Hairy Root Culture For The Production Of Useful Secondary Metabolites

Hairy root is induced when Agrobacterium rhizogenes, a naturally occurring gram-negative soil bacterium, infects a plant that is susceptible to infection. During the infection process of the A. rhizogenes to a plant, parts of its plasmid DNA (T-DNA) in the Ri plasmid will be transferred and integrated into the nuclear genome of the host plant. This transformation process eventually resulted in a valuable by-product called as hairy root. During infection of A. rhizogenes the plant oncogenes (i.e. rol A, rol B, rol C and rol D) present in bacteria are incorporated into the plant genomes and cause tumour formation resulting in hairy root disease. The characteristic feature of hairy root is that they have the capability to grow fast on basal media, genetic and biosynthetic stability and ability to produce elevated amount of several useful secondary metabolites. This chapter reviews the recent reports on hairy root culture and secondary metabolite production in various plant species.