1、殺菌劑毒理學(xué)-Introduction,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。,1,Introduction,Fungicides are used to eradicate or prevent the undesirable growth of fungal microorganism in many agricultural, horticultural

2、, and industrial situations.,Introduction,殺菌劑（fungicide）： 殺真菌劑（fungicide） 抑真菌劑 (fungistat) 殺細(xì)菌劑（bactericide） 殺病毒劑 （viricides）,3,殺菌劑的發(fā)展,1、第一代殺菌劑（inorganic chemicals）; 2、第二代殺菌劑（organic chemicals） 傳統(tǒng)保護(hù)劑(conventional protectants) 植物藥害(phytotoxicity) ； 3、第三代殺菌劑：內(nèi)吸性殺菌劑（systemic fungicide ） 4、第四代殺菌劑：三環(huán)唑等較早

3、使用的無殺菌毒性化合物。,4,殺菌劑的發(fā)展,1、無機(jī) -有機(jī) 2、多作用位點(diǎn)-少作用位點(diǎn)-單一位點(diǎn) 3、非內(nèi)吸-內(nèi)吸 4、保護(hù)劑-治療劑,5,Ideal fungicide characteristics,low mammalian toxicity low ecotoxicity low phytotoxicity high penetration rates for spores and mycelia limited biodegradation on the plant surface.,6,Classification of Fungicide,In addition to clas

4、sification by chemical structural grouping, fungicides can be categorized agriculturally and horticulturally according to the mode of application (use) as:,7,Classification according to use,(a) soil application fungicides, (b) foliar fungicides which are applied to plants above the ground; (c) dress

5、ing fungicides applied after harvesting with the aim of preventing fungus development on stored crops.,8,Classification according to action,Fungicides may also be described according to their general mode of action: (a) protective fungicides inhibiting the development of fungi by either sporicidal e

6、ffects or foliar effects creating an environment on the plant surface not conducive to fungal growth;,9,Classification according to action,(b) post-infection curative fungicides which kill (inhibit) the developing mycelium in the plant epidermis. (c) Post-symptomatic eradication fungicides which pen

7、etrate and kill the mycelium and new spores.,10,Classification according to action,保護(hù)型殺菌劑 protective fungicide 鏟除性殺菌劑 eradication fungicide 治療性殺菌劑 curative fungicide 內(nèi)吸性殺菌劑 systemic fungicide,11,Toxicity of fungicide,In general, fungicides are of low to moderate mammalian toxicology, although they a

8、re believed to have a higher overall incidence than other pesticides to cause developmental toxicology and oncogenesis.,12,Toxicity of fungicide,It has, for example, been estimated that more than 80 per cent of all oncogenic risk from the use of pesticides comes from a few fungicides.,13,Toxicity of

9、 fungicide,Fungicides usually are responsible for only a small proportion of pesticide-related deaths, and account for only about 5 per cent or less of human pesticide exposures reported to Poison Control Centers.,14,Toxicity of fungicide,It has been noted that since fungi differ significantly in mo

10、rphology and physiology from other forms of life, they may be successfully combated by compounds of low toxicity to other organisms, notably mammals.,15,Part II Mode of Action,16,殺菌劑毒理學(xué),殺菌作用(fungitoxicity) 抑菌作用(fungistasis) 內(nèi)吸性殺菌劑(systemic fungicides, systemics) 抗產(chǎn)孢劑(antisporulants),17,內(nèi)吸性殺菌劑（system

11、ic fungicide ）,選擇性(selectivity) (1) 靶標(biāo)位點(diǎn)(target site)和作用位點(diǎn)(site of action) (2)靶標(biāo)受體(receptor)對藥劑的親合力(affinity)的差異 (3)藥劑對原生質(zhì)膜滲透性(permeability)的差異 (4)對殺菌劑的積累(或排出)、解毒(detoxify)作用的差異等,18,殺菌劑毒理學(xué),離體（in vitro） 活體（in vivo） 無殺菌毒性化合物(non-fungitoxic compounds) (1)干擾病原菌的致病機(jī)理，削弱病原菌的致病力或使病原菌不能侵入；三環(huán)唑(tricyclazole)為

12、抗穿透劑(antipenetrant) (2)提高寄主植物的抗病能力。系統(tǒng)性獲得抗病性(systemic acquired resistance, SAR) ;植物防衛(wèi)激活劑(plant defense activators) .,19,殺菌劑毒理學(xué),病害防治化合物(disease control compounds): 無殺菌毒性但是又能夠防治植物病害的化合物。 在離體下無殺菌毒性，在活體內(nèi)通過削弱病原菌的致病能力或者提高寄主抗病能力來達(dá)到防治病害的作用機(jī)理也被稱為間接作用機(jī)理(indirect mode of action) 。,20,Mechanisms of Fungicide Act

