Evolutionary perspectives on the role of plant secondary metabolites

Plants are considered to be the most successful form of life on the Earth, despite their inability to move. They have evolved numerous characteristics to overcome this challenge, through physical and biochemical pathways, enabling the engineering of their own pollination and seed dispersals, combating variations in climatic changes and the coexistence with herbivorous and pathogenic intruders. Biochemical pathways permitted the synthesis of phytochemicals, known as secondary metabolites. Once thought to be worthless waste material, secondary metabolites are now considered to be invaluable constituents of plants being expressed to gain a selective, adaptive advantage by these sessile organisms. This chapter provides a brief appreciation of the basis for such thought and evidence available to support this view and highlights routes in which man has made use of their expression for his own use.