| Summary: | 碩士 === 臺灣大學 === 植物科學研究所 === 98 === Sporamin is a storage protein which is abundant in the tuberous root of sweet potato, Which has been identified with trypsin inhibitor activity, and considered as a defender against predators and pathogens. According to the research of the promoter region of sporamin on which our lab focused, we identified a sequence element, SWRE ( sporamin wounding response element ) ,which was wounding inducible. Through yeast one-hybrid assay, we found two transcriptional factors: IbNAC and IbWRKY , which could bind to SWRE. It was reported that in other plant species, Calmodulin can bind with WRKY Ⅱd subgroup proteins to which IbWRKY is attributed.
We verified whether the binding of IbWRKY and Calmodulin also works in sweet potato, and for the signaling pathway of induction of sporamin through the expression pattern of sporamin、 IbNAC、 IbWRKY and IbCaM under treatment of wounding and several defense relevant hormones. It revealed that sporamin would be induced by wounding, SA and JA, as shown by our lab. And additionally the two transcription factors were induced by these treatments. It suggests that these two transcription factors are relevant to the regulation of sporamin expression.
IbCaM is induced in wounding , and functions through its binding to IbWRKY. It suggests that the pathway of second messenger Ca2+ could be involved in wounding response.
In Gel Shift Assay and CaM Overlay Assay, IbCaM can bind to IbWRKY in the existence of Ca2+, suggesting Ca2+could be involved in regulation of expression of sporamin. Although some NAC family members have the domain for binding Calmodulin, IbNAC lacks the domain and its transcription ability seems not regulated by Ca2+.
Key words: sweet potato, wounding, sporamin, NAC, WRKY, Calmodulin.
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