目前已报道的很多内生菌株对植物抗病性具增强作用。但内生菌群与宿主品种抗/感病能力间的相关性研究较少。溃疡病是威胁柑橘生产的重要病害之一，充分了解寄主的抗病机制是防治该病的前提。本项目在前期工作的基础上，拟选用温州蜜柑（抗溃疡品种）和赣南纽荷尔脐橙（感溃疡品种）为材料，①应用454焦磷酸测序技术分别研究两种柑橘在不同生长期体内细菌菌群结构特征与功能差异，结合可培养菌株的相关信息系统分析内生细菌菌群与宿主品种抗/感溃疡病能力的相关性；②接种优势内生细菌和（或）溃疡病菌于两种柑橘无菌苗，通过测定植株发病程度、电镜观察病菌形态和分布、qRT-PCR检测植株中PDF 1.2基因表达情况，明确优势内生细菌对宿主抗/感病能力的影响和作用，验证内生细菌菌群与柑橘品种抗/感溃疡病能力的相关性。研究结果可为充分认识柑橘品种抗/感溃疡病的本质提供理论依据，亦可为深入了解内生菌群体与宿主的互作关系奠定理论基础。

Many endophyte strains reported is able to enhance the resistance of plant to host currently. However, it is few researched that there is relativity between the endophytic community and the resistance or susceptibility of host variety. Citrus canker is an important disease of orange, and it is essential to control the disease that the mechanism of citrus resistance is known thoroughly. On base of the former work, the research will be done involving two contents by using Citrus unchiu Marc. (variety with resistance to citrus canker) and Citrus sinensis Osbeck (variety with susceptibility to citrus canker). ① Detecting all endophytic bacteria from orange by Pyrosequencing, and combining with the correlative informations of cultured endophytic bacteria obtained, the relativity will be analysed. ② After inoculating the main endophytic bacteria from host and (or) Xanthomonas axonopodis pv. citri to two orange sterile seedlings, the disease will be graded, and the cellar ultrastructure and the distributing of pathogen will be observed by using electronmicroscope, and the gene express of Plant Defensin 1.2 (PDF1.2) in citrus is inspected by applying the Quantitative Real Time Polymerase Chain Reaction (qRT-PCR), all which will cleared the influence and the action of the main endophytic bacteria from orange on the resistance of host variety, and the relativity of endophytic bacteria community with the ability of orange variety against the citrus canker will be validated. The results will be able to provide a theoretical evidence to reveal the nature of the varietal resistance or susceptibility of orange to citrus canker, and establish a theoretical foundation to understand further the interaction between endophytic bacteria community and their hosts.