Exogenous salicylic acid and kinetin modulate reactive oxygen species metabolism and glyoxalase system to confer waterlogging stress tolerance in soybean (Glycine max L.)

Abstract

We conducted this study to investigate the positive effects of foliar-applied salicylic acid (SA) and kinetin (KN) in improving waterlogging stress tolerance, by upregulating reactive oxygen species (ROS) metabolism and antioxidant defense including glyoxalase system in soybean (Glycine max cv. Sohag) grown under different levels of waterlogging. Waterlogging was imposed on plants at 15 days after sowing at four different durations viz. waterlogging for 0 days (W0), waterlogging for 3 days (W3), waterlogging for 6 days (W6), waterlogging for 9 days (W9), and plants were supplemented with exogenous SA (0.5 mM) and KN (0.1 mM). Waterlogging increased lipid peroxidation (malondialdehyde content), hydrogen peroxide content, leaf electrolyte leakage, proline content, and glutathione S-transferase (GST) activity while ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), catalase (CAT), glutathione peroxidase (GPX), peroxidase (POD), glyoxalase I (Gly I) and glyoxalase II (Gly II) activities were decreased. On the contrary, exogenous SA and KN reduced the MDA content, H2O2 content, proline content, and leaf electrolyte leakage under waterlogging. Further, supplementation of SA and KN enhanced the activity of APX, MDHAR, DHAR, GR, CAT, GST, GPX, POD, Gly I, and Gly II under waterlogging stress. In the current study, the results indicate that both exogenous SA and KN effectively improved the ROS metabolism and waterlogging stress tolerance in soybean by enhancing the antioxidant defense and upregulating the glyoxalase system.