3-dehydroquinate synthase contributes to anthocyanin accumulation and flower pigmentation in petunia.

Anthocyanin biosynthesis in plants depends on the supply of aromatic amino acids. These amino acids are produced through the shikimate pathway. DHQS functions in an early reaction of the shikimate pathway and mediates the production of 3-dehydroquinate (DHQ) from 3-deoxy-D-arabino-heptulosonate 7-phosphate (DAHP). However, it is unclear whether DHQS contributes to the biosynthesis of flavonoids and anthocyanins. In this study, a single member of the DHQS family, PhDHQS, was identified in Petunia hybrida. GFP fusion protein analysis showed that PhDHQS is localized in chloroplasts. PhDHQS was highly expressed in the corolla, with the highest expression at the flower coloration stage, corresponding to flower buds of approximately 4 cm in length. Silencing of PhDHQS caused lighter flower coloration and significantly lower anthocyanin levels. Metabolomic analysis showed that six core anthocyanin compounds were significantly downregulated in PhDHQS-silenced corollas. These results suggest that PhDHQS contributes to anthocyanin accumulation by modulating the supply of phenylalanine-related precursors, providing new insights into the contribution of upstream shikimate pathway enzymes to flower color formation.