An efficient and rapid in vitro propagation system of Thymus hyemalis Lange, a wild medicinal and aromatic plant of Mediterranean region

The objective of this study was to develop an in vitro regeneration protocol of Thymus hyemalis Lange. Initially, shoots were obtained from in vitro seedlings grown on Murashige & Skoog (MS) basal medium containing 3% (w/v) sucrose and 0.4% (w/v) gellan gum. Four basal media were tested for establishing their capacity for in vitro cultivation of T. hyemalis. Then several factors, namely explant type, plant growth regulators, genotype and various concentrations and type of sugar were tested to assess the shoots proliferation capacity. The optimal duration for shoot proliferation was also determined. Shoots were excised from proliferation medium and transferred in to rooting medium containing various auxins.Compared to White medium, B5 or MS media, the results indicated that MS basal salt medium was found to be optimal for in vitro establishment. After 4 weeks, the maximum proliferation) was observed (corresponding to 6.58± 0.22 number of shoots) for nodal explants cultured on MS medium containing 3% (w/v) of sucrose and supplemented with 1.8 μM of kinetin (KIN). The results also showed that in vitroculture was genotype dependant. Extension of the culture period up to 5 weeks improved the number of shoots up to 9.33 ± 1.01. The best rooting of shoots was obtained on auxin-free MS medium or supplemented with 7.4 μM indole-3-butyric acid (IBA). Well-rooted plants were successfully establishedin dimpled plates filled by peat and vermiculite (2/3:1/3 v/v) mixture, with a survival rate of 90%. The regenerated plants were morphologically uniform and exhibited similar growth characteristics and vegetative morphology.