Indole acetic acid is responsible for protection against oxidative stress caused by drought in soybean plants: The role of heme oxygenase induction

Abstract

Objectives: This study was focused on the role of indole acetic acid (IAA) in the defense against oxidative stress damage caused by drought in soybean plants and to elucidate whether heme oxygenase-1 (HO-1) and nitric oxide (NO) are involved in this mechanism. IAA is an auxin that participates in many plant processes including oxidative stress defense, but to the best of our knowledge no information is yet available about its possible action in drought stress. Methods: To this end, soybean plants were treated with 8% polyethylene glycol (PEG) or 100 μM IAA. To evaluate the behavior of IAA, plants were pretreated with this compound previous to PEG addition. Lipid peroxidation levels (thiobarbituric acid reactive substances (TBARS)), glutathione (GSH) and ascorbate (AS) contents, catalase (CAT), superoxide dismutase (SOD), and guaiacol peroxidase (POD) activities were determined to evaluate oxidative damage. Results: Drought treatment (8% PEG) caused a significant increase in TBARS levels as well as a marked decrease in the non-enzymatic (GSH and AS) and enzymatic (CAT, SOD, and POD) antioxidant defense systems. Pre-treatment with IAA prevented the alterations of stress parameters caused by drought, while treatment with IAA alone did not produce changes in TBARS levels, or GSH and AS contents. Moreover, the activities of the classical enzymes involved in the enzymatic defense system (SOD, CAT, and POD) remained similar to control values. Furthermore, this hormone could enhance HO-1 activity (75% with respect to controls), and this increase was positively correlated with protein content as well as gene expression. The direct participation of HO-1 as an antioxidant enzyme was established by performing experiments in the presence of Zn-protoporphyrin IX, a well-known irreversible inhibitor of this enzyme. It was also demonstrated that HO-1 is modulated by NO, as shown by experiments performed in the presence of an NO donor (sodium nitroprusside), an NO scavenger (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), or an NO synthesis inhibitor (N-nitro-L-arginine methyl ester, NAME). Discussion: It is concluded that IAA is responsible, at least in part, for the protection against oxidative stress caused by drought in soybean plants through the modulation of NO levels which, in turn, enhances HO-1 synthesis and activity.

Response of Downy Oak (Quercus pubescens Willd.) to Climate Change: Transcriptome Assembly, Differential Gene Analysis and Targeted Metabolomics

“…The downregulation of tryptophan, the precursor of auxin biosynthesis, as well as that of auxin efflux, suggest that drought impairs auxin biosynthesis and transport. Our results seem to be in contradiction with other works that show that the application of auxin improves plant resistance to water stress [ 47 , 48 ]. Indeed, auxin efflux is mediated by specific PIN-FORMED transporters regulating the asymmetric spatiotemporal distribution of auxin in the whole plant.…”

Anti-Inflammatory and Anti-Oxidative Activity of Indole-3-Acetic Acid Involves Induction of HO-1 and Neutralization of Free Radicals in RAW264.7 Cells

“…HO-1 is one of the key detoxification enzymes that plays a crucial role in the prevention of oxidative and inflammatory injury [31]. Previous results from soybean plants have reported that the resistance of IAA on oxidative stress caused by drought depends on the induction of HO-1 [32]. On the other hand, HO-1 induction relies on the production of NO.…”

Exogenous application of IAA alleviates effects of supplemental ultraviolet‐B radiation in the medicinal plant Withania somnifera Dunal

“…Pre‐treatment with IAA prevented a decrease in ascorbate content produced upon application of 8% PEG in soybean (Lecube et al . ). However, a decline in ascorbate content in the present study upon IAA application could be correlated with increased APX activity, which uses ascorbate as substrate.…”

“…Activity of SOD, CAT and POX was comparable to controls in soybean treated with 8% polyethylene glycol (PEG) and 100 μ m IAA (Lecube et al . ). Other antioxidant enzymes (APX, GR and PPO) also synergistically increased under s‐UV‐B+IAA1 and s‐UV‐B+IAA2.…”