Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/97760
標題: AtG-LecRK-I.2調節細菌性斑點病菌感染下的氣孔免疫反應
AtG-LecRK-I.2 regulates Pst DC3000 resistance through stomatal immunity
作者: 簡志丞
Chih-Cheng Chien
關鍵字: 阿拉伯芥
細菌性斑點病菌
氣孔免疫
水稻黃單胞菌
基因組序列
光桿菌
生物製劑
抗菌活性
Arabidopsis thaliana
Pseudomonas syringae pv. tomato DC3000
stomatal immunity
Xanthomonas oryzae pv. oryzae
population
genome sequence
Photorhubdus luminescens
bio-agent
anti-microbe activity
摘要: 全球氣候變遷近來成為農業中的一個重要問題,每年頻繁性的自然災害發生都會造成巨大的經濟損失。因此,提高作物對生物和非生物逆境的抗性是一個刻不容緩的議題。本論文採用分子生物學結合大數據分析的新一代測序等新技術,使我們能夠加速育種進程或提高生物製劑(如殺菌劑)的效率,而不會進一步損害環境。 為了提供研究者對於植物逆境下更好地處理方式,我們需要了解植物對生物/非生物逆境的反應。在本論文的第二章中,我以半活體寄生型(hemi-biotrophic)的細菌性斑點病病原菌(Pseudomonas syringae pv. tomato DC3000 (Pst DC3000))與阿拉伯芥(Arabidopsis thaliana)為模型探討植物防禦反應。本論文主要研究了第二大膜蛋白激酶家族的阿拉伯芥突變株,即凝集素受體激酶(LecRKs),以了解植物如何感知病原菌並誘導它們對病原體的抗性。在本章中,我們發現其中一種G型LecRK(G-LecRK)突變株 glecrki.2對於Pst DC3000與Col-0野生型相比較感病。此外,本章闡述G-LecRK-I.2參與氣孔免疫的相關反應,此受體激酶是Pst DC3000或flg22(細菌衍生肽)誘導氣孔關閉所必需的。該受體與FLS2 / BAK1防禦複合物(defense complex)交互作用並影響保衛細胞(guard cell)中的Ca2+,NO和ROS訊號。此外,G-LecRK-I.2可能是通過直接調節AHA1活性和間接調節RbohD或相關Rbohs來調控氣孔關閉。在第三章中,我總結了G-LecRK-I.2的發現以及LecRK研究的未來前景。 了解病原體如何感染植物的過程對於改善作物生產也很重要。因此,在本論文附錄A中我將探討導致水稻白葉枯病的細菌性水稻黃單胞菌(Xanthomonas oryzae pv. oryzae (Xoo))。在這項研究中,我使用比較基因體學和其他分子標記來鑑定不同的Xoo族群以及這些Xoo菌株如何影響水稻宿主台農67號(Oryza sativa subsp. japonica TNG67)的基因表達。我確定了台灣的五個Xoo族群,其中兩個,G2a和G3為台灣主要的族群。此外,通過與已知的Xoo基因組序列的比較,我還發現此菌第六型分泌系統的第二組基因區段(T6SS-2)在Xoo與水稻交互作用中是重要的。此外,通過本研究中完成的兩株台灣水稻黃單胞菌株XF89b和XM9的完整基因組序列,亦提供了台灣菌株與從其他國家收集的參考菌株(reference strains)的演化關係。 最後,在附錄B中,我利用潛在的生物製劑,Photorhubdus luminescens (Pl) 0813-124在形態上兩種不同的相變體(phase variants)來研究此細菌對病原菌的防治機制。Pl 0813-124 Phase 1具有高抗真菌和抗細菌活性以及殺蟲活性。然而,Pl 0813-124 Phase 2僅具有弱或不具有抗真菌與殺蟲活性。Phase 2來自Phase 1,且Phase 2無法逆轉回到Phase 1。通過這兩個Phase的比較基因體學,我發現了Phase 2菌株基因組中20kb的缺失。該區域可能含有一些抗微生物活性的重要基因。 在本論文中主要進行了三項研究; 首先,我報導了阿拉伯芥中凝集素受體激酶 I.2(Lectin receptor kinase I.2, LecRKI.2)在植物抗病反應中扮演之角色,此受體家族(receptor family)最近被發現可能具有表面病原菌特定分子標誌(pathogen-associated molecular patterns, PAMPs)及損傷相關性的分子標誌(damage associated molecular patterns, DAMPs)的感知(perception)特性,並以此來辨認病原菌的入侵。此尚未被報導之受體G-LecRK-I.2,在本論文中我發現它主要調控氣孔免疫,進而參與抗菌反應。此外,透過對Xoo和Pl的研究,我們近一步了解如何發展從基礎研究到應用農業的策略。最重要的,本論文提供了有關農業植物育種和病原體控制的新訊息。
Global climate change become an important issue in agriculture. Frequent natural disasters cause a huge economic loss every year. Therefore, improving crop resistance against biotic and abiotic stresses is an emerging issue now. Fortunately, the new techniques such as next-generation sequencing incorporating with big data analysis allow us to facilitate the breeding process or improve the efficiency of bio-agents such as fungicides without further harming the environment. To better deal with the environmental stimuli, we need to understand the plant responses against biotic/abiotic stresses. In CHAPTER II of this thesis, an Arabidopsis-Pseudomonas syringae pv. tomato DC3000 model was used for studying of plant defense responses. Mutants of the second largest family of membrane kinases, Lectin receptor-like kinases (LecRKs), were studied to