Involvement of triadimefon induced early ABA-dependent H2O2 accumulation in soybean against water stress

Abstract

The present study showed that pretreatment of triadimefon (TDM), a triazole compound, could improve tolerance of soybean seedlings to subsequent water stress. TDM pretreatment resulted in early and late rise in superoxide dismutase (SOD) and catalase (CAT) activities, and upregulation of ascorbate (AsA) content in non-stressed and water-stressed seedlings, leading to late increase in net photosynthetic rate (Pn), late decrease in hydrogen peroxide (H2O2) and electrolyte leakage in stressed ones. These TDM-induced changes were blocked by application of abscisic acid (ABA) biosynthesis inhibitor tungstate, which inhibited early rise of ABA and H2O2 contents in non-stressed and stressed seedlings. However, ABA pretreatment overcomed the effects of this inhibitor. Application of NADPH oxidase inhibitor diphenyleneiodonium (DPI), polyamine oxidase (PAO) inhibitor 2-hydroxyethylhydrazine (2-HEH) and H2O2 scavenger dimethylthiourea (DMTU) prevented early TDM-induced rise of H2O2 content. DPI, 2-HEH and DMTU also decreased SOD, CAT and AsA levels, but did not affect ABA content during early and late phases in both seedlings pretreated with TDM. In addition, these chemicals decreased Pn, and increased H2O2 content and electrolyte leakage during late phase in TDM-pretreated stressed seedlings. Overall, these results indicated that TDM pretreatment alleviated adverse effects of water stress on soybean seedlings, which was at least in part, due to increase of antioxidant capacity and decrease of oxidative damage induced by early ABA-dependent H2O2 generation.

Keywords

• Triadimefon (TMD)
• Abscisic acid
• Hydrogen peroxide
• Antioxidant ability
• Water stress
• Soybean