| Summary: | 碩士 === 國立臺灣大學 === 植物科學研究所 === 102 === A NAC-domain transcription factor, IbNAC1, is known to positively regulate SPORAMIN expression, which has been identified as an unique insect-resistant gene in sweet potato, via binding to the wound-responsive cis-element of SPORAMIN promoter. This wound signal transduction requires MAPK cascades to amplify the signal to activate IbNAC1. In this study, we identified a wound-, MeJA- and H2O2-inducible MAPK gene named IbWIPK. Co-transformation of 35S::IbWIPK effector and proIbNAC1::GUS reporter in plant showed the increased GUS activity compared to reporter alone, suggesting that IbWIPK plays a positive and directive role on IbNAC1 activation. Notably, the Arabidposis plants overexpressing IbWIPK (IbWIPK-OE) exhibited sensitive to salt stress and showed JA/ET-response phenotype. The indicator genes of JA, ET and auxin were elevated in IbWIPK-OE plants, implying that those phenotypes were formed by accumulation of JA and auxin. These plants were increasingly resistant to Spodoptera litura due to high expression of VSP2, CYSTEINE PROTEINASE and TERPENE SYNTHASE. In transgenic sweet potato, the activity of SPORAMIN was enhanced by the overexpression of IbWIPK. Moreover, IbMEK1 (MAPKK), which was physically interacted with IbWIPK, was also identified and characterized in this study. Collectively, these results suggest that IbWIPK plays a critical role in coordinating herbivore signal in JA/ET pathway against herbivory in plants.
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