Abstract

The purpose of this study was to develop a biotechnological technique to standardize micro-propagation procedures in Mentha pulegium L. (Lamiaceae) via direct and indirect organogenesis from nodal and shoot tip explants, recurrent production of biomass and phyto-chemical study. The protocols are designed to provide optimal axillaries-buds multiplication using MS and WPM basalts salts mediums. The shoot-tip explants were more responsive (100?) than the nodal ones (42.1?). The MS medium promoted a significant shoot culture growth compared to WPM one. The most effective medium for shoots proliferation rate (100?) and shoot number (14 shoots.explants-1) was MS medium supplemented with 0.5 mg.l-1 BAP. The rate of callus induction was positively correlated with concentration of 2,4-D and explants type. Callus proliferated predominantly from the shoot-tip explants (95?) and sporadically from the nodal explants (80?). The viable and organogenic calli were maintained at reduced concentration of 2,4-D (0.1 mg l-1). These calli were transferred to MS medium supplemented with various concentrations of BAP (0.5-2 mg.l-1) for shoot regeneration. The regeneration rate was highest at 1 mg.l-1 BAP, where 79% and 87% of cultured callus developed from nodal and shoot-tip explants, respectively. During the multiplication stage, the rate of micro-shoots regeneration was identified to maintain the same level for 24 month without loss of vigor. Rooting in M. pulegium micro-shoots from direct and indirect organogenesis occurred spontaneously without the addition of PGRs in the culture medium. Regenerated plantlets were acclimatized and transferred to pot containing commercial potting mix, which grew normally with a survival rate of 95% and without any phenotype aberration neither in the vegetative stage nor in the floral one. Abbreviations: 2,4-D: 2,4-dichlorophenoxyacetic acid; BA: 6-benzyladenime; BAP: benzylarninopurine; IAA: indoleacetic acid; IBA: indole 3- butyric acid; Kin: kinetin; NAA: naphthalene acetic acid; PGR: plant growth regulators.