Thomidis T, Exadaktylou E
Alexander Technological Education Institute of Thessaloniki, Department of Crop Production, 57400, Sindos Macedonia, Greece.
Plant Dis. 2011 Jan;95(1):79. doi: 10.1094/PDIS-07-10-0514.
In spring 2010, plants of pomegranate (Punica granatum L.) cv. Wonderful with symptoms of crown rot were observed in the Prefecture of Xanthi, Thrace, Greece. Close examination of these plants revealed distinct symptoms of crown rots. Isolations from the lower margins of the necrotic area were made by plating tissues of approximately 3 mm on acidified (2.5 ml of 85% lactic acid per liter of nutrient medium to create a pH = 3.5 after autoclaving) potato dextrose agar. The plates were incubated at 23°C for 5 to 7 days, and consistent colonies with light yellow, leathery mycelia and abundant, black, solitary pycnidia of various sizes were observed. Hyphae were septate and conidia were hyaline, one-celled, and ellipsoid to fusiform (average 10.1 to 20.2 × 3.2 to 4.3 μm). The pathogen was identified as Pilidiella granati Saccardo (synonym Coniella granati (Saccardo) Petrak & Sydow (3)) based on mycelium and spore morphology and ribosomal ITS1-5.8S-ITS2 sequences, which were identical to GenBank No. FN908875. Koch's postulates were completed in the laboratory by inoculating 20 1-year-old plants of pomegranate cv. Wonderful. With a 7-mm-diameter cork borer, a wound was created in the middle of each collar by removing the bark. A 6-mm-diameter agar plug bearing mycelia and spores from a 15-day-old culture of P. granati was inserted into each wound. The wound was covered with petroleum jelly and wrapped with adhesive tape to prevent desiccation. Ten trees were inoculated with sterile potato dextrose agar plugs to serve as controls. All plants were incubated at 25°C for 10 days, at which time necrosis was observed. Koch's postulates were satisfied after reisolating the fungus from inoculated plants that developed symptoms similar to those observed in the field. Control plants produced no symptoms of disease. To our knowledge, this is the first report of P. granati from pomegranate plants with symptoms of crown rots in Greece. The role of predisposing factors such as herbicides and frost damage to infection by P. granati is unknown. This pathogen has been reported to cause fruit rot of pomegranate in Spain (2) and California (1). References: (1) T. J. Michailides et al. (Abstr.) Phytopathology 100(suppl.):S83, 2010. (2) L. Palou et al. New Dis. Rep. Online publication. doi:10.5197/j.2044-0588.2010.022.021, 2010. (3) G T. Tziros and K. Tzavella-Klonari. Plant Pathol. 57:783, 2007.
2010年春季，在希腊色雷斯地区的克桑西州发现了患有根腐病症状的“奇妙”石榴（Punica granatum L.）植株。对这些植株进行仔细检查后，发现了明显的根腐病症状。从坏死区域的下缘进行分离，方法是将约3毫米的组织接种在酸化（每升营养培养基中加入2.5毫升85%乳酸，高压灭菌后pH值为3.5）的马铃薯葡萄糖琼脂上。平板在23°C下培养5至7天，观察到形成了一致的菌落，其菌丝体浅黄色、似皮革，有大量大小各异的黑色单生分生孢子器。菌丝有隔膜，分生孢子无色、单细胞，椭圆形至梭形（平均10.1至20.2×3.2至4.3微米）。根据菌丝体和孢子形态以及核糖体ITS1 - 5.8S - ITS2序列，该病原菌被鉴定为石榴盘梗霉（Pilidiella granati Saccardo）（同义词石榴小穴壳菌（Coniella granati (Saccardo) Petrak & Sydow (3)）），其序列与GenBank编号FN908875相同。通过接种20株1年生的“奇妙”石榴植株，在实验室中完成了柯赫氏法则验证。用直径7毫米的打孔器在每个植株茎基部中间去除树皮造成伤口。将一个直径6毫米、带有来自石榴盘梗霉15天龄培养物的菌丝体和孢子的琼脂块插入每个伤口。伤口用凡士林覆盖并用胶带包扎以防止干燥。10株树接种无菌马铃薯葡萄糖琼脂块作为对照。所有植株在25°C下培养10天，此时观察到坏死现象。从出现与田间观察到的症状相似症状的接种植株中重新分离出该真菌后，柯赫氏法则得到满足。对照植株未出现病害症状。据我们所知，这是希腊首次报道石榴植株出现根腐病症状是由石榴盘梗霉引起。诸如除草剂和冻害等诱发因素对石榴盘梗霉感染的作用尚不清楚。据报道，该病原菌在西班牙（2）和加利福尼亚（1）会导致石榴果实腐烂。参考文献：（1）T. J. 米凯拉ides等人（摘要）《植物病理学》100（增刊）：S83，2010年。（2）L. 帕洛等人《新病害报道》在线发表。doi:10.5197/j.2044 - 0588.2010.022.021，2010年。（3）G. T. 齐罗斯和K. 察韦拉 - 克洛纳里《植物病理学》57:783，2007年。
