Root in vitro cultures of six Gypsophila species and their saponin contents

A simple and rapid method of excised root cultures from six Gypsophila species was performed allowing continuous growth without phytohormones. Established on MH3 medium from solid-grown seedlings these roots were subcultured for 1 year on a solid medium before being transferred in a liquid medium to obtain substantial biomass for saponin content analysis. Morphologically, the different root lines presented different growth behaviors and different physical aspects: some have linear growth by the tip of the main axial root from the original seedling; others have additional lateral root initiations producing a hairy root-system more or less dense. A marked increase of biomass was observed in the light by comparison with dark conditions. Significant growth for Gypsophila glomerata was achieved within 3 weeks on liquid medium; biomass grew up to 50-fold in batch cultures reaching 10 g DW. The fingerprints of the saponin HPLC profiles of the six Gypsophila species were drastically different with at least up to 30 different saponins detected for some of them. The roots of Gypsophila elegans accumulated saponins up to 65 mg/g DW. These amounts were higher than in Gypsophila paniculata roots classically found as the best producing ones. On the contrary the root lines of G. glomerata showed a smaller quantitative amount of saponins (between 1.3 and 7.10 mg/g DW) than those of G. elegans but nearly the same HPLC profiles as for root extracts of G. paniculata plants grown directly in the fields.