ABSTRACT
Plants produce a high diversity of secondary metabolites (SMs), which have evolved during the last 400 million years of evolution as defense chemicals against animal herbivores and pathogenic bacteria, fungi, and viruses (Wink, 1988, 2003, 2008a). Some SM also serve as signal compounds to attract pollinating and seed-dispersing animals. Others are important as antioxidants, for UV protection, carbon, or nitrogen storage. Plants not only synthesize SMs, but also store them in usually large amounts: Hydrophilic SMs are sequestered in the vacuole, whereas lipophilic SMs accumulate in resin ducts, lacticifers, oil or glandular cells, trichomes, or on the cuticle (Wink, 1993a,b, 2010a,b).
