First Report of Pseudomonas tolaasii Causing Bacterial Brown Blotch of White Hypsizygus marmoreus in Taiwan

Hypsizygus marmoreus (Peck) H. E. Bigelow 1976, commonly known as the white elf mushroom (白精靈菇) when cultivated in a sawdust bag, is a commercially important mushroom species in Taiwan. In March 2023, infected samples showing yellow sticky symptoms on the lower parts of stipes were collected from a cultivated farm in Changhua, Taiwan. Bacterial ooze was observed flowing out of the infected stipes when they were suspended in sterile water. The isolated bacterium from the infected fruiting bodies was grown on a nutrient agar (NA) medium, forming circular colonies with smooth surfaces and a milky yellow color. It also exhibited yellow-green fluorescence on King’s B medium. To confirm the pathogenicity of the bacterial isolate on white elf mushroom, its suspension in sterile water was sprayed on the surfaces of fruiting bodies, resulting in yellow and water-soaked symptoms within 1–3 d after inoculation. Over time, the symptoms expanded, leading to severe brown blotching and rot of the fruiting body tissues, accompanied by a sticky odor on the 7 d after inoculation. Based on the results of observation of cultural characteristics and pathogenicity tests that conform to Koch’s postulates, as well as the result of 16S rRNA sequence analysis, the causal agent of the bacterial brown blotch disease on white H. marmoreus was identified as Pseudomonas tolaasii Paine. This paper represents the first report of bacterial brown blotch disease on white H. marmoreus in Taiwan. In the future, further surveys of the brown blotch disease in different cultivation areas are needed. Additionally, the disease control effect of environmental disinfectants such as hypochlorous acid-containing water will be tested to reduce the economic losses caused by the bacterial disease. 白精靈菇是台灣常見的商業化栽培品種之一，以太空包栽培白色鴻喜菇而聞名 (白精靈菇)。於2023 年3 月，從彰化縣白精靈菇栽培業者處採集子實體樣本，其菌柄底部表面出現黃褐化、呈水浸狀病徵，並且有細菌菌泥流出。進一步使用營養培養基 (nutrient agar; NA) 與King’s B (KB) 培養基進行分離純化。在NA 培養基上，所得的分離株呈乳黃色且表面光滑之圓形菌落。而在KB 培養基上則產生黃綠色螢光色素。經由將所得分離株以噴霧方式重新接種於市售外觀健康的白精靈菇體，結果出現黃白色水浸狀病斑，且病斑隨時間擴大。接種後7 d，罹病部分出現大面積褐化與腐爛現象，同時散發惡臭，顯示所分離之細菌對白精靈菇具有病原性。進一步鑑定此病原菌，本研究對該菌之16s rDNA 進行增幅並進行序列分析後，初步鑑定該菌為Pseudomonas tolaasii Paine。依據柯霍式法則與核酸序列分析結果可確認，白精靈菇細菌性褐菇病係由P. tolaasii 所引起。本篇為國內首次報導P. tolaasii 導致白精靈菇細菌性褐菇病之發生，未來將持續調查其他菇場之發生情形，同時也將探討以次氯酸水等環境消毒劑防治本病害之可行性，以找尋本病害之病害管理方法。

Subjects

White Hypsizygus marmoreus

Bacterial Brown Blotch

Pseudomonas tolaasii

白精靈菇

細菌性褐菇

Pseudomonas tolaasii

Publisher

農業試驗所

Type

journal article

File(s)

Name

72-4-6.pdf

Size

1.8 MB

Format

Adobe PDF

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