Transcriptional level of representative lignin degradation-related genes during the composting of yellow poplar chips. (A) Manganese peroxidase (MnP 1 and MnP 2). (B) Lignin peroxidase (LiP A/B, D, H and J). Gene sequences of fungus Phanerochaete chrysosporium were used to design primers for real-time RT-PCR. For each gene the expression level at each sampling time point of composting was compared to its expression level at 3 weeks (which was set as 1 fold).