殺菌劑毒理學(上)(1)-資料下載頁
2025-01-12 13:53本頁面
【正文】 d 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 Glucanase（葡聚糖酶） ? Systemic accumulation of antimicrobial pounds called phytoalexins（植物抗毒素） . 53 Chitinases ? Chitin is the major ponent of all fungal cell walls except for the Oomycetes ? Chitinases break down fungal cell walls ? Chitinases can break down insect exoskeletons ? Activity is greatly enhanced by Glucanase 54 223。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 microanisms。 ? Erwinia amylovora, E. chrysanthemi, Pseudomonas syringae, Pseudomonas solanecarum, Xanthomonas campestris. ? Biological control anisms 58 Mode of action Actigard Induction of Systemic Acquired Resistance 59 SAR gene expression Classical SAR and other gene expression Pest resistance Gene expression involved in plant growth Increased nutrient uptake Increased photosynthesis Signal amplification receptor harpin Ionexchange Salicylic Acid Pathway Jasmonic Acid Pathway Mode of action Messenger 60
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