Plant Chemical Ecology Finally Gets to its Root(s)

Abstract

Plants produce a wide array of secondary compounds that play critical roles in the interaction with their dynamic environment. Since the first issues of the Journal of Chemical Ecology in 1974, numerous papers have been published detailing the function of volatile and non-volatile plant compounds in interactions between plants, herbivores, and their natural enemies. Initially, plant chemical-ecological studies focused mainly on aboveground interactions. One can only speculate about what caused this focus; most likely because it is somuch easier to work on organisms and plant organs that one can see. However, roots have a ‘life of their own’ below the ground and may have as many, or even more, interactions with other organisms as the shoots. It has been known for centuries that plant roots contain high levels of medicinal compounds. A famous example is the roots of the legendary mandrake (Mandragora officinale), whose toxic and hallucinatory compounds have been used to concoct witchcraft potions as well as to kill opponents. Moreover, many well-studied defense compounds, such as pyrrolizidine alkaloids in common ragwort (Jacobaea vulgaris) and nicotine in (wild) tobacco, are exclusively produced in the roots before they are transported aboveground. For some reason, however, this was not interpreted as a sign that roots might need those chemicals as protection against herbivores and other enemies as well. Actually, roots generally were considered to be less prone to attack because they were assumed to be less apparent to herbivores.