殺菌劑毒理學(xué)I課件

1、殺菌劑毒理學(xué)夏海洋初期中期末期初期中期末期病害侵染循環(huán)模式圖木瓜海棠龍柏銹病轉(zhuǎn)主寄生銹孢子器性孢子器冬孢子角殺菌劑Fungicide ：A substance possessing the power of killing or preventing the growth of fungi. 殺菌劑（fungicide）：殺菌、抑菌、提高抗病力，所有這種能達(dá)到防治植物病害的農(nóng)藥都是殺菌劑。Bactericide：殺細(xì)菌劑A bactericide is a substance that kills bacteria and, preferably, nothing else. Fungicid

2、e ResistanceWays pathogens are resistant to a fungicide: a. decrease entrance into the fungus b. the fungicide is detoxified c. decreased effectiveness at the target site within the fungus d. there is compensation for the Adamage the fungicide does, etc.Why pathogens are resistant to fungicide: a. g

3、enetic mutations occur and/or b. natural occurring individuals are not affected (insensitive), and then by reproduction these become the majority pathogen in the turf.保護(hù)性和內(nèi)吸性Contact - Fungicides must come in contact with the pathogen, so all plant parts that may be exposed to the pathogen must be co

4、vered with the fungicide so the plant is protected. Think of painting the turf, turf not painted is not protected.(Fore and Daconil are examples.)Systemic - Fungicide enters and moves within the plant. (Not all systemics are the same. The direction and degree of movement vary.) - Local penetration a

5、nd limited long distance movement. -Upward movement (acropetal) -Upward and downward movement (acropetal and basipetal)Mobility of Fungicide乙膦鋁可向上下兩個方向傳導(dǎo)。廣譜和專一性General or Nonspecific or Broad Spectrum Biochemical - fungicide affects the pathogen in many ways.Specific or Narrow Biochemical - Mode of

6、Action - fungicide activity is targeted at a specific site in the pathogen. (Because these affect only one biochemical function or pathway, genetic changes or naturally insensitive fungus have a much greater chance to overcome the fungitoxic effect resulting in the development of resistance.)殺菌劑分類按化

7、學(xué)成分來源和化學(xué)結(jié)構(gòu)可分為無機(jī)殺菌劑:如硫酸銅、石硫合劑。有機(jī)殺菌劑:有機(jī)硫、有機(jī)汞、有機(jī)砷、有機(jī)磷、氨基甲酸酯類等。生物殺菌劑:農(nóng)用抗生素、植物源殺菌劑及生物活體殺菌劑殺菌劑分類按使用方法分土壤處理劑指通過噴施、灌澆、翻混等方法防治土壤傳帶的病害的藥劑，如氯化苦、石灰、五氯硝基苯等；葉面噴灑劑通過噴霧或噴粉主要施于作物的殺菌劑，如波爾多液、石硫合劑等種子處理劑用于處理種子的殺菌劑，主要防治種子傳帶的病害，或者土傳病害，如戊唑醇等殺菌劑分類按作用對象分殺真菌劑殺細(xì)菌劑A typical cell and cell components殺菌劑分類按作用機(jī)理分抑制或干擾病菌能量的生成抑制或干擾病菌

8、的生物合成對病菌的間接作用對糖酵解和脂質(zhì)氧化的影響百菌清、克菌丹和滅菌丹可以與磷酸甘油醛脫氫酶的-SH結(jié)合，使其失去催化3-磷酸甘油醛/磷酸二羥丙酮形成1,3-二磷酸甘油醛的活性。抑制輔酶A活性的殺菌劑如克菌丹、二氯萘醌等都會影響脂肪的氧化，減少能量的生成。脂肪酸氧化殺菌劑抑制輔酶A的活性，使脂肪酸的-氧化就不能進(jìn)行,作用于輔酶A的殺菌劑主要有：克菌丹、三氯萘醌、代森類，都是脂肪酸-氧化的抑制劑。對乙酰輔酶A形成的影響克菌丹能夠特異性抑制丙酮酸脫氫酶的活性，阻止乙酰輔酶A的形成。作用位點(diǎn)是丙酮酸脫氫酶系中的硫胺素焦磷酸(TPP)。TPP在丙酮酸脫羧過程中起轉(zhuǎn)移乙?；淖饔?，而TPP接受乙?；鶗r

