Liu Dong, Xin Ming, Zhou Xiuyan, Wang Chunhua, Zhang Yanju, Qin Zhiwei
College of Horticulture and Landscape Architecture, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Northeast Agricultural University, Harbin, 150030, China.
College of Agriculture, Northeast Agricultural University, Harbin, 150030, China.
BMC Plant Biol. 2017 Jun 5;17(1):96. doi: 10.1186/s12870-017-1049-8.
Cucumber downy mildew, caused by P. cubensis, is an important leaf disease that can severely affect cucumber production. In recent years, cucumber target spot, caused by C. cassiicola, has been reported in both Asia and Europe and is now considered as a major disease disrupting cucumber production. Single-disease-resistant cucumber varieties have been unable to satisfy production needs. To explore the molecular mechanisms of cucumber resistance to these two diseases, cucumber cultivars D9320 (resistant to downy mildew and target spot) and D0401 (susceptible to downy mildew and target spot) were used as experimental materials in this study. We used transcriptome sequencing technology to identify genes related to disease resistance and verified using transgenic technology.
We screened out the cucumber resistance-related gene CsERF004 using transcriptome sequencing technology. Induction by pathogens, salicylic acid (SA), and ethylene (ET) resulted in the up-regulation of CsERF004. Three treatments, namely, inoculation with C. cassiicola alone, inoculation with P. cubensis alone, and simultaneous inoculation with both pathogens, all resulted in the significant and sustained up-regulation of CsERF004 in the resistant cultivar D9320, during the early stage of infection. In the susceptible cultivar D0401, CsERF004 expression was also significantly up-regulated at the later stage of infection but to a lesser extent and for a shorter duration than in the resistant cultivar D9320. The CsERF004 gene encodes a protein localizes to the nucleus. The over-expression of CsERF004 in the susceptible cultivar D0401 resulted in the significant up-regulation of the CsPR1 and CsPR4 genes and increased the levels of SA and ET, which enhanced the resistance of cucumber to downy mildew and target spot.
Analyses of the CsERF004 expression pattern in disease-resistant and susceptible cucumber cultivars and transgenic validation indicate that CsERF004 confers resistance to P. cubensis and C. cassiicola. The findings of this study can help to better understanding of mechanisms of response to pathogens and in establishment the genetic basis for the development of cucumber broad-spectrum resistant cultivars.
由古巴假霜霉菌引起的黄瓜霜霉病是一种重要的叶部病害，会严重影响黄瓜产量。近年来，亚洲和欧洲均报道了由瓜棒孢菌引起的黄瓜靶斑病，目前它被视为扰乱黄瓜生产的主要病害。单一抗病的黄瓜品种已无法满足生产需求。为探究黄瓜对这两种病害的抗性分子机制，本研究以黄瓜品种D9320（抗霜霉病和靶斑病）和D0401（感霜霉病和靶斑病）为实验材料。我们利用转录组测序技术鉴定与抗病性相关的基因，并通过转基因技术进行验证。
我们利用转录组测序技术筛选出黄瓜抗病相关基因CsERF004。病原体、水杨酸（SA）和乙烯（ET）诱导均导致CsERF004上调。三种处理，即单独接种瓜棒孢菌、单独接种古巴假霜霉菌以及两种病原体同时接种，在感染早期均导致抗病品种D9320中CsERF004显著且持续上调。在感病品种D0401中，CsERF004表达在感染后期也显著上调，但程度低于抗病品种D9320，且持续时间更短。CsERF004基因编码一种定位于细胞核的蛋白质。在感病品种D0401中过表达CsERF004导致CsPR1和CsPR4基因显著上调，并提高了SA和ET水平，增强了黄瓜对霜霉病和靶斑病的抗性。
对抗病和感病黄瓜品种中CsERF004表达模式进行分析及转基因验证表明，CsERF004赋予黄瓜对古巴假霜霉菌和瓜棒孢菌的抗性。本研究结果有助于更好地理解黄瓜对病原体的响应机制，并为培育黄瓜广谱抗病品种奠定遗传基础。
