The PuERF27-PuMYB10-PuGSTF12 Module Regulates Melatonin-Induced Anthocyanin Biosynthesis in Pear Fruits

Anthocyanins, flavonoids with strong
antioxidant activity, give
rise to a fruit peel color and provide health benefits. Studies have
revealed that melatonin promotes anthocyanin accumulation. However,
the function of endogenous hormones in this process remains elusive.
Here, we investigated the effect of ethylene signaling on anthocyanin
accumulation in melatonin-treated pear fruit. Melatonin promoted anthocyanin
accumulation while repressing ethylene production; its effect on anthocyanin
biosynthesis in the background of ethephon pretreatment was eliminated.
Transcriptome analysis revealed PuERF27, a melatonin-induced
ethylene response factor (ERF), as a candidate gene. Transient overexpression
of PuERF27 is essential for enhancing anthocyanin
accumulation and activating anthocyanin biosynthesis genes, whereas PuERF27 silencing repressed melatonin-induced anthocyanin
accumulation. Yeast one-hybrid, electrophoretic mobility shift, and
GUS assays indicated that PuERF27 could bind directly to and positively
regulate the PuMYB10 and PuGSTF12 promoters. Further studies revealed that PuERF27, together with
PuMYB10, synergistically transactivates the PuGSTF12 promoter. These results indicate that melatonin-induced PuERF27
may directly promote PuGSTF12 expression and indirectly
activate structural genes through PuMYB10, thereby leading to the
biosynthesis and transport of anthocyanins.