Etude de la micropropagation de Mentha x rotundifolia (L.)Huds et Mentha pulegium L.

Abstract

Micropropagation of two local species M. rotundifolia and M. pulegium has been carried with two main objectives: firstly, to set up optimal conditions for culture and regeneration of the two species, then evaluate temperature and photoperiod stress conditions on the EO composition and the antioxidant and antimicrobial activities. Explant of the two species was settled on culture with MS medium, acclimated under temperature and photoperiod stress conditions. Mother plants and vitro plants EO were obtained by hydrodistillation and analyzed by GC-MS. Antioxydant and antimicrobial activities of EO were carried out with standards methods (DPPH, ABTS, and CUPRAC) and (diffusion), respectively. Cultures inductions were achieved with MS medium supplemented with 1 mg/l BAP + 1 mg/l GA3. Explants multiplications of M. rotundifolia and M. pulegium were successfully done on MS medium supplemented with 0,5 mg/l BAP +0,5 mg/l GA3 and 0,5 mg/l BAP +1 mg/l GA3, respectively. In vitro rooted plants of the two mints species were well acclimated with a total survival rate greater than 96%. Regarding EO production, photoperiod and light stress assays have shown a significant increase in EO content and selective biosynthesis orientations in relation with phyto-constituents with high value (l-menthone, oxyde de piperitenone) or with side effects (hépatotoxic pulegone).This study has shown that abiotic parameters (light and photoperiod) positively affect vitro plants EO antioxidant activities, while no obvious effect was observed for antimicrobial activities. Finally, the results of this study led to the establishment of an effective in vitro micropropagation protocol from Mentha axillary buds, with the possibility to increase yield and / or to direct the chemical profile of EO for future commercial use.