Abstract
In grapevine, the MYB transcription factors play an important role in the flavonoid pathway. Here, a R2R3-MYB transcription factor, VvMYBC2L2, isolated from Vitis vinifera cultivar Yatomi Rose, may be involved in anthocyanin biosynthesis as a transcriptional repressor. VvMYBC2L2 was shown to be a nuclear protein. The gene was shown to be strongly expressed in root, flower and seed tissue, but weakly expressed during the fruit development in grapevine. Overexpressing the VvMYBC2L2 gene in tobacco resulted in a very marked decrease in petal anthocyanin concentration. Expression analysis of flavonoid biosynthesis structural genes revealed that chalcone synthase (CHS), dihydroflavonol 4-reductase (DFR), leucoanthocyanidin reductase (LAR) and UDP glucose flavonoid 3-O-glucosyl transferase (UFGT) were strongly down-regulated in the VvMYBC2L2-overexpressed tobacco. In addition, transcription of the regulatory genes AN1a and AN1b was completely suppressed in transgenic plants. These results suggested that VvMYBC2L2 plays a role as a negative regulator of anthocyanin biosynthesis.
Highlights
IntroductionFlavonoids (including flavonols, anthocyanins and proanthocyanidins) are important plant secondary metabolites, which play multi-biological roles in plants [1,2]
Flavonoids are important plant secondary metabolites, which play multi-biological roles in plants [1,2]
By ANOVA and Tukey’s test (* p < 0.05). These results indicated that VvMYBC2L2 functions as a repressor of. These results indicated that VvMYBC2L2 functions as a repressor of anthocyanin anthocyanin biosynthesis
Summary
Flavonoids (including flavonols, anthocyanins and proanthocyanidins) are important plant secondary metabolites, which play multi-biological roles in plants [1,2]. Fruit skin color is mainly determined by the content and composition of anthocyanins which contribute to wine organoleptic properties such as color, taste, bitterness and astringency [3,4]. It is valuable to understand the regulatory mechanism of flavonoid biosynthesis in grapevine. The MYB family is one of the largest transcription factor families in higher plants, and it plays an important role in the flavonoid pathway. Based on the number of the highly repeat conserved domains (R), MYB proteins can be classified into four major types: 2R-MYB (R2R3-MYB), 3R-MYB (R1R2R3-MYB), 4R-MYB (R1R2R2R1), and MYB- related proteins (or 1R-MYB) [5,6].
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