中译英
    植物病原菌侵染寄主植物的过程是非常复杂的，一般经过吸附、识别、侵入、定殖、扩展、显症等过程，且每一个过程都涉及相应的基因参与。在原核细胞中存在着一类类似真核细胞组蛋白的拟核结合蛋白，被称为类组蛋白。其中，整合宿主因子(IHF)和DNA结合转录调节子HU (U93)是类组蛋白中最重要的成员，在许多细胞生命过程中起到重要作用^[2-6]。IHF是由具约35%相似性的两个亚基IHFα（ihfA基因编码）和IHFβ（ihfB基因编码）组成一个大小为20kDa的异型二聚体(αβ)^[7-9]。HU是由具约70%相似性的两个亚基HUα（hupA基因编码）和HUβ（hupB基因编码）组成同型(αα或ββ)或异型二聚体(αβ)^[10-12]。当结合到DNA 上以后，IHF或HU蛋白能在其DNA 靶位点引起DNA构象的变化，这可能是IHF和HU能广泛参与细菌DNA复制、重组、和转录的原因^[13-15]。很多研究表明，IHF和HU蛋白在许多病原细菌中作为全局性调控因子，主要与RNA聚合酶直接相互作用，以促进或抑制很多启动子的活性，从而改变病原细菌毒性基因的转录表达，起致病性调控作用^[16-18]。有关IHF和HU蛋白在植物病原细菌中的功能和作用研究较少，在重要病原细菌D.zeae中，IHF和HU蛋白的作用、功能迄今未见报道。本研究采用无痕基因敲除的方法，构建D.zeaeEC1的ihfA、ihfB、hupA、hupB和基因缺失突变体，拟揭示玉米狄克氏菌的致病机理、完善植物病原细菌的致病性综合调控网络，为寻找和开发新型药物靶标及制定病害防控策略提供理论基础。

Invasion of the host plant by phytopathogenic fungi and bacteria is a very complex process, which usually cover processes of adsorption, recognition, invasion, colonization, spread and symptom appearance. Different genes are involved in each step. Nucleoid-associated proteins, also known as histone-like proteins, are found in the prokaryotic cells. Integration host factor (IHF) and DNA-binding transcriptional factor histone-like protein from strain U93 (HU) are important histone-like proteins, which serve indispensable function in many cellular processes^[2-6]. IHF is a 20kDA heterodimer(αβ) comprising of two subunits, IHFα (coded by ihfA gene) and IHFβ (coded by ihfBgene), which have about 35% identity to each other^[7-9]. HU is a homodimer (αα or ββ) or heterodimer (αβ) comprising of two subunits, HUα (codedby hupA gene) and HUβ (coded by hupB gene), which have about 70% identity to each other^[10-12]. Upon binding to the DNA, IHF or HU causes a conformational change of DNA at the target site. This is considered as a mechanism by which IHF and HU are involved in bacterial DNA replication, recombination and transcription^[13-15]. IHF and HU act as global regulators in many pathogenic bacteria, and promote or inhibit the activities of several promoters by directly reacting with the RNA polymerase. As a result, they can change the transcriptional expression of virulence genes in the pathogenic bacteria, thereby regulating the virulence^[16-18]. However, only a few studies are devoted to the function of IHF and HU in phytobacteria.The specific role of IHF and HU in D.zeae is much less understood. In this study, unmarked gene deletion was used to construct ihfA, ihfB, hupA and hupB of the D.zeae strain EC1 and the corresponding deletion mutants. The purpose was to reveal the virulence mechanism and the virulence regulatory network of D.zeae in host plant invasion, so as to identify the potential targets and to formulate the pest control and prevention strategies.