阿拉伯芥白胺酸重複受體激酶IOS1 與半胱胺酸重複受體激酶誘發初級免疫反應之功能性分析

Functional Analysis of Arabidopsis Leucine-rich Repeat Receptor-like Kinase IOS1 and Cysteine-rich Receptor-like Kinases in Pattern-triggered Immunity

葉鈺鴻(Yu-Hung Yeh)

指導教授 ： 金洛仁

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/NTU201704412

摘要

在阿拉伯芥細胞膜上的受體激酶蛋白質，可以辨識微生物或病原菌相關分子模式，進而啟動植物抗病反應。例如，模式辨識受體FLS2可以辨識病原菌的鞭毛，進而啟動植物初級免疫反應。由於，FLS2是透過與一群輔助受體蛋白質在生理上的結合,達成調控下游的初級免疫反應。因此，細胞膜上的受體激酶蛋白質，在植物誘發相對應抗病反應，以對抗病原菌的入侵扮演重要的角色。值得注意的是，我發現受體激酶蛋白質CRK4，CRK6，和CRK36也是FLS2 complex 中的一員，並且能強化初級免疫反應(Appendix 1)。另一方面，我也發現受體激酶蛋白質IOS1，可以促進FLS2與其的輔助受體蛋白質BAK1的結合，進而加速啟動初級免疫反應(Appendix 2)。在我第三個研究，我著重於植物的抗病反應與生長發育間的交互作。由於能量的限制，抗病反應與生長發育的交互作用是一個雙向的負調控作用。因此，植物也可透過消耗生長發育所需的能量，進而啟動初級免疫反應反應。在此研究中，我分析植物是如何透過受體激酶蛋白質CRK18，達成調控初級免疫反應和油菜素類固醇所誘導植物生長發育。結果顯示，CRK18可以透過和FLS2的結合以及維持FLS2蛋白質的含量，進而強化初級免疫反應。我也發現CRK18參與在初級免疫反應所誘發植物生長發育的負向調控。更進一步的研究成果顯示，初級免疫反應透過CRK18負向調控油菜素類固醇訊號傳遞，進而弱化了植物生長發育反應。因此，我們的研究指出，CRK18在植物的抗病反應與生長發育間的交互作扮演一個重要的角色，結果顯示CRK18參與在植物初級免疫反應與油菜素類固醇油菜素類固醇所誘導植物生長發育之間雙向的負調控作用。

關鍵字

阿拉伯芥 ； 模式辨識受體 ； 初級免疫反應 ； 油菜素類固醇訊號傳遞

並列摘要

In Arabidopsis, cell-surface receptor-like kinases (RLKs) such as the pattern recognition receptor (PRR) FLAGELLIN-SENSING 2 (FLS2) recognize bacterial microbe/pathogen-associated molecular patterns (MAMPs/PAMPs) such as flagellin (or its derived peptide flg22) to activate pattern-triggered immunity (PTI). Activation of PTI by FLS2 is performed through the physiological interaction with its co-receptors, such asBRI1-ASSOCIATION KINASE 1 (BAK1). Therefore, cell-surface RLKs play key roles in the activation of appropriate responses upon pathogen invasion. Notably, I showed that cysteine-rich RLK4 (CRK4), CRK6, and CRK36 are part of the PRR FLS2 complex and enhance PTI responses (Appendix 1). In addition, I also found that the RLK IMPAIRED OOMYCETE SUSCEPTIBILITY1 (IOS1) positively regulates PTI through the modulation of FLS2/BAK1 formation leading to a primed PTI response (Appendix 2). In my third project, I studied the crosstalk between defense and development. Notably, we know that due to resource restrictions, the crosstalk between defense and development is negative and bidirectional. Therefore, PTI could potentially promote defense at the expense of growth signaling. In this text, I focus on the crosstalk between PTI and growth-promoting brassinosteroids (BR) signaling through CRK18. I showed CRK18 enhances PTI responses through the association of FLS2 complex and maintenance of FLS2 protein levels. I also found CRK18 is involved in flg22-mediated plant growth inhibition. Further studies revealed that flg22-regulated CRK18 represses plant growth through the reduction of BR signaling. Thus, our results identify CRK18 as a key play in the tradeoff between immunity and development, revealing a negative and bidirectional crosstalk between PTI and BR signaling.

並列關鍵字

Arabidopsis ； pattern recognition receptor ； pattern-triggered immunity ； brassinosteroids signaling

參考文獻

Acharya, B.R., Raina, S., Maqbool, S.B., Jagadeeswaran, G., Mosher, S.L., Appel, H.M., Schultz, J.C., Klessig, D.F., and Raina, R. (2007). Overexpression of CRK13, an Arabidopsis cysteine-rich receptor-like kinase, results in enhanced resistance to Pseudomonas syringae. Plant J. 50: 488-499.

Albrecht, C., Boutrot, F., Segonzac, C., Schwessinger, B., Gimenez-Ibanez, S., Chinchilla, D., Rathjen, J.P., de Vries, S.C., and Zipfel, C. (2012). Brassinosteroids inhibit pathogen-associated molecular pattern-triggered immune signaling independent of the receptor kinase BAK1. Proc. Natl. Acad. Sci. USA 109: 303-308.

Apel, K., and Hirt, H. (2004). Reactive oxygen species: Metabolism, oxidative stress, and signal transduction. Annu. Rev. Plant Biol. 55: 373-399.

Belkhadir, Y., Jaillais, Y., Epple, P., Balsemao-Pires, E., Dangl, J.L., and Chory, J. (2012). Brassinosteroids modulate the efficiency of plant immune responses to microbe-associated molecular patterns. Proc. Natl. Acad. Sci. USA 109: 297-302.

Bourdais, G., Burdiak, P., Gauthier, A., Nitsch, L., Salojarvi, J., Rayapuram, C., Idanheimo, N., Hunter, K., Kimura, S., Merilo, E., Vaattovaara, A., Oracz, K., Kaufholdt, D., Pallon, A., Anggoro, D.T., Glow, D., Lowe, J., Zhou, J., Mohammadi, O., Puukko, T., Albert, A., Lang, H., Ernst, D., Kollist, H., Brosche, M., Durner, J., Borst, J.W., Collinge, D.B., Karpinski, S., Lyngkjaer, M.F., Robatzek, S., Wrzaczek, M., Kangasjarvi, J., and Consortium, C. (2015). Large-scale phenomics identifies primary and fine-tuning roles for CRKs in responses related to oxidative stress. Plos Genet. 11: e1005373