Impact of Ethyl Methane Sulphonate Mutagenesis in L. under NaCl Stress.

The present investigation aimed to obtain salt-tolerant L. to develop a constant form through in vitro mutagenesis with ethyl methane sulphonate (EMS) as the chemical mutagen. NaCl tolerance was evaluated by the ability of the callus to maintain its growth under different concentrations, ranges from (0 mM to 500 mM). However, NaCl salinity concentration at (500 mM) did not show any development of callus, slight shrinking, and brown discoloration taking place over a week. Thus, all the biochemical and antioxidant assays were limited to (0-400 mM) NaCl. On the other hand, selected calluses were treated with 0.5% EMS for 30, 60, and 90 min and further subcultured on basal media fortified with different concentrations of 0-400 mM NaCl separately. Thus, the callus was treated for 60 min and was found to induce the mutation on the callus. The maximum salt-tolerant callus from 400 mM NaCl was regenerated in MS medium fortified with suitable hormones. Biochemical parameters such as chlorophyll, carotenoids, starch, amino acids, and phenol contents decreased under NaCl stress, whereas sugar and proline increased. Peroxidase (POD) and superoxide dismutase (SOD) activities peaked at 200 mM NaCl, whereas catalase (CAT) was maximum at 100 mM NaCl. Enhanced tolerance of 0.5% the EMS-treated callus, attributed to the increased biochemical and antioxidant activity over the control and NaCl stress. As a result, the mutants were more tolerant of salinity than the control plants.