Salinity and age induced upscaling of biochemical attributes in callus cultures of Urena lobata L.

Abstract

The experiment was conducted to study the effect of sodium chloride (NaCl) at concentrations of 50mM, 100mM, and 150mM on the callus culture of Urena lobata, an important wild medicinal plant. Callus cultures were initiated from stem explants on Murashige and Skoog (MS) medium supplemented with 1mg/L 2,4-D and 2mg/l kinetin. Callus was subcultured on the same medium with different salt concentrations for 4, 6, and 8 weeks. The studied growth parameters showed that mass productivity and Growth Index of callus decreased under increasing salt concentration. However, moisture content increased at 150mM salt compared to the control. The protein, proline, organic carbon, phenolic, sodium and calcium content too, increased under salt treatments, especially at higher concentrations, but total nitrogen and potassium decreased. Thus, Phenolics (non-nitrogenous secondary metabolites) accumulated at all the concentrations of the salts tested, as an induced protective response in Urena lobata. These results suggest that in Urena lobata, proline accumulation is an index of salinity tolerance through osmo protection along with accumulation of nonnitrogenous defence compounds, phenolics (antioxidant), which are up scaled during salinity tolerance response.