| With the increase of mining and industrial activities,cadmium pollution is becoming more and more serious.Cadmium has serious harm to animals and plants,especially the accumulation of cadmium in vegetables and fruits.Through the enrichment of food,it will eventually cause a great potential for human health.General plant responses to stress include reducing injury,increasing tolerance and stress-induced morphogenesis.H2 can play a role in protecting plant cells under abiotic stresses including paraquat,salt,heavy metals,ultraviolet radiation and strong light stress.In addition,it was found that hydrogen rich water(HRW)treatment could improve cadmium tolerance of alfalfa and Chinese cabbage by reducing cadmium uptake and increasing antioxidant capacity.Heme oxygenase 1/carbon monoxide system(HO1/CO)is a kind of signal system in plants.It has been found that cadmium stress can induce the expression of HOI gene,increase HO activity and increase the release of endogenous CO from alfalfa.Endogenous CO regulates glutathione metabolism by upregulated antioxidant enzymes,and ultimately helps alfalfa resist cadmium stress.But so far,we know little about its regulatory mechanism.To solve the above questions,we studied the topics by pharmacological and genetic evidences,and acquired results as follows:1.Exogenous hydrogen pretreatment improved the cadmium tolerance of alfalfa and effectively decreased the TBARS level under cadmium stress.Hydrogen rich water pretreatment can improve the content of non protein thiols in the roots of alfalfa,whether under or without cadmium stress.At the same time,hydrogen enriched water greatly alleviated cadmium induced ion depletion and increased the content of Fe and Zn in roots of seedlings under Cd stress.Further proteomic analysis identified 248 differential abundance proteins(DAPs).Further GO analysis and KEGG pathway analysis were performed to identify the key proteins in cadmium tolerance of hydrogen.The results showed that the sulfur metabolism process,redox process and metal ion balance of Alfalfa Seedlings Roots under cadmium stress were the key processes induced by H2.This is in agreement with the previous research results,indicating that hydrogen can increase the cadmium tolerance of alfalfa and enhance the body's antioxidant capacity,activate sulfur metabolism,and regulate the homeostasis of ions by regulating the transporters.2.Cadmium stress inhibited cucumber root elongation,induced adventitious root formation and CysHO1 expression.The treatment of HO inducer hemin(Hemin)and active inhibitor zinc protoporphyrin(ZnPP)showed that Hemin could alleviate the inhibition of the main root and promote the occurrence of adventitious roots.ZnPP shows the opposite phenomenon.The three products of Hemin,including carbon monoxide(CO),ferrous ion(Fe2+)and bilirubin(BR),show that the effect of Hemin is mostly from CO.The results of Arabidopsis wild type,heme oxygenase mutant hyl-100 and overexpressed 35S:HY1 showed that heme oxygenase was involved in cadmium induced SIMR.Further detection revealed that the relationship between CsHO1 transcriptional level and the change of auxin content showed time line.Under the treatment of Hemin,the content of auxin increased,while the content of auxin decreased under ZnPP treatment.Through Arabidopsis transgenic material PIN-GFP,it was found that the content of auxin increased under cadmium stress,and the accumulation of adventitious root primordium on stem was also observed.Hemin treatment further increased the level of auxin and the accumulation of adventitious roots under or without cadmium treatment.Under the treatment of ZnPP,ghrelin content was significantly lower than the normal value,while blocking the induction of auxin by cadmium.The results showed that cadmium stress induced the expression of HOI,further regulated the changes of auxin through CO,and finally regulated the stress induced morphogenics response process. |
PDF Full Text Request