第三章 病原物致病相关基因

1、第三章 病原物致病相关基因,第一节 病原物侵染的生物学特性,(主要内容关于侵入器官和侵入途径等问题，普病中学过，请自习),第二节 病原物基因组的结构特征,一 植物病原真菌基因组 属真核生物 有核基因组和线粒体基因组 有较少的重复DNA序列 单倍体基因组大小平均为21074107bp （如下图） 通常组织在68个染色体 上 染色体外DNA包括线粒体DNA和质粒DNA,The genome of a plant pathogenic fungiBelong to eukaryotesNuclear mitochondrial genome and the genomeThere are fewer

2、 repeat DNA sequencesHaploid genome size of an average of 2 107 4 107bp (see below)Usually organized in six to eight chromosomesExtrachromosomal DNA including mitochondrial DNA and plasmid DNA,真菌核基因,二、植物病原细菌基因组,细菌染色体是一个高度折叠的环状DNA大分子,大小约31065106bp ,一般每个细菌可携带500个基因 质粒是细菌染色体外基因组 也是环状DNA分子并能独立复制,质粒一般都不是

3、细胞生命所必须 在植物病原细菌中与致病功能有关的基因很多是成族排列或相距很近的 Bacterial chromosome is a highly folded circular DNA molecules About the size of 3 106 5 106bp Generally speaking, each bacterium can carry 500 genesPlasmids are extra-chromosomal bacterial genome Also circular DNA molecules and can replicate independently Pla

4、smids generally are not necessary for cell lifeIn plant pathogenic bacteria and pathogenic genes involved in many a family arrangement, or in close proximity,三 植物病毒基因组,以核酸为核心，外被外壳蛋白 绝大多数含ssRNA(单链RNA) 少数为dsDNA(双链DNA)、ssDNA(单链DNA)、dsRNA(双链RNA) 主要RNA植物病毒粒体的组分见表32 Nucleic acid core, outside coat protein

5、The vast majority contain ssRNA (single stranded RNA)A small number of dsDNA (double stranded DNA), ssDNA (single-stranded DNA), dsRNA (double stranded RNA)The main components of the plant RNA virus particles are shown in Table 3-2,病毒粒体的组分,ssRNA的基因组有四种类型,1. 单分体基因组 2. 两分体基因组 3三分体基因组,四、植物线虫基因组,包括核基因组和

6、线粒体基因组两个方面 自由生活的线虫Caenorhabditis elegans 核基因组大小为80Kb, 线粒体基因组13.794Kb 蛔虫类Ascaris suum 核基因组为290Kb, 线粒体基因组14.284Kb。 根结线虫Meloidogyme spp. 核基因组51Kb, 线粒体基因组20一23Kb。 Including two nuclear genome and mitochondrial genomes Free-living nematode Caenorhabditis elegans Nuclear genome size of 80Kb, Mitochondrial

7、 genome 13.794Kb Roundworm Ascaris suum class The nuclear genome of 290Kb, Mitochondrial genome 14.284Kb. Root-knot nematode Meloidogyme spp.Nuclear genome 51Kb, Mitochondrial genomes from 20 to 23Kb.,第三节 病原物致病基因的类型,一 决定亲和性的基因 1 病原物编码致病因子的基因 已发现编码胞壁水解酶 致病毒素 与植物生长调节物质合成有关酶 2 逃避和克服寄主防卫反应的基因 胞壁脂多糖(LPS)

8、 胞外多糖 植物病原真菌对植保素的解毒酶基因(pda),determine gene affinity1 gene encoding pathogen virulence factorsIt has been found to encode cell wall hydrolasePathotoxinAnd plant growth regulators synthesis enzyme2 escape and overcome the host defense response genesCell wall lipopolysaccharide (LPS)ExopolysaccharidePl

9、ant pathogenic fungi for phytoalexin detoxification enzyme gene (pda),第三节 病原物致病基因的类型,二 决定不亲和性的基因 1无毒基因 无毒基因被定义为与寄主抗病基因互作，其产物与寄主抗病基因产物互补的基因。从植物病原细菌、真菌和病毒中都发现存在无毒基因且与相应的寄主植物抗病基因互作。 如番茄叶霉病菌的无毒基因avr9 2 决定非寄主不亲和性的基因,Decisions taken by the incompatibility of genes1 non-toxic gene Toxic gene is defined as

10、the host resistance gene interactions, and host resistance gene whose product is complementary to the gene product. From plant pathogenic bacteria, fungi and viruses are found in the presence of non-toxic gene and the corresponding host plant resistance gene interactions. Such as non-toxic gene avr9

11、 fulva of2 Decide non-host incompatibility genes,第四节 植物病原细菌的致病相关基因,一 与病理过程有关的基因 (一) 与病原菌侵染有关的基因 根癌土壤杆菌是由伤口侵染的，已签定出一个染色体基因chvE与其细菌的趋化性有关 水稻黄单胞茵的有趣现象: 从气孔或水孔侵入 但分子机制 不明 A gene associated with a pathological process(A) the genetic and pathogen infectionAgrobacterium tumefaciens is a wound infection, it

