A Gene Related to Yeast HOS2 Histone Deacetylase Affects Extracellular Depolymerase Expression and Virulence in a Plant Pathogenic Fungus

Abstract

A gene, HDC1, related to the Saccharomyces cerevisiae histone deacetylase (HDAC) gene HOS2, was isolated from the filamentous fungus Cochliobolus carbonum, a pathogen of maize that makes the HDAC inhibitor HC-toxin. Engineered mutants of HDC1 had smaller and less septate conidia and exhibited an approximately 50% reduction in total HDAC activity. Mutants were strongly reduced in virulence as a result of reduced penetration efficiency. Growth of hdc1 mutants in vitro was normal on glucose, slightly decreased on sucrose, and reduced by 30 to 73% on other simple and complex carbohydrates. Extracellular depolymerase activities and expression of the corresponding genes were downregulated in hdc1 mutant strains. Except for altered conidial morphology, the phenotypes of hdc1 mutants were similar to those of C. carbonum strains mutated in ccSNF1 encoding a protein kinase necessary for expression of glucose-repressed genes. These results show that HDC1 has multiple functions in a filamentous fungus and is required for full virulence of C. carbonum on maize.

Histone deacetylases in fungi: novel members, new facts

“…Shortly thereafter we also found orthologs of these enzymes in the plant pathogenic fungus Cochliobolus carbonum (33,34). Interestingly, engineered Cochliobolus mutants of one of these genes had smaller conidia, exhibited a ~50% reduction in total HDAC activity, and showed a reduction in growth on certain carbohydrates (33). Very recently, another fungal class 1 HDAC was identi®ed in the corn smut fungus Ustilago maydis, which can substitute for RPD3 in S.cerevisiae.…”

“…Recently, we have characterized RpdA and HosA, two class 1 enzymes of Aspergillus nidulans, which were the ®rst HDACs identi®ed in a ®lamentous fungus (32). Shortly thereafter we also found orthologs of these enzymes in the plant pathogenic fungus Cochliobolus carbonum (33,34). Interestingly, engineered Cochliobolus mutants of one of these genes had smaller conidia, exhibited a ~50% reduction in total HDAC activity, and showed a reduction in growth on certain carbohydrates (33).…”

Plant defence suppression is mediated by a fungal sirtuin during rice infection by Magnaporthe oryzae

“…Classical HDACs and their interacting partners have been characterized for roles in plant pathogenicity in a few pathosystems. In the maize pathogen Cochliobolus carbonum, the class II HDAC-encoding orthologue of yeast HOS2, HDC1, was found to be required for virulence (Baidyaroy et al, 2001). In Fusarium graminearum, the cause of head blight in wheat and barley, the HOS2 orthologue HDF1 was required for virulence on wheat heads and corn stalks .…”

PFP1 , a Gene Encoding an Epc-N Domain-Containing Protein, Is Essential for Pathogenicity of the Barley Pathogen Rhynchosporium commune

“…The HDC1 gene of the maize pathogen Cochliobolus carbonum is related to the yeast HDAC gene HOS2 (30). Due to reduced penetration efficiency, disruption mutants were strongly reduced in virulence, whereas growth ex planta was normal on glucose, slightly reduced on sucrose, and strongly affected on other different media.…”

“…The FTL1 gene of Fusarium graminearum (28) and the TIG1 gene of Magnaporthe oryzae (29), both of which encode transducin ␤-like components of a histone deacetylation (HDAC) complex, are defective in plant infection and conidiogenesis. Moreover, deletion of the HDC1 gene in Cochliobolus carbonum, which is related to Saccharomyces cerevisiae HOS2 HDAC, yielded mutants with reduced penetration efficiency and strongly reduced virulence (30).…”