由Fusarium oxysporum引起之小花蕙蘭假球莖腐敗病

Pseudobulb Rot of Cymbidium Caused by Fusarium oxysporum

黃巧雯(Chiao-Wen Huang) ； 黃晉興(Jin-Hsing Huang) ； 李怡靜(Yi-Ching Li) ； 陳純葳(Chun-Wei Chen) ； 謝廷芳(Ting-Fang Hsieh)

《台灣農業研究》 69卷1期 (2020/03) Pp. 65-76

https://doi.org/10.6156/JTAR.202003_69(1).0005

摘要

假球莖腐敗病（pseudobulb rot）為小花蕙蘭生產過程中重要病害之一。受害植株初期下位葉片失去光澤、失水，爾後呈現黃化、萎凋狀。當葉片整片褐化後易抽起與葉鞘分離，只遺留假球莖及殘留之葉基部，最後造成植株死亡，剖開罹病植株可見假球莖與連接根部組織呈黑褐化腐敗病徵。由罹病組織可穩定分離到一種鐮孢菌，該類鐮孢菌在馬鈴薯葡萄糖瓊脂（potato dextrose agar; PDA）。於室溫25-30℃、光照環境下，其培養菌落形態可區分為兩型（type），type-I菌株之菌落為淡紫色，而type-II菌株之菌落為土黃色。依據病原菌形態特徵及分子序列鑑定結果，此兩型的鐮孢菌皆被鑑定為Fusarium oxysporum。此兩型的病原菌，皆可造成蕙蘭屬中報歲蘭與四季蘭之假球莖與根部黑褐色腐敗。此兩型的病原菌菌絲生長溫度範圍為16-32℃，最適溫度為24-28℃；孢子發芽溫度範圍為16-36℃，最適溫度為24-36℃；最適本病害發生溫度為25-30℃。此兩型的病原菌不僅危害報歲蘭與四季蘭外，亦可在虎頭蘭之假球莖上造成類似病徵，但在其他蘭花如文心蘭、仙履蘭、嘉德麗雅蘭及石斛蘭植株上皆未見病徵產生。

關鍵字

小花蕙蘭 ； 假球莖腐敗病 ； 鐮孢病菌

並列摘要

A kind of disease causing pseudobulb rot disease was commonly observed in Cymbidium cultivation area in Taiwan. The disease symptoms included yellowing or withering of leaves and finally plant death. All the infected plants showed brown rot of pseudobulb and root. Two strains of Fusarium sp. showing different colony types were consistently isolated from the infected pseudobulbs and roots. On potato dextrose agar at 25-30℃ cultured under 12 h photoperiod for more than 2 weeks, type-I isolates presented light purple colony and type-II isolates presented terra yellow colony. In disease investigation, the isolation frequency of type-I Fusarium was much higher than type-II Fusarium. Both of these two types of Fusarium sp. were identified as Fusarium oxysporum based on morphological characteristics as well as sequence analysis of the internal transcribed spacer (ITS) and translation elongation factor 1 alpha (TEF-1α) genes. Pathogenicity test of these two pathogens on Cymbidium sinense and Cymbidium ensifolium (by inoculation of spore suspension on root, pseudobulb and leaf) was confirmed for fulfilling the Koch's postulates. The temperature range for mycelial growth of these two types of pathogen was the same at 16-32℃ (optimal at 24-28℃), and for spore germination was the same at 16-36℃ (optimal at 24-36℃). The temperature range for disease development of type- 1 F. oxysporum was 15-30℃ (optimal at 25-30℃). The host range test showed that these two types of pathogen could infect C. sinense, C. ensifolium and Cymbidium hookerianum, but not other tested orchids, such as Oncidium flexuosum, Paphiopedilum insigne, Cattleya and Dendrobium moniliforme.

並列關鍵字

Cymbidium ； Pseudobulb ； Root rot ； Fusarium oxysporum