It has been demonstrated that virulent phytopathogenic
fungi are able to bio-transform metabolites which would
otherwise be toxic (Zikmundova et al. 2002). This strategy
helps pathogens to overcome host defences (i.e. antibiotics
produced by plants) or to withstand adverse
environmental conditions, such as those where toxic compounds
are produced by antagonistic agents (Bowyer
et al. 1995; Friebe et al. 1998). Different fungal pathogens
can transform the Trichoderma 6PP into isomeric mixtures
of monohydroxylated derivates or, in some cases,
into carboxylic acids by further oxidation (Cooney et al.
1997; Poole and Whitaker 1997; Cooney and Lauren
1999). Therefore, the quantity of secondary metabolites
accumulated by Trichoderma in co-cultures with fungal
pathogens depends on the balance between the eliciting
effect and the rate of biotransformation exerted by the
host pathogen.