Cyclophilin A and calcineurin functions investigated by gene inactivation, cyclosporin A inhibition and cDNA arrays approaches in the phytopathogenic fungus Botrytis cinerea

Summary Calcineurin phosphatase and cyclophilin A are cellular components involved in fungal morphogenesis and virulence. Their roles were investigated in the phytopathogenic fungus Botrytis cinerea using gene inactivation, drug inhibition and cDNA macroarrays approaches. First, the BCP1 gene coding for cyclophilin A was identified and inactivated by homologous recombination. The bcp1Δ null mutant obtained was still able to develop infection structures but was altered in symptom development on bean and tomato leaves. Opposite to this, calcineurin inhibition using cyclosporin A (CsA) modified hyphal morphology and prevented infection structure formation. CsA drug pattern signature on macroarrays allowed the identification of 18 calcineurin‐dependent (CND) genes among 2839 B. cinerea genes. Among the co‐regulated CND genes, three were shown to be organized as a physical cluster that could be involved in secondary metabolism. The signature of BCP1 inactivation on macroarrays allowed the identification of only three BCP1 cyclophilin‐dependent (CPD) genes that were different from CND genes. Finally, no CsA drug pattern signature was observed in the bcp1Δ null mutant which provided a molecular target validation of the drug.