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Aspergillus niger, which is a fungal pathogen, causes rot in a variety of fruits. In this study, the cystathionine β-synthase cbsAgene was deleted by homologous recombination to study its role in sulfur metabolism and pathogenicity of A. niger.The results showed that ΔcbsAstrain maintained normal mycelia growth and sporulation compared with the control strain A. nigerMA 70.15, whereas the contents of cysteine and glutathione (GSH) increased significantly after cbsAdeletion. However, ΔcbsAstrain showed reduced endogenous H2S production. Further results showed that cbsAgene deletion induced higher resistance to cadmium stress and stronger infectivity to pears. It was also found that a stronger response of reactive oxygen species (ROS) production was induced in ΔcbsAmutant-infected pear compared with the control strain. In all, the present research suggested the important role of cbsAin sulfur metabolism and pathogenicity of A. nigerin pear fruit.

Aspergillus niger, a common saprophytic fungus, causes rot in many fruits. We studied the role of a putative catalase-peroxidase-encoding gene, cpeB, in oxidative stress and virulence in fruit. The cpeBgene was deleted in A. nigerby homologous recombination, and the ΔcpeBmutant showed decreased CAT activity compared with that of the wild type. The cpeBgene deletion caused increased sensitivity to H2O2stress, and spore germination was significantly reduced; in addition, the reactive-oxygen-species (ROS) metabolites superoxide anions (·O2–), hydrogen peroxide (H2O2), and malondialdehyde (MDA) accumulated in the ΔcpeBmutant during H2O2stress. Furthermore, ROS metabolism in A. nigerinfected apples was determined, and our results showed that the ΔcpeBmutant induced an attenuated response in apple fruit during the fruit–pathogen interaction; the cpeBgene deletion significantly reduced the development of lesions, suggesting that the cpeBgene in A. nigeris essential for full virulence in apples.