Optimization of Callus Induction in Pennyroyal (Mentha pulegium)

Findings in relation to the inhibitory effects of natural substances against microorganisms showed that herbal products may be alternatives to synthetic and chemical drugs due to their significant therapeutic effects. The pennyroyal (Mentha pulegium) as an important medicinal plant, which belongs to the Lamiaceae family is applied in the pharmaceutical and food industries. In recent years, plant tissue culture techniques have appeared as a powerful tool for the micropropagation and breeding of many plant species. The aim of current study was to find the best medium composition for callus induction in M. pulegium. For this purpose, three explants (leaf, root and stem) of M. pulegium were cultured on MS medium supplemented with BAP (0.5 and 1.0 mg/L) and 2,4-D (0.0, 1.0, 2.0 and 4.0 mg/L) in a factorial experiment. The results showed that the leaf explant had the highest effect on callus induction (9.65 mm in callus diameters at 28 days after culture) and hormone levels of 1 mg/L 2,4-D and BAP-free were identified as the most efficient concentrations for callus growth rate (0.29 mm/d). Also statistical analysis demonstrated that among interaction effects the leaf explant in 1 mg/l 2,4-D and BAP-free was found as the highest effect for callus induction (12.35 mm in callus diameter at 28 days after culture).