A reliable and efficient protocol for induction of hairy roots in Agastache foeniculum

Hairy root culture system is a valuable tool to study the characteristics of gene expression, gene function, root biology, biochemical properties and biosynthesis pathways of secondary metabolites. In the present study, hairy roots were established in Anise hyssop (Agastache foeniculum) via Agrobacterium rhizogenes. Three strains of Agrobacterium rhizogenes (A4, A7 and 9435), were used for induction of hairy roots in four various explants (hypocotyl, cotyledon, one-month-old leaf and five-month-old leaf) of Anise hyssop. The highest frequency of transformation was achieved using A4 strain in one-month-old leaves (51.1%). The transgenic states of hairy root lines were confirmed by PCR (Polymerase chain reaction) method. High performance liquid chromatography analysis revealed that the production of rosmarinic acid (RA) in transformed roots of A. foeniculum was almost 4-fold higher than that of the non-transformed roots. In a separate experiment, hairy roots obtained from one-month-old leaves inoculated with A4 strain, were grown in liquid medium and the effects of different concentrations of salicylic acid (0.0, 0.01, 0.1 and 1 mM) and chitosan (0, 50, 100 and 150 mg L^?1) (as elicitor) and sucrose (20, 30, 40 and 50 g L^?1) on the growth of hairy roots were evaluated. The results showed that, 30 g L^?1 sucrose and 100 mg L^?1 chitosan increased the biomass of hairy root cultures and application of salicylic acid reduced the growth of hairy roots compared with control roots.