13、ion,Biosynthesis: Sterol, Nucleic acid, protein, mitosis and cell division, lipid, glucan(葡聚糖), cell wall Respiration: Electron transport, oxidative phosphorylation Growth regulator: cell wall biosynthesis-inhibiting oomyceticides Structure,21,1: Nucleic acids synthesis,(1) RNA polymerase I PhenylAm

14、ides苯酰胺類: Metalaxyl甲霜靈 (2) Adenosin-deaminase hydroxy-pyrimidines(嘧啶): Resistance in powdery mildews (3) DNA/RNA synthesis (4) DNA topoisomerase,22,2: Mitosis and cell division,(1)-tubulin assembly in mitosis Benzimidazole: Carbendazim多菌靈 Diethofencarb乙霉威 Negative cross resistance to Diethofencarb乙霉

15、威,23,Respiration,(1) Complex I NADH Oxidoreductase: Pyrimidinamine (2) Complex II: succinate-dehydrogenase琥珀酸脫氫酶 SDHI(Succianate dehydrogenase inhibitor) Boscalid:啶酰菌胺,24,Respiration,(3) Complex III: cytochrome bc1 (ubiquinol 輔酶oxidase at Qo site (cyt b) Qol (Quinone outside Inhibitors) Azoxystrobin

16、,嘧菌酯 kresoxim-methyl,醚菌酯,25,Respiration,(4) complex III: cytochrome bc1 (ubiquinone-reductase) at Qi site Qil-fungicides (Quinone inside inhibitors) (5) uncouplers of oxidative phosphorylation (6) inhibitors of oxidative phosphorylation, ATP synthase: organo tin compounds,26,4 amino acids and protei

17、n synthesis,(1)methionine biosynthesis Pyrimethanil 嘧霉胺 (2) protein synthesis Antibiotic: kasugamycin春雷霉素，streptomycin鏈霉素，oxytetracycline土霉素,27,5 signal transduction,(1) G-proteins in early cell signalling: quinolines(喹啉類) (2) MAP (Mitogen-activated protein ) /Histidine-Kinase on osmotic signal tran

18、sduction: dicarboximides二甲酰亞胺類 ：iprodione異菌脲，procymidone 速克靈，vinclozolin乙烯菌核利，,28,6 lipids and membrane synthesis,(1) phospholipid biosynthesis, methyltransferase: pyrazophos 定菌磷 (2) lipid peroxidation: (3) cell membrane permeability, fatty acids: (4) phospholipid biosynthesis and cell wall depositi

19、on: Carboxylic acid amides (5) microbial disrupter of pathogen cell membranes: Microbial (Bacillus sp)枯草桿菌,29,7 Sterol biosynthesis in membrances,(1) C14-demethylase in sterol biosynthesis : DMI-fungicides (DeMethylation inhibitors) imidazole,咪唑類，imazalil抑霉唑 Triazoles: propiconazole,丙環(huán)唑 triadimefon三

20、唑酮，diniconazole烯唑醇，difenoconazole苯醚甲環(huán)唑 (世高),30,7 Sterol biosynthesis in membrances,(2) 3-keto reductase, C4-demethylation Fenhexamid 環(huán)酰菌胺 (3) squalene(角)鯊烯epoxidase in sterol biosynthesis,31,8. Glucan葡聚糖synthesis,(1) trehalase海藻糖酶and inositol (纖維醇, 纖維糖)-biosynthesis: antibiotic, validamycin有效霉素 (2)c

21、hitin synthase: polyoxins多氧菌素,32,9 melanin synthesis in cell wall,(1) reductase in melanin biosynthesis MBI-R (Melanin Biosynthesis inhibitors- reductase) Tricyclazole:三環(huán)唑 (2) dehydratase in melanin biosynthesis MBI-D (Melanin Biosynthesis inhibitors -dehydratase),33,10 host plant defence induction,

22、(1)salicylic acid(水楊酸) pathway Acibenzolar-S-methyl阿拉酸式苯S-甲基 Probenazole噻菌靈,34,11 Multi-site contact activity,(1) inorganic: copper, sulphur (2) dithiocarbamate and relatives: mancozeb代森錳鋅，thiram福美雙 (3) chloronitriles氯化氰類: chlorothalonil百菌清 (4) sulfamides 硫酰胺類 Dichlofluanid抑菌靈,35,11 Multi-site conta

