阿拉伯芥NPF6.4調控對丁香假單胞病原菌防禦反應之探討

The role of NPF6.4 in response to Pseudomonas syringae in Arabidopsis thaliana

蔡伯暄(Bo-Shuan Tsai)

指導教授 ： 王雅筠

國立臺灣大學/生命科學院/植物科學研究所/碩士(2020年)

https://doi.org/10.6342/NTU202000372

摘要

植物病原菌引發各種作物的疾病，常損害產量並造成重大經濟衝擊。據報導，負責硝酸鹽吸收、分配和儲存的硝酸鹽/短胜肽運輸蛋白家族 (nitrate transporter 1/peptide transporter family, NPF) 亦參與在植物的逆境和防禦反應中。先前的研究指出阿拉伯芥npf6.4突變株表現出對多胺 (polyamine) 的抗性。此外，公開轉錄組資料庫亦顯示阿拉伯芥NPF6.4的基因表現量會受丁香假單胞菌 (Pseudomonas syringae, Pst) 誘導。但是NPF6.4在對多胺反應或病原體免疫中的功能和作用仍然未知。本研究發現，基因表現的部分，在野生型阿拉伯芥葉子的NPF6.4表現量會在被Pst DC3000菌株感染24小時後提升，且此表現依賴於FLAGELLIN SENSING 2 (FLS2)。此外，npf6.4突變株之病程相關基因(pathogenesis-related gene) PATHOGENESIS-RELATED GENE 1 (PR1) 表現量變低，顯示NPF6.4參與調控PR1受到丁香假單胞菌誘導的過程。在表現型試驗中，與野生型相比，npf6.4突變株葉和花對Pst DC3000和Pst DC3000 hrcC-更加感病，但對Pst AvrRpm1則無顯著性，顯示在抵抗病原菌時，NPF6.4參與在病原相關分子標誌觸發免疫 [PAMP-triggered immunity (PTI)]，而非效應子觸發免疫 [effector-triggered immunity (ETI)]。在細胞免疫功能中，npf6.4突變株之葉片在處理flg22後，組織中的胝質累積度 (callose deposition) 和活性氧化物含量 [reactive oxygen species (ROS) production] 都減少。另一方面，在多胺試驗中，野生型之NPF6.4在處理精胺 (spermine) 24小時後會被誘導。在葉子注射精胺24小時後，npf6.4突變株的活性氧化物含量較高，細胞程序凋亡 (programmed cell death) 程度亦較嚴重。綜合上述成果，我們發現NPF6.4參與在阿拉伯芥的病原相關分子模式觸發免疫 (PTI)，以及由多胺誘導的活性氧化物產生和細胞程序凋亡反應。

關鍵字

NPF ； NPF6.4 ； 免疫反應 ； 丁香假單胞菌 ； 多胺

並列摘要

Abstract
Various diseases caused by plant pathogens often lead to significant economic loss in crops. Nitrate transporter 1/Peptide transporter Family (NPF), which is involved in nitrate uptake, allocation, and storage, are reported to be involved in stress and defense responses. In previous study, npf6.4 mutants exhibit polyamine (PA) resistance in Arabidopsis. In addition, public transcriptome database showed that NPF6.4 is induced by Pseudomonas syringae (Pst) DC3000 infection. However, the roles of NPF6.4 in PA-related responses or pathogen immunity are not clear. In this study, we have demonstrated that leaves of NPF6.4 were induced by Pst DC3000 in wild type after 24-hour infection. This induction is dependent on the flg22 receptor, FLAGELLIN SENSING 2 (FLS2). Furthermore, leaves of npf6.4 displayed reduced expression of PATHOGENESIS-RELATED GENE 1 (PR1), suggesting that NPF6.4 involves in the induction of PR1 by Pst DC3000. In phenotype assay, the leaves and flowers of npf6.4 mutants exhibited more susceptible to Pst DC3000 and Pst DC3000 hrcC- than wild type, but not sensitive to Pst AvrRpm1, suggesting that NPF6.4 participates in PTI but not in ETI in response to pathogen. In cellular immunity, less callose deposition and reactive oxygen species (ROS) production were discovered in the leaves of npf6.4 mutants after flg22 treatment. On the other hand, NPF6.4 was induced in wild type after 24-hour treatment of spermine, a type of PA. After being infiltrated leaves with spermine, npf6.4 mutants showed enhanced PA-induced ROS production and programmed cell death. Taken together, these results support that NPF6.4 participates in PTI in response to pathogen, and PA-induced ROS production and programmed cell death in Arabidopsis.

並列關鍵字

NPF ； NPF6.4 ； immunity response ； Pseudomonas syringae ； polyamine

參考文獻

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