According to the heatmap analysis of the PPO family genes in VW-resistant MBI8255 and VW-susceptible CCRI36 infected with V991 at 0, 1, and 2 DAI (days after inoculation), all the GhPPOs dramatically showed various expression patterns, of which most had higher expression levels in CCRI36 than those in MBI8255 under the same V991-infection period (Figure 6A). This evidence concerns the gene PPOX and infection.