Radisek S, Majer A, Jakse J, Javornik B, Matoušek J
Plant Protection Department, Slovenian Institute of Hop Research and Brewing, Cesta Zalskega tabora 2, SI-3310, Zalec, Slovenia.
Centre for Plant Biotechnology and Breeding, Agronomy Department, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, SI-1000 Ljubljana, Slovenia.
Plant Dis. 2012 Apr;96(4):592. doi: 10.1094/PDIS-08-11-0640-PDN.
Hop (Humulus lupulus), of the Cannabaceae family, is a dioecious perennial climbing plant that is native to Asia, North America, and Europe and is commercially grown in many countries for its use in brewing and the pharmaceutical industry. Slovenia has a more than 100-year-old hop-growing tradition and it is an important national agricultural business, with 90% of production exported to foreign markets. Since 2007, symptoms similar to Hop stunt viroid (HSVd) infection have been observed in several hop gardens with cvs. Celeia, Bobek, and Aurora in the Savinja Valley and Koroška Region. Symptoms include stunting, leaf curl, small cone formation, and dry root rot. In the first year of finding the disease, the incidence varied from 1 to 30% and increased rapidly (by as much as 10%) each subsequent year, predominantly along plant rows. For molecular identification of the pathogen, RNA was extracted from leaves and cones of symptomatic and asymptomatic plants from two different hop gardens with cv. Celeia using Tri Reagent (T9424; Sigma-Aldrich, St Louis, MO). Reverse transcription-PCR was carried out using two pairs of specific HSVd primers, HSVdI/HSVdII and HSVdeI/HSVdeII (3,4). Both primer pairs gave a single PCR product from tissue from symptomatic plants, with expected lengths of ~300 bp, but no amplicons were produced using samples from asymptomatic plants. PCR products from HSVdI/HSVdII were subjected to direct sequencing and HSVdeI/HSVdeII products were cloned in PCR Script SK (+) (Stratagene, La Jolla, CA) vector and sequenced. Five sequences (EMBL Accession Nos. HE575344, HE575345, HE575346, HE575347, and HE575348) were obtained, which revealed 96 to 99% sequence identity with various HSVd variants (grapevine, citrus, and cucumber) reported in GenBank of the National Centre for Biotechnology Information (NCBI). HSVd belonging to the Hostuviroid genus, Pospiviroidae family, has been previously reported in hop in Japan, South Korea, North America, and China (1,2). To our knowledge, this is the first report of the detection of HSVd on hop in Europe. Strict phytosanitary measures have been taken to prevent further spread and to eradicate HSVd infections. References: (1) K. C. Eastwell and T. Sano. Hop Stunt. Page 48 in: Compendium of Hop Diseases and Pests. W. F. Mahaffee et al., eds. The American Phytopathological Society, St. Paul, MN, 2009. (2) L. Guo et al. Plant Pathol. 57:764, 2008. (3) J. Matoušek et al. Plant Soil Environ. 49:168, 2003. (4) J. Matoušek et al. J. Virol. Methods 122:153, 2004.
啤酒花（Humulus lupulus）属于大麻科，是一种雌雄异株的多年生攀缘植物，原产于亚洲、北美洲和欧洲，许多国家都有商业化种植，用于酿造和制药行业。斯洛文尼亚拥有超过100年的啤酒花种植传统，它是一项重要的国家农业产业，90%的产量出口到国外市场。自2007年以来，在萨温贾山谷和科罗什卡地区的几个种植有Celeia、Bobek和Aurora品种啤酒花的花园中，观察到了与啤酒花矮化类病毒（HSVd）感染相似的症状。症状包括生长受阻、叶片卷曲、形成小果穗以及根部干腐。在发现这种病害的第一年，发病率从1%到30%不等，随后每年迅速上升（高达10%），主要沿着植株行蔓延。为了对病原体进行分子鉴定，使用Tri Reagent（T9424；Sigma-Aldrich，圣路易斯，密苏里州）从两个种植有Celeia品种啤酒花的不同花园中，有症状和无症状植株的叶片和果穗中提取RNA。使用两对特定的HSVd引物HSVdI/HSVdII和HSVdeI/HSVdeII进行逆转录PCR（3,4）。两对引物都从有症状植株的组织中得到了单一的PCR产物，预期长度约为300 bp，但使用无症状植株的样本未产生扩增子。来自HSVdI/HSVdII的PCR产物进行直接测序，HSVdeI/HSVdeII的产物克隆到PCR Script SK(+)（Stratagene，拉霍亚，加利福尼亚州）载体中并测序。获得了五个序列（EMBL登录号为HE575344、HE575345、HE575346、HE575347和HE575348），这些序列与美国国立生物技术信息中心（NCBI）GenBank中报道的各种HSVd变体（葡萄、柑橘和黄瓜）的序列同一性为96%至99%。属于寄主类病毒属、马铃薯纺锤块茎类病毒科的HSVd此前已在日本（1,2）、韩国、北美和中国的啤酒花中报道过。据我们所知，这是欧洲首次关于在啤酒花中检测到HSVd的报告。已采取严格的植物检疫措施以防止进一步传播并根除HSVd感染。参考文献：(1) K.C. Eastwell和T. Sano。啤酒花矮化。载于：《啤酒花病虫害汇编》第48页。W.F. Mahaffee等人编。美国植物病理学会，圣保罗，明尼苏达州，2009年。(2) L. Guo等人。植物病理学。57:764，2008年。(3) J. Matoušek等人。植物土壤环境。49:168，2003年。(4) J. Matoušek等人。病毒学方法杂志。122:153，2004年。
