Antioxidative responses in calli of two populations of Acanthophyllum laxiusculum with and without B-chromosomes under salt stress.

Salinity is one of the most significant stresses that affect plant growth and agricultural production. Considerable efforts have therefore been made to investigate how plants respond to salt stress. To investigate the responses of Acanthophyllum to salinity stress, changes on lipid peroxidation, H2O2 content and the activity of antioxidant enzymes in calli of two Acanthophyllum laxiusculum variants, without (variant A) and with (variant B) B-chromosomes, were analyzed. Under salinity stress, lipid peroxidation and H2O2 content decreased in variant A compared to variant B. Moreover, variant A produced a higher amount of proline under salt stress than variant B. In calli of variant A, salinity stress preferentially enhanced the activities of the superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11) and glutathione reductase (GR, EC 1.6.4.2), whereas it decreased their activity in variant B. Guaiacol peroxidase (GPX, EC 1.11.1.7) activity decreased with increasing NaCl concentrations in variant A but its activity increased in variant B. After native polyacrylamide gel electrophoresis (PAGE) analysis, calli of both A and B variants had only Mn-SOD and Fe-SOD isoforms. Expression of the isoforms mentioned above, showed marked increase in variant A; while in variant B salinity caused a significant reduction as compared to control. Moreover, changes in the CAT and GPX isoforms pattern of treated plants were in accordance with the activity changes in time. These results suggest that variant A was able to induce better antioxidative responses against salt stress than variant B.