Cloning And Functional Analysis Of Transcription Factor Gene Ab06986of Alternaria Brassicicola

Black spot disease of cruciferous vegetables is a worldwide fungal disease caused by Alternaria Nees.Since the 1990s,the disease has been severe in the north of China,and it still poses a great threat to the production of cruciferous vegetables.Alternaria brassicicola is one of the main pathogens of this disease and transcription factors are important regulatory factors involved in the growth,development and pathogenicity of pathogens.Therefore,studying the pathogenic related transcription factors of A.brassicicola helps to understand its pathogenic molecular mechanism of action,and it is very important for the prevention and control of Black spot disease caused by A.brassicicola.Zn₂Cys₆ in zinc finger proteins is a unique transcription factor in fungi and it regulates various physiological processes of fungi including the growth,sporulation of fungi and infestation of the host by fungi.This type of transcription factor has not been systematically studied in the species of A.brassicicola.This study was mainly based on Ab06986 gene in Zn₂Cys₆ transcription factor of A.brassicicola.In this paper,Ab06986 gene was cloned and the biological traits of Ab06986gene deletion mutant were studied,and the Biological function of Ab06986 gene was systematically explored.In this study,three Ab06986 gene deletion mutants were obtained.The results of the functional comparison with the wild type and the complement were as follows:（1）Ab06986 gene is involved in regulating colony phenotype and aerial mycelium growth of A.brassicicola:On the MM medium,the colonies of the three mutants were light yellow in the center,and the edges of the colonies were off-white while the mycelium is mostly buried mycelium and without conidia;The center of wild type is dark green and the surrounding is gray-green,there is few aerial mycelium with a conidia layer on the surface.In the PDA medium,three mutants appeared grayish white and the mycelium growth was dominated by aerial mycelium with no conidium layer was on the surface.The wild type appeared dark green,and mainly grew with buried mycelia,and the surface layer of the colony covered thick Conidial layer;（2）The Ab06986 gene is involved in the regulation of the growth rate of A.brassicicola:On MM medium,the growth rate ofΔAb06986 colonies was significantly lower than that of the wild type;however,there was no significant difference between them in PDA medium;（3）The Ab06986 gene is involved in the regulation of the production of spores by A.brassicicola:No obvious difference was found between the three mutant mycelium and wild type,but the ability to produce spores was lost;（4）The Ab06986 gene negatively regulates the antioxidant capacity of A.brassicicola:In the medium containing H₂O₂,the growth rate of the three mutants is higher than that of the wild strain;（5）The Ab06986 gene regulates the in vitro penetrating power of A.brassicicola:Each strain can grow on the cellophane.Removed the cellophane and continuously cultivated the strain,the study found the diameter of the mutant colony is significantly smaller than the wild strain and its complement,indicating its penetration ability is much weaker than wild fungi;（6）The Ab06986 gene regulates the pathogenicity of A.brassicicola:Inoculation with intact leaves and wounded leaves revealed that the three mutants showed significantly lower pathogenicity than wild strains.