Lowery D T, French C J, Bernardy M
Agriculture and Agri-Food Canada, Pacific Agri-Food Research Center, Summerland, British Columbia, V0H 1Z0, Canada.
Plant Dis. 2005 Feb;89(2):205. doi: 10.1094/PD-89-0205A.
Blueberry scorch virus(BlScV) is a carlavirus that causes a serious disease of blueberries (Vaccinium corymbosum L.) in North America (2). In aphid-transmission studies of BlScV using blueberry as host and test species, we found the rate of transmission to be low, and a lengthy incubation period was required before BlScV could be detected. For sequencing studies, RNA extraction from blueberry using standard methods was unreliable and inefficient. These problems prompted a search for alternate hosts. Of 12 herbaceous hosts screened for BlScV transmission using the blueberry aphid, Ericaphis fimbriata Richards, with mechanical transmission, only Nicotiana occidentalis (Wheeler) became infected. After 3 to 4 weeks, infection of N. occidentalis with BlScV resulted in mild symptoms that included pronounced leaf twisting and swollen leaf veins. Infection with BlScV was confirmed using a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) kit (Agdia Inc., Elkhart, IN), polyclonal antibodies to BlScV from the antiserum collection at the Pacific Agri-Food Research Center, Summerland, British Columbia, Canada, and reverse transcription-polymerase chain reaction (RT-PCR). Forward (5'-NTAAACACTCCCGAATATAC-3') and reverse (5'-CAGATTGCTTATCCGGCTTC-3') primers were designed with the published sequence of BlScV isolate NJ-02 (GenBank Accession No. NC003499). An amplicon of the expected size was generated and sequenced. BLAST analysis indicated that the nucleotide sequence of the amplified fragment was 87% identical to the corresponding sequence in NJ-02 (1). N. occidentalis was readily infected with BlScV following aphid or mechanical inoculations from blueberry. With E. fimbriata as the aphid vector, the transmission rate from blueberry to N. occidentalis was approximately 26%, compared with 70% for mechanical inoculations. Mechanical transfer of BlScV between infected N. occidentalisplants resulted in a 100% transmission rate. Recently, with N. occidentalis, we have completely sequenced two strains of BlScV from British Columbia, Canada and identified several aphid vector species. The identification of N. occidentalis as an herbaceous host of BlScV greatly facilitates future studies on the virus. References: (1) T. D. Cavileer et al. J. Gen. Virol. 75: 711, 1994. (2) R. R. Martin and P. R. Bristow. Phytopathology 78:1636, 1988.
蓝莓焦枯病毒（BlScV）是一种香石竹潜隐病毒属病毒，在北美可引发蓝莓（Vaccinium corymbosum L.）的严重病害（2）。在以蓝莓为宿主和试验物种对BlScV进行蚜虫传播研究时，我们发现传播率较低，且在检测到BlScV之前需要较长的潜伏期。对于测序研究而言，使用标准方法从蓝莓中提取RNA既不可靠也效率低下。这些问题促使人们寻找替代宿主。在用蓝莓蚜（Ericaphis fimbriata Richards）进行机械传播对12种草本宿主筛选BlScV传播时，只有西方烟草（Nicotiana occidentalis (Wheeler)）被感染。3至4周后，西方烟草被BlScV感染会出现轻微症状，包括叶片明显扭曲和叶脉肿胀。使用双抗体夹心酶联免疫吸附测定（DAS - ELISA）试剂盒（Agdia公司，印第安纳州埃尔克哈特）、来自加拿大不列颠哥伦比亚省萨默兰太平洋农业食品研究中心抗血清库的针对BlScV的多克隆抗体以及逆转录 - 聚合酶链反应（RT - PCR）来确认BlScV感染。根据已发表的BlScV分离株NJ - 02（GenBank登录号NC003499）序列设计正向引物（5'-NTAAACACTCCCGAATATAC-3'）和反向引物（5'-CAGATTGCTTATCCGGCTTC-3'）。产生了预期大小的扩增子并进行了测序。BLAST分析表明，扩增片段的核苷酸序列与NJ - 02中的相应序列有87%的同一性（1）。在通过蚜虫或从蓝莓进行机械接种后，西方烟草很容易被BlScV感染。以蓝莓蚜作为蚜虫载体，从蓝莓到西方烟草的传播率约为26%，而机械接种的传播率为70%。在受感染的西方烟草植株之间机械传播BlScV的传播率为100%。最近，利用西方烟草，我们已完成了来自加拿大不列颠哥伦比亚省的两株BlScV的全序列测定，并鉴定出了几种蚜虫载体物种。将西方烟草鉴定为BlScV的草本宿主极大地促进了对该病毒的后续研究。参考文献：（1）T. D. Cavileer等人，《普通病毒学杂志》75: 711，1994年。（2）R. R. Martin和P. R. Bristow，《植物病理学》78:1636，1988年。
