Abstract:

In order to clarify the role of the Zn(Ⅱ)2Cys6 transcription factor gene VDAG_ 04814 in the growth, development and pathogenicity of the Verticillium dahliae. It constructed a VDAG_04814 gene knockout mutant using homologous recombination mediated by polyethylene glycol. Wild-type and mutant strains were inoculated separately onto PDA media supplemented with hydrogen peroxide, sodium chloride, potassium chloride, sorbitol, sodium dodecyl sulfate, Congo red, as well as onto media overlaid with sterile cellophane, to analyze their levels of resistance to oxidative stress, salt stress, osmotic stress, stress on cell wall and plasma membrane integrity, and strain penetration ability. Their pathogenicity was assayed, and the fungal biomass in potato plants was detected. After hygromycin selection and PCR validation, the correct knockout transformants were able to amplify DNA bands of 1 500 bp upstream and downstream, respectively, as well as the full-length 4 500 bp knockout fragment sequence. The results demonstrated that the growth rate and melanin formation ability of the ΔVDAG_04814 mutants were significantly reduced. On media subjected to oxidative stress and salt stress with the addition of hydrogen peroxide, sodium chloride, and potassium chloride, ΔVDAG_04814 showed a higher inhibition rate compared to the wild-type. On osmotic stress media with sorbitol, the growth inhibition rate of ΔVDAG_04814 was significantly lower than the wild type. No growth inhibition was observed for ΔVDAG_04814 on media subjected to cell wall and membrane integrity stress with the addition of sodium dodecyl sulfate and Congo red. On media overlaid with sterile cellophane, no colonies grew for ΔVDAG_04814, whereas the wild-type strain produced normal colonies. Pathogenicity tests indicated that the wilting index of ΔVDAG_04814 was significantly reduced compared to the wild-type, with wilting index ranging from 47.22 to 55.56. It has been demonstrated that VDAG_04814 can regulate the growth, development, stress resistance, penetration ability and pathogenicity of V. dahliae towards potato. This study provides a new target for the control of potato Verticillium wilt disease.

Key words: Verticillium dahliae, Transcription factor, Gene function validation, Ability of infection