PdeERF114 recruits PdeWRKY75 to regulate callus formation in poplar by modulating the accumulation of H 2 O 2 and the relaxation of cell walls.

Callus formation is important for numerous biological processes in plants. Previously, we revealed that the PdeWRKY75-PdeRBOHB module positively regulates hydrogen peroxide (H 2 O 2 ) accumulation, thereby affecting callus formation in poplar. In this study, we identified and confirmed a transcription factor, PdeERF114, that interacts with PdeWRKY75 both in vitro and in vivo. Gene expression analysis identified both PdeRBOHB and PdeEXPB2 as downstream genes of PdeERF114 and PdeWRKY75. Overexpression (OE) and reduced-expression (RE) transgenic poplar lines for these four genes were generated, and the observation of callus formation was also performed in all plant materials. We demonstrated that PdeERF114 and PdeWRKY75 formed a protein complex and that this complex could bind W-Box motifs in the promoters of PdeRBOHB and PdeEXPB2, thereby positively regulating the expression of PdeRBOHB and PdeEXPB2. The OE/RE transgenic lines for these four genes also showed enhanced/reduced callus formation. Overall, we revealed a novel gene regulatory network for the regulation of callus formation in plants that involves four genes and regulates callus formation through two pathways: the accumulation of H 2 O 2 in explants and the relaxation of cell walls. In the future, the four genes could be used to enhance transformation effectiveness in genetic engineering.