Phytophthora palmivora引起之觀賞植物疫病新紀錄

Abstract

在台灣，自1999年至2015年於田間採集擬似疫病菌危害之觀賞作物標本，共發現與鑑定8種由Phytophthora palmivora引起的台灣觀賞作物疫病新紀錄。罹患疫病的8種觀賞寄主植物包括：軟枝黃蟬、洋桔梗、長壽花、含笑花、桂花、杜鵑花、鵝掌藤及美女櫻等。發病部位包括花、葉、嫩莖及根系組織，嚴重時導致病株全株萎凋、枯萎死亡。本實驗共分離到37株P. palmivora（7A^1:30A^2）菌株，均為典型菌株（typical type）。孢囊為單假軸著生，橢圓形、卵圓形或檸檬形，兩側大致對稱，具明顯乳突與脫落性；藏卵器表面平滑，藏精器單生單室底著；具厚膜孢子。生長溫度最高可達34－36℃，最適生長溫度為24－28℃。ITS DNA序列與收集在NCBI GenBank資訊庫中P. palmivora的相同度高達99.49－100%，屬於Cooke等人分子分類群的第IV群（clade）。本試驗結果顯示P. palmivora基因序列的比對結果與形態鑑定結果具一致性。 From 1999 to 2015, diseased samples caused by Phytophthora species were collected from gardens and fields in Taiwan. A total of 8 species of ornamental crops infected with Phytophthora palmivora were identified and recorded for the first time in Taiwan. These 8 species of ornamental crops infected with Phytophthora consisted of campanilla (Allamanda cathartica), prairie gentian (Eustoma exaltatum ssp. russellianum), kalanchoe (Kalanchoe blossfeldiana), banana shrub (Michelia figo), sweet osmanthus (Osmanthus fragrans), azalea (Rhododendron sp.), umbrella tree (Schefflera arboricola) and garden verbena (Verbena hybrida). Among these plants, sever disease symptoms were observed on prairie gentian and azalea. A total of 37 isolates (7A^1:30A^2) of the P. palmivora infecting these ornamental plants were obtained. All of them showed typically morphological characteristics of P. palmivora. Sporangia were produced simple sympodiumly on sporangiophores, and ovoid, oval to lemon-shaped, symmetrical or slightly asymmetrical on both sides, papillate prominently, and deciduous. Oogonialwalls were smooth and antheridia were amphigynous. Chlamydospores were abundant. Maximum temperature for mycelial growth was 34-36℃, with optimum temperature at 24-28℃. The sequences identities of ITS DNA region of these isolates were up to 99.49-100 % with the best fit sequences of P. palmivora collected in NCBI GenBank database, and these can be classified as Phytophthora clade IV (Cooke et al. 2000). Blasting results of these P. palmivora isolates were consistent with morphological characters.