Fig. 6From: Genome-wide investigation and expression profiling of polyphenol oxidase (PPO) family genes uncover likely functions in organ development and stress responses in Populus trichocarpaExpression profile of PPO genes under developmental and stress conditions. a Heat maps showing the expression levels of 18 PtrPPO genes in different tissues at different developmental stages based on transcriptome data. b Heat maps depicting the expression levels of 18 PtrPPO genes following drought-, beetle-, and mechanical damage. The color bar represents the range of maximum and minimum values of relative expression in the heat mapBack to article page