Effects Of 2,2',4,4'-tetrabromodiphenyl Ether(SDE-47)on The Metabolism And Key Gene Expression In Rice(oryza Sativa L.)

Persistent organic pollutants(POPs)can affect the quality of crops by affecting their genetics and metabolism.The intensity of effects of POPs on metabolites,metabolic pathways and the gene expression in crops,as well as their intrinsic relationships,is still unavailable.Therefore,we took rice as the model crop and 2,2',4,4'-tetrabromobiphenyl ether(BDE-47)as the representative POPs.Based on the study of the toxic effect of BDE-47 on rice,transcriptomics and metabolomics were applied to try to reveal the influence of BDE-47 on the three parts.The main findings are summarized as below:(1)There was no significant difference in the absorption and accumulation of BDE-47 among different rice varieties,but the degree of oxidative damage varied with different rice cultivars.When the hydroponic concentration was 500 ?g/L,the activity of superoxide dismutase(SOD)in tolerant rice cultivar was increased by 1.56-folds,and the content of malondialdehyde(MDA)was not significantly different.The activity of SOD decreased by 36.9% and MDA increased by 1.14-folds in sensitive rice cultivar,leading to lipid peroxidation,rupture of cell membrane and nuclear membrane and serious DNA damage.(2)BDE-47 significantly affected the contents of saccharides,amino acids and organic acids in rice,and the intensity of the disturbance is related to the concentration of BDE-47 and rice cultivars.At 1-50 mg/kg,starch and sucrose metabolism,alanine,aspartic acid and glutamate metabolism,TCA cycle and other processes are disturbed by the regulation of hexokinase,glycine-hydroxymethyl transferase,actinic acid hydrase and other coding genes.At 1 and 10 mg/kg,the content of metabolites in sensitive rice cultivar increased by 0.4-2.2 folds.At 50 mg/kg,D-mannose and Lalanine decreased by 77% and 63% respectively,and inhibited the elongation of stem and leaf,while the increased by 0.3-18.9 folds in the tolerance rice cultivar,in which the content of D-mannose,L-lysine and citric acid increased by 2.0-,6.4-and 4.2-folds respectively,and the antioxidant capacity was enhanced.Starch and sucrose metabolism,alanine,aspartic acid and glutamic acid metabolism,and TCA cycle were also significantly disturbed.(3)BDE-47 can significantly affect the expression of key encoding genes in rice,such as ?-amylase,hexokinase,glycine-hydroxymethyl transferase and aconitine hydrase,and further disturb the synthesis of saccharides and amino acids and the energy metabolism.The key coding genes of sensitive cultivar were significantly up-regulated at 1 and 10 mg/kg.At 50 mg/kg,it was significantly down-regulated(FC>4)and inhibited the metabolism of fructose and mannose,while the key encoding genes of tolerance rice cultivar were significantly up-regulated(FC>2.2)and promoted the metabolism of starch and sucrose,alanine,aspartic acid and glutamate,and TCA cycle.This study provides a new perspective for comprehensively understanding and evaluating the potential ecological risks of PBDEs and ensuring the safety of rice production.