Glutathione Restores Hg-Induced Morpho-Physiological Retardations by Inducing Phytochelatin and Oxidative Defense in Alfalfa

Abstract

Mercury (Hg) is toxic to plants, but the effect of glutathione in Hg alleviation was never studied in alfalfa, an important forage crop. In this study, Hg toxicity showed morphological retardation, chlorophyll reduction, and PSII inefficiency, which was restored due to GSH supplementation in alfalfa plants treated with Hg. Results showed a significant increase of Hg, but Fe and S concentrations substantially decreased in root and shoot accompanied by the downregulation of Fe (MsIRT1) and S (MsSultr1;2 and MsSultr1;3) transporters in roots of Hg-toxic alfalfa. However, GSH caused a significant decrease of Hg in the shoot, while the root Hg level substantially increased, accompanied by the restoration of Fe and S status, relative to Hg-stressed alfalfa. The subcellular analysis showed a substantial deposition of Hg in the root cell wall accompanied by the increased GSH and PC and the upregulation of MsPCS1 and MsGSH1 genes in roots. It suggests the involvement of GSH in triggering PC accumulation, causing excess Hg bound to the cell wall of the root, thereby reducing Hg translocation in alfalfa. Bioinformatics analysis showed that the MsPCS1 protein demonstrated one common conserved motif linked to the phytochelatin synthase domain (CL0125) with MtPCS1 and AtMCS1 homologs. These in silico analysis further confirmed the detoxification role of MsPCS1 induced by GSH in Hg-toxic alfalfa. Additionally, GSH induces GSH and GR activity to counteract oxidative injuries provoked by Hg-induced H2O2 and lipid peroxidation. These findings may provide valuable knowledge to popularize GSH-derived fertilizer or to develop Hg-free alfalfa or other forage plants.

Physiological, Transcriptome, and Metabolome Analyses Reveal the Tolerance to Cu Toxicity in Red Macroalgae Gracilariopsis lemaneiformis

“…These results suggest that Cu stress has reduced the nitrogen assimilation efficiency of G. lemaneiformis. A similar effect was observed in rice, where Cu stress reduced the enzyme activities of NR and GS, leading to a reduction in plant biomass [26].…”

Seed Priming and Foliar Supplementation with β-aminobutyric Acid Alleviates Drought Stress through Mitigation of Oxidative Stress and Enhancement of Antioxidant Defense in Linseed (Linum usitatissimum L.)

“…In this study, the improvement of plants attributes through exogenous supplementation BABA is newly reported in linseed. Additionally, BABA decreased the MDA content in linseed plants exposed to varying levels of DS This decrease in MDA level protect from membrane disruption [64]. Increase level of MDA and H 2 O 2 was found in salt stressed plants [65,66].…”

Glomus mosseae improved the adaptability of alfalfa (Medicago sativa L.) to the coexistence of cadmium-polluted soils and elevated air temperature

“…Reverse transcription quantitative PCR (RT-qPCR) was used to examine relative expression of Cu/Zn-SOD , POD , CAT and PCS genes using the LightCycler ® 480 II thermocycler system (Roche, Switzerland). The primers for Cu/Zn-SOD ( Yang et al, 2015 ), POD (L36157.1) ( Helaoui et al., 2020 ), CAT (GU984379) ( Desoky et al., 2019 ), PCS (AM407892.1) ( Rahman et al., 2020a ), and actin (JQ028730.1) ( Rahman et al., 2020b ) were found in Table S1 . The actin gene was used as an internal reference to standardize the expression level of four genes.…”