understand how plants sense pathogens and induce their resistance toward the pathogens. In this chapter, I identified a G-type LecRK (G-LecRK) mutant, which was more sensitive after challenging Pst DC3000 compared to Col-0 wild type. This receptor, G-LecRK-I.2, was involved in stomatal immunity and was required for Pst DC3000 or flg22, a bacterial-derived peptide, induced stomatal closure. This receptor interacts with FLS2/BAK1 defense complex and affects Ca2+, NO, and ROS signaling in guard cells. Besides, G-LecRK-I.2 affecting stomatal immunity is probably through direct regulation of AHA1 activity and indirect regulation of RbohD- or other Rboh-mediated stomatal closure. In CHAPTER III, I have concluded the finding of G-LecRK-I.2 and future perspectives in LecRK studies. Understanding the process of how pathogens infect plants is also important to improve the crop production. Therefore, in APPENDIX A, a bacterial pathogen, Xanthomonas oryzae pv. oryzae (Xoo), that causes the rice blight disease was focused. In the study, I used comparative genomics and other molecular markers to identify different populations of Xoo and how these Xoo strains affected gene expressions of the host, Oryza sativa subsp. japonica TNG67. Five populations of Xoo in Taiwan were identified, and two of them were dominant in Taiwan. In addition, by comparing with available Xoo genome sequences, I discovered that type VI secretion system 2 (T6SS-2) was important in Xoo-rice interaction. Besides, through the complete genome sequences of two Taiwanese Xoo strains, XF89b and XM9, done in this study, an evolutionary relationship of Taiwanese strains with reference strains collected from other countries was also provided. Last, in APPENDIX B, I studied one of the potential bio-agent, Photorhubdus luminescens (Pl) 0813-124, which has two different phase variants in morphology. Pl 0813-124 Phase 1 had a high anti-fungal and anti-bacterial activity as well as a pesticide activity. However, Pl 0813-124 Phase 2 only had weak or no anti-fugus and pesticide activity. Phase 2 came from Phase 1, and Phase 2 could not reverse to Phase 1 in this case. Through the comparative genomics of these two phases, a 20-kb deletion in the genome of Phase 1 strain was identified. This region might encode some important proteins that contribute to anti-microbe activities. In short, in this thesis, I carried out three studies. First, I investigated the functions of a novel family of plant receptors that is recently discovered as a potential PAMP/DAMP sensing receptor family. I found an uncharacterized receptor, G-LecRK-I.2, that is involved in stomatal immunity. Also, I described a strategy in how to deal with agricultural problems from basic researches to applications through the studies on Xoo and Pl. This thesis provides information on the new direction of plant breeding and pathogen controls in agriculture.
URI: http://hdl.handle.net/11455/97760
文章公開時間: 2021-01-29
Appears in Collections:生物科技學研究所

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