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標題: 植物酚化物caffeicacid對桃褐腐病菌的角質分解酵素基因MfCUT1表現之調控
The regulation of Monilinia fructicola cutinase gene MfCUT1 expression by plant phenolic caffeic acid
作者: 邱秋閔
Chiu, Chiu-Min
關鍵字: Monilinia fructicola;桃褐腐病菌;caffeic acid;cutinase;redox;植物酚化物;角質分解酵素;氧化還原
出版社: 植物病理學系所
植物酚化物 caffeic acid 對桃褐腐病菌的角質分解酵素基因 MfCUT1 表現之調控
Caffeic acid (CA) 為一種植物酚化物,於桃子果實發育過程以第二期青果果表含量最高,此時期亦為桃褐腐病之抗病時期。植物酚化物對細胞之影響具有抗氧化及氧化之兩面特性。先前研究指出 CA 可抑制 Monilinia fructicola 角質分解酵素基因 MfCUT1 之表現,並促進細胞內 glutathione 增加,為了解此一抑制現象是否經細胞內氧化還原狀態之改變而進行調控,本研究建立 medium shift 之系統以探討細胞內氧化狀態與 MfCUT1 表現之關係。利用 2’, 7’-dichlorofluoresce diacetate (DCFDA) 測定細胞內氧化物質之含量及 5,5''-Dithio-2-nitrobenzoic acid (DTNB) 呈色法測定細胞內還原態 glutathione (GSH) 之含量, 顯示 CA 在抑制 MfCUT1 表現同時亦造成細胞內趨向還原之狀態。CA 處理明顯促進 glutathione reductase (GR) 之活性,顯示細胞內環境趨向還原狀態。另外使用 glutathione 合成抑制劑 buthionine sulfoximine (BSO) 處理可促進 MfCUT1 表現。而使用 CA 處理可影響glutathione peroxidase、glutathione reductase (GR)、glucose-6-phosphate dehydrogenase 及 yAP-1 like 基因之表現。顯示 caffeic acid 可藉由調節細胞內 glutathione 氧化還原狀態做為訊號傳遞路徑之一而抑制 MfCUT1 之表現。

The regulation of Monilinia fructicola cutinase gene MfCUT1 expression by plant phenolic caffeic acid
Monilinia fructicola causes brown rot blossom blight and fruit rot in stone fruits. Infections occur in immature fruit and can remain quiescent, but then develop into rotting lesions during fruit ripening. In a previous study, we provided evidence for a role of host exocarp phenols, notably chlorogenic acid and caffeic acid (CA), in suppression of green fruit infections. CA inhibited the formation of appressoria, the production of virulence factors (cutinase, polygalacturonase), and lesion development. The inhibition of the expression of the cutinase gene, MfCUT1, is associated with changes in intracellular glutathione pools. In this study we used 2', 7'-dichlorofluorescein diacetate (DCFDA) and total glutathione measurement to demonstrate that exogenous CA can alter the intracellular redox status in M. fructicola. Genes involved in the GSH cycle, including glutathione peroxidase (GPx), glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PD), were isolated and the effect of CA on enzyme activities and gene expression was determined. Addition of buthionine sulfoximine (BSO), a specific inhibitor of γ-glutamylcysteine synthetase involved in GSH synthesis, increased the expression of MfCUT1. An ortholog of yAP-1, a redox-regulated transcription factor involved in oxidative stress management in yeast, was isolated and its expression shown to be up-regulated by CA. Our results suggest that CA inhibits MfCUT1 expression in part by altering the intracellular redox potential as reflected by an increase in the level of reduced GSH.
Appears in Collections:植物病理學系

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