Development of a bioassay to assess resistance to Fusarium oxysporum (Schlecht.) in asparagus ( Asparagus officinalis L.)

Fusarium oxysporum is one of the major pathogens causing root and crown rot in asparagus. Breeding of cultivars resistant to F. oxysporum would be the most efficient strategy for pathogen control. In this study, a bioassay was developed for screening seedling resistance. The non-destructive bioassay comprises inoculation with a highly aggressive F. oxysporum isolate, incubation in a climate chamber and quantification of disease symptoms by a digital image analysing system and a PTA-ELISA. This bioassay is simple to implement and demonstrated high reproducibility. Subsequently, it was used to determine the resistance behaviour of 16 asparagus genotypes to F. oxysporum. The asparagus cultivars revealed different levels of susceptibility, whereas the wild relative A. densiflorus was confirmed to be resistant.