*3.7. cDNA Synthesis and Gene Amplification*

Isolation of total RNA from mycelium of *P. sapidus* at culture day six and cDNA synthesis were performed as described previously [13] using the primer 5 -AAGCAGTGGTATCAACGCAGAGT ACGCTTTTTTTTTTTTTTTTTTT-3 for reverse transcription. Specific primers for gene amplification were deduced from the ORF-start (P1: 5 -ATGACTACACCTGCACCACCCCTCGACCTC-3 ) and -stop (P2: 5 -TCAAGCAGAGATTGGAGCTTGGGTSWGAGGA-3 ) region of the homologous peroxidase of *Pleurotus ostreatus* PC15 (GenBank accession no. KDQ22873.1). PCRs were performed with Phusion High-Fidelity DNA Polymerase and the Master Cycler gradient (Eppendorf, Hamburg, Germany) as described elsewhere [45]. The cycler program was as follows: denaturation for 2 min at 98 ◦C, 35 cycles at 98 ◦C for 1 min, 62 ◦C for 30 s and 72 ◦C for 90 s, and a final elongation at 72 ◦C for 10 min. Analysis of PCR products, ligation, transformation in *Escherichia coli*, colony PCR, and sequencing were performed as described by Behrens et al. [13]. Translation of DNA sequences was performed

using SnapGene® (GSL Biotech LLC, Chicago, IL, USA). Sequence homology was examined using BLAST [46]. Alignments were produced by ClustalOmega [47].
