, an Anthocyanin-Related Glutathione S-Transferase Gene, Is Essential for Petal Coloration in Tree Peony.

Anthocyanins, as the most important chromogenic substances in flavonoids, are responsible for the red, purple, and blue coloration of flowers. Anthocyanins are synthesized in the cytoplasmic surface of the endoplasmic reticulum (ER) but accumulate predominantly in the vacuole, while glutathione S-transferases (GSTs) are considered to be mainly responsible for the transport process. Our previous studies showed that the expression of was positively correlated with anthocyanin content in tree peony tissues, which is a key candidate gene for anthocyanin accumulation. Here, we successfully cloned and characterized full-length containing three exons and two introns. Subcellular localization showed that was localized in the nucleus and ER membrane. Functional complementation of the transparent testa19 () mutant indicated that was responsible for the transport of anthocyanins but not of proanthocyanidins (PAs). Virus-induced gene silencing (VIGS) of not only led to a decrease in anthocyanin accumulation but also caused a reduction of structural genes in the anthocyanin biosynthesis pathway (ABP) to varying degrees. Heterologous overexpression of was found to increase the anthocyanin accumulation in tobacco petals. Furthermore, the yeast two-hybrid (Y2H) assay showed that interacted with PsDFR, which together contributed to the coloration of petals. In conclusion, these results demonstrate that encodes an important GST transporter of anthocyanin in tree peony petals and provides a new perspective for the associated transport and regulatory mechanisms.