Soil dynamics modulation of stress enzymes and secondary metabolites in allium cepa (L.) under salinity stress

Abstract

In Allium cepa (L.) cultivation, salinity stress is the most important environmental factor worldwide that affects plant growth, protection as well as yield stability. The present study was carried out to examine the alterations in soil dynamics, antioxidants, biochemical and secondary metabolic profile of A. cepa under alkaline stress. Various parameters of A. cepa were studied under salinity stress by exposing them to different concentrations of sodium carbonate (SC) and sodium bicarbonate (SBC) salts (0, 10 and 100 mM). Treatment of both SC and SBC in A. cepa increases superoxide dismutase, glutathione peroxidase and catalase concentrations. These were attributed to increase in peroxide, lipid peroxides as well as carbonyl groups. The salinity stress was driven by the alterations in the soil dynamics. Of note, the salt stress induces secondary metabolites changes in A. cepa. The compounds like phenol 2 4-bis (1 1-dimethylethyl), hexadecane, 7,9-di‑tert‑butyl‑1-oxaspiro(4,5) deca-6,9-diene-2,8‑dione, 1,2-benzenedicarboxylic acid, butyl octyl ester, 1,2-benzenedicarboxylic acid, diisooctyl ester are elevated. In addition, the level of total proteins is reduced in all the groups except 10 mM and Proline amino acid in the shoot is elevated. Reversing all the parameters tested to achieve control levels in A. cepa indicates that significant cellular mechanism appeared in stress condition that brings back the altered parameters to normal levels. The biochemical and secondary metabolite profile analysis of the petroleum ether extracts of A. cepa under various alkaline stress conditions reveals that the composition of secondary metabolites and their concentration in A. cepa varies depending on the extent of alkaline stress.