Development, micropropagation and characterization of colchiploid of Echinacea purpurea (L.) Moench

To enhance the genetic resource base of Echinacea purpurea (L.) Moench, a tetraploid was developed by treating seeds with different concentrations of colchicine. For further multiplication, in vitro micropropagation through adventitious shoot induction and proliferation was achieved. Shoot buds were induced directly on adaxial surface of mature leaf tissues growing on MS medium supplemented with equimolar concentration of BAP and IBA. The optimum initial shoot regeneration frequency (63%) with average 2.3 shoots per explant was achieved after 30 d of culture initiation. Maximum shoot organogenesis, with 8-10 shoots per culture flask, was obtained on the same medium after 10 subculture. Proliferating callus with intermixed shoot buds was derived from leaf tissue explants placed on MS medium supplemented with 1 mg L each of BAP and IAA. The regenerated shoots were rooted on MS medium devoid of any growth regulator. Rooted plantlets were hardened under greenhouse conditions at 20-22°C with 85-90% RH. About 95% plantlets survived acclimatization, producing phenotypically normal plants in the greenhouse. After 4 wks, rooted plants were successfully transferred to soil in experimental field station at Jammu. Comparable field trials were laid with parental diploids. Tetraploids were dwarf, showed low seed set but were superior because of higher caffeic acid content. The results of this study have established a procedure for development and propagation of tetraploid of E. purpurea having higher caffeic acid content.