This hypothesis is consistent with the observation that peroxidase and PAL contents were higher in asparagus inoculated with protective than with pathogenic strains and increased more rapidly after inoculation with the pathogen (He et al., 2002). Similarly, in banana, several defense-related genes were first down-regulated upon inoculation with nonpathogenic F. oxysporum endophytes and then up-regulated after challenge with the nematodeRadopholussimilis (Paparu et al., 2007).