Molecular characterization of the two-component histidine kinase gene from Monilinia fructicola.

Brown rot of stone fruit caused by Monilinia fructicola (G. Wint) Honey is one of the most common fungal diseases in California. In this study, two laboratory-induced iprodione-resistant (LIR) mutants of M. fructicola were characterized by osmotic sensitivity, virulence on prune and sequence of the two-component histidine kinase gene (Mfos-1). The LIR mutants showed more sensitivity to osmotic stress and lower virulence on prune than their wild-type parent. Analysis of deduced amino acid of Mfos-1 showed that this protein exhibited all the characteristic features of the two-component histidine kinase genes, including osmotic sensing domain, six 90-amino-acid repeat motifs (coiled coil region) and kinase core and response regulator domains. Comparison of DNA sequences of the Mfos-1 from LIR mutants and the wild-type sensitive (S) isolate showed that LIR mutants had single point mutations in the coiled coil region of Mfos-1.