Journal Article

Hydrogen sulfide is a crucial element of the antioxidant defense system in Glycine max–Sinorhizobium fredii symbiotic root nodules

Lin, Xue-Yuan, Zou, Hang, Wei, Ge-Hong, Zhang, Wei-Qin, Zhang, Jian-Hua, Zhang, Ni-Na, Chen, Juan

2020

Overview

Aim H 2 S is emerging as a signaling molecule involved in the regulation of many physiological processes in plants. Here, we investigated the potential antioxidant role of H 2 S in soybean ( Glycine max )-rhizobia ( Sinorhizobium fredii ) symbiotic root nodules. Method An endogenous H 2 S production deficit rhizobia mutant ∆ CSE was constructed to study the effect of decreased content of H 2 S in soybean nodules. Fluorescent probes and confocal microscope were used to observe the production and accumulation of H 2 S and reactive oxygen species. Transmission electronic microscopy was conducted to study the structural changes in ∆ CSE soybean nodules. Finally, qRT-PCR, enzymatic activity, and oxidative damage parameters were measured. Result The results demonstrated that abundant H 2 S was generated in the nitrogen-fixing zone of soybean nodules. The deletion of the cystathionine γ-lyase ( CSE ) gene in S. fredii ( ∆CSE ) caused a sharp decrease in H 2 S production in both free-living rhizobia and soybean nodules. We found that decrease in the H 2 S level in nodule cells inhibited nitrogenase activity. In addition, to elevated H 2 O 2 and malondialdehyde accumulation, increased protein carbonyl content and decreased O 2 − scavenging ability was observed in ∆CSE root nodules. Transmission electron microscopy revealed that an H 2 S deficit caused the deformation of bacteroids and damage of peribacteroid membranes in nodule cells. Moreover, the expression of some rhizobial and soybean genes related to antioxidant defense was up-regulated in ∆CSE nodules. Conclusion H 2 S is crucial for the nitrogen-fixation ability of soybean nodules by acting as an antioxidant element that protects nodule cells and bacteroids from oxidative damage.

• Publisher: Springer International Publishing,Springer,Springer Nature B.V
• Subject: Accumulation / antioxidant activity / Antioxidants / Bacteroids / Biomedical and Life Sciences / Carbonyl compounds / Carbonyls / cystathionine / Damage / Defense industry / deformation / Deformation mechanisms / Ecology / Enzymatic activity / enzyme activity / Enzymes / Fixation / fluorescence / Fluorescent indicators / Gene deletion / Gene expression / genes / Glycine max / Hydrogen peroxide / Hydrogen sulfide / Life Sciences / Malondialdehyde / Microscopy / mutants / Nitrogen / Nitrogen fixation / Nitrogenase / Nitrogenation / Nodules / Physiological aspects / Plant Physiology / Plant Sciences / Reactive oxygen species / Regular Article / Root nodules / Scavenging / Sinorhizobium fredii / soil / Soil Science & Conservation / Soybean / Soybeans / Transmission electron microscopy