Nitric oxide (NO) is an important signal molecule involved in plant defense responses. It also induces the activation of the mitogen-activated protein kinase (MAPK). To study the expression of MAPK genes in exogenous NO induced disease resistance to Penicillium digitatum in the postharvest citrus fruits,Aijitangcheng (Citrus Sinensis) fruits were immersed in SNP aqueous solution,the disease incidence and lesion diameter were measured and recorded during the experiment. Time-course changes in the expression of MAPK genes in response of citrus fruits peel to P. digitatum inoculation were quantified by using real-time quantitative PCR (RT-qPCR). The results show that exogenous NO can effectively reduce the green mold incidence and lesion diameter of citrus fruit during storage. The expression of MAPK genes was induced by exogenous NO in the citrus fruits peel.CsMAP1, CsMAP15 and CsMAP13-like expression were induced rapidly by NO after 1 h of NO treatment.CsMAP,CsMAP9,CsMAP9-like,CsMAP13-like,CsMAP19-like and CsMAP20-like expression level were induced during the early stages of storage and peaked at 4 h after SNP treatment.CsMAP4-like,CsMAP7,CsMAPNTF3 reached their highest expression level at 12 h after NO treatment.CsMAP1,CsMAP15,CsMAPMMK1 and CsMAPMMK2 showed high expression level at 4 h and 12 h after NO treatment. The results suggest that the expression of MAPK genes in the citrus fruits peel may involve in the resistance of the citrus fruits againstP. digitatum by treating with exogenous NO.%一氧化氮(NO)是植物逆境响应的重要信号分子,能够诱导激活丝裂原激活蛋白激酶(MAPK)的活性.为了分析外源NO诱导下MAPK基因在采后柑橘果实抗绿霉病中的表达情况,以埃及糖橙(Citrus Sinensis)果实为材料,使用硝普钠(SNP)溶液处理果实,统计接种柑橘绿霉病菌后果实的发病率和病斑面积,荧光定量PCR检测果实中MAPK基因的相对表达量和变化趋势.结果表明:外源NO能够降低试验期间柑橘果实绿霉病的发病率;果皮中MAPK基因的表达受外源NO诱导;CsMAP1、CsMAP15和CsMAP13-like基因在NO处理1 h即受诱导表达,CsMAP、CsMAP9、CsMAP9-like、CsMAP13-like、CsMAP19-like和CsMAP20-like在NO处理4 h达到表达高峰,CsMAP4-like、CsMAP7和CsMAPNTF3在NO处理12 h达到表达高峰,CsMAP1、CsMAP15、CsMAPMMK1和CsMAPMMK2分别在NO处理4 h和12 h有两个表达高峰.说明外源NO提高了柑橘果实对绿霉病的抗性,果皮中MAPK基因的诱导表达可能在抗病中发挥作用.
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