Effect of Different Strength of Medium on Organogenesis, Phenolic Accumulation and Antioxidant Activity of Spearmint (Mentha spicata l.)

We investigated the effect of inorganic salt concentration on the in vitro organogenesis of spearmint (Mentha spicata L.) by using Murashige and Skoog culture medium of different strength (full, half- and quarter strength). The highest number of shoots and roots induced per explant (3.5 and 10, respectively), as well as the maximum average shoot length (16 cm) was observed on half strength medium. The maximum leaf number (35 per explant) and average root length (7 cm) were associated with regeneration on full medium. The highest average phenolic content was observed on shoot extracts (7.20 mg/g f.w.) and root extracts (5.93 mg/g f.w.) cultured onto quarter and half strength medium, respectively. The strength of the culture medium was inversely correlated with the antioxidant activity of plant extracts. Therefore, for spearmint organogenesis, half strength MS medium offers a compromise between optimum growth in vitro and antioxidant phenolic accumulation.