IbpreproHypSys在甘藷中的訊息傳遞與調控

Signal Transduction and Regulation of IbpreproHypSys in Sweet Potato

李昱錡(Yu-Chi Li)

指導教授 ： 鄭石通

國立臺灣大學/生命科學院/植物科學研究所/博士(2017年)

https://doi.org/10.6342/NTU201700685

摘要

Hydroxyproline-rich glycopeptides (HypSys)是一種小片段的訊號傳遞胜肽，包含了18到20個胺基酸。當甘藷(Ipomoea batatas cv. Tainung 57)受到傷害或IbHypSys處理後，透過茉莉酸(jasmonic acid)和過氧化氫(H2O2)，IbHypSys的前驅物IbpreproHypSys基因會被誘導表現。透過基因轉殖甘藷大量表現 (OE) 和抑制表現 (RNAi) IbpreproHypSys來驗證IbpreproHypSys在生物體內的功能。在OE基改甘藷中進行傷害處理，傷害誘導基因Ipomoelin (IPO)在原位葉和系統葉上的基因表現量大於野生種和RNAi基改甘藷。除此之外，嫁接實驗顯示，野生種甘藷當砧木的情況下對接穗轉殖甘藷葉片進行傷害處理，接穗為OE基改甘藷較RNAi基改甘藷能在砧木野生種甘藷中誘導較高的IPO基因表現。然而，當基改甘藷為砧木野生種為接穗時，對野生種甘藷葉片進行傷害處理，在OE基改甘藷砧木中的IPO也是表現最高的，這代表了大量表現IbpreproHypSys轉殖甘藷不但能加強傷害的訊息傳送，也能加強傷害的訊息接收。分析參與在phenylpropanoid pathway的基因表現指出，人工合成的IbHypSys可以誘導木質素的生合成。並且IbpreproHypSys的基因表現可以抑制斜紋夜盜蛾幼蟲的生長。因此，傷害處理能夠誘導IbpreproHypSys基因表現，IbpreproHypSys基因能夠轉譯出IbpreproHypSys蛋白並且被剪切成IbHypSys，其中IbHypSys能夠促進IbpreproHypSys和IPO基因的表現，並且增強木質素的生合成，這些結果都有助於植物對抗昆蟲的侵襲。

關鍵字

IbpreproHypSys ； ipomoelin ； IbHypSys ； 訊息傳遞 ； 系統性作用 ； 茉莉酸 ； 過氧化氫 ； 斜紋夜盜蛾 ； 木質素

並列摘要

Hydroxyproline-rich glycopeptides (HypSys) are small signaling peptides containing 18–20 amino acids. The expression of IbpreproHypSys, encoding the precursor of IbHypSys, was induced in sweet potato (Ipomoea batatas cv. Tainung 57) through wounding and IbHypSys treatments by using jasmonate and H2O2. Transgenic sweet potatoes overexpressing (OE) and silencing (RNAi) IbpreproHypSys were created. The expression of the wound-inducible gene ipomoelin (IPO) in the local and systemic leaves of OE plants was stronger than the expression in wild-type (WT) and RNAi plants after wounding. Furthermore, grafting experiments indicated that IPO expression was considerably higher in WT stocks receiving wounding signals from OE than from RNAi scions. However, wounding WT scions highly induced IPO expression in OE stocks. These results indicated that IbpreproHypSys expression contributed toward sending and receiving the systemic signals that induced IPO expression. Analyzing the genes involved in the phenylpropanoid pathway demonstrated that lignin biosynthesis was activated after synthetic IbHypSys treatment. IbpreproHypSys expression in sweet potato suppressed Spodoptera litura growth. In conclusion, wounding induced the expression of IbpreproHypSys, whose protein product was processed into IbHypSys. IbHypSys stimulated IbpreproHypSys and IPO expression and enhanced lignin biosynthesis, thus protecting plants from insects.

並列關鍵字

IbpreproHypSys ； ipomoelin ； IbHypSys ； signal transduction ； systemic effect ； jasmonate ； hydrogen peroxide ； Spodoptera litura ； lignin

參考文獻

Bandyopadhyay S., Roy A. & Das S. (2001) Binding of garlic (Allium sativum) leaf lectin to the gut receptors of homopteran pests is correlated to its insecticidal activity. Plant Science 161, 1025-1033.

Berger B. & Baldwin I.T. (2007) The hydroxyproline-rich glycopeptide systemin precursor NapreproHypSys does not play a central role in Nicotiana attenuata's anti-herbivore defense responses. Plant, Cell and Environment 30, 1450-1464.

Bhattacharya R., Koramutla M.K., Negi M., Pearce G. & Ryan C.A. (2013) Hydroxyproline-rich glycopeptide signals in potato elicit signalling associated with defense against insects and pathogens. Plant Science 207, 88-97.

Bienert G.P., Schjoerring J.K. & Jahn T.P. (2006) Membrane transport of hydrogen peroxide. Biochimica et Biophysica Acta 1758, 994-1003.

Carles C.C. & Fletcher J.C. (2003) Shoot apical meristem maintenance: the art of a dynamic balance. Trends in Plant Science, 8, 394-401.