Salt-induced hydrogen peroxide is involved in modulation of antioxidant enzymes in cotton

Salt severely restricts cotton(Gossypium hirsutum) growth and production.The present study was undertaken to study the effect of salt-induced hydrogen peroxide(H_2O_2) on antioxidant enzymes in cotton.Na Cl treatment or exogenous H_2O_2 was used to investigate the relationship between H_2O_2 content and levels of antioxidant enzymes including superoxide dismutase(SOD),ascorbate peroxidase(APX),peroxidase(POD),and catalase(CAT),as well as the transcriptional levels of corresponding genes.H_2O_2 content increased within 24 h following 200 mmol L^(–1)Na Cl treatment.Both Na Cl-induced and exogenous H_2O_2 increased the activity of antioxidant enzymes including APX and SOD and upregulated the transcriptional levels of Ghc APX1,Gh Fe SOD,and Ghchl CSD.These increased activities and upregulated transcriptional levels were inhibited when the salt-induced H_2O_2 was scavenged by NAC.These results indicate that salt-induced H_2O_2 as a second signaling messenger modulates APX and SOD activities by regulating the transcription levels of corresponding genes,alleviating oxidative stress,and increasing salt tolerance in cotton.