biologia plantarum

Biologia plantarum 59:745-756, 2015 | DOI: 10.1007/s10535-015-0542-x

Roles of exogenous glutathione in antioxidant defense system and methylglyoxal detoxification during salt stress in mung bean

K. Nahar^1,2, M. Hasanuzzaman³, M. M. Alam¹, M. Fujita^1,*

¹ Laboratory of Plant Stress Responses, Department of Applied Biological Science, Faculty of Agriculture, Kagawa University, Kagawa, Japan

² Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Bangladesh

³ Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Bangladesh

The protective roles of glutathione (GSH) applied on salt stress-affected mung bean (Vigna radiata L.) seedlings were studied. The salt stress (200 mM NaCl) significantly increased the malondialdehyde (MDA), methylglyoxal (MG), H₂O₂, and proline (Pro) content, O₂ ^.- generation rate, and lipoxygenase (LOX) activity and reduced the leaf relative water content (RWC) and chlorophyll (Chl) content. The salt stress also significantly reduced the ascorbate (AsA) content, increased the endogenous GSH and glutathione disulfide (GSSG) content, and reduced the GSH/GSSG ratio. The activities of mono-dehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and catalase (CAT) decreased; and the activities of ascorbate peroxidase (APX), glutathione reductase (GR), superoxide dismutase (SOD), glutathione S-transferase (GST), and glutathione peroxidase (GPX) increased under the salt stress. The activities of glyoxalase I (Gly I) and glyoxalase II (Gly II) decreased under the salt stress (except the Gly II activity at 48 h). Mung bean seedlings which were treated with NaCl together with GSH showed an improved AsA and GSH content, GSH/GSSG ratio, higher activities of APX (only at 24 h), MDHAR, DHAR, GR, SOD (only at 24 h), CAT, GPX (only at 48 h), GST (only at 24 h), Gly I and Gly II under the salt stress compared with those treated with NaCl alone. The improved antioxidant and glyoxalase systems by GSH application decreased the MDA, H₂O₂, and MG content, O₂ ^.- generation rate, as well as increased the leaf RWC and Chl content. Thus, exogenous GSH improved the response of the mung bean seedlings to the salt stress.

Keywords: abiotic stress tolerance; ascorbate-glutathione cycle; glyoxalase enzymes; osmotic stress; reactive oxygen species

Subjects: glutathione; salinity; ascorbate-glutathione cycle; antioxidative enzymes; malondialdehyde; reactive oxygen species; catalase; superoxide dismutase; glyoxalase; mung bean

Received: August 14, 2014; Revised: March 13, 2015; Accepted: March 27, 2015; Published: December 1, 2015Show citation