臺灣嘉德麗亞蘭疫病菌(Phytophthora palmivora)之形態與生理特性

Physiological and morphological characteristics of Phytophthora palmivora causing black rot of Cattleya in Taiwan

葉濟蒼(J. T. Yeh) ； 謝式坢鈺(S. P. Y. Hsieh) ； 安寶貞(P. J. Ann)

《植物病理學會刊》 7卷2期 (1998/06) Pp. 85-93

https://doi.org/10.6649/PPB.199806_7(2).0003

摘要

嘉德麗亞蘭為台灣目前栽培洋蘭中，較易罹患疫病之蘭花屬。由本省中部、西部及東部之蘭園中採集病株，經分離得20疫病菌株，經鑑定都屬於Phytophthora palmivora (Butler) Butler，除P -9258菌株為A^2配對型(mating type) 外，其餘皆為A^1配對型。菌落在5% V-8瓊脂培養基為白色無特殊花紋。菌絲寬約3 -5μm，以近似直角分支，其基部有縊縮現象。胞囊以單合軸方式著生，形狀為卵圓形或橢圓形，有乳頭狀突起，平均長度為44.3 - 51.0μm，寬為26.1 - 29.7μm，長寬比值(L/W)平均為1.61 - 1.75。菌絲生長適溫在24∼32 C間，最低及最高溫度分別為10 及35 C。在嘉德麗亞蘭葉表和在5% V-8固體培養基上，產胞之最適溫約為24 C；相對濕度100%時，產胞囊量最多，而相對濕度80%以下則不產生胞囊。胞囊分化成游走子以16 C時最佳，而於35 C時不分化成游走子。胞囊直接發芽之最適溫為24 C，游走子發芽適溫在20~28 C間，發芽率達60.5 - 77.1 %，高溫較不利於游走子之發芽。

關鍵字

嘉德麗亞蘭 ； 疫病菌 ； 胞囊 ； 游走子 ； 產胞 ； 胞子發芽

並列摘要

A total of twenty isolates of Phytophthora were isolated from diseased tissues of Cattleya orchid plants which were collected from 17 commercial orchid gardens located at central, western and eastern areas of Taiwan, respectively. All Phytophthora isolates from Cattleya were identified as P. palmivora belonging to A^1 mating type except the P9258 isolate from Taitung, which appeared to belong to A^2 mating type. All test isolates formed white colonies without special patterns on 5% V-8 agar. The mycelia branched by straight angle, constricted at the base, and had the diameter measured about 3-5μm. Sporangia were elongated ellipsoid or elongated ovoid, papillate, and deciduous with pedicel length less than 5 μm. Average range of length and width of sporangia were 44.3-51.0×26.1 - 29.7μm with the L/W ratios of 1.61-1.75. The maximum, optimum and minimum temperatures for mycelial growth of the tested isolates were approximately 35, 24-32 and 10 C, respectively. The optimum temperature for sporangial production both on 5% V-8 agar and on surface of Cattleya leaves was 24 C. The number of sporangia produced on V-8 agar was the highest under 100% relative humidity (RH), whereas no sporangia were formed under conditions of RH below 80%. Sporangia of tested isolates were able to indirectly germinate from 8C through 32C with an optimum temperature at 16 C. The optimum temperature for direct germination of sporangia of tested isolates was at 24 C. No zoospores were formed at 35 C. High temperature was not suitable for zoospore germination either. The optimum temperature ranges for zoospore germination on 5% V-8 agar were 20- 28C, the germination rates were around 60.5-77.1%.

並列關鍵字

Cattleya orchids ； Phytophthora palmivora ； sporangium zoospore ； sporulation ； spore germination