Comparative study of micropropagated plants of Grand Naine banana during in vitro regeneration and ex vitro acclimatization

An improved micropropagation protocol was established from field grown sword suckers of Banana Grand Naine (Musa acuminata AAA) by evaluating the mircopropagules combating reactive oxygen species (ROS) during acclimatization. Optimization of surface sterilization of sprouted apical meristematic buds and pre-culture on Shoot Bud Induction Medium [MS + 4.0 mg l -1 BA under dark conditions for 3 weeks] resulted ideal number of multiple shoot clusters (12.20 +/- 0.30). Subculture of these shoot clusters on Shoot Bud Multiplication Medium (SBMM) fortified with 2 mg l -1 BA and 20 mg l -1 AdS induced highest shoot buds (15.00 +/- 0.75) in 3 weeks and showed consistent till seven passages. The individual in vitro shoots upon transferring onto MS + 2 mg l -1 KN +1.0 mg l -1 IBA + activated charcoal (3 g l -1) resulted in elongated shoots and in vitro rooting after 3 weeks at a photoperiod of 16 h light and 8 h dark conditions. Evaluation of antioxidant defense status in micropropagated plantlets during acclimatization revealed altered levels of MDA, chlorophyll, catalase, ascorbate peroxidase and glutathione reductase. Our study throws an insight into decisive/differential role of cytokinins (Kinetin) in combating oxidative stress during acclimatization of in vitro regenerated plantlets. The present investigation facilitates the massive propagation (90% survival rate) of healthy and quality in vitro plantlets of banana.