| Summary: | 碩士 === 國立中興大學 === 植物病理學系所 === 100 === Redox sensing is a common mechanism regulating celluar activity. Fungal pathogens have to face oxidative stress produced by the host plant via oxidative burst during plant-microbe interactions. The transcription factor activator protein 1 (AP-1), which has been characterized as a regulator in reactive oxygen species resistance in mammalian and fungi, has a crucial role in fungal virulence. An MfAP1 gene in Monilinia fructicola has been cloned and sequenced, which encoded a polypeptide that resembles many yeast AP1-like transcription factors of yeasts and fungi. Expression of MfAP1 gene is varied in different infection stages. Quantitative rt-PCR analysis of redox related genes of Monilinia fructicola after treated with caffeic acid and hydrogen peroxide shows that gene expression of these genes is in a redox-dependent manner. To investigate the role of MfAP1 in the infection process , two strategies were used in this experiment. One is PEG/CaCl2 mediated protoplast transformation to develop the MfAP1 silencing transformants; the other is Agrobacterium mediated T-DNA transformation to generate the MfAP1 overexpression transformants. When pathogenicity assay of MfAP1 silenced transformants was analyzedon rose petals, a significant reduction on brown rot lesion development was observed. On the other hand, the ability to develop lesion of MfAP1 overexpression transformants was promoted. When MfAP1 gene expression was silenced, these transformants were less effective in detoxifying H2O2. On the contrary, MfAP1 overexpression transformants were more resist to the oxidative stress. Our results demonstrate that MfAP1 is important in response to oxidative stress in M. fructicola and is a virulence factor of M. fructicola during peach fruit infection.
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