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標題: | 初級免疫反應在番茄Hawaii 7996數量性狀位點Bwr12抗青枯病能力扮演重要角色 Innate immunity plays an important role in the resistance of tomato Hawaii 7996 QTL Bwr12 against Ralstonia solanacearum |
作者: | Feng-Chi Cheng 鄭峰繼 |
指導教授: | 鄭秋萍 |
關鍵字: | 青枯病,青枯病菌,數量性狀位點,H7996,LRR,RLK,PTI, Bacterial wilt,Ralstonia solanacearum,QTL,Hawaii 7996,LRR,RLK,PTI, |
出版年 : | 2015 |
學位: | 碩士 |
摘要: | 由Ralstonia solanacearum (Rs)引起之青枯病為土壤性維管束疾病,其寄主範圍相當廣泛且尚無有效的化學防治方法,因此抗病作物育種極為重要。番茄Hawaii 7996 (H7996)是目前抗青枯病最穩定的品系,雖然H7996抗青枯病之多個QTL已被定位,但是其抗病分子機制與具主導之抗病基因仍未明朗。本研究旨在研究pathogen-associated molecular patterns (PAMP)-trigger immunity (PTI)在H7996抗病機制中扮演之角色,並辨認在抗第一型Rs之主控QTL Bwr12中之關鍵防禦基因。為了檢測在番茄中的PTI反應,我們已經成功地建立了根部與葉部PTI反應之分析系統。實驗結果顯示抗病品系H7996之PTI反應比感病品系WVa700強,且對於多種特性不同之病原菌之抗病性也較強。另外,Bwr12之存在與較強之番茄根部PTI反應具有顯著關連性,故PTI防禦應參與在Bwr12主導之青枯病抗病機制中。此外,功能性遺傳與基因表現特性等分析所得結果顯示,12g520與12g550在番茄PTI反應與抵抗多種病原菌之抗病反應中為正向調控者,分析大量表現12g520與12g550之轉殖菸草所得結果中亦有一致的結論,而12g690則是透過調控水楊酸 (salicylic acid, SA) 與茉莉酸 (jasmoic acid, JA) 訊息傳導路徑而在植物抗病反應中扮演負調控者。此外,蛋白質定位結果顯示12g520座落於細胞膜上,12g550會被分泌至細胞外,而12g690 N端之36個胺基酸座落於細胞膜上。以上研究結果對於了解番茄之PTI訊息傳遞與番茄抗青枯病之分子機制提供了關鍵且重要訊息。 Bacterial wilt (BW) caused by Ralstonia solanacearum (Rs) is a complex and serious disease affecting a wide range of important crops, and breeding for durable resistance is the only effective means for disease control. Tomato cultivar Hawaii 7996 (H7996) is currently the most stable BW-resistance source. Despite BW-resistance associated quantitative trait loci (QTLs) have been mapped on H7996 chromosomes, the involved molecular mechanism and the gene identity remain undetermined. This study aims to investigate the role of pathogen-associated molecular patterns (PAMPs)-triggered immunity (PTI) in H7996 disease defense and to identify genes involved in the resistance mediated by Bwr12, the major QTL associated with the H7996 resistance against Rs phylotype I strains. We have established assay systems for Rs-induced PTI responses in tomato leaf and root. We found that H7996 displays stronger PTI responses and better tolerance to multiple bacteria than BW-susceptible (BWs) cultivar WVa700. Furthermore, Bwr12 correlates with stronger root PTI responses, suggesting the involvement of PTI in Bwr12-mediated BW-defense. Results of functional genetic, gene expression analyses and disease responses of overexpressing transgenic tobacco plants further reveal a positive role of 12g520 and 12g550 in PTI against distinct pathogens and a negative role of 12g690 in defense via modulating SA and JA pathways. In addition, 12g520-GFP localizes at the plasma membrane, 12g550-GFP could be secreted to extracellular space, and 12g6901-36-GFP localizes at the plasma membrane. These results shed light on the mechanism of PTI signaling and the disease-defense mechanisms in tomato. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/52905 |
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顯示於系所單位: | 植物科學研究所 |
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