9、只能以氧化型(TPP+)進(jìn)行。但有克菌丹存在的情況下，TPP+結(jié)構(gòu)受破壞，失去轉(zhuǎn)乙酰基的作用，乙酰輔酶A不能形成。對檸檬酸循環(huán)的影響福美雙、克菌丹、硫磺、二氯萘醌等能夠使乙酰輔酶A失活，并可以抑制檸檬酸合成酶、烏頭酸酶的活性；代森類殺菌劑和8-羥基喹啉等可以與菌體檸檬酸循環(huán)中的烏頭酸酶螯合，使酶失去活性；克菌丹通過破壞酮戊二酸脫氫酶的輔酶-硫胺素焦磷酸結(jié)構(gòu)使活性喪失；硫磺和萎銹靈可抑制琥珀酸脫氫酶和蘋果酸脫氫酶的活性；含銅殺菌劑能夠抑制延胡索酸酶的活性呼吸鏈對呼吸鏈的影響殺蟲劑魚藤酮(rotenone)和殺菌劑敵磺鈉(fenaminosulf)是復(fù)合物I抑制劑羧酰替苯胺類(carboxamid

10、e)殺菌劑是復(fù)合物II抑制劑。對于復(fù)合物III的2個活性中心，抗菌素粘噻唑菌醇(myxothiazol)和幾種重要的殺菌劑是Qo位點(diǎn)抑制劑，抗霉素A(antimycin)和氰霜唑(cyazofamid ，IKF916)等新殺菌劑是Qi位點(diǎn)抑制劑。氰化物(cyanide)和疊氮化物(azide)是復(fù)合物抑制劑，一些含有-CN基團(tuán)的殺菌劑則是復(fù)合物IV的強(qiáng)烈抑制劑，如二硫氰基甲烷殺菌、殺線蟲劑。水楊基氧污酸(salicyl-hydroxamic acid，SHAM)是旁路氧化酶抑制劑。氧化磷酸化抑制劑，即ATP解偶聯(lián)劑包括：敵螨普(dinocap)、敵菌酮(drazoxolon)、三苯錫(fent

11、in)等有機(jī)錫(organo-tin)和氟啶胺(fluazinam)等二硝基苯胺殺菌劑等等，它們影響質(zhì)子通過線粒體膜，而不是作用于ATP 合成酶活性。寡霉素(oligomycin)是ATP 合成酶抑制劑。對呼吸鏈電子傳遞的影響對旁路氧化途徑的影響旁路氧化酶( alternative oxidase, 簡寫AOX)水楊基肟酸(SHAM)是AOX的特異性抑制劑，普遍存在于植物體內(nèi)的(類)黃酮類物質(zhì)也能夠強(qiáng)烈抑制旁路氧化作用。(類)黃酮類物質(zhì)與AOX的相互作用至少包括通過清除自由氧抑制AOX的誘導(dǎo)和直接抑制AOX酶活性兩種方式抑制或干擾病菌的生物合成抑制細(xì)胞壁組分的生物合成抑制細(xì)胞膜組分的生物合成抑

12、制核酸生物合成和細(xì)胞分裂抑制病菌氨基酸和蛋白質(zhì)生物合成抑制細(xì)胞壁組分的生物合成對肽多糖生物合成的影響對幾丁質(zhì)生物合成的影響對黑色素生物合成的影響對肽聚糖生物合成的影響青霉素作用機(jī)理對幾丁質(zhì)生物合成的影響 對黑色素生物合成的影響抑制細(xì)胞膜組分的生物合成對麥角甾醇生物合成的影響對卵磷脂生物合成的影響對脂肪酸生物合成的影響對細(xì)胞膜的直接作用對麥角甾醇生物合成的影響對卵磷脂生物合成的影響磷脂和脂肪酸是細(xì)胞膜雙分子層結(jié)構(gòu)的重要組分。硫趕磷酸酯類的異稻瘟凈、敵瘟磷等的作用機(jī)理是抑制細(xì)胞膜的卵磷脂生物合成。通過抑制S-腺苷高半光氨酸甲基轉(zhuǎn)移酶的活性，阻止磷脂酰乙醇胺的甲基化，使磷脂酰膽堿(卵磷脂)的生物合成

13、受阻，改變細(xì)胞膜的透性。例如細(xì)胞膜的透性改變可以減少UDP-N-乙酰葡萄糖胺泌出，進(jìn)一步影響幾丁質(zhì)的生物合成。對脂肪酸生物合成的影響脂肪酸是細(xì)胞膜的重要組分。已知稻瘟靈殺菌劑的作用靶標(biāo)是脂肪酸生物合成的關(guān)鍵酶乙酰CoA羧化酶，干擾脂肪酸生物合成，改變細(xì)胞膜透性。對細(xì)胞膜的直接作用有機(jī)硫殺菌劑與膜上亞單位連接的疏水鍵或金屬橋結(jié)合，致使生物膜結(jié)構(gòu)受破壞，出現(xiàn)裂縫、孔隙、膜失去正常的生理功能。含重金屬元素的殺菌劑可直接作用于細(xì)胞膜上的ATP水解酶，改變膜的透性。抑制核酸生物合成和細(xì)胞分裂抑制RNA生物合成干擾核酸代謝干擾細(xì)胞分裂嘌呤堿與苯并咪唑類內(nèi)吸劑的結(jié)構(gòu)對核酸合成的間接影響在嘌呤合成中，F(xiàn)H4（

