Involvement of FpTRP26, a thioredoxin-related protein, in oxalic acid-resistance of the brown-rot fungus Fomitopsis palustris

Brown-rot fungus Fomitopsis palustris grows vigorously at high concentrations of oxalic acid (OA), which is fungal metabolite during wood decay. We isolated a cDNA FpTRP26 from F. palustris by functional screening of yeast transformants with cDNAs grown on plates containing OA. FpTRP26 conferred a specific resistance to OA on the transformant. OA-content in transformants grown with 2 mM OA decreased by 65% compared to that of the control. The amount of FpTRP26 transcript in F. palustris amplified with increasing OA-accumulation, and was maintained at high levels even in the stationary phase. Its transcription in F. palustris was inducible in response to exogenously added OA. These results suggest that FpTRP26 is involved in the OA-resistance in F. palustris.