Efficient micropropagation protocol of Spilanthes acmella L. possessing strong antimalarial activity

Micropropagation has been achieved in a promising larvicidal asteraceous taxon Spilanthes acmella L. using seedling leaf explants. The explants were reared on a variety of growth regulators, namely 2,4-dichlorophenoxyacetic acid, 1-naphthalene acetic acid, Indole-3-butyric acid, N-6-benzyladenine, and kinetin either alone or in combination on Murashige and Skoog's (MS) medium. The best green and compact callus was obtained on 1 mu M NAA and 10 mu M benzyladenine (BA) in 15 d. The callus on subculture to the same but fresh medium after every 30 d differentiated an average of 12.90 +/- 0.32 shoot buds in 50% cultures. Elongation in shoot buds occurred only if they were transferred to NAA lacking MS+BA medium. An average number of 4.22 +/- 0.83 shoots and 15 +/- 0.84 shoot buds per explant were obtained in 70.3% cultures on MS + 10 mu M BA in 30 d. One hundred percent excised shoots rooted in MS(1/2) + 0.1 mu M IBA within 2 wk. The plants were gradually hardened and established in soil where they flowered and set viable seeds. The regenerated plants were morphologically similar to the field grown plants and showed 100% larvicidal activity against malaria and filarial vectors.