MYB and infection: To gain an initial understanding of the poplar susceptibility regulatory mechanisms related to TFs during E4 infection, promoters corresponding to the region 500 bp upstream of the predicted transcription start sites of genes in each GO cluster were screened for overrepresentation of NAC-, MYB-, ERF-, AP2-, and WRKY-binding motifs based on the genomic data of P. trichocarpa V 3.0 (Figure 5A).