| Summary: | 碩士 === 國立高雄大學 === 生物科技研究所 === 101 === Sugar is an important biological compound for plant growth and development. Not only serves as important energy source but also acts as signaling molecule in plants. Invertase (INV) can be hydrolysis of sucrose to fructose and glucose during pathogen infection. Glucose signal regulates reactive oxygen species (ROS) generation through mitochondrial hexokinase (HXK) during pathogen infection. As signals, ROS induces several defense responses including cell wall thickening, phytoalexin synthesis and pathogenesis-related (PR) proteins transcription. The plant ferredoxin - like protein (PFLP), isolated from sweet peppers, shows high homology to sequence of Fd-I, an electron carrier in photosynthesis. Previous studies reported that constitutive expression of pflp in transgenic plants exhibited highly photosynthesis efficiency, increased soluble sugars contents, and altered HXK expression pattern. Many studies also have been reported that continuously expression of PFLP in transgenic plants encourages the generation of ROS and participates in pathogen-resistant mechanism. However, the function of sugar associated enzyme involved in pathogen-resistant mechanism is unclear. This study is to investigate the role of INV and HXK in pflp transgenic plants resistant to bacterial blight. In this report, we demonstrated that PFLP can enhance disease resistance to bacterial blight and quickly induce PR protein transcription in early phase of pathogen infection. Additionally, the expressions of cwINV in transgenic plants showed 2-folds higher than TNG67 after Xoo infection, and accumulated glucose content 1.6 times higher than TNG67 in transgenic plants. This result was due to increased HXK2 and HXK6 2-fold and 2.5-fold gene expression pattern. In ROS generation, the transgenic rice generated ROS about 2.5 times higher than TNG67 in early Xoo infection phase. Generated ROS induced defense responses of against bacterial blight. Altogether, we demonstrated PFLP transgenic rice plants accumulated higher levels of glucose via INV and tolerance against bacterial blight was improved through glucose activation HXK, which regulated ROS production in pathogen infection early phase.
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