Differential expression of laccase and manganese peroxidase activities of Trametes versicolor in response to chemical stress by copper and xylidine.

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White-rot basidiomycetes such as Trametes versicolor are major producers of lignin-modifying enzymes (LMEs). Here, we quantified laccase and MnP production by T. versicolor BCC159 under simultaneous and sequential copper/xylidine supplementation regimes and profiled early transcriptional responses using long-read Nanopore cDNA sequencing with poly(A) tail-length estimation. Cultures were grown in submerged fermentation with copper sulphate (1 mM), xylidine (0.5 mM), or both, added either at inoculation or on day 3. Extracellular laccase and MnP activities were quantified, and long-read RNA-seq (Nanopore cDNA-seq) was used to profile differential gene expression and poly(A) tail length. Copper strongly induced laccase and MnP production, whereas xylidine alone triggered a stress-like response but negligible enzyme secretion. The combined treatment yielded the highest titers, with laccase activity reaching 97.1 U/mL when xylidine was added to copper-preconditioned cultures on day 3. Transcriptomic analysis showed that copper upregulated multiple laccase genes together with copper-binding and detoxification factors while downregulating copper transporters, whereas xylidine mainly induced stress- and translation-related genes. Co-treatment integrated elements of both responses and was associated with treatment-specific changes in poly(A) tail length for selected laccase and MnP transcripts. These findings identify copper as the primary inducer of LMEs biosynthesis in T. versicolor BCC159, with xylidine acting mainly as a context-dependent modulator of stress signaling and post-transcriptional control, and indicate that appropriately timed copper-xylidine supplementation can be used to improve LMEs titers in controlled biotechnological settings.