Pectobacterium chrysanthemi為文心蘭細菌性軟腐病主要病原之探討

Pectobacterium chrysanthemi as the causal agent of bacterial soft rot on Oncidium orchid

李佩如(Pei-Ju Lee)

指導教授 ： 林宜賢

國立屏東科技大學/農學院/植物醫學系所/碩士(2013年)

https://doi.org/10.6346/NPUST.2013.00017

摘要

摘　要

學號：M9827008
論文題目： Pectobacterium chrysanthemi 為文心蘭細菌性軟腐病主要病原之探討
總頁數：57
學校名稱：國立屏東科技大學　　　　系（所）別：植物醫學系
畢業時間及摘要別：一百零一 學年度第一學期碩士學位論文摘要
研究生：李佩如　　　　　　　　　　指導教授：林宜賢　博士
論文摘要內容：
細菌性軟腐病，可由Pectobacterium carotovorum subsp. carotovorum（Pcc）或Pectobacterium chrysanthemi（Pch）所引起，為文心蘭之重要限制因子。由民國99年至101年之三年期間，田間採集文心蘭罹病之軟腐組織進行病原菌分離，經聚合酶連鎖反應鑑定後皆為Pch，卻無Pcc菌株。於屏東地區重新採集及偵測文心蘭軟腐病之樣品，亦顯示Pch為唯一可分離之病原。為何文心蘭軟腐之病原主要為Pch，是否與台灣中南部之溫度較高有關或與寄主之差異有關，因此，本論文將分別針對此二方面進行探討。首先，分別將Pch（PLO3）與Pcc（ECC5）菌株接種在不同溫度及馬鈴薯、白蘿蔔、胡蘿蔔與文心蘭等寄主，結果顯示除文心蘭外之其他作物，Pcc及Pch在致腐能力上無明顯寄主選擇性。Pch僅有在高溫下於白蘿蔔上之致腐能力較Pcc高。進一步以多個Pcc及Pch菌株穿刺接種於多種不同作物上之結果亦顯示，Pch在不同作物上均具有致腐能力，但卻非全數Pcc菌株可在蝴蝶蘭與文心蘭可造成致腐。此結果說明，Pch為文心蘭軟腐病之主要病原，且寄主之選擇可能為主要因子。進一步以ECC5及PLO3菌株接種於文心蘭上並分析其族群發展，結果亦顯示軟腐細菌族群建立之速度與前述軟腐病徵之趨勢一致，且PLO3在不同溫度下族群建立皆較ECC5快。可推測文心蘭具有延緩Pcc菌株族群建立之作用。因此，藉由細菌之生長曲線分析植物萃取液之添加是否對Pcc之生長聚抑制作用，卻顯示文心蘭萃取液可顯著促進Pcc之生長。因此，可進一步推測文心蘭對Pcc生長的抑制作用，可能與活細胞之防禦反應有關。為證明此防禦反應是否為病原菌被辨識後可增加Ca2+進入細胞，並誘導NADPH氧化酵素之活性，造成ROS之產生啟動的植物免疫反應。分別將ECC5混合不同濃度之NADPH氧化酵素的抑制劑DPI或Ca2+通道的抑制劑LaCl3後，皆可顯示隨抑制劑處理濃度之提高而增加此菌株於文心蘭葉片中族群之建立與軟腐病徵之產生。此外，亦證明ECC5可在文心蘭葉片中產生較多之ROS累積，且此ROS之產生可能與抑制ECC5之生長有關。綜合上述之結果說明，Pch為文心蘭的主要病原與植物辨識Pcc後產生之免疫反應具高度相關。

關鍵字

細菌細軟腐病病原菌 ； 文心蘭 ； 寄主範圍 ； 溫度 ； 植物免疫

並列摘要

Abstract

Student ID: M9827008
Title of thesis: Pectobacterium chrysanthemi as the causal agent of bacterial soft rot on Oncidium orchid
Total page: 57
Name of institute: Department of Plant Medicine, National Pingtung University of Science and Technology
Graduate date: 101/12　　　　　　　　　Degree conferred: Master
Name of student: Pei-Ju Lee 　　　Adviser: Dr. Yi-Hsien Lin
The contents of abstract in this thesis:
Oncidium orchids are important ornamental flowers for export in Taiwan. Their production is limited by bacterial soft rot pathogens. The common bacterial soft rot pathogens are Pectobacterium carotovorum subsp. carotovorum (Pcc) and P. chrysanthemi (Pch). During our survey, we found Pch is a unique pathogen could be isolated from Oncidium. However, the possible reasons of this phenomenon is still unknown. In this study, we tried to find out the possible factors in pathogenicity of Pcc and Pch on Oncidium (Gower Ramsey). We first assayed the temperature factors. Results Pcc (ECC5) and Pch (PLO3) caused soft rot symptoms without significant on potato, radish, carrot, and under various temperature. However, PLO3 caused more severe soft rot symptoms on Oncidium than that caused by ECC5. In addition, we found the soft rot symptoms on Oncidium and Phalaenopsis. These results suggested that host selection on Pcc and Pch is more important than that on temperature factor. Moreover, bacterial populations of ECC5 and PLO3 were measured on Oncidium. We also found that PLO3 established its population on Oncidium was more rapidly than that did by ECC5. To clarify the inhibitory effect on Pcc, we further found the growth curve of ECC5 was not inhibited by leaf extract obtained from Oncidium. Taken together, we suggested that the inhibitory effects of Oncidium on Pcc might be determined by functional host cells mediated defense response. We further demonstrated that this defense response of Oncidium against ECC5 was related to plant immune signals including reactive oxygen species (ROS) generation, Ca2+ influx, and actvities of NADPH oxidase. In this study, we provided evidences that Pch is the dominant soft rot pathogen on Oncidium, not Pcc. Plant immune system on Oncidium (Gower Ramsey) triggerd by Pcc is the key factor.

並列關鍵字

bacterial soft rot pathogens ； Oncidium orchids ； host ronge ； temperature ； Plant immunity

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