Garibaldi A, Gilardi G, Gullino M L
Centre of Competence AGROINNOVA, University of Torino, Via Leonardo da Vinci 44, 10095 Grugliasco, Italy.
Plant Dis. 2010 Mar;94(3):382. doi: 10.1094/PDIS-94-3-0382A.
Fuchsia × hybrida (Onagraceae) is widely used in gardens and very much appreciated as a potted plant. During the summer of 2008, a severe foliar disease was observed on 1- to 2-year-old plants in several gardens located near Biella (northern Italy). Small necrotic spots were observed on the upper and lower sides of infected leaves. Spots enlarged to form round areas of 2 to 12 mm in diameter and were well defined by a brown-purple margin at temperatures between 15 and 25°C. Severely infected leaves wilted and abscised as disease progressed. The disease occurred on 100% of the plants and at least 30% of the leaf surface was affected. Stems and flowers were not affected by the disease. A fungus was consistently isolated from infected leaves on potato dextrose agar amended with 25 mg/liter of streptomycin. The fungus was grown on leaf extract agar, including 30 g of autoclaved fuchsia leaves per liter, and maintained at 22°C (12-h light, 12-h dark). After 30 days, black pycnidia 150 to 450 μm in diameter developed, releasing abundant hyaline, elliptical, nonseptate conidia measuring 5.6 to 14.3 (10.3) × 1.9 to 5.6 (3.5) μm. On the basis of these morphological characteristics, the fungus was identified as a Phoma sp. (2). The internal transcribed spacer (ITS) region of rDNA of the isolate coded FuHy1 was amplified using primers ITS4/ITS6 (3) and sequenced. BLAST analysis (1) of the 488-bp segment obtained showed an E-value of 0.0 with Phoma multirostrata. The nucleotide sequence has been assigned GenBank Accession No. GU220539. Pathogenicity tests were performed by spraying leaves of healthy 6-month-old potted Fuchsia × hybrida plants with a spore and mycelial suspension (1 × 10 spores or mycelial fragments per milliliter). Noninoculated plants sprayed with water served as controls. Five plants were used for each treatment. Plants were covered with plastic bags for 5 days after inoculation and kept under greenhouse conditions at 20 to 24°C. Symptoms previously described developed on leaves 12 days after inoculation, whereas control plants remained healthy. The fungus was consistently reisolated from the lesions of the inoculated plants. The pathogenicity test was carried out twice. To our knowledge, this is the first report of the presence of P. multirostrata on fuchsia in Italy as well as worldwide. The importance of the disease is still limited in Italy. References: (1) S. F. Altschud et al. Nucleic Acids Res. 25:3389, 1997. (2) G. H. Boerema and G. J. Bollen. Persoonia 8:111, 1975. (3) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997.
倒挂金钟（柳叶菜科）在园林中广泛应用，作为盆栽植物备受喜爱。2008年夏季，在意大利北部比耶拉附近的几个花园中，1至2年生的倒挂金钟植株上出现了一种严重的叶部病害。在感病叶片的上、下表面均观察到小的坏死斑。病斑扩大形成直径2至12毫米的圆形区域，在15至25°C的温度下，病斑边缘呈棕紫色，界限清晰。随着病情发展，严重感病的叶片枯萎并脱落。该病在所有植株上均有发生，至少30%的叶面积受到影响。茎和花未受该病影响。在添加了25毫克/升链霉素的马铃薯葡萄糖琼脂上，从感病叶片中 consistently 分离出一种真菌。该真菌在叶提取物琼脂上生长，每升含有30克经高压灭菌的倒挂金钟叶片，并在22°C（12小时光照，12小时黑暗）下培养。30天后，形成直径150至450微米的黑色分生孢子器，释放出大量透明、椭圆形、无隔膜的分生孢子，大小为5.6至14.3（10.3）×1.9至5.6（3.5）微米。根据这些形态特征，该真菌被鉴定为茎点霉属（Phoma sp.）（2）。使用引物ITS4/ITS6（3）扩增分离株FuHy1的rDNA内部转录间隔区（ITS），并进行测序。对获得的488碱基对片段进行BLAST分析（1），结果显示与多喙茎点霉（Phoma multirostrata）的E值为0.0。该核苷酸序列已被赋予GenBank登录号GU220539。通过向健康的6个月大盆栽倒挂金钟植株的叶片喷洒孢子和菌丝体悬浮液（每毫升1×10个孢子或菌丝片段）进行致病性测试。喷洒水的未接种植株作为对照。每种处理使用5株植物。接种后用塑料袋覆盖植株5天，并置于20至24°C的温室条件下。接种12天后，接种植株的叶片出现了先前描述的症状，而对照植株保持健康。从接种植株的病斑中 consistently 重新分离出该真菌。致病性测试进行了两次。据我们所知，这是意大利以及全球范围内关于倒挂金钟上存在多喙茎点霉的首次报道。在意大利，该病的重要性仍然有限。参考文献：（1）S. F. Altschud等人，《核酸研究》25:3389，1997年。（2）G. H. Boerema和G. J. Bollen，《真菌学报》8:111，1975年。（3）D. E. L. Cooke和J. M. Duncan，《真菌研究》101:667，1997年。
