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Pseudomonas syringae引起之茼蒿細菌性葉斑病

Bacterial Leaf Spots on Chrysanthemum coronarium Caused by Pseudomonas syringae

摘要


2011 年於雲林縣西螺鎮的蔬菜生產區,首次發現茼蒿植株接近地表下位葉的葉背或葉緣處初期出現水浸狀斑點,病斑會漸癒合成大型不規則褐色斑,經由罹病組織分離出一病原細菌,將此菌接種至茼蒿葉片,可產生相同病徵,完成柯霍氏法則。此病原菌經電子顯微鏡觀察,其型態為桿狀極生多根鞭毛,經生理生化測定得知其可產生果聚醣,並可利用蔗糖及山梨醇,輔以Biolog 鑑定系統及16S-23S intergenic transcribed spacer (ITS) 序列比對,確認此菌為Pseudomonas syringae。進一步以16S-23S ITS 片段序列與基因庫登錄之P. syringae 不同病原型的序列進行比較,發現其與P. syringae pv. antirrhini、P. syringae pv. tomato、P. syringae pv. maculicola 及P. syringae pv. lachrymans 之16S-23S ITS 核苷酸序列相似度可達99.5 ~ 100%。將此序列以鄰聚連結法 (neighbor-joining method) 繪製親緣演化分析樹狀圖,得知本病原菌與上述4病原型皆屬於第三基因種 (genomospecies),此病原菌是否為新的病原型則需進一步測試方能確認。以濾紙擴散法在培養基上測試市售9 種藥劑對本菌的抑制效果,結果顯示除嘉賜黴素、鋅錳乃浦及三元硫酸銅3 種藥劑於供試濃度下對該菌之生長無抑制作用外,其餘6 種包括鏈四環黴素、鏈黴素、多保鏈黴素、氫氧化銅、嘉賜銅及歐索林酸等藥劑於供試濃度均能抑制其生長,其中又以多保鏈黴之效果最佳。

並列摘要


In February 2011, Chrysanthemum coronarium leaves with necrotic spot symptoms were collected from Xiluo Township, Yunlin County in Taiwan. Symptoms began as small water soaked lesions on the leaf and gradually expanded to become irregular brown spots. A G(-) bacterial pathogen was isolated from infected leaf tissue. This pathogen was a rod shaped bacteria that possessed many polar flagella. It was able to induce hypersensitive reactions in tobacco, produce levan, and utilize sucrose and sorbitol as carbon sources. Using physiological and biochemical analyses, Biolog identification, PCR analysis, and 16S-23S ITS rDNA sequence analysis, we identified the pathogen as Pseudomonas syringae. Pathogenicity was verified by Koch’s postulates. The 16S-23S ITS rDNA sequences of the tested strains were 99.5 ~ 100% identical to the ITS sequences of P. syringae pv. antirrhini, P. syringae pv. tomato, P. syringae pv. maculicola, and P. syringae pv. lachrymans. We constructed a phylogenetic tree using the neighbor joining method and determined that the tested strains were clustered with genomospecies 3 classified by Gardan. We then investigated the ability of 9 agrochemicals to control this pathogen by disc diffusion assays, and found that Streptomycin + Tetracycline, Streptomycin, Thiophanate methyl + Streptomycin, Kasugamycin, Copper hydroxid, and Oxolinic acid had inhibitory activities against the pathogen.

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