Horizontal Chromosome Transfer between Pathogenic and Non-pathogenic Fusarium oxysporum Strains Isolated from Cabbage

Horizontal chromosome transfer (HCT) has been demonstrated in Fusarium oxysporum. Several pathogenic F. oxysporum strains have been used as donors in HCT experiments, while the non-pathogenic strain Fo47 has mainly been employed as a recipient. It currently remains unknown whether other non-pathogenic F. oxysporum strains are recipients of mobile chromosomes. In the present study, we investigated whether the non-pathogenic strain 08C-3B, obtained from cabbage, acquired the mobile chromosomes of F. oxysporum f. sp. conglutinans strain Cong:1-1, which infects cabbage. We detected HCT between Cong:1-1 and 08C-3B in a conidial anastomosis tube (CAT) fusion-inductive medium, yielding HCT progeny strains that carried scaffolds (SCs) 8 and 9 of Cong:1-1. These progeny strains exhibited reduced colony growth on potato dextrose agar plates and produced no symptoms on cabbage. These results suggest that SC8 and/or SC9 hinder vegetative growth, but do not confer virulence to 08C-3B. We then conducted HCT experiments to assess whether the HCT progeny strain transfers the acquired chromosomes to other strains. However, no progeny strains were obtained, suggesting that 08C-3B does not function as a donor for mobile chromosomes.