MoCRZ1, a gene encoding a calcineurin-responsive transcription factor, regulates fungal growth and pathogenicity of Magnaporthe oryzae

Ca2+-dependent signaling plays important roles in cellular development and metabolism in fungi. Pharmacological and molecular evidence clearly indicates that Ca2+-dependent signaling is required for infection-related development and pathogenicity in the rice blast fungus Magnaporthe oryzae. However, little information is available on downstream regulators in the Ca2+-dependent signaling pathway. To understand the role of a calcineurin-dependent transcription factor in the rice blast fungus, an ortholog of Saccharomyces cerevisiae CRZ1 in M. oryzae, MoCRZ1, was identified and functionally characterized. The Delta mocrz1 mutant exhibited impaired growth in the presence of Ca2+ ions or cell wall perturbing agents. The Delta mocrz1 mutant also showed reduced conidiation and reduced pathogenicity, which is mainly due to a defect in host penetration. MoCRZ1 fused to EGFP was trans-localized into the nucleus in a Ca2+/calcineurin-dependent manner. The MoCRZ1 gene is also required for the calcineurin-dependent transcriptional induction of FKS1, a gene encoding a beta-1,3 glucan synthase, CHS2 and CHS4, genes encoding two chitin synthases, and PMC and PMR gene families encoding P-type ATPases in response to Ca2+. These results suggest that MoCRZ1 is a downstream regulator in Ca2+-dependent signaling for pathogenicity in M. oryzae, and its biochemical mechanisms are well conserved among fungal species. (C) 2008 Elsevier Inc. All rights reserved.