Cucumber downy mildew and cucumber target leaf spot caused by Pseudoperonospora cubensis (Berk.&M.A.Curtis) Rostovzev and Corynespora cassiicola (Berk and Curt) Wei are the important diseases in cucumber production.Article used cucumber cultivar'D9320'(anti-C.cassiicola and P.cubensis) and cucumber cultivar'D0401'(susceptible C.cassiicola and P.cubensis) as test materials,by using transcriptome sequencing technology screened the CsCBS as a candidate gene for disease resistance of cucumber to explore the role of CsCBS gene in the resistance of cucumber to two diseases.The cloned cucumber CsCBS,which contained 1 263 bp open reading frames,encoded 420 amino acids.There were 11 exons and nine introns in the coding region,which contain one CBS domain and one DUF domain.Three treatments of single inoculation of C.cassiicola,single inoculation of P.cubensis and two kinds of pathogens at the same time,the expression of CsCBS in the resistant cultivar'D9320'was significantly higher than that in the control of 2 to 24 h;the expression of two kinds of pathogenic bacteria was the highest at 4 h,which was 57 times as high as that of the control.The response of CsCBS to the leaf spot pathogen was the strongest,and the duration was long.In the susceptible cultivar'D0401',the expression level was lower than that of the control or similar with the control,and the expression was very low.And overexpression of CsCBS could significantly improve the resistance to downy mildew and leaf spot disease.At the same time,the content of malondialdehyde (MDA) in the T0 generation of CsCBS transgenic cucumber was significantly lower than that of the control,and the content of soluble sugar was higher than that of the control.The research results provided a theoretical basis for the further exposition of the molecular mechanism of cucumber double resistance.%黄瓜霜霉病和棒孢叶斑病由藻界卵菌门古巴假霜霉菌[Pseudoperonospora cubensis(Berk.&M.A.Curtis)Rostovzev]及多主棒孢霉[Corynespora cassiicola(Berk &Curt)Wei]侵染引起,是黄瓜生产主要病害.文章利用抗霜霉病与棒孢叶斑病黄瓜品种‘D9320’和感霜霉病与棒孢叶斑病黄瓜品种‘D0401’为试验材料,通过转录组测序技术筛选黄瓜抗病性候选基因CsCBS,探究CsCBS基因在黄瓜抗两种病害中作用.克隆获黄瓜CsCBS,其包含1个1 263 bp开放阅读框,编码420个氨基酸.在编码区有11个外显子,9个内合子,含1个CBS结构域和1个DUF结构域.在单一接种棒孢叶斑病菌、霜霉病菌及同时接种两种病原菌3种处理下,接种2～24 h,CsCBS在抗病品种‘D9320’中表达量均显著高于对照;同时接种2种病原菌处理在4h时表达量最高,为对照57倍.CsCBS对棒孢叶斑病菌响应最强烈,且持续时间长.在感病品种‘D0401’中,CsCBS表达量均低于对照或与对照持平,表达量极低且过表达CsCBS,显著提高其对霜霉病及棒孢叶斑病抗性.CsCBS转基因黄瓜T0代植株丙二醛含量显著低于对照,可溶性糖含量高于对照.研究结果为阐述黄瓜双抗分子机理提供理论基础.
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