23、ct activity,(4) guanidines胍 (5) triazines三嗪類 Anilazine敵菌靈 (6) quinones醌類 Dithianon二噻農(nóng),36,Biological mode of actionFungicidal action can be expressed in one of two physically visible ways.,Inhibition of spore germination. Inhibition of fungus growth.,37,Physiological mode of action What happens at th

24、e cellular level to cause the visible effects on spore germination and fungal growth?,38,Why is it important to be familiar with the physiological mode of action of a fungicide ?,For resistance management and preservation of fungicide effectiveness.,39,The physiological mode of action,Fungicides are

25、 metabolic inhibitors and their modes of action can be classified into four broad groups. Inhibitors of electron transport chain. Inhibitors of enzymes. Inhibitors of nucleic acid metabolism and protein synthesis. Inhibitors of sterol synthesis.,40,Inhibition of electron transport chain(Respiration

26、in mitochondria),Sulfur Disrupts electron transport along the cytochromes Strobilurins (azoxystrobin, kresoxim-methyl, pyraclostrobin, trifloxystrobin) Inhibit mitochondrial respiration, blocking the cytochrome bc1 complex.,41,Inhibition of enzymes,Copper Nonspecific denaturation of proteins and enz

27、ymes. Dithiocarbamates (maneb(代森錳), manzate, dithane, etc) Inactivate SH groups in amino acids, proteins and enzymes.,42,Inhibition of enzymes,Substituted aromatics (chlorothalonil, 百菌清) Inactivate amino acids, proteins and enzymes by combining with amino and thiol groups. Organophosphonate (fosetyl

28、-Al，三乙磷鋁) Disrupts amino acid metabolism.,43,Inhibition of nucleic acid metabolism and protein synthesis,Benzimidazoles (thiophanate-methyl) Inhibit DNA synthesis (nuclear division). Phenylamides (mefenoxam精甲霜靈) Inhibits RNA synthesis. Dicarboximides (iprodione, vinclozolin) Inhibits DNA and RNA syn

29、thesis, cell division and cellular metabolism.,44,Inhibition of sterol synthesis (Inhibit demethylation of ergosterol),Ergosterol (麥角固醇) is the major sterol in most fungi. It is essential for membrane structure and function.,45,Sterol inhibiting fungicides,Imidazoles (imazalil抑霉唑) Triazoles (propico

30、nazole, myclobutanil腈菌唑, tebuconazole戊唑醇, triflumazole) Morpholines (dimethomorph烯酰嗎啉) Inhibits sterol production at different site than imidazoles and triazoles. Affects cell wall production.,46,Why is it important to know the physiological mode of action of fungicides ?,For resistance management a

31、nd preservation of fungicide effectiveness. Incorporate fungicides with different modes of action into a disease management program. In alternation or as a mixture.,47,Plant activators,In contrast to conventional fungicides, plant activators have no direct effect on pathogens. Plant activators induc

32、e plants to produce natural disease-fighting compounds.,48,Plant activators,Acibenzolar (Actigard苯并噻二唑) Harpin (Messenger) Biological control organisms,49,Natural Plant Defense Mechanisms,Salicylic acid (水楊酸) pathway Induces SAR (systemic acquired resistance), a natural biological defense response t

33、o pathogen attack. Jasmonic Acid(茉莉酸) Pathway- Induces the production of disease and insect defense compounds.,50,Salicylic Acid Pathway,Production of active oxygen (hydrogen peroxide, peroxidase) Peroxidases have been associated with fungal cell wall degradation and pathogen defense signaling Thick

34、ening plant cell wall Increasing lignification(木質(zhì)化) Production of phenolic esters that strengthen cross linking,51,Salicylic Acid Pathway,Systemic and local accumulation of Pathogenesis Related Proteins (PR-Proteins) chitinases -1,3 Glucanase（葡聚糖酶） Systemic accumulation of anti-microbial compounds c

35、alled phytoalexins（植物抗毒素）.,52,Chitinases,Chitin is the major component of all fungal cell walls except for the Oomycetes Chitinases break down fungal cell walls Chitinases can break down insect exo-skeletons Activity is greatly enhanced by Glucanase,53,-1,3 Glucanases （葡聚糖酶）,Glucans and cellulose are the major components of Oomycete cell walls Antifungal activity is most often in combination with Chitinase Direct defense: Degrade fungal cell walls Indirect defense: Promoting the release of oligosaccharides that act as elicitors of defense reactions,54,Jasmonic Acid (茉莉酸) Pathway,