12、 has signed a chromosomal gene chvE its related bacterial chemotaxis Xanthomonas Yin interesting phenomenon: the invasion of water from the pores or holes but the molecular mechanism is unknown,一 与病理过程有关的基因,(二) 决定显症的基因, determine significant disease 胞壁降解酶-组织浸离 腐烂症状, Cell wall degrading enzymes - tis

13、sue soaked from rot symptoms 毒素-坏死症状, Toxin - necrosis symptoms 毒素和多糖-萎蔫症状, Toxins and polysaccharides - wilting symptoms 激素-畸形, hormones-abnormal,一 与病理过程有关的基因,(三) 决定寄主范围的基因 1) 正向调控寄主范围的基因 根癌土壤杆菌 毒性基因 virC、virE、virF和vir H突变都可以减低致病性和限定寄主范围。 青枯假单胞菌 pGxl234上带有一类正向调控寄主范围的基因 水稻白叶枯黄单菌 hrp基因可使小种V对IR26从原来的不

14、亲和反应变为亲和反应。,Gene (iii) determine host range1) Forward host range gene regulation Agrobacterium tumefaciens Virulence genes virC, virE, virF and vir H mutation may reduce the virulence and host range is defined. Pseudomonas solanacearum A Class of positive host range gene regulation with the pGxl234

15、white rice leaf yellow single strain hrp gene can race from the original V for IR26 incompatibility response into the affinity reaction.,(三) 决定寄主范围的基因,2) 负向决定寄主范围的基因 无毒基因是负向调控寄主范围的基因 水稻白叶枯病菌小种V的无毒基因avrXa4决定对IR26的不亲和性 无毒基因-引起甘兰黑腐病菌菌株8004-在拟南芥上的致病性丧失 2) negative decision host range genesToxic gene is

16、negatively regulated genes host rangeToxic gene avrXa4 oryzae races Vs decision to IR26 incompatibilityToxic gene, causing cabbage black rot bacteria strains 8004- pathogenicity in Arabidopsis loss,关于无毒基因 热点,(1)植物病原细菌无毒基因的克隆 首个克隆基因-avrA 已克隆到40多个无毒基因(表37) 大多数都是通过基因文库互补法进行分离的 plant pathogenic bacteria

17、 toxic CloningThe first cloned gene -avrAIt has been cloned more than 40 non-toxic genes (Table 3-7)Most are carried out by separate gene libraries complementary method,关于无毒基因, toxin gene,(2)无毒基因的命名 普通接受由维维安等(AVivian和Mansfields) 1993提出的命名法 无毒基因的来源。 与无毒基因匹配的抗病基因的特征。 确定的顺序。 (2) non-toxic gene nomencla

18、tureCommon embraced by Vivian et (A.Vivian and Mansfields) named 1993 proposed law Source toxic genes. characteristics match with toxic genes of resistance genes. sequence determined,命名释义,一个无毒基因的命名应包括属名的第一个大写字母 种名或致病变种前两个字母 无毒基因分离序号及等位基因数 最后还应加上与无毒基因匹配的抗病基因名称 例如P.s.pv.pisii(抗病基因为R2)中发现的第一个无毒基因应命名为av

19、rPpiA1R2。,Naming a toxic gene should include first generic name in capital lettersSpecies or two letters before pvToxic gene number and the number of alleles isolatedFinally, we should add the name of resistance and non-toxic gene Gene matchFor example Pspv.pisii (resistance gene R2) the first gene

20、found to be non-toxic named avrPpiA1 R2.,关于无毒基因,(3)无毒基因的生理功能 似应被摒弃 应有适应性的功能 pthA是X. citri中分离的诱发柑桔溃疡的致病基因，但若将其导入Xc pvmalvacearum中却发现pthA起着无毒基因功能。 是一个有待进一步揭示的问题 3, the physiological function of non-toxic geneIt seems to be abandonedShould be adaptive functionpthA pathogenic genes isolated from X. citr

21、i citrus-induced ulcers, but if import X. c. pv. malvacearum pthA play in but found toxic gene function.It is a question for further disclosed,(四) 决定致病性或毒性的基因,1胞壁降解酶基因 (1)果胶酶 现已从至少5种病原细菌克隆到果胶酶基因(表38),1胞壁降解酶基因, Cell wall degrading enzyme gene,(2)纤维素酶 从Ech(菊欧菌)中鉴定出2种纤维素酶CelZ和CelY，其中CelZ是较重要的 Ecc(胡萝卜欧菌

22、)也能产生两种纤维素酶CelV和CelS。 (2) CellulaseIdentification from Ech (chrysanthemum Europe bacteria) in the two kinds of cellulases CelZ and CelY, which is more important CelZEcc (carrot Europe bacteria) can produce two cellulases CelV and CelS.,1胞壁降解酶基因,(3)蛋白酶 离体条件下荧光假单胞蛋白酶缺失突变体完全丧失了致病性 软腐欧氏杆菌中已经克隆了不少蛋白酶基因,

