Harnessing the potential of hairy roots: dawn of a new era.

In the past two decades, hairy root research for the production of important secondary metabolites has received a lot of attention. The addition of knowledge to overcome the limiting culture parameters of the regulation of the metabolic pathway by specific molecules and the development of novel tools for metabolic engineering now offer new possibilities to improve the hairy root technique for the production of metabolites. Furthermore, engineering hairy roots for the production of animal proteins of therapeutic interest in confined and controlled in vitro conditions is seen as one of the exciting spin-offs of the technology. Recent progress made in the scale-up of the hairy root cultures has paved the way for industrial exploitation of this system. This review highlights some of the significant progress made in the past three years and discusses the potential implications of that research.