'Radicle' biochemistry: the biology of root-specific metabolism.

The roots of higher plants are a fascinating and largely unexplored biological frontier. One of their features is the ability to synthesize a remarkable diversity of secondary metabolites, and to adjust their metabolic activities in response to biotic and abiotic stress. This includes the ability to exude a complex array of micro- and macromolecules into the rhizosphere, with the potential to affect the inter-relationships between plants and beneficial or deleterious soil-borne organisms. In the past, research on root biology has been hampered by the underground growth habit of roots and by the lack of a suitable experimental system. However, recent progess in growing roots in isolation has greatly facilitated the study of root-specific metabolism and contributed to our understanding of this remarkable plant organ.