Chemical diversity in nature is bewildering. Repertoire of chemicals in plants is especially rich. A great majority (almost all) of the single-compound drugs have been discovered in plants: salicylic acid (Aspirin), artemisinin (anti-malarial), thebaine (analgesic derived from opium) are just a quick few to spell out. All these chemicals are products of specialized secondary metabolic pathways in plants. Chemical compounds forming specialized metabolites protect plants against various abiotic stresses and mediate an array of interspecies interactions, ranging from seduction of pollinators and seed dispersers to defense against pathogens and herbivores. For instance, extrafloral nectaries are well-know mediators of plant-animal interaction.
Another very significant class of secondary metabolites produced by plants are organic volatile compounds emitted by trees. Compounds emitted from forests are highly hygroscopic and serve as seeds to cloud formation. Terrestrial vegetation is estimated to release 90 million tons of such compounds per year to the atmosphere. This is a significant contribution to the global aerosol dynamics. These compounds oxidize and form larger even more hygroscopic aerosols that can further increase cloud condensation nuclei. They can therefore play an important role for the climate, especially in the vast forested regions such as the taiga or the tropical rainforests. Trees are important not only for the carbon they capture and store, but also for what they capture, convert and release into the air as aerosols.
In addition, several classes of plant specialized metabolites also serve as hormones, perceived by complementary signaling networks in host plants to trigger physiological changes in response to environmental cues. Understanding specialized metabolism in plants will yield new therapeutics for treating diseases and provide sustainable solutions for energy and materials.
Jing-Ke Weng of the Whitehead Institute for Biomedical Research and an Assistant Professor of Biology at Massachusetts Institute of Technology focuses his research on the evolution of chemical diversity in Nature.