14、四氫葉酸）是一輔酶，使用磺酰胺類化合物（如敵銹鈉）與葉酸分子結(jié)構(gòu)中的氨基苯甲酸部分相似，因而與對氨基甲酸爭奪酶系統(tǒng)，阻礙了菌體正常的葉酸合成。甲菌啶（Dimethrimol）、乙菌啶（Ethirmol）是葉酸代謝甲基化中醛縮酶輔酶吡哆醛磷酸的抑制劑，甲菌啶、乙菌啶在結(jié)構(gòu)上與吡哆醛磷酸相似，冒充了吡哆醛，使參與四氫葉酸代謝作用酶的活性受到抑制，從而干擾了葉酸傳遞過程中C-1轉(zhuǎn)移反應(yīng)腺苷脫氨形成次黃苷是重要的核酸代謝反應(yīng)之一，而且次黃苷與白粉病菌的致病性有關(guān)。烷基嘧啶類的乙菌定作用機(jī)理是抑制腺苷脫氨酶的活性，阻止次黃苷的生物合成。 腺苷脫氨酶乙菌定腺苷次黃苷抑制病菌氨基酸和蛋白質(zhì)生物合成殺菌劑（如

15、放線菌酮）可與核糖體結(jié)合，影響tRNA、mRNA與核糖體的結(jié)合，失去了tRNA、mRNA的正常作用。氯硝胺、春雷霉素主要與菌體核糖體中的小亞基結(jié)合，放線菌酮、稻瘟散主要與大亞基結(jié)合，破壞菌體原有核糖體結(jié)構(gòu)，從而阻礙了氨酰-tRNA與核糖體的結(jié)合，使肽鏈不能伸長。殺菌劑影響葉酸代謝和轉(zhuǎn)氨基作用，使蛋白質(zhì)合成受阻。甲菌定和乙菌定能干擾在葉酸代謝和轉(zhuǎn)氨基作用作為輔酶的磷酸吡哆醛，使蛋白質(zhì)合成受阻。影響氨基酸的活化tRNA只能與活化的氨基酸結(jié)合，如氨基酸類殺菌劑可以取代活化的氨基酸，形成攙假的tRNA。 影響蛋白質(zhì)合成的轉(zhuǎn)位與轉(zhuǎn)肽 轉(zhuǎn)位：合成蛋白質(zhì)有起始和終止位點(diǎn)，殺菌劑如鏈霉素可把tRNA固定在起始

16、位點(diǎn)上，而不能達(dá)到終止位點(diǎn)。 轉(zhuǎn)肽：稻瘟散和放線菌酮可影響轉(zhuǎn)肽。影響終止（兩個亞基不能分開） 肽鏈增長是在核糖核蛋白體的基礎(chǔ)上增長的，到一定長度肽鏈要分開，但使用鏈霉素，茴香霉素，放線菌酮可影響肽鏈繼續(xù)加長，形成異樣pr失去原有pr的功能，主要是抗生素與菌體中的DNA分子中的鳥嘌呤脫氧核苷，以氫鍵相連形成特殊的復(fù)合物。干擾細(xì)胞分裂苯并咪唑類藥劑通過與構(gòu)成紡錘絲的微管的亞單位-微管蛋白結(jié)合，阻礙其與另一組分-微管蛋白裝配成微管，或使已經(jīng)形成的微管解裝配，破壞紡錘體的形成，使細(xì)胞有絲分裂停止，表現(xiàn)染色體加倍，細(xì)胞腫漲。苯菌靈和硫菌靈在生物體內(nèi)也是轉(zhuǎn)化成多菌靈發(fā)揮作用的對病菌的間接作用離體與活體殺菌

17、劑體內(nèi)活化誘導(dǎo)抗性殺菌劑在離體下對病菌的孢子萌發(fā)和菌絲生長沒有抑制作用，或作用很小。但施用到植物上以后能夠表現(xiàn)很好的防病活性。三環(huán)唑除了抑制附著胞黑色素生物合成，阻止稻瘟病菌對水稻的穿透侵染以外，還能夠在稻瘟病菌侵染的情況下誘導(dǎo)水稻體內(nèi)O2-產(chǎn)生及POX等抗病性相關(guān)酶的活性和抑制稻瘟病菌的抗氧化能力等作用。因此，三環(huán)唑在水稻上防治稻瘟病的有效劑量遠(yuǎn)遠(yuǎn)低于離體下對黑色素合成的抑制劑量。三乙膦酸鋁在離體下對病菌生長發(fā)育幾乎沒有抑制作用，施用于番茄上可以防治致病疫霉(Phytophthora infestans)引起的晚疫病，但在馬鈴薯上不能防治同種病菌引起的晚疫病。這是因?yàn)槿异⑺徜X在番茄體內(nèi)可以

