Studies on the micropropagation of the local squill : Drimia maritima (L.) stearn

Abstract

Drimia maritima is the only local medicinal plant which was harvested and exported and thus, besides being important for its medical properties it also contributed to the national economy in the past. The development of rural areas into agricultural or urban areas is endangering the plant. Thus the need of conservation of this plant is being felt more than ever before. Micropropagation methods were thus investigated for their potential to increase the stock of local squill. Explants were taken from several parts of the plant for the studies. A surface sterilisation technique had to be developed first since squill was never studied before. After the explants, taken from various plant parts, were surface sterilised successfully, experiments were conducted to regenerate new plantlets from the explants. Direct and indirect organogenesis techniques were investigated by exposing the different explants to several types of nutrient media. Moreover, the production of secondary metabolites by in vitro plant cell cultures was to be investigated. Nowadays, active ingredients which used to be extracted from intact plants are produced from fermenters in which plant cells are being cultured in a liquid nutrient medium. Callus tissue had thus to be initiated so that it could be then analysed for the presence of the active glycosides. Drimia maritima (L.) steam was regenerated successfully using direct organogenesis of 4-5mm explants consisting of bulb scales joined at the base by a small piece of base plate. This is the first record for Drimia species to obtain bulblet formation on explants in vitro. The base plate explants took an extremely long time and several subcultures on various hormone concentrations were needed for the induction of bulblet formation. Callus tissue was also successfully initiated on explants retrieved from seedlings, but only after using unusually high concentrations of auxins (4mg/I 2,40 + 2mg/I NAA). Indirect organogenesis, that is the formation of roots from the callus tissue, was obtained when the callus tissue was removed from high auxin medium to a hormone balanced medium. The production of secondary metabolites by the callus tissue was not conducted because the amount of callus tissue obtained from the explants by the end of this study was not sufficient.