Improving effects of exogenously applied epibrassinolide on apricot (Prunus armeniaca) growing under in vitro and ex vitro conditions

To evaluate the potential effects of exogenous application of 24-epibrassinolide (EBL) on apricot (Prunus armeniaca) growing under in vitro and ex vitro conditions, shoot-tip explants were cultured in Murashige & Skoog (MS) solid media containing different concentrations and combinations of 24-epibrassinolide (EBL), cytokinin [6-benzylaminopurine (BAP)] and auxins [1-naphthaleneacetic acid (NAA) and indole-3-butyric acid (IBA)]. The percentage of explants producing shoot buds, the number and length of shoots, and the number of nodes were significantly increased in MS medium supplemented with 0.2 MG/L EBL and 2 MG/L BAP. However, the callus growth capacity and the percentage of callus induction were significantly increased in MS medium supplemented with 0.1 MG/L EBL and 0.5 MG/L NAA, whereas the rooting percentage of shoots and the number and length of roots were significantly increased in MS medium supplemented with 0.1 MG/L EBL and 0.25 MG/L IBA. The application of lower concentrations of EBL to the soil mixture of transplanted plants increased the number and length of shoots, the number and length of roots, and the dry weight of shoots and roots. It also increased the chlorophyll, proline, soluble protein and relative water contents, and the activity of antioxidant enzymes, superoxide dismutase (SOD), peroxidase (PDX) and catalase (CAT), but reduced the malondialdehyde content and electrolyte leakage percent. Based on this investigation, it can be concluded that the exogenous application of 24-epibrassinolide (EBL) to apricot (Prunus armeniaca) not only promotes the organogenesis and callus formation under in vitro culture conditions, but also stimulates the morphological and physiological parameters under ex vitro culture conditions.