Effect of Light Intensity on Blueberry Fruit Coloration, Anthocyanin Synthesis Pathway Enzyme Activity, and Gene Expression
Xiaolan Guo, Jianbin Hu, D. L. Wang
Abstract
Abstract The fruit skin color is an important economic trait of blueberries (Vaccinium spp.) and is determined by the concentration of anthocyanins. Light intensity significantly affects anthocyanin accumulation. Anthocyanin content is closely related to enzyme activity and gene expression. In this study, the anthocyanin content, the activity of related enzymes and the expression of genes involved in the development process of 5-year ‘Pink Blue’ cranberry were studied. The results showed that with increasing light intensity, the content of anthocyanin glycosides increased, while that of flavonoids, chlorophylls and carotenoids decreased. Except for chalcone isomerases (CHI) and flavonol synthetases (FLS), all enzymes involved in anthocyanin synthesis showed the same trend as anthocyanin glycosides. The expression of genes for transcription factors, such as VcMYB1 and VcbHLH004, and certain photoreceptor factors were significantly downregulated under shading conditions. Correlation analysis showed that flavonoid 3',5'-hydroxylase (F3'5'H) and VcF3'5'H4 are the key enzymes for anthocyanin glycoside synthesis in blueberry as well as the corresponding enzyme genes. This study provides a foundation for further research on the mechanism of light-induced anthocyanin synthesis in blueberry.