Copper induces transcription of laccase gene in phytopathogenic fungus, .

Laccases are one of many groups of inducible enzymes produced by the filamentous fungus, during colonisation of host plant tissues. While the processes involved in laccase induction are not fully understood, Cupric ions (e.g. CuSO) and gallic acid (GA) have been reported as laccase inducers. This study investigates laccases activities and the expression of three laccase genes () in three isolates grown in laccase-inducing medium (LIM) supplemented with CuSO and GA. Laccase activity in culture filtrates with CuSO increased after 48 h of growth in LIM at 24°C. The induction of transcription was greatest at a concentration of 0.6 mM CuSO, concentrations greater than 0.6 mM inhibited fungal growth. In contrast, no laccase induction was observed in the presence of GA. Liquid chromatography-mass spectroscopy (NanoLC ESI MS/MS) analysis confirmed the presence of a 63.4 kDa protein, the isoform in the culture filtrate with 0.6 mM CuSO. Analysis of mRNA transcripts further showed was also inducible and the expression of and was isolate-dependent. In conclusion, CuSO induces a 63.4 kDa laccase in by induced transcription of the gene.