The mechanismoflead-inhibitoryeffectsonseedgerminationandseedlinggrowthwasinvestigatedin
wheat cv.Xihan2subjectedtodifferentPb(NO3)2 concentrations.Highconcentrationsofleadand
exogenousH2O2 significantlyinhibitedseedgerminationandthegrowthofrootsandshoots.
Dimethylthiourea,catalaseordiphenyleneiodoniumcouldreverselead-inhibitoryeffectsonseed
germination.SignificantelevatedH2O2 generationwasobservedingerminatingseedsexposedtolead.
Analysisusingfluorescentdye20,70-dichlorodihydrofluoresceindiacetateshowedsignificantlyincreased
H2O2 levelintheroottissueinresponsetoleadtreatment.Nitricoxide(NO)donorsodiumnitroprusside
couldalleviatethePb-inhibitoryeffectsonseedgerminationandshootgrowth,whichwasblockedby
guanylylcyclaseinhibitormethyleneblue.Therefore,NADH-dependentgenerationofextracellularH2O2
is responsibleforPb-inhibitoryeffectonseedgermination,theprotectionofexogenousNOagainstlead
toxicityinvolvedinseedgerminationandseedlingsshootgrowthmaybeassociatedwithcGMP
signalingpathway.