Saving resources: the exploitation of endophytes by plants for the biosynthesis of multi-functional defence compounds

Plants are effective in defending themselves against herbivores, parasites and pathogens. To accomplish this, they employ various strategies, one of them being the synthesis of antimicrobial and antiherbivory compounds. To reduce the amount of energy spent, such compounds can be efficiently synthesized in multi-enzyme complexes and may have multiple roles in plant life. The synthesis can further be economized when the plant exploits associated microorganisms for the synthesis of these 'plant' compounds. Due to the potential multi-functionality of plant compounds, it is often difficult to establish what their roles are in the plant's physiology and ecology, particularly because these various roles can be quite unrelated. The research on endophytes, their synthetic abilities and their role in the ecology of the plant may, however, shed light on this issue. Indeed, it was found that particular compounds produced by endophytes, which are considered phytohormones, have additional activities, being toxic for nematodes.