23、但其在致病过程中的作用还不太清楚 已从甘蓝黑腐病病菌中克隆了蛋白酶基因，但其对致病过程仅起微效作用。 (3) ProteaseAway from Pseudomonas fluorescens protease deletion mutants under body conditions completely lost pathogenicityErwinia soft rot in many protease genes have been cloned, but its role in the pathogenic process is not yet clearCabbage black

24、 rot bacteria from cloned protease gene, but its pathogenesis play only minor role.,2毒素基因,(1) 丁香菌素(syringmycin) ：三个丁香菌素合成基因：syrB、syrC和syrD在7Kb DNA片段中成簇排列 (2) 冠毒素(doronatin)：大豆丁香假单胞的冠毒素合成基因在90Kb的质粒上，并在30Kb的区域中成簇排列。 (3) 菜豆毒素(phaseolotoxin) ：菜豆假单胞产生该毒素的大多数基因也是成簇排列的 (4) 烟毒素(tabtoxin) ：合成姻毒素的基因簇由基因tblA和t

25、blB，以及调控基因lemA基因组成的,(1) cloves streptozotocin (syringmycin): Three cloves streptozotocin synthetic genes: syrB, syrC and syrD are clustered in 7Kb DNA fragment(2) Crown toxin (doronatin): Soybean crown toxin Pseudomonas syringae synthetic gene in the plasmid 90Kb and 30Kb are clustered in the area.(

26、3) kidney bean toxin (phaseolotoxin): Phaseolus vulgaris Pseudomonas most genes that produce the toxin are also arranged in clusters(4) tobacco toxin (tabtoxin): Synthesis of marriage toxin gene cluster and the gene tblA tblB, as well as the regulation of gene lemA genetic makeup,3胞外多糖基因,许多植物病原细菌中已证

27、明胞外多糖与其致病性有关 玉米细菌性枯萎病菌(E. stewardtii)引起植物萎蔫和叶枯。粘粒克隆pES2144含有5个胞外多糖基因epsAE 青枯假单胞中至少有3个基因簇对EPS的生物合成是重要的 Many plant pathogenic bacteria has proved Exopolysaccharide its pathogenicityCorn bacterial wilt pathogen (E. stewardtii) cause plant wilting and leaf blight. PES2144 cosmid clone containing five ex

28、tracellular polysaccharide gene epsA EPseudomonas solanacearum at least three gene clusters for EPS biosynthesis is important,4激素基因,吲哚乙酸的合成，需要两种酶：色氨酸单氧化酶和吲哚乙酰胺水解酶，这两种酶分别是由基因iaaM 和iaaH编码的。两个基因组成IAA操纵子。 根癌土壤杆菌也有类似的功能的基因iaaM 和iaaH Indole acetic acid synthesis requires two enzymes: tryptophan monooxygen

29、ase and indole acetic acid amide hydrolase, these two enzymes are genetically encoded iaaM and iaaH. IAA two genes operon.Agrobacterium tumefaciens gene iaaM have similar functions and iaaH,注意,毒素基因、多糖基因、激素基因的实质,5hrp基因,是决定病原菌对寄主植物致病性和诱导非寄主植物过敏反应的基因。 hrp基因最初是1986年由林达格伦(PBLindgren)等描述的 绝大多数植病细菌存在两类hrp基

30、因族：一类大的：为1741kb，一类小的：2.54 kb hrp基因结构和功能存在保守性 hrp基因是一类基因产物未知的基因 对hrp基因产物在植物一病原苗互作中的精确功能还不太清楚,It is to decide on the host plant gene pathogenic and non-host plants induce allergic pathogens.hrp gene originally in 1986 by Linda Glenn (P.B.Lindgren) and other describedThe vast majority of Plant Patholog

31、y There are two types of bacteria hrp gene families: one large: as 17-41kb, a class of small: 2.5-4 kbhrp gene structure and function of the presence of conservedhrp gene is a gene product of genes of unknown typeHrp precise function of the gene product in the plant a seedling pathogen interaction i

32、n not yet clear,6dsp(disease specific pathogenicity)基因,只影响对寄主植物的侵染能力，而不影响在非寄主植物上诱导过敏反应的能力的基因称为dsp基因 dsp基因多数没有得到充分的研究 Only the effects on the ability to infect the host plant without affecting the non-host plants ability to induce allergic reaction called dsp gene geneMost dsp gene has not been adequately studied,7外泌基因 extracellular secretion gene,细菌的分泌功能被破坏，一般表现为完全丧失致病性 Bacterial secretory function is damaged, the general performance of a complete loss of pathogenicity,8致病性调控基因,致病性调控基因是指那些不直接编码致病因子，但对致病因子产生的总体水平发生影响的基因。 Pathogenicity regul