台灣之檳榔疫病

Phytophthora disease of betel palm in Taiwan

自1996年至2014年採集罹患疫病的檳榔（Areca catechu）組織，採集地點包括台中霧峰、南投（埔里、水里、國姓）、及高雄等五處果園，所有疫病菌均自腐敗之莖基部組織分離得到，共獲得12株檳榔疫病菌。接種試驗顯示，疫病菌游走子可造成檳榔幼苗葉片、莖部及根系腐敗，導致植株死亡，與田間病徵一致。不同地區獲得之菌株的形態與生理特性十分相近，甚而完全一致，顯示為害台灣檳榔的疫病菌為同一種。該菌在水中或經鹽液漂洗均可形成大量的孢囊，孢囊單假軸著生，圓形或橢圓形，具顯著乳突，脫落性，脫落孢囊具短柄；該菌形成大量厚膜孢子；所有菌株均為A2配對型，藏卵器表面平滑，藏精器單生單室底著。菌絲在12-33℃下可生長，最適生長溫度為28℃；該菌的形態與生理特性與Phytophthora palmivora最為相近，而且兩者之核醣體內轉錄區（ITS1-5.8S-ITS2）之DNA序列相似度高達99-100%。

"From 1996 to 2014, disease samples of betel palm caused by Phytophthora species were collected from five orchards located at Taichung city, Puli, Shuili, and Guoxing in Nantou County, and Kaohsiung city. A total of 12 Phytophthora isolates were obtained from the rotted tissues of diseased basal stems. Pathogenicity tests showed that zoospores of Phytophthora were capable of causing rot symptoms of the inoculated leave, stem, and root system of betel palm, which were identical to those found in the field. Morphological and physiological characteristics of the isolates collected from different locations were similar or identical, indicating that Phytophthora rot of betel palm was caused by the same Phytophthora specie in Taiwan. Abundant sporangia were formed on V8 agar or in distilled water. Sporangia were born sympodially on, and sporangiophores, ovoid to elliptical, papilate prominently, caduceus, and with short pedicels. Chlamydospores were also produced abundantly. All isolates were of the A2 mating type. Oogonial walls were smooth and antheridia were amphigynous. The temperature range for mycelial growth was 12-33℃with optimum at 28℃. Morphological and physiological characteristics of the betel palm isolates were similar to those of Phytophthora palmivora. In addition, the sequence identity of ITS region between betel palm isolates and that of P. palmivora collected in NCBI data base was 99-100%."