Vol.:(0123456789) 1 3 Journal of Plant Growth Regulation https://doi.org/10.1007/s00344-020-10097-1 Brassinosteroids Regulate Functional Components of Antioxidative Defense System in Salt Stressed Maize Seedlings Amandeep Rattan 1  · Dhriti Kapoor 2  · Nitika Kapoor 3  · Renu Bhardwaj 1  · Anket Sharma 1,4 Received: 15 September 2019 / Accepted: 9 March 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020 Abstract 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 diferent concen- trations 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 favonoid content, and 1,1-diphenylpicrylhydrazyl (DPPH) free radical scavenging activity. The results of our fnding 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 favonoid 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. Keywords Antioxidative enzymes · Brassinosteroids · Flavonoid content · Osmoprotectants · Phenolic content · Salt stress Introduction Salinity stress restraining the agricultural production and yield throughout the world. Almost 45 million hectare of irrigated land and 32 million of dry land agriculture were estimated to be salt afected (FAO 2016). The detrimen- tal efects of salinity stress mainly involve the hyperos- motic stress, which reduces the water potential in roots and hyperionic stress, which causes the acquisition of Na + and Cl − ions to a damaging level (Shabala and Cuin 2008; Marschner 2011). The other consequences of salt stress include the nutritional stress, oxidative stress, and reduc- tion in photosynthetic performance (Tomescu et al. 2017; Tang and Luo 2018; Ahanger et al. 2019). In nutritional stress, Na + ions replace the K + ions and alter the normal metabolic processes regulated by potassium, such as sto- matal regulation, osmoregulation, protein synthesis, and Amandeep Rattan and Dhriti Kapoor have contributed equally to this work. * Renu Bhardwaj renubhardwaj82@gmail.com * Anket Sharma anketsharma@gmail.com; anketsharma@zafu.edu.cn 1 Plant Stress Physiology Laboratory, Department of Botanical and Environmental Sciences, Guru Nanak Dev University, Amritsar, Punjab 143005, India 2 School of Bioengineering & Biosciences, Lovely Professional University, Jalandhar, Punjab 144 411, India 3 PG Department of Botany, Hans Raj Mahila Maha Vidyalaya, Jalandhar, Punjab 144008, India 4 State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China