The tritrophic trinity: a source of pollutant-degrading enzymes and its implications for phytoremediation

Barring bioavailability and nutritional limitations, virtually all organic anthropogenic chemicals can be naturally biodegraded. It is to this phenomenon we owe thanks to the long established 'tritrophic trinity' of microbe-plant-insect interactions. Over hundreds of millennia these organisms have coevolved, producing hundreds of thousands of different chemicals that are used to attract, defend, antagonize, monitor and misdirect one another. In comparison, the numbers of truly novel chemicals of anthropogenic origin are negligible. It is only now that we are beginning to appreciate the fortuitous evolution of xenobiotic-degrading enzymes from these interactions. We argue that success in phytoremediation can be hastened through understanding the structure, sources, uses and targets of these secondary metabolites. Owing to recent developments in molecular biology, particularly stable isotope probing, we eagerly anticipate highly significant insights into trophic interactions, particularly in the rhizosphere, providing phytoremediation with a solid mechanistic understanding.