| Cadmium(Cd)pollution is often present in water and soil,and can be accumulated in the food chain after being absorbed by plants,thereby causing damage to ecosystems and human health.The absorption and transport of heavy metals in plants is accomplished by metalloproteinases of essential nutrients,such as the natural resistance-associated macrophage protein(Nramp).Recent studies have found that hydrogen(H2)is an important regulatory signal for plants to respond to abiotic stress.It regulates cell signal transduction and redox homeostasis in plant response to Cd stress,but its specific mechanism of action not sure.Regarding the issue above,this study combined with transcriptomics,pharmacology and genetic experiments,preliminary studies on the role of glutathione metabolism and MsNramp5 in H2 to enhance the cadmium tolerance of alfalfa.The specific results are as follows:1.Firstly,this paper analyzed the transcriptome changes of the roots of sorghum seedlings treated with cadmium and hydrogen-rich water(HRW).A total of 1968 differentially expressed genes were identified.The bioinformatics analysis revealed that it was mainly classified as glutathione.Metabolic,oxidative stress,transporter and other cellular pathways or processes;in view of the importance of glutathione metabolism,further use of inhibitor BSO(L-buthionine-S,R-sulfoximine)by pharmacological methods for the role of glutathione in hydrogen-induced cadmium resistance verification.The results showed that hydrogen-activated glutathione metabolism can alleviate the toxicity of cadmium to alfalfa by increasing cadmium chelation and increasing cell antioxidant capacity.2.The expression of MsNramp5 gene in alfalfa under cadmium stress and hydrogen-rich water treatment showed that it was mainly expressed in roots and leaves.Subcellular localization analysis found that it was located at least in the plasma membrane.Furthermore,the MsNramp5 gene was overexpressed into Arabidopsis thaliana,combined with the Arabidopsis Nramp gene AtNramp1 mutant localized to the plasma membrane and the wild-type Arabidopsis Col-0.The MsNramp5 gene was mediated to enhance the cadmium tolerance of alfalfa by H2.The role played by it.It was found that H2 down-regulated the transcript level of Nramp5 ion transporter,reduced cadmium accumulation in plant roots under cadmium stress,and maintained ionic homeostasis,especially iron homeostasis,under cadmium stress,thereby alleviating cadmium stress on alfalfa and the toxicity of Arabidopsis.In summary,glutathione-mediated cadmium chelation and anti-oxidation and MsNramp5-regulated cellular ion homeostasis are important mechanisms for improving cadmium tolerance in alfalfa in H2-mediated cadmium tolerance.The research results have certain guiding significance for the study of hydrogen biological function method and the safe production of animal husbandry. |
