Malate synthase gene AoMls in the nematode-trapping fungus Arthrobotrys oligospora contributes to conidiation, trap formation, and pathogenicity
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Malate synthase (Mls), a key enzyme in the glyoxylate cycle, is required for virulence in microbial pathogens. In this study, we identified the AoMls gene from the nematode-trapping fungus Arthobotrys oligospora. The gene contains 4 introns and encodes a polypeptide of 540 amino acids. To characterize the function of AoMls in A. oligospora, we disrupted it by homologous recombination, and the ΔAoMls mutants were confirmed by PCR and Southern blot analyses. The growth rate and colony morphology of the ΔAoMls mutants showed no obvious difference from the wild-type strains on potato dextrose agar (PDA) plate. However, the disruption of gene AoMls led to a significant reduction in conidiation, failure to utilize fatty acids and sodium acetate for growth, and its conidia were unable to germinate on minimal medium supplemented with sodium oleate. In addition, the trap formation was retarded in the ΔAoMls mutants, which only produced immature traps containing one or two rings. Moreover, the nematicidal activity of the ΔAoMls mutants was significantly decreased. Our results suggest that the gene AoMls plays an important role in conidiation, trap formation and pathogenicity of A. oligospora.
KeywordArthrobotrys oligospora Malate synthase (Mls) Gene disruption Mutant Trap formation Nematodes
We are grateful to Prof. Jianping Xu of the Dept. Biology, McMaster University, for valuable comments and critical discussions. The research described here is jointly supported by the National Basic Research Program of China (2013CB127500), the National Natural Science Foundation of China (approved nos. 31272093 and 31360019), the West Light Foundation of the Chinese Academy of Sciences (to Jinkui Yang), and the China National Tobacco Corporation (110201002023). We also thank the anonymous reviewers for their valuable suggestions.
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