Systemin 對茉莉酸甲酯誘導菸草毛狀根及幼苗中的尼古丁累積之影響

The Effect of Systemin on the Methyl Jasmonate-induced Nicotine Accumulation in Tobacco Hairy Roots and Seedlings

張晏寧(Yen-Ning Chang)

指導教授 ： 李昆達

國立臺灣大學/生命科學院/生化科技學系/碩士(2021年)

https://doi.org/10.6342/NTU202103745

摘要

植物在面臨危險諸如環境壓力、受損及食草動物攻擊時，植物會生產二級代謝物。當Nicotiana tabacum受到損傷或是食草動物攻擊時，會釋出茄科植物特有的信號胜肽──系統素並從受傷細胞傳遞至整株植株，誘導茉莉酸信號途徑進而刺激下游防禦途徑以生產尼古丁；而外添加茉莉酸甲酯刺激茉莉酸信號途徑同樣會增加菸草的尼古丁累積。為了想進一步提升菸草毛狀根中的尼古丁累積量，實驗室先前研究嘗試對菸草毛狀根同時添加系統素及茉莉酸甲酯，然而，在實驗結果卻發現，比起只添加茉莉酸甲酯，混合添加茉莉酸甲酯及系統素含有較低的尼古丁累積量，額外的系統素添加並未增加更多尼古丁累積反而抑制來自茉莉酸甲酯的刺激。為了更深入了解此一現象，首先進行了不同菸草組織的確認，以不同株菸草毛狀根及菸草幼苗實驗，結果顯示在尼古丁含量上有類似模式，確認此現象可能存在於不同菸草組織。為了解其中抑制及調節機制，選取有關系統素誘導、尼古丁合成及傳送、多個植物激素誘導基因等進行基因表現分析。根據基因表現量分析結果，混合添加組比起單添加茉莉酸甲酯組在茉莉酸標記基因及尼古丁生合成基因表現量上調，其基因表現結果與代謝物結果相反，且乙烯標記基因表現量也有上調的情形。因此，我們提出假說，額外添加系統素於茉莉酸甲酯的背景下，系統素可能對茉莉酸信號途徑及乙烯信號途徑產生影響，且造成影響位於核酸層級以及代謝物層級前，導致了尼古丁累積量的下降。

關鍵字

系統素 ； 毛狀根 ； 茉莉酸甲酯 ； 菸草 ； 尼古丁 ； 二級代謝物

並列摘要

Plants produce secondary metabolites when encountering danger, such as environmental stress, wounding and herbivores. As Nicotiana tabacum encounters wounding or herbivores attacks, it will release a Solanaceae-specific signaling peptide -- systemin and transported it from wounded cells to the whole plant, then induce the jasmonate (JA) signaling pathway, thus triggers the downstream defense pathway to produce nicotine. Moreover, additional methyl jasmonate (MeJA) treatment in tobacco also induces the increase of nicotine accumulation. In order to increase nicotine accumulation in tobacco hairy roots, simultaneous treatment of Sys/MeJA on tobacco hairy roots was undertaken in our lab. However, according to the results by our lab, treating MeJA and tomato systemin (TomSys) at the same time showed lower accumulation of nicotine compared with treating only MeJA, the additional treatment of TomSys did not increase more nicotine accumulation but inhibited the stimulation from MeJA. To thorough understand the phenomenon, first of all is confirmation of different toabacco tissues, different clones of hairy roots and seedlings were tested. The results showed a similar pattern on nicotine content, thus confirming the phenomenon does not only exist in specific plant tissues. Gene expression analysis was performed for investigating the mechanisms of inhibition and regulation. Selecting systemin-induced genes, nicotine biosynthesis and nicotine transporter genes, and multiple plant hormone signaling marker genes for gene expression levels analysis. According to the results of gene expression analysis, the expression of nicotine biosynthesis gene and JA marker gene were up-regulated in the group of MeJA/TomSys compared with only MeJA treatment which is contrasted by the metabolite results. Also, the marker gene of ethylene is up-regulated, indicated that the pathways might be simultaneously regulated by ethylene signaling. Therefore, we hypothesize that the additional treatment of TomSys with the background of MeJA treatment, TomSys might have an effect on the regulation of JA signaling pathway and ethylene signaling pathway, and may occur on RNA level and also before metabolite level, leading to the decrease of nicotine accumulation.

並列關鍵字

systemin ； hairy roots ； methyl jasmonate ； Nicotiana tabacum ； nicotine ； secondary metabolites

參考文獻

Andrijany, V. S., Indrayanto, G., Soehono, L. A. (1998). Simultaneous effect of calcium, magnesium, copper and cobalt ions on sapogenin steroids content in callus cultures of Agave amaniensis. Plant Cell Tissue and Organ Culture, 55(2), 103-108.

Baldwin, I. T. (1989). Mechanism of damage-induced alkaloid production in wild tobacco. Journal of Chemical Ecology 15(5), 1661-1680.

Bourgaud, F., Gravot, A., Milesi, S., Gontier, E. (2001). Production of plant secondary metabolites: a historical perspective. Plant Science, 161(5), 839-851.

Clarke, E. G. C. (1970). Chapter 7 The forensic chemistry of alkaloids. The Alkaloids: Chemistry and Physiology, 12.

Constabel, C. P., Yip, L., Ryan, C. A. (1998). Prosystemin from potato, black nightshade, and bell pepper: primary structure and biological activity of predicted systemin polypeptides. Plant Molecular Biology, 36(1), 55-62.