Changes in osmotic potential, protein content and proline accumulation in response to NaCl salinity and phosphorus in cucumber microshoots grown on proliferation medium

The aim of this work was to explore the contributions of phosphorus in mitigating the salinity impacts on osmotic potential, protein content and proline accumulation of cucumber grown in vitro on proliferation medium. Microshoots were grown on Murashige and Skoog (MS) proliferation media containing 1 mg/l kinetin and supplemented with a combination of NaCl at 0.0, 25, 50, 75, 100 mM with 0.5, 1.0 or 2.0 mM phosphorus using KH₂PO₄. Leaf osmotic potential was reduced with increasing NaCl concentration and within each of the 50, 75 and 100 mM NaCl concentrations, the incorporation of 2 mM KH₂PO₄ was needed to significantly increase leaf osmotic potential. Protein content of cucumber microshoots was shown to decrease with NaCl concentration, this reduction was lessened with increase in KH₂PO₄ level applied. In vitro-induced salinity caused profound proline accumulation in cucumber microshoots and combinations having 2 mM KH₂PO₄ showed lower proline accumulation especially at the highest two concentrations of NaCl.