병원균의 부재 시 전신획득 저항성을 유도하는 이동성 신호물질의 확인 = Identification of mobile signals to induce systemic acquired resistance in absence of pathogen

국문 초록 (Abstract)

전신획득저항성(systemic acquired resistance)은 식물의 면역 시스템 반응 중 하나이다. SAR을 일으키는 신호전달물질은 병원체가 감염된 부위에서 생성되어 비 감염된 부분으로 전달되는 것으로 알려져 있다. 그러나 이러한 SAR의 정확한 발생 경로나 메커니즘은 지금까지 잘 알려져 있지 않다. 이전의 연구들을 통해SAR을 일으키는 이동성 신호전달 물질은 지질 계열 일 것이라 추측할 수 있다. 따라서 어떠한 지질 계열의 물질이 SAR을 일으키는 신호전달 물질인지 알아보기 위해 Pst DC3000 avrRps4 박테리아의 AvrRps4 effector 유전자가 삽입 된 형질전환 식물체를 생성하였다. 형질전환 식물체에inducer인 β-estradiol을 처리하였을 때 식물의 세포 내에서 gene-for-gene 상호작용에 의하여 HR이 발생하였고 ETI만으로도SAR이 유도됨을 확인 하였다. 특히ETI에 의해 유도된HR이 발생한 잎의 petiole exudates를 받아 지질의 조성을 분석한 결과 식물 유래의 PC와 PE가 가장 많이 증가됨을 확인 하였다. Petiole exudates 에서 증가 된 PC, PE중 Arabidopsis의 잎에 많이 존재 할 것으로 예상되는 16:0/18:2 PC, PE를 Col-0에 처리 하였을 때 SAR이 유도됨을 확인 하였다. 또한 16:0/18:2 PC, PE를 Col-0에 처리 후 SAR의 중요한 마커 유전자 중 하나인PR1과JA signaling에 관련된 유전자인LOX2와 PDF1.2유전자의 발현이 증가됨을 확인 하였다. 이 결과들을 통하여 PC, PE에 의해 유도된SAR에 JA signaling이 관여함을 추측해 볼 수 있다. 또한 petiole exudates에서 증가한 식물 유래의PC와 PE가 SAR을 일으키는 이동성 신호전달 물질의 후보가 될 수 있음을 추측 할 수 있다.
따라서 본 연구를 바탕으로 SAR의 정확한 기작과 SAR을 유도하는 신호전달 물질의 확인을 통하여 실제 병충해로 인한 농작물의 피해를 예방 및 경감하는 것에 공헌할 수 있을 것으로 기대한다.

다국어 초록 (Multilingual Abstract)

SAR is a part of the plant immune system. The mobile signals of SAR are transported from the site of pathogen infection to the distant areas of the plants. However, the exact pathway and mechanism is still not well understood. Aim of this study was to develop pathogen resistant plants using SAR mechanism to reduce subsequent infection. Following this purpose, to identify which lipids are used as the SAR mobile signal, the transgenic plant inserted with Pseudomonas syringae pv. tomato strain DC3000 expressing AvrRps4 effector was generated. When the β-estradiol was treated to this transgenic plant, the AvrRps4 effector was expressed in the plant cell resulting in HR and the SAR was induced by ETI alone. Especially HR induced by ETI showed abundant existence of plant originated PE and PC in petiole exudates. 16:0/18:2 PC and PE, which are expected to exist a lot in plants, induced SAR in Col-0 plant. In addition, the lipids expressed PR1 one of the SAR marker gene, LOX2 and PDF1.2 involved in JA signaling. Collectively, it is possible to assume that JA signaling pathway may induce SAR by plant derived PC and PE. In addition, PC and PE can be candidates of SAR mobile signal. Based on these results, it is expected that this study will benefit agricultural control to decrease of yield by pathogen.

목차 (Table of Contents)

• Contents
• I. Introduction ·················································· 1
• 1. Plant immunity ··········································· 1
• 2. Lipid composition in Arabidopsis thaliana leaves and
• the structures of phospholipids ······························ 7
• II. Materials and methods ··································· 11
• 1. Plant Materials, Growth Conditions and soil composition· 11
• 2. Construction of XVE:AvrRps4/Col-0 transgenic lines ·· 11
• 3. Pathogen, ß-estradiol inoculation and SAR assay ······· 12
• 4. DNA extraction and reverse-transcription PCR ·········· 13
• 5. RNA extraction and real time PCR ························ 14
• 6. Collection of phloem exudates and LC-MS/MS analysis ·14
• 7. Inoculation of PE, PC to the plant for SAR CFU and RNA assay ························································· 15
• III. Results ························································· 17
• 1. Expression of bacterial effector AvrRps4 induces
• hypersensitive response in transgenic Arabidopsis ········ 17
• 2. Expression of bacterial effector AvrRps4 induces SAR in
• transgenic Arabidopsis ······································· 22
• 3. Phosphatidylethanolamine and Phosphatidylcholine are
• enrich in the petiole exudates during the SAR ············· 26
• 4. Phosphatidylethanolamine and Phosphatidylcholine derived
• from plants can induce SAR ································· 30
• 5. The 16:0/18:2 PE and PC induce expression of key genes involved in JA signal pathway ······························ 32
• IV. Discussion ···················································· 42
• References ·········································· 48