Adventitious shoot regeneration of scotch spearmint (Mentha x gracilis Sole)

The effect of different cytokinins on in vitro adventitious shoot regeneration from internodal explants of Mentha X gracilis Sole (scotch spearmint) was investigated. Murashige and Skoog (MS) medium containing 100 mg l^-1 myo-inositol, 0.4 mg l^-1 thiamine-HCl, 2.0% (w/v) sucrose, 10% (v/v) coconut water and supplemented with 4.5 μM thidiazuron (TDZ) was effective in inducing adventitious shoot formation from callus. The greatest percentage of explants with shoots (85%) with the highest mean number of shoots per explant (29) was obtained with explants from the 1st and the 2nd internodes from 2-wk-old stock plants growing on a medium containing MS basal salts, 2% sucrose, 100 mg l^-1 myo-inositol, 0.4 mg l^-1 thiamine-HCl, at TDZ 4.5 μM and 10% (v/v) coconut water and solidified with 0.2% (w/v) phytagel. The regenerated shoots rooted on a medium containing MS basal salts, 100 mg l^-1 myo-inositol, 0.4 mg l^-1 thiamine-HCl, 2.0% sucrose, and 0.054 μM naphthalene acetic acid (NAA). Micropropagated plantlets were transplanted into soil and acclimated to greenhouse conditions. This is the first report describing adventitious shoot regeneration of scotch spearmint.