Gesell and C.P. Constabel, unpublished data).…”

The Grapevine R2R3-MYB Transcription Factor VvMYBF1 Regulates Flavonol Synthesis in Developing Grape Berries

“…Grapevine is one of the studied crop plants in terms of the regulation of flavonoid synthesis by transcription factors in fruit, and regulators of flavonoid biosynthesis have also been found in other fruitproducing plants, including strawberry (Fragaria species; Aharoni et al, 2001) and apple (Takos et al, 2006a;Espley et al, 2007). However, a transcription factor that regulates flavonol synthesis in fruit has not been functionally characterized so far in grapevine or any other plant species.…”

Seasonal Abscisic Acid Signal and a Basic Leucine Zipper Transcription Factor, DkbZIP5, Regulate Proanthocyanidin Biosynthesis in Persimmon Fruit

“…This is important because the phenological expression of some flavonoid-derived traits also affects the quality of commercial crops. Early progress has been made in the study of the phenological regulation of anthocyanin biosynthesis, which plays a role in the coloration of Rosaceae and Vitis species by regulating the expression of Myb TFs (Kobayashi, 2009;Lin-Wang et al, 2010) in response to seasonal environmental factors, such as light (Takos et al, 2006;Koyama and Goto-Yamamoto, 2008;Matus et al, 2009) or temperature, coincident with abscisic acid (ABA) concentration (Spayd et al, 2002;Yamane et al, 2006). Although the responses of anthocyanin accumulation to environmental conditions have been discussed, the fundamental mechanisms that regulate the expression of Myb TFs in response to environmental factors need to be further elucidated.…”