PbZAT12, Independent of PbMYB10, Activates Structural Genes to Promote Anthocyanin Biosynthesis in 'Red Zaosu' Pear Fruit (Pyrus bretschneideri Rehd.)

The red color of the pear peel in red-skinned European pear is due to the accumulation of anthocyanins. Numerous transcription factors play pivotal roles in anthocyanin biosynthesis, with zinc finger proteins frequently implicated in the regulation of this process via MYB10, as documented in earlier studies. In this article, we identified a zinc finger protein gene, named PbZAT12, that does not rely on PbMYB10, to regulate anthocyanin biosynthesis. The PbZAT12 protein was localized within the nucleus and exhibited a positive influence on the accumulation of anthocyanins in the peel of 'Red Zaosu' pears. Moreover, overexpression of PbZAT12 resulted in a significant up-regulation of PbDFR, PbANS, and PbUFGT expression levels in pear fruitlets. Y1H assays demonstrated a direct binding ability of PbZAT12 to proPbDFR, proPbANS, and proPbUFGT, which was supported by a dual luciferase assay, indicating its potential to activate the transcriptional activity of these promoters. However, in contrast to its effect on the aforementioned promoters, PbZAT12 did not exhibit an activation of PbMYB10. In summary, our findings suggest that a zinc finger transcription factor, PbZAT12, exerts a positive influence on anthocyanin biosynthesis in pear fruit through direct upregulation of the expression levels of PbDFR, PbANS, and PbUFGT.