Abstract:

To explore the relationship between light and anthocyanin synthesis of blood orange peel,some PE bags with different light transmittance was used to perform shading experiments on the fruit during the ripening period. This experiment determined the dynamic content of total anthocyanins and the dynamic expression of 12 anthocyanin synthesis-related genes in blood orange peels under different shading treatments. The results showed that coloring time, coloring area and coloring degree of the blood orange fruit were hindered by different degrees of shading. The degree of obstruction was related to the light transmittance of the PE bags, but the PE bags shading promoted the increase of the brightness of the blood orange fruit surface. In the natural state,the expression of 8 structural genes GST, ANS, CHS, DFR, F3H, UFGT, PAL, 4CL and two regulatory genes Ruby and MYBF1 showed a rapid increase during the color conversion period, and different degrees of shading hindered them. So these 10 genes were the key genes of blood orange peel anthocyanin synthesis regulated by light. After the comprehensive analysis of the dynamic content of total anthocyanins, the dynamic expression of key genes and the corresponding PE bags light transmittance data, it could be inferred that the UVB ultraviolet light might regulate the synthesis of blood orange peel anthocyanins in the light. According to the dynamic determination results of related genes, it was speculated that the critical period of blood orange peel anthocyanin synthesis appeared on 249 d after flowering. For better appearance quality, it was more appropriate to pick blood oranges on 249 d after flowering. Transparent PE film or other films with higher UV transmittance should be used to protect the fruit of blood orange in winter.

Key words: blood orange, anthocyanin, light, gene expression