18、降解為亞磷酸發(fā)揮抗菌作用，而在馬鈴薯體內(nèi)則不能降解成亞磷酸。Plant activators In contrast to conventional fungicides, plant activators have no direct effect on pathogens.Plant activators induce plants to produce natural disease-fighting compounds.Plant activators Acibenzolar (Actigard)Harpin (Messenger)Biological control organism

19、sNatural Plant Defense MechanismsSalicylic acid pathway Induces SAR (systemic acquired resistance), a natural biological defense response to pathogen attack. Jasmonic Acid Pathway - Induces the production of disease and insect defense compounds.Salicylic Acid Pathway Production of active oxygen (hyd

20、rogen peroxide, peroxidase)Peroxidases have been associated with fungal cell wall degradation and pathogen defense signalingThickening plant cell wallIncreasing lignificationProduction of phenolic esters that strengthen cross linkingSalicylic Acid PathwaySystemic and local accumulation of Pathogenes

21、is Related Proteins (PR-Proteins) chitinases-1,3 GlucanaseSystemic accumulation of anti-microbial compounds called phytoalexins.ChitinasesChitin is the major component of all fungal cell walls except for the Oomycetes Chitinases break down fungal cell wallsChitinases can break down insect exo-skelet

22、onsActivity is greatly enhanced by Glucanase-1,3 Glucanases Glucans and cellulose are the major components of Oomycete cell wallsAntifungal activity is most often in combination with ChitinaseDirect defense: Degrade fungal cell wallsIndirect defense: Promoting the release of oligosaccharides that ac

23、t as elicitors of defense reactionsJasmonic Acid PathwayFarmer and Ryan (1990) discovered that jasmonic acid volatilized from sagebrush could trigger defense gene expression in adjacent tomatoesJasmonic acid volatiles act as attractants for beneficial insectsJasmonic acid induces the production of d

24、isease and insect defense compounds.Defense ProteinsPhytochemicalsPhytochemicalsDifferent from phytoalexins in that phytochemicals are induced by wounding. PhenolicsFuranocoumarins, Coumarins, Tannins, Lignin, other phenolicsTerpenoidsAlkaloidsExamples of plant activators Acibenzolar (Actigard)Harpi

25、n (Messenger)Harpin is a natural protein found in many common pathogenic microorganisms;Erwinia amylovora, E. chrysanthemi, Pseudomonas syringae, Pseudomonas solanecarum, Xanthomonas campestris.Biological control organismsMode of action - ActigardInduction of Systemic Acquired ResistanceSAR gene exp

26、ressionClassical SARPDF1.2 and othergene expressionPest resistanceGene expressioninvolvedin plant growthIncreased nutrient uptakeIncreased photosynthesisSignal amplificationreceptorharpinIon-exchangeSalicylic Acid PathwayJasmonic Acid PathwayMode of action - MessengerBiological FungicidesAccording t

27、o USDA, they are beneficial Fungi and Bacteria which attack and control Plant pathogens and the disease which they Cause.How Do Biological Fungicides Work?Direct CompetitionAntibiosisPredation or parasitismInduced resistance of host plant.Direct Competition Before infection by pathogen occurs BCO(Bi

28、ological Control Organisms) must become associated with roots; area is called rhizosphere. This area is nutrient rich, a food sourceGenerally BCO must be present in large numbers to competeAntibiosisAntibiosis involves the production of toxins which inhibit the growth of the pathogen.Once the pathog

29、en enters the root, antibiosis may have no effect.BCO may have antibiosis and antagonistic abilities.Predation or ParasitismPredation or parasitism is when the BCO attacks and feeds on the pathogen.Again the BCO must be present before the pathogen invadesA、木霉菌寄生于棉花枯萎病菌菌絲B、木霉菌寄生于腐霉菌菌絲C、木霉菌寄生于立枯絲核菌菌絲A

30、CBInduced Host ResistanceOnce attacked a defense system kicks in.Not an immune system, but internal biochemical warfare to inhibit infectionHost plants are purposely inoculated to induce this resistance. The BCO is the trigger.Advantages of Biological FungicidesThey help reduce chemical useThey help

31、 in resistance managementThey are mostly safer to use than chemicalsThey have lower REI s in most casesThey are generally less phytotoxicDisadvantages of Biocontrol FungicidesTend to be more difficult to implementGenerally have a narrow target rangeMay not work as quickly as chemicalsDo not eradicat

32、e pathogen or rescue the host plantMay have a shorter shelf-lifeGenerally more expensiveMay not be compatible with chemical fungicides or bactericidesDelivery of Biological Control OrganismsFoliar sprays, Powdery Mildew, AQ10Sprays or drench, Phytophthora, Botrytis, Alternaria, MycostopGranular incorporation into soil mix,