Description: A living collection of Leucojum aestivum L. (Amaryllidaceae) was established at the Institute of Botany, Sofia, in 2001. In vitro cultures originating from a single mother bulb have been maintained since 2003 on MS-based agar-solidified medium supplemented with 30 g L-1 sucrose, 2 mg L-1 BAP and 0.15 mg L-1 NAA under equal temperature and light conditions in plastic containers. Part of the regenerated plantlets were successfully adapted ex vitro and planted in open-air trenches in 2007. Uniform shoot clumps were selected and grown for seven weeks during the vegetation peirod in spring 2009 on solid and in a liquid medium with the same compostion. Main physiological characteristics of the field cultivated plants and plantlets from long-term in vitro cultures were compared. Leaves were taken from field grown and field adapted plants, and in vitro obtained plantlets on solid and in liquid media, all genetically identical. The photosynthetic rate of field grown plants was twice higher than that of in vitro plantlets. Moreover, the results for the plants adapted to open-air conditions were similar to those initially planted on the field, whereas the photosynthesis and the biomass accumulation were more expressed by the in vitro plantlets cultured in a liquid medium compared to those grown on agar-solidified one. The liquid shoot-clump culture of L. aestivum was determined as a suitable system for in vitro alkaloid production.

Remarks: Proceedings of the XI National Conference on Plant Physiology, 18-19 november 2009, Sofia, Bulgaria