Tang Q H, Niu X Q, Yu F Y, Zhu H, Song W W, Qin W Q
Coconut Research Institute, Chinese Academy of Tropical Agricultural Sciences, Wenchang, Hainan 571339, P. R. China. The project was funded by Key Foundation of Hainan Province (No. ZDXM20130004).
Plant Dis. 2014 Sep;98(9):1282. doi: 10.1094/PDIS-04-14-0395-PDN.
On January 12th, 2012, a novel disease with an incidence of 50% was discovered in Pindo palm Butia capitata (Mart.) Becc from the Coconut Grant View Garden (19°33.137' N, 110°47.482' E) located in Wenchang, Hainan Province. Diseased leaflets at the base of the rotted heart leaves had reddish brown lesions; when the infection progressed, the leaves turned yellow and became blighted from the inner to the outer part of the crown. Once the growing point was destroyed, the entire tree ultimately died. Tissues from the edges of lesions from diseased leaflet samples were placed onto potato dextrose agar (PDA) and incubated at 25°C for 3 days. The color of colonies of five isolates obtained turned from white to black in 48 h. The optimum temperature for mycelium growth was from 20 to 30°C, and no growth occurred at temperatures higher than 40°C or lower than 5°C (n = 5). The cylindrical colorless to pale brown conidia were 7.5 to 17.5 μm long × 5.0 to 7.5 μm wide (n = 100); oval black chlamydospores were 12.5 to 22.5 × 7.5 to 15.0 μm (n = 100). The sequence (497 bp) of the internal transcribed spacer (ITS) region of the representative isolate BX3 (China Center for Type Culture Collection No. CCTCC AF2014002) was amplified using primer pair ITS1/ITS4 (GenBank Accession No. KF939052) and shared 99% sequence identity with Ceratocystis paradoxa strain xie331-4 (JQ039332). Based upon these biological characteristics and ITS sequence, this pathogen was identified as C. paradoxa (Dade) C. Moreau (anamorph Thielaviopsis paradoxa (de Seynes) Höhn.) (3). Pathogenicity tests were conducted on 8-cm-long sections of young leaflets excised from a 12-year-old pindo palm tree. One side of the midrib of 10 sections was wounded with a sterilized scalpel at the center and the other side was non-wounded, then a PDA plug (4 to 6 × 4 to 6 mm) from the edge of an actively growing colony of BX3 incubated for 3 days were inoculated onto each wounded or non-wounded site. As controls, plain PDA plugs were placed on wounded and non-wounded spots of another 10 sections following the above procedure. Pathogenicity was tested twice. Each inoculated section was then put into a 9-cm petri dish in which two filter papers (Φ = 9 cm) were placed and 8 ml of sterile water were added to maintain high humidity, and then all dishes were placed in a dark incubator at 25°C. After 5 days, typical symptoms developed only on the wounded points inoculated with mycelium plugs. C. paradoxa was re-isolated from the margins of the expanding lesions. C. paradoxa causing fruit rot of B. capitata was reported in Uruguay (2), but to our knowledge, there are no previous reports of this species in China or infecting leaves of B. capitata worldwide (1). We report here a new Ceratocystis disease on B. capitata, and it was named as pindo palm heart rot based on its symptoms. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , Feb 21, 2014. (2) V. Gepp et al. New Dis. Rep. 27:12, 2013. (3) F. Y. Yu et al. Plant Dis. 96:290, 2012.
2012年1月12日，在海南省文昌市椰林湾景园（北纬19°33.137′，东经110°47.482′）的矮棕榈（Butia capitata (Mart.) Becc）上发现了一种发病率为50%的新病害。腐烂的心叶基部的病小叶有红棕色病斑；随着感染的发展，叶片变黄，从树冠内部到外部逐渐枯萎。一旦生长点被破坏，整株树最终死亡。将病小叶样本病斑边缘的组织接种到马铃薯葡萄糖琼脂（PDA）上，于25°C培养3天。获得的5个分离株的菌落颜色在48小时内从白色变为黑色。菌丝体生长的最适温度为20至30°C，在高于40°C或低于5°C时不生长（n = 5）。圆柱形的无色至浅棕色分生孢子长7.5至17.5μm×宽5.0至7.5μm（n = 100）；椭圆形黑色厚垣孢子为12.5至22.5×7.5至15.0μm（n = 100）。使用引物对ITS1/ITS4（GenBank登录号KF939052）扩增代表性分离株BX3（中国典型培养物保藏中心保藏号CCTCC AF2014002）的内部转录间隔区（ITS）区域序列（497 bp），其与奇异长喙壳菌（Ceratocystis paradoxa）菌株xie331-4（JQ039332）的序列一致性为99%。基于这些生物学特性和ITS序列，该病原菌被鉴定为奇异长喙壳菌（C. paradoxa (Dade) C. Moreau）（无性型为奇异拟茎点霉（Thielaviopsis paradoxa (de Seynes) Höhn.））（3）。对从一棵12年生矮棕榈树上切下的8厘米长的幼嫩小叶进行致病性测试。用灭菌手术刀在10个切片的中脉一侧中央划伤，另一侧不划伤，然后将在PDA上培养3天的BX3活跃生长菌落边缘的PDA菌块（4至6×4至6毫米）接种到每个划伤或未划伤部位。作为对照，按照上述步骤将普通PDA菌块放置在另外10个切片的划伤和未划伤部位。致病性测试进行了两次。然后将每个接种的切片放入一个9厘米的培养皿中，其中放置两张滤纸（Φ = 9厘米），并加入8毫升无菌水以保持高湿度，然后将所有培养皿置于25°C的黑暗培养箱中。5天后，仅在接种菌丝体菌块的划伤部位出现典型症状。从扩展病斑边缘重新分离出奇异长喙壳菌。乌拉圭曾报道奇异长喙壳菌引起矮棕榈果实腐烂（2），但据我们所知，此前在中国或全球范围内均无该物种感染矮棕榈叶片的报道（1）。我们在此报道一种新的矮棕榈长喙壳菌病害，并根据其症状将其命名为矮棕榈心腐病。参考文献：（1）D. F. Farr和A. Y. Rossman。真菌数据库，美国农业部农业研究局系统真菌学和微生物学实验室。检索自http://nt.ars-grin.gov/fungaldatabases/，2014年2月21日。（2）V. Gepp等人。《新病害报道》27:12，2013年。（3）F. Y. Yu等人。《植物病害》96:290，2012年。
