Plant-microbe interactions: chemical diversity in plant defense.

The chemical diversity within the plant kingdom is likely to be a consequence of niche colonization and adaptive evolution. Plant-derived natural products have important functions in defense. They also have broader ecological roles and may in addition participate in plant growth and development. Recent data suggest that some antimicrobial phytochemicals may not serve simply as chemical barriers but could also have functions in defense-related signaling processes. It is important, therefore, that we should not to be too reductionist in our thinking when endeavoring to understand the forces and mechanisms that drive chemical diversification in plants.