| Summary: | Crops drought tolerance is a trait of outmost importance for agriculture especially today when climate change is affecting more the production for food and feed. The scope of this article is to evaluate in vitro drought stress response of <i>Nicotiana tabacum</i> L., “Baladi”. The experiment was set up for four successive stages starting with in vitro seedling development, hypocotyl cultivation, three generations of micropropagation, pre-acclimatization and acclimatization. The effect of abscisic acid (ABA) and/or polyethylene-glycol 6000 (PEG) on tobacco hypocotyl caulogenesis and micropropagation were investigated. Superoxide-dismutases (SODs) and peroxidases (POXs) are more active and different isoforms patterns have been identified compared to the control for cualogenesis. A decrease of internodes length and a higher shoots multiplication rate were observed. However, under PEG treatment plantlets expressed hyperhydration and ceased rooting. Pre-treatments effects study of ABA and/or PEG were finalized in acclimatization phase for 18 tobacco clones. A summary of our results revealed that ABA and/or PEG induce among others a higher oxidative stress compared to the control in the first stage that is not maintained for all clones until acclimatization. Certain clones expressed a lower SOD activity compared to the control during acclimatization but maintaining higher POX activity.
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