Brassinosteroids Regulate Functional Components of Antioxidative Defense System in Salt Stressed Maize Seedlings

The purpose of current investigation was to explore the role of brassinosteroids (BRs) in Zea mays L. var. DKC 9106 seedlings subjected to salt stress. The seedlings were raised under controlled laboratory conditions and subjected to different concentrations of NaCl (0, 40, 60, 80, 100 mM) for 10 days. The impact of pre-sowing treatment of both 28-homobrassionolide (HBL) and 24-epibrassinolide (EBL) on defense system of Z. mays L. under salt stress was studied by analyzing Na+ and K+ ions, malondialdehyde content (MDA), antioxidative enzymes activities (peroxidase, POD; catalase, CAT; dehydroascorbate reductase, DHAR; monodehydroascorbate reductase, MDHAR), osmoprotectants (proline, glycine betaine, mannitol, and total osmolytes content), total phenolic content, total flavonoid content, and 1,1-diphenylpicrylhydrazyl (DPPH) free radical scavenging activity. The results of our finding showed that treatment of both HBL and EBL under high salt stress balanced the ionic status by decreasing the Na+ ions content by 21.23% and 38.94%, respectively, and enhancing the K+ ions content by 51.94% and 26.66%, respectively. Treatment of both BRs also overcome the oxidative damage induced due to salinity stress by reducing the MDA accumulation 19.50% and 45.0%, respectively, and enhancing the activities of antioxidative enzymes. The osmoprotectants: proline (50.08% and 17.03%), glycine betaine (35.57% and 28.16%), and mannitol content (2.80% and 20.98%) were markedly increased by the treatment of both HBL and EBL, respectively. Further, treatment of both HBL and EBL also increased the total phenolic content by 11.68% and 5.80%, total flavonoid content by 31.56 and 31.09% and DPPH free radical scavenging activity by 37.99% and 77.41%, respectively. Overall the treatment of BRs before seed sowing considerably conquer the salinity-induced damage by stimulating functional components of antioxidative defense system and ultimately reduced oxidative damage.