Nitric Oxide Effect On Growth And Proteomics In Wheat Under Copper And Cadmium Stress

Copper(Cu)is an essential element that plays an important role in the growth and development of plants.Cadmium(Cd)is an important stress factor that hinders the normal growth of plants.Their accumulation in the soil is now considered to be a serious environmental problem that endangers agricultural production and human health.Nitric oxide(NO)is a multifunctional gas signal molecule that plays an important role in many physiological processes of plants.In this study,wheat(Triticum aestivum L.)was used as the experimental material and indoor water culture method was used to investigate the effects of different concentrations of exogenous NO on the growth and resistance physiology of wheat seedlings under Cu and Cd stress.The iTRAQ proteome was also used to explore the mechanism of mitigating Cu stress by exogenous NO.The results of the study are as follows:1.Under Cu treatment,the growth of wheat seedlings was significantly inhibited,and fresh weight,dry weight,total root length,total root surface area,and root volume were all lower than those of the control.The fresh weight,dry weight,total root length,total root surface area,and root volume of wheat seedlings after addition of different concentrations of exogenous NO had been observed.Compared with the single heavy metal Cu treatment,all indexs of wheat seedlings were increased significantly under SNP400 treatment.Under Cu stress,oxidative damage was induced in wheat roots,and the addition of NO showed a tendency of low concentration promote while high-level inhibition.SNP400 treatment could alleviate the lipid peroxidation.It could also remove excess reactive oxygen species(ROS)by increasing the activity of superoxide dismutase(SOD),thus alleviating the oxidative damage of wheat seedlings under Cu stress.2.Application of exogenous nitric oxide can effectively alleviate the damage of Cd stress to wheat seedlings.The best relieving effect was obtained when the concentration of SNP was 400 ?mol/L.The fresh weight,dry weight,relative water content,total root length,and total root weight of wheat seedlings under the treatment were significant.The surface area,root volume and number of apical roots were significantly increased compared to single heavy metal Cd treatment,but still lower than the control.Wheat root cells were damaged,electrolyte leakage,malondialdehyde(MDA)content increased,and Cd damage could be reduced by direct clearance of ROS.The NO relieving effect showed a tendency of low concentration to promote high-concentration inhibition.Among the lower NO concentrations,the remission effect of SNP400 treatment was significant at 48 hours.3.Using iTRAQ proteomics,a total of 12867 NO reduced wheat Cu root stress proteins were identified in the Poaceae database.Among them,Cu/CK group up-regulated 253 differentially expressed proteins and down-regulated 265;Cu+SNP/CK group up-regulated 348 differentially expressed proteins and down-regulated 354;Cu+SNP/Cu group up-regulated 142 differentially expressed proteins and down-regulated 174.After GO enrichment function and KEGG pathway analysis,the functions of these differentially expressed proteins mainly catalyzes related enzyme activities,ion binding,and oxidative stress reactions.These differentially expressed proteins mainly participate in ribosome and amino acid metabolism,cytochrome processes,and organic metabolic processes,cell metabolism and other important biological processes.These findings help to elucidate the mitigating mechanism of exogenous NO on wheat Cu stress at the molecular level,and provide more information for future research on wheat stress resistance mechanism.