Objective  As a genetic marker, the green fluorescent protein gene (gfp) of Fusarium oxysporum f. sp. momodicae (Fom), one of the most serious fungal pathogens that caused the fusarium wilt on bitter gourd, was identified and transformed into bacterium to facilitate the study on the infection process and control of the disease.

  Method  A highly pathogenic wild-type strain, FJAT-3018, isolated from diseased bitter gourds was transformed with the gene encoding gfp using an Agrobacterium-mediated method. The genetically stable transformants, FJAT-31290 and FJAT-31284, were verified by their colony morphology, growth rate, and pathogenicity.

  Result  The efficiency of transforming FJAT-3018 was approximately 14.5 transformants per 10⁶ spores. After 10 generations of subculture, the transformants did not significantly differ from the wild-type strain with respect to the colony morphology, growth rate, and pathogenicity. Strong constitutive expression of gfp could be seen in the fungal hyphae and conidia of the transformants. In addition, under a confocal laser scanning microscope, the transformant-infected bitter gourd plants showed growth of the fungal hyphae inside the roots and stem xylem.

  Conclusion  The gfp gene had been successfully transformed into FJAT-31290 and FJAT-31284 with genetic stability and without apparent pathogenicity deviation from the highly pathogenic wild-type strain FJAT-3018.