Strain Identification and Distribution of Citrus Huanglongbing Bacteria in Taiwan

本試驗自台灣熱帶與亞熱帶地區7柑橘主要產區，從疑似黃龍病株採集457個病材料，以聚合酶連鎖反應(PCR)偵測黃龍病菌(Huanglongbing bacteria=HLBB)，並經過濾植物去除病毒後，得到48個無病毒之黃龍病代表分離株以進行病原性與毒性之生物檢定。將各代表分離株嫁接接種在四種不同感病性之柑橘鑑別品種包括有椪柑(Citrus reticulate Blanco)、柳橙(C. sinensis Osb.)、文旦(C. grandis f. buntan Hay.)及檸檬(C. limon Burm)實生苗，觀察其發病狀況。共鑑別出四種黃龍病菌系統，系統Ⅰ僅對椪柑與柳橙具高病原性並產生典型黃龍病病徵。系統Ⅱ對四種鑑別品種皆具高毒性，並可快速增殖其內。系統Ⅲ在椪柑與柳橙引起中度病徵，在文旦僅出現輕度病徵，然而卻無法感染檸檬。系統Ⅳ則僅可感染椪柑及柳橙，幾無病徵表現。經調查台灣田間病菌系統分佈，系統Ⅱ為目前分佈廣之最優勢族群，系統Ⅲ及Ⅰ次之。田間採集疑似黃龍病材料中，實際上約三分之一感染黃龍病(32.6%)，而看似健康之各品種柑橘株僅1.9%感染黃龍病菌，並只在文旦(5%)與檸檬株(5.7%)發現。於本次收集之黃龍病材料中，椪柑、桶柑、柳橙與金柑(Fortunella margarita(Lour.) Swingle)普遍複合感染了柑橘萎縮病毒(Citrus tristeza closterovirus=CTV)與破葉病毒(Citrus tatter leaf capillovirus=CTLV)。單獨感染黃龍病者佔32%。椪柑及桶柑之黃龍病株大多複合感染CTV，但於文旦與檸檬之黃龍病株則少見CTV之複合感染。

關鍵字

柑橘黃龍病；柑橘黃龍病菌系統；病原性

並列摘要

The 48 representative Huanglongbing bacteria (HLBB) isolates were selected from 457 disease samples collected from Huanglongbing (HLB)-diseased citrus trees grown in seven main citrus-producing areas, including tropical and subtropical regions of Taiwan. After indexing and eliminating the citrus viruses, the selected HLBB isolates, free from the viruses, were used for identification of HLBB strains based on a pathogenicity and virulence test with the following differential citrus cultivars: Ponkan mandarin (Citrus reticulata Blanco), Liucheng sweet orange (C. sinensis Osb.), Wentan pummelo (C. grandis f. buntan Hay.), and Eureka lemon (C. limon Burm.). Four strains of HLBB were identified. Strain Ⅰ showed pathogenicity on mandarin and sweet orange by inducing typical HLB symptoms. Strain Ⅱ showed high virulence on all differential cultivars and multiplied fast in all cultivars. Strain Ⅲ caused intermediate symptoms on mandarin and sweet orange and mild symptoms on pummelo, but did not infect Eureka lemon. Mild strain Ⅳ infected mandarin and sweet orange without causing symptoms and was rarely isolated. Strain Ⅱ, which attacked all citrus cultivars grown in Taiwan, was found to dominate over the other strains in the field. Strains Ⅲ and Ⅰ were second in quantity. One-third (32.6%) of the diseased samples showing HLB-like symptoms in the field survey were found to be infected by HLB pathogen in PCR detection. Only 1.9% of healthy-looking citrus trees surveyed, including Wentan pummelo (5%) and Eureka lemon (5.7%), were infected by HLBB. The HLBB-isolates collected from mandarin, tangor, sweet orange, and kumquat (Fortunella margarita [Lour.] Swingle) were commonly co-infected with Citrus tristeza closterovirus (CTV) and/or Citrus tatter leaf capillovirus (CTLV). About 32% of the HLBB-infected trees examined were infected with HLBB only. Most HLB-affected mandarin (66.7%) and tangor (69%) trees were also infected by CTV while CTV was rarely detected in HLBB-infected pummelo (5%) or lemon (0%).

並列關鍵字

Huanglongbing ； HLBB strain ； Pathogenicity

國際替代計量

Strain Identification and Distribution of Citrus Huanglongbing Bacteria in Taiwan

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