Fig. 4From: Genome-wide investigation and expression profiling of polyphenol oxidase (PPO) family genes uncover likely functions in organ development and stress responses in Populus trichocarpaCollinearity analysis of PPO genes in poplar and four typical plant species. The gray lines in the background represent collinear blocks between Populus and another species’ genomes, while the red lines highlight the syntenic PPO gene pairs. P.trichocarpa, Populus trichocarpa; S.purpurea, Salix purpurea; M.domestica, Malus domestica; O. sativa, Oryza sativaBack to article page