Biological functions of the catalase-peroxidase gene ApKatG1 in Alternaria panax

Abstract:

[Background] Ginseng Alternaria leaf and stem blight caused by Alternaria panax is one of the major diseases in ginseng production. It mainly occurs in Changbai Mountain and other ginseng-growing areas in China, causing severe losses to ginseng production. [Objective] To clarify the biological functions of the catalase-peroxidase gene ApKatG1 in A. panax. [Methods] The ApKatG1 knockout mutant and complemented mutant were obtained by homologous recombination. The effects of ApKatG1 on the growth rate, sporulation, responses to different stress factors, and pathogenicity were analyzed to elucidate the roles of ApKatG1 in A. panax. [Results] ApKatG1 encoded a catalase-peroxidase containing two typical peroxidase domains. The knockout mutant ΔApkatG1 exhibited the mycelial growth rate, conidiation level, and carbon utilization efficiency comparable to the wild type. However, ΔApkatG1 demonstrated enhanced sensitivity to environmental stress factors such as sorbitol and the cell wall stress factor Congo red, accelerated protoplast release, and significantly increased sensitivity to high concentrations of H₂O₂. The expression level of ApKatG1 significantly increased after H₂O₂ treatment. The knockout of ApKatG1 affected the expression of other catalase genes in A. panax. ApKatG1 did not participate in regulating the pathogenicity of A. panax in ginseng.[Conclusion] ApKatG1 plays a vital role in maintaining cell wall integrity and responding to H₂O₂ stress in A. panax.