Salt stress affects mitotic activity and modulates antioxidant systems in onion roots

This study was aimed to explore the effect of short-term salt stress and recovery on cytology and the activity of antioxidant enzyme in roots of onion (Allium cepa L.) plant. Roots of A. cepa were treated with different concentrations of NaCl (0, 50, 100, 150, 200 mM), and cytological and physiological indicators in the root of plant were measured in different processing time. With the increase of NaCl concentrations and processing time, mitotic activity and relative division rate (RDR) were reduced. However, during recovery, mitotic activity and RDR were restored but their values were less than control values. Salt stress caused an increase while in recovery experiments there was a slight reduction in chromosomal aberrations. A significant increase in SOD and POX activities except in 200 mM occurred after 18 h of stress which was still higher than control in recovered plants. CAT activity showed 53.90 % decrease after 18 h of salt stress and also a significant decrease was observed after 24 h post stress. The results suggest that at high salt stress up to 150 mM, the roots of A. cepa are capable to rapidly activate antioxidant defence system to resist the salt-induced oxidative stress, but could not control the cytogenetical activities. The results also suggest that the recovery is possible at physiological and cytogenetical level by retaining chromosomal and DNA integrity.