Garibaldi A, Minuto A, Gullino M L
Centre of Competence for the Innovation in the Agro-Environmental Sector (AGROINNOVA), Via Leonardo da Vinci 44, 10095 Grugliasco, Italy.
Plant Dis. 2008 Mar;92(3):484. doi: 10.1094/PDIS-92-3-0484A.
Bellis perennis (English daisy) is a flowering plant belonging to the Asteraceae and is increasingly grown as a potted plant in Liguria (northern Italy). In February 2007, severe outbreaks of a previously unknown powdery mildew were observed on plants in commercial farms at Albenga (northern Italy). Both surfaces of leaves of affected plants were covered with white mycelia and conidia. As the disease progressed, infected leaves turned yellow. Mycelia and conidia also were observed on stems and flower calyxes. Conidia were hyaline, ellipsoid, borne in chains (as many as three conidia per chain), and measured 27.7 × 16.9 (15.0 to 45.0 × 10.0 to 30.0) μm. Conidiophores measured 114.0 × 12.0 (109.0 to 117.0 × 11.0 to 13.0) μm and showed a foot cell measuring 78.0 × 11.0 (72.0 to 80.0 × 11.0 to 12.0) μm followed by two shorter cells. Fibrosin bodies were absent. Chasmothecia were not observed in the collected samples. The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 415 bp obtained showed an E-value of 7e with Golovinomyces cichoracearum (3). The nucleotide sequence has been assigned the GenBank Accession No. AB077627.1 Pathogenicity was confirmed through inoculations by gently pressing diseased leaves onto leaves of healthy B. perennis plants. Twenty plants were inoculated. Fifteen noninoculated plants served as a control. Plants were maintained in a greenhouse at temperatures ranging from 10 to 30°C. Seven days after inoculation, typical symptoms of powdery mildew developed on inoculated plants. The fungus observed on inoculated plants was morphologically identical to that originally observed. Noninoculated plants did not show symptoms. The pathogenicity test was carried out twice. To our knowledge, this is the first report of powdery mildew on B. perennis in Italy. The disease was already reported in other European countries (2). Voucher specimens are available at the AGROINNOVA Collection, University of Torino. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) U. Braun The Powdery Mildews (Erysiphales) of Europe. Gustav Fischer Verlag, Jena, Germany, 1995. (3) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000.
雏菊是一种属于菊科的开花植物，在利古里亚（意大利北部）越来越多地作为盆栽植物种植。2007年2月，在意大利北部阿尔本加的商业农场中，观察到一种先前未知的白粉病严重爆发。受影响植株的叶片两面都覆盖着白色菌丝体和分生孢子。随着病情发展，受感染的叶片变黄。在茎和花萼上也观察到了菌丝体和分生孢子。分生孢子无色透明，椭圆形，呈链状着生（每条链多达三个分生孢子），大小为27.7×16.9（15.0至45.0×10.0至30.0）μm。分生孢子梗大小为114.0×12.0（109.0至117.0×11.0至13.0）μm，基部细胞大小为78.0×11.0（72.0至80.0×11.0至12.0）μm，后面跟着两个较短的细胞。无纤维状小体。在所采集的样本中未观察到闭囊壳。使用引物ITS4/ITS6扩增核糖体DNA的内部转录间隔区（ITS）并进行测序。对获得的415 bp进行BLASTn分析（1）显示，与瓜叶单囊壳白粉菌（3）的E值为7e。该核苷酸序列已被赋予GenBank登录号AB077627.1。通过将病叶轻轻压在健康雏菊植株的叶片上进行接种来确认致病性。接种了20株植株。15株未接种的植株作为对照。植株在温度为10至30°C的温室中养护。接种七天后，接种植株上出现了典型的白粉病症状。接种植株上观察到的真菌在形态上与最初观察到的相同。未接种的植株未出现症状。致病性试验进行了两次。据我们所知，这是意大利关于雏菊白粉病的首次报道。该病害在其他欧洲国家已有报道（2）。凭证标本保存在都灵大学的AGROINNOVA标本馆。参考文献：（1）S. F. Altschul等人，《核酸研究》25:3389，1997年。（2）U. Braun，《欧洲白粉菌（白粉菌目）》。德国耶拿古斯塔夫·费舍尔出版社，1995年。（3）U. Braun和S. Takamatsu，《Schlechtendalia》4:1，2000年。
