Genome-wide identification of C1-1i-ZFP genes and functional analysis of ZFP6a gene from Platanus × acerifolia.

Key message: 31 PaC1-1iZFP genes were identified from Platanus × acerifolia genome. Overexpression of PaZFP6a promoted initiation of trichome of tobacco leaves and Arabidopsis thaliana sepals. Platanus × acerifolia is known as the king of the street tree, but its annual seed trichome and leaf trichome problem seriously affects human health and life. C2H2-zinc finger protein (C2H2-ZFP) regulates plant stress, flower development, leaf morphogenesis, and trichome formation. The sing C2H2 ZFP family is a subfamily of ZFP involved in the development of trichome. In this study, we used bioinformatic-based techniques to identify 31 single ZFP genes. The results of conserved motifs analysis showed that all members had highly conserved QALLGGH sequences. By cis-acting element analysis, it was found that the PaC1-1i-ZFPs promoter responds to many hormone and stress-related elements. Most of the genes were expressed in all tissues, with PaZFP6a being the most highly expressed in the trichome, so it was used as a target gene and transformed model plants for functional verification. The findings demonstrated that PaZFP6a possessed transcriptional activation activity and was located in the nucleus. Overexpression of the gene in tobacco results in a two-fold increase in leaf glandular hair density and a three-fold increase in glandular hair length. The expression of endogenous NtCTTC, NtPhP and NtCYP7D16 were significantly increased in PaZFP6a transgenic tobacco lines. In Arabidopsis thaliana, overexpression of PaZFP6a leads to an increase in sepal trichomes. Meanwhile, the interactions of PaZFP6a protein with PaZFP8 and PaZFP5a were identified by Y2H and BIFC experiments. In this study, we further comprehended the regulation of trichome formation by single C2H2 zinc finger proteins, laying the groundwork for producing hairless P. × acerifolia.