植物青枯病菌及其噬菌體交互關係之探究

Elucidation of the interaction between Ralstonia solanacearum and its bacteriophages

王冠中(Kuan-Chung Wang)

指導教授 ： 鄭秋萍

國立臺灣大學/生命科學院/植物科學研究所/碩士(2009年)

https://doi.org/10.6342/NTU.2009.10083

摘要

青枯菌為土壤中常見的植物病原菌之一，可感染超過兩百種植物，其中包含番茄、馬鈴薯等極具經濟價值的作物。土壤中的青枯菌侵入植物體後，可在木質部大量增殖並分泌胞外多醣或是細胞壁分解酵素，受到感染的植物常因為木質部水分運輸受阻進而造成全株死亡。針對青枯菌造成的細菌性萎凋病，到目前為止尚無有效的藥劑可以預防或是控制其病徵產生。因此生物性防治法便成為一個值得期待的防治方法。為了瞭解青枯病菌與其噬菌體間之交互作用，並期許可以應用於青枯病的防治，本論文初步在台灣數個地區的土壤中分離青枯菌的噬菌體。由基因組隨機定序結果得知本研究目前所分離之噬菌體與T7類有高度的胺基酸相似性，並且對其進行了基本的特性分析、宿主範圍測試和溶菌效果分析等，而進一步的生物防治測試也證明外加噬菌體確實可降低番茄青枯病的發生率。此外，為了更加了解噬菌體與青枯菌的分子層級交互關係，本研究大量篩選青枯菌跳躍子插入之突變株庫，發現二十一個與噬菌體感染相關之青枯菌基因；其中約半數是屬於表面脂多糖 (lipopolysaccharides) 生合成相關酵素基因，其餘則為與ABC類運送蛋白或甘露糖運輸與代謝相關基因，以及某些尚待研究的新穎基因。透過這些分子層面的研究使得我們對青枯菌及其噬菌體交互關係有更進一步了解，且對研擬病害生物防治策略也提供了許多重要的啟發。

關鍵字

青枯菌 ； 細菌性萎凋 ； 噬菌體 ； 生物防治 ； 脂多醣

並列摘要

Ralstonia solanacearum is a soil-borne, xylem-inhabited plant pathogen. The wide host range (Hayward, 1991) and the lethal wilting symptom render R. solanacearum a globly important pathogen. Commercial pesticides and antibiotics are generally ineffective in controlling bacterial wilt (BW) caused by the pathogen (Denny, 2006). Therefore, biological control methods would be one of the feasible approaches to reduce crop losses caused by this bacterium. In this study, indigenous R. solanacearum bacteriophages were isolated and identified to be T7-like phages. The characteristics of these phages, including host range, lytic ability and optimal pH for the isolated phages have been determined. Their potential of being employed as biocontrol agents against tomato BW was also demonstrated. Furthermore, a systematic survey of R. solanacearum genes essential for phage infection has been carried out and led to the identification of 21 genes. About a half of these genes are or could be involved in biosynthesis of lipopolysaccharides (LPS). The rest of the identified genes included those involved in sugar metabolism and unknown function genes. The elucidation of phage infection mechanism not only is valuable for basic research, but also could be useful for boosting the efficiency of phage therapy by artificially introducing infection essential genes into the phage genomes. These studies collectively are expected to pave the way for elucidating phage-host interactions and establishing useful biocontrol means.

並列關鍵字

Ralstonia ； bacterial wilt ； bacteriophage ； biocontrol ； lipopolysaccharides

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