Light modulates the transcriptomic accumulation of anthocyanin biosynthetic pathway genes in red and white grapes

Light modulates the transcriptomic accumulation of anthocyanin biosynthetic pathway genes in red and white grapes

Anthocyanin, an important component in the grape berry skin, strongly affects grape quality. The transcription factors VvMYBA1 and VvMYBA2 (VvMYBA1/2) control anthocyanin biosynthesis. In addition, cultivation and environmental factors, such as light, influence anthocyanin accumulation. The present study aimed to clarify the effect of shading (reduced light condition) on the transcriptomic regulation of anthocyanin biosynthesis using a red-wine grape cultivar, Vitis vinifera ‘Pinot Noir’, and its white mutant, ‘Pinot Blanc’, caused by the deletion of the red allele of VvMYBA1/2. The grape berry skins were analyzed for anthocyanin content and global gene transcription accumulation. The microarray data were later validated by quantitative real-time PCR. A decisive influence of VvMYBA1/2 on the expression of an anthocyanin-specific gene, UDP glucose: flavonoid 3-O-glucosyltransferase, was observed as expected. In contrast, upstream genes of the pathway, which are shared by other flavonoids, were also expressed in ‘Pinot Blanc’, and the mRNA levels of some of these genes decreased in both cultivars on shading. Thus, the involvement of lightsensitive transcription factor(s) other than VvMYBA1/2 was suggested for the expression control of the upstream genes of the anthocyanin biosynthetic pathway. Furthermore, it was suggested that the effects of these factors are different among isogenes.