殺菌劑毒理學(xué)(上)(1)-閱讀頁
2025-01-27 13:53本頁面
【正文】 e, 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. 47 Why is it important to know the physiological mode of action of fungicides ? ? For resistance management and preservation of fungicide effectiveness. ? Incorporate fungicides with different modes of action into a disease management program. –In alternation or as a mixture. 48 Plant activators ?In contrast to conventional fungicides, plant activators have no direct effect on pathogens. ?Plant activators induce plants to produce natural diseasefighting pounds. 49 Plant activators ? Acibenzolar (Actigard苯并噻二唑 ) ? Harpin (Messenger) ? Biological control anisms 50 Natural Plant Defense Mechanisms ? Salicylic acid (水楊酸 ) pathway – Induces SAR (systemic acquired resistance), a natural biological defense response to pathogen attack. ? Jasmonic Acid(茉莉酸 ) Pathway Induces the production of disease and insect defense pounds. 51 Salicylic Acid Pathway ? Production of active oxygen (hydrogen peroxide, peroxidase) ? Peroxidases have been associated with fungal cell wall degradation and pathogen defense signaling ? Thickening plant cell wall ? Increasing lignification(木質(zhì)化 ) ? Production of phenolic esters that strengthen cross linking 52 Salicylic Acid Pathway ? Systemic and local accumulation of Pathogenesis Related Proteins (PRProteins) ? chitinases ? 223。1,3 Glucanases （ 葡聚糖酶 ） ? Glucans and cellulose are the major ponents of Oomycete cell walls ? Antifungal activity is most often in bination with Chitinase ? Direct defense: Degrade fungal cell walls ? Indirect defense: Promoting the release of oligosaccharides that act as elicitors of defense reactions 55 Jasmonic Acid (茉莉酸 ) Pathway ? Farmer and Ryan (1990) discovered that jasmonic acid volatilized from sagebrush could trigger defense gene expression in adjacent tomatoes ? Jasmonic acid volatiles act as attractants for beneficial insects ? Jasmonic acid induces the production of disease and insect defense pounds. – Defense Proteins – Phytochemicals 56 Phytochemicals ? Different from phytoalexins (植物抗毒素 ) in that phytochemicals are induced by wounding. ? Phenolics –Furanocoumarins, Coumarins(香豆素類 ) , Tannins(單寧 ), Lignin(木質(zhì)素 ), other phenolics ? Terpenoids(萜類化合物 ) ? Alkaloids (生物堿 ) 57 Examples of plant activators ? Acibenzolar (Actigard) ? Harpin (Messenger) ? Harpin is a natural protein found in many mon pathogenic microan
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