Role of exogenous 24-epibrassinolide in enhancing the salt tolerance of wheat seedlings

To understand the functions of exogenous 24-Epibrassinolide (EBR) in enhancing the salt tolerance of wheat (T. aestivum L.) seedlings to salt stress, a hydroponic experiment was performed to investigate the effects of EBR on chlorophylls, root activity, H+-ATPase, malondialdehyde (MDA), electrolyte leakage, free proline, soluble protein, reactive oxygen species (ROS), antioxidant enzymes and minerals content in wheat plants subjected to non-stress conditions or salt stress (120 mM NaCl) with foliar application of EBR (1, 10 and 100 nM). Results showed that spray of low concentrations EBR (1 and 10 nM) under non-stress conditions could promote wheat plant growth. 120 mM NaCl induced osmotic stress, oxidative stress and imbalance in mineral nutrients absorption. However, EBR enhanced the ability of resistance to osmotic stress by increasing free proline and soluble protein content, and enhanced the ability of resistance to oxidative stress by increasing antioxidant enzymes activities. As a result of increase of chlorophyll content, root activity and H+-ATPase activity, the inhibition of K, Ca, Mg, Fe and Zn uptake was ameliorated and consequently, decline in plant growth induced by NaCl stress was alleviated. Based on these results, we conclude that EBR had a positive role in regulating wheat growth and development under salt stress, and spray of 10 nM EBR had the most significant alleviating effect against NaCl toxicity.