Arbuscular mycorrhizal fungi (AMF) induced acclimatization, growth enhancement and colchicine content of micropropagated Gloriosa superba L. plantlets

Gloriosa superba L. is an endangered medicinal perennial tuberous climbing herb well-known for its abortifacient, anti-gout, antileprotic, antipyretic, thermogenic and anticancerous properties. Complete plantlets of G. superba were raised by direct organogenesis from non-dormant tuber explants on Murashige and Skoog (MS) medium supplemented with 2.0mg/l 6-benzylaminopurine (BAP)+0.5mg/l α-naphthalene acetic acid (NAA). Micropropagated plantlets of G. superba were inoculated during early weaning stage of acclimatization with three arbuscular mycorrhizal fungi (AMF) strains namely, Glomus mosseae, Acaulospora laevis and a mixed AMF strain as biohardening agents to improve their survival, growth and colchicine content. The survival rate was significantly higher in all inoculated plantlets. Plantlets inoculated with A. laevis alone gave highest survival followed by combined treatment of A. laevis and G. mosseae. The predominant effect of A. laevis alone was also evident on increased plant height, leaf number, tuber length and different biochemical attributes. A. laevis and G. mosseae combination inoculated plantlets were found to be most effective in improving leaf area and root length. However, total soluble sugar content showed a slight decrease in all AMF treated plantlets. The colchicine content was also determined in the tubers of different AMF treated plants by HPLC using the same retention time (1.5min) as that of the standard colchicine. The higher colchicine content was extracted from the tubers of A. laevis+G. mosseae inoculated plants. It can be concluded that inoculation of appropriate AM fungi during the initial period of the acclimatization phase showed stimulatory effects for achieving better growth and survival of micropropagated plantlets.