| Summary: | 碩士 === 國立臺灣大學 === 農藝學研究所 === 101 === Plants are often suffered by wounding stresses caused by biotic and abiotic factors during growth and development, and they will modulate physiological and metabolic behavior to process repair and defense responses. Sugars play an important role to provide carbon and energy source for healing at wound site. The expression of OsSUT4 gene, one of rice sucrose transporter family member, was significantly enhanced by mechanical woundsing and Spodoptera litura chewing stimuli. However, when rice plants was attacked by sap-sucking pest, i.e. Nilaparvata lugens, OsSUT4 gene expression in rice culm was down-regulated. In addition to OsSUT4 expression, the transcript levels of the cell wall invertase gene (OsCIN1) and monosaccharide transporter gene (OsMST6) were also increased in mechanical wounding-treated rice plants. Expression of OsSUT4 can be promoted by exogenous jasmonate (JA) and ethylene. Furthermore, if JA biosynthesis pathway was blocked, the wound-induced OsSUT4 expression would be repressed. In addition, since NADPH oxidase inhibitor treatment can reduce the wounding effect on OsSUT4 expression, H2O2 was considered to function as a signal factor involved to the regulatory pathway of wound-regulated OsSUT4 expression. According to OsSUT4 promoter activity analysis in transgenic rice plants, it was suggested that the wounding-responsive element on OsSUT4 promoter was located at the region within 248 bp upstream of the translation start codon.
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