Bioproduction of azadirachtin-A, nimbin and salannin in callus and cell suspension cultures of neem (Azadirachta indica A. Juss.).

摘要

A study was conducted to analyse the accumulation of triterpenoids azadirachtin-A, nimbin and salannin in neem callus cultures from different explants and cell suspension cultures raised from internodal segments. Vegetative parts (e.g. internodes, nodes and leaflets) and floral parts (e.g. sepal, petal, staminal tube, anther, ovary, style and stigma) were used as explants. Cotyledon and embryos were excised from the penultimate falling seeds. Callus cultures were initiated on MS medium with various auxins and cytokinins. Cell suspension cultures were initiated from 120-day-old callus from internodal segments. Accumulation of all triterpenoids was detected only towards the end of the third subculture (120th day). Calluses raised from all the explants synthesized and accumulated all three triterpenoids. Flower buds exhibited low azadirachtin-A content; however, callus tissues raised from each of the floral parts synthesized several folds of azadirachtin-A. Azadirachtin-A content was highest (11 790 micro g/g dry weight) in nodal segment-derived callus tissues in medium with 5 mg BA/litre and 10 mg/litre each of IBA and NAA. Salannin content was highest (3.97 mg/g dry weight) in stigma-derived callus, while nimbin content was highest (67.8 micro g/g dry weight) in internodal segment-derived callus. Among all explants, internode-derived callus tissues accumulated appreciable amounts of azadirachtin-A, nimbin and salannin. Biosynthesis of azadirachtin-A, nimbin and salannin was lower in cell suspension cultures than callus cultures. Azadirachtin-A accumulation was highest towards the end of the cell suspension culture growth stage. A rapid increase in nimbin accumulation was observed between day 18 and 21. Salannin was maximum on the 15th day of culture. Azadirachtin-A and salannin were detected from the 3rd day of culture, while nimbin was detected only from the 6th day. All triterpenoids were actively synthesized after the linear growth phase of cells..