番茄材料对疮痂病菌T3小种侵染响应的细胞学机理研究

Tomato bacterial spot, caused by Xanthomonas, is a disease that severely affects tomato production in open and protected fields in China. The use of resistant varieties is the most economical and effective approach to control the disease due to the lack of resistant varieties and efficient chemicals in current production. However, the pathogen causing tomato bacterial spot are various and the resistance to disease in tomato is complicated. To date, researchers in various countries are still devoting themselves to characterizing the pathogen, screening the resistant materials and cloning the resistance genes. Less work has been done on pathogenicity and resistance mechanism using combined cellular and molecular techniques, then hindered the usage of resistant materials effectively. Therefore, the project proposed here intends to investigate T3 pathogen which be as the predominant race in China, its invasion and diffusion in tomato lines with different levels of resistance and susceptibility, and to compare the cellular response differences between resistant materials and susceptible material, show the cellular basis of resistance in resistant tomatoes, to verify the function of the resistance gene Rx4 during the response to T3 infection process through using the fluorescent labeled pathogen and host cells and the live and real time imaging technology of Confocal Laser microscopy. These results allow us to illustrate the celluar mechanism of resistance to T3 pathogen in resistant tomatoes and the data obtained in this project will provide some fundamental basis to the use of resistant tomato lines and resistance breeding to bacterial spot.

番茄疮痂病是由黄单胞杆菌引起的严重影响我国露地和设施番茄生产的一种细菌性病害，目前生产上还没有抗性品种和有效的防治药物，培育抗病品种是最经济有效的防治措施。但是，番茄疮痂病原菌种类繁多，抗病材料的抗性表现复杂，各国的研究者们仍在致力于新的病原菌小种鉴定、抗性材料筛选和抗病基因克隆等方面的研究，缺乏从细胞学和分子生物学两个层次结合的抗病机理研究，进而阻碍了抗性材料的利用。为此，本项目将以2份不同抗性的抗病材料和1份感病材料为研究对象，通过荧光标记病原菌和寄主细胞，进行实时动态观察，系统地解析我国番茄疮痂病的优势小种——T3小种菌侵染番茄细胞和扩散的过程，比较感病材料和抗病材料对该菌侵染响应的细胞学异同，发现抗病材料抗性的细胞学基础，并探究抗性基因Rx4在细胞响应病原菌侵染过程中的作用，最终阐明番茄材料对T3小种抗性的细胞学机理，为番茄疮痂病的抗病材料利用和抗性育种提供理论依据。

番茄疮痂病是由黄单胞杆菌引起的严重影响我国番茄生产的一种细菌性病害，目前生产上还没有抗性品种和有效的防治药物，培育抗病品种是最经济有效的防治措施。但是，番茄疮痂病原菌种类繁多，抗病材料的抗性表现复杂，国内外的研究缺乏从细胞学和分子生物学两个层次结合的抗病机理研究，进而阻碍了抗性材料的利用。.为此，本项目以2份不同抗性的抗病材料和1份感病材料为研究对象，系统地解析我国番茄疮痂病的优势小种——T3小种病原菌侵染番茄细胞和扩散的过程，比较感病材料和抗病材料对该菌侵染响应的细胞学异同，发现抗病材料抗性的细胞学基础。.通过研究发现，疮痂病病原菌主要由气孔和破损的毛状体进入番茄组织内部。侵染后感病材料表皮气孔的响应变化导致其对细菌的导入能力远高于抗病材料。感病材料表皮上较高密度的毛状体也是保持更多病原菌入侵的因素。病原菌入侵后，主要定殖在细胞间隙；有部分细菌能在维管束定殖。病原菌在感病材料的入侵深度几乎贯穿整个叶片(93%)，而过敏抗性材料仅达到叶片厚度的46%。侵染后两份抗病材料均发生细胞壁结构相关的细胞学响应，表现在细胞壁加厚、papilla结构出现及维管束细胞胞质变浓稠等。此外项目还验证了Rx4抗性基因在抗感材料之间的序列及功能差异，除了与CDS有关外，启动子区域对抗性功能也有影响。.本项目首次详细比较了番茄抗感材料上疮痂病T3小种的侵染过程，发现了疮痂病抗性材料抗病性的细胞学基础，为后续进一步的抗性利用提供了理论依据。