台灣葡萄皮爾斯病及媒介昆蟲研究現況

Abstract

葡萄皮爾斯病 (Pierce’s disease, PD) 為國際檢疫病害，是由棲息導管細菌Xylella fastidiosa 所引起，台灣往昔並無紀錄。行政院農業委員會動植物防疫檢疫局 (Bureau of Animal and Plant Health Inspection and Quarantine, 以下簡稱防檢局(BAPHIQ)) 在 2002 年 針 對 國 內 是 否 存 有 PD ， 啟 動 偵 測 調 查 (detection survey)，歷年來透過分離技術及 PCR 檢測確認及剷除的 PD 罹病株約有 12023 棵，另確認雙輪瓜 (Diplocyclos palmatus (L.) C. Jeffrey)、漢氏山葡萄 (Ampelopsis brevipedunculata (Maxim.) Trautv var. hancei (Planch.) Render)、葎草 (Humulus scandens (Lour.) Merr.) 及白匏仔 (Mallotus paniculatus (Lam.) Muell. -Arg.) 也是 PD 的寄主植物；在媒介昆蟲的研究部分， 透 過 柯霍氏法則確認白邊大葉蟬 ( Kolla paulula (Walker)) 為台灣 PD 的媒介昆蟲，歷年來的野外調查則未發現國外已記錄可傳播 PD 的媒介昆蟲。分析國內各地 PD 葡萄菌株、媒介昆蟲白邊大葉蟬體內菌株與 4 種雜草寄主植物體內菌株，進行 16S rRNA 與 16-23SrRNA 區間序列基因解序，並與 X. fastidiosa 不同植物寄主菌株比對，寄主包含 台灣的梨樹與國外的葡萄、桑椹、李、核桃、無花果及夾竹桃等，再利用最大似然法 (Maximum Likelihood) 親緣樹狀圖的分析，結果顯示各地區植物體內的 X. fastidiosa 菌株，可分為五個菌群：第一群為葡萄與桑椹菌群，第二群為咖啡與柑橘菌群，第三群為胡桃、李、桃及無花果菌群，第四群為夾竹桃菌群，第五群為梨菌群；而台灣的葡萄、雜草寄主與蟲媒體內的 PD 菌系，應該屬於第一群，且兩者的基因序列相似度達 99-100%，幾可確認具有同源性。未來台灣應積極防杜國外已知蟲媒藉由種苗植物入侵，並持續偵測調查 PD 在台灣的寄主植物範圍與本土性的媒介昆蟲，以探討兩者在 PD 流行病學所扮演的角色。 There is no record of Pierce’s disease (PD) of grapes incidence in Taiwan, even though PD of grapes caused by Xylella fastidiosa, a xylem-limited bacterium, has been listed as one of the international quarantine plant diseases. In 2002, the Bureau of Animal and Plant Health Inspection and Quarantine launched a survey project to find out if PD occurs in Taiwan. By using isolations and PCR protocols, a total of 12023 grapevines were confirmed to be infected by X. fastidiosa and hence eradicated. Other than grapes, the following four plants were confirmed to be the alternative hosts of PD strains: Diplocyclos palmatus (L.) C. Jeffrey, Ampelopsis brevipedunculata (Maxim.) Trautv var. hancei (Planch.) Render, Humulus scandens (Lour.) Merr., and Mallotus paniculatus (Lam.) Muell. -Arg. In the search of insect vectors for PD strains dissemination in Taiwan, Kolla paulula (Walker) was confirmed to be the vector by the fulfillment of Koch’s postulates. Over the years, survey results indicated that there are no foreign reportedly known vectors in Taiwan. PD strains including originally isolated from tissues of grapes showing PD symptoms collected from around the country, from vector Kolla paulula, and from tissues of 4 alternative hosts were compared with pear leaf scorch strains and strains of foreign origins from grapes, mulberry, plum, pecan, sycamore, and oleander by sequence analyses of 16S rRNA and 16S-23S rRNA internal transcribed spacer region (ITS). The phylogenetic trees constructed by Maximum Likelihood revealed that X. fastidiosa strains from different hosts could be divided into the following five subgroups: (1) grape and mulberry strains, (2) citrus and coffee strains, (3) pecan, peach, plum and sycamore strains, (4) oleander strains and (5) pear strains. The similarity index of all Taiwanese’s PD strains ncluding the above-mentioned three various sources were both 99-100% based on 16S rRNA and 16S-23S rRNA ITS region. The homology of Taiwanese’s PD strains placed them in line with the subgroup of grape and mulberry. The urgent prevention of importing foreign proven vectors via nursery stocks will be critical in disease control. The continuing efforts on the identification of alternative hosts and their relationships with local vectors warrant further attentions for the understanding of the epidemiology of PD diseases in Taiwan.