Evaluation of Growth and Antioxidant Activity in Suaeda monoica and Suaeda nudiflora Callus Cultures under Sequential Exposure to Saline Conditions

Abstract

Background: Plant in vitro culture systems serve as a useful tool to study the regulatory routes which are related to plant growth and survival under altered environmental conditions. Methods: Callus culture of Suaeda monoica and Suaeda nudiflora were established for studying the salt tolerance mechanism at the cellular level. Calli of both the species were induced from seedling’s epicotyls on Murashige and Skoog (MS) medium supplemented with a different combination of auxin and cytokinins. A sequential stress treatment was given to the callus of both the species. The growth rate of callus, osmolytes and antioxidant activities was investigated after 28 days. A control callus was maintained in each experiment without any salt in the growth medium. Results: Efficient callus regeneration was obtained by exposing the callus tissue to MS medium supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D, 1.0 mg/l), benzylaminopurine (BAP, 0.5 mg/l) and 2,4-D (0.5 mg/l), kinetin (Kn, 0.25 mg/l) for S. monoica and S. nudiflora, respectively. A substantial increase was observed in proline content and a strong positive correlation was found between the total phenolic content and antioxidant activity under increasing salt concentrations. Conclusion: This is the first report on S. monoica callus regeneration. The specific cell lines which were generated through callus culture under sequential saline conditions provide a promising foundation for studying salinity induced expression of enzymes. Further comparison of transcriptomic profiles of control and salt-treated callus cultures can serve as a promising system for the detection of genes responsible for the change in expression under salt stress.