Salinity tolerance improvement of in vitro propagated Paulownia tomentosa using proline

Abstract Background Paulownia tomentosa has been used as an ornamental plant and is still vastly used for this objective and can be utilized for the production of energy, wooden building materials, and paper pulp. The aim was to improve the in vitro propagation ability under salinity stress. Methodology This experiment was conducted on Paulownia tomentosa at Tissue Culture Technique Lab., Central Laboratories, Department of Ornamental Plants and Woody Trees, National Research Centre (NRC), Egypt, to examine the micropropagation behavior using different plant growth regulators (BA, Kin, and IBA) and improve the in vitro propagation ability of plant under the effect of salinity levels (500, 1000, 2000, and 4000 ppm) using two concentrations of proline (0.2 and 0.4 g/l). Results For in vitro propagation behavior, the best results for both shooting and rooting behaviors were obtained when MS culture medium was supplemented with BA at 0.2 mg/l, and Kin and IBA at 0.1 mg/l. For the improvement of the in vitro propagation ability under salinity stress, the survival was 100% when the shootlets of Paulownia grown on MS culture medium supplemented with 0.5 g NaCl plus 0.2 or 0.4 g/l proline and 1 g NaCl plus 0.2 g/l proline which were similar to control treatment. Conclusion Micropropagation ability of Paulownia tomentosa under salinity stress was optimized when the explants were cultured on MS medium supplemented with BA at 0.2 mg/l, and Kin and IBA at 0.1 mg/l using proline at 0.2 g/l. This study will help the producers to cultivate Paulownia trees in saline soils up to 1000 ppm such as some new lands which are not suitable for growing other crops.