Gao F, Xiang Z, Zhang Y L
Key Laboratory of Prevention and Control for Oasis Crop Disease, Shihezi University, Xinjiang, 832003, China.
Plant Dis. 2012 Apr;96(4):586. doi: 10.1094/PDIS-10-11-0910.
Chinese jujube (Ziziphus jujuba Mill.) is widely planted in Xinjiang Province of China for fruit and as an effective herbal remedy. Wilt symptoms were observed on field-grown Z. jujuba during the spring and fall of 2010 and 2011. Diseased plants exhibited symptoms including wilted leaves, stunted growth, extensive brown discoloration on stems, and eventually death. In severe cases, approximately 60% of the plants in the field died. Repeated isolations from discolored stem vascular tissues were made on potato dextrose agar (PDA) after disinfestation in 1% HgCl for 1 min and dipping in 70% ethanol for 10 s. Petri dishes were then incubated in complete darkness at 26°C for 7 days. All colonies on PDA had pale pink-salmon-colored mycelia. Macroconidia were mostly three to five septate, slightly curved, and ranged from 2.9 to 11.9 × 29.5 to 45 μm. Microconidia were abundant, generally single celled, oval to kidney shaped, and ranged from 2.5 to 5 × 7.5 to 11.5 μm in false heads on short monophialides. Chlamydospores were single or in pairs and profusely distributed. These characteristics were similar to those of Fusarium oxysporum (2). The internal transcribed spacer (ITS) rDNA region was amplified with primers ITS1/ITS4 and sequenced (1). BLASTn analysis of the sequence (GenBank Accession No. JQ039331) showed a 99% homology with several isolates of F. oxysporum in the GenBank database. Pathogenicity tests were conducted on healthy, 2-month-old seedlings and 1-month-old rooted cuttings of Z. jujuba under greenhouse conditions. Plants were inoculated with sterilized mixtures of wheat and barley seeds (1:1) that were incubated in a F. oxysporum isolate spore suspension (1 × 10 conidia/ml) at 25°C for 7 to 10 days. The seeds (3 g per plant) were placed around the collar of each healthy plant under the soil surface and incubated at 25 to 28°C in a greenhouse. Control plants were sown in sterile soil without inoculated seeds. In 3 weeks, inoculated plants developed leaf wilt and chlorosis, stunted growth, brown discolored vascular tissue on stems, and finally died, which is similar to that observed in the field. F. oxysporum was reisolated from the stems of diseased plants, confirming Koch's postulates. Control seedlings were symptom free. F. oxysporum has been known to cause wilt disease on cotton and tomato in Xinjiang Province (3). However, to our knowledge, this is the first report of a natural occurrence of Chinese jujube wilt disease on commercial fields caused by F. oxysporum in China. References: (1) G. M. Arruda et al. Plant Pathol. 54:53, 2005. (2) J. F. Leslie and B. A. Summerell. The Fusarium Laboratory Manual. Blackwell Publishing, Ames, IA, 2006. (3) F. X. Tian et al. Acta Phytopathol. Sin. 11:27, 1981.
枣树（Ziziphus jujuba Mill.）在中国新疆广泛种植，用于收获果实以及作为一种有效的草药。在2010年和2011年的春秋季节，田间种植的枣树出现了萎蔫症状。患病植株表现出叶片萎蔫、生长受阻、茎部广泛褐变，最终死亡。在严重的情况下，田间约60%的植株死亡。在1%氯化汞中消毒1分钟并在70%乙醇中浸泡10秒后，从变色的茎维管组织中反复在马铃薯葡萄糖琼脂（PDA）上进行分离。然后将培养皿在26°C的完全黑暗条件下培养7天。PDA上的所有菌落都有浅粉红色至鲑鱼色的菌丝体。大型分生孢子大多有三到五个隔膜，略弯曲，大小为2.9至11.9×29.5至45μm。小型分生孢子丰富，通常为单细胞，椭圆形至肾形，在短单瓶梗上的假头状体中大小为2.5至5×7.5至11.5μm。厚垣孢子单个或成对，大量分布。这些特征与尖孢镰刀菌（Fusarium oxysporum）的特征相似（2）。用引物ITS1/ITS4扩增内部转录间隔区（ITS）rDNA区域并进行测序（1）。对该序列（GenBank登录号JQ039331）的BLASTn分析显示，与GenBank数据库中尖孢镰刀菌的几个分离株有99%的同源性。在温室条件下，对健康的2个月大的枣树苗和1个月大的枣生根插条进行致病性测试。用灭菌的小麦和大麦种子混合物（1:1）接种植株，将其在尖孢镰刀菌分离株的孢子悬浮液（1×10⁶分生孢子/ml）中于25°C培养7至10天。将种子（每株植物3克）放置在土壤表面下每株健康植物的茎基部周围，并在温室中于25至28°C培养。对照植株播种在未接种种子的无菌土壤中。3周后，接种的植株出现叶片萎蔫和黄化、生长受阻、茎部维管组织褐变，最终死亡，这与在田间观察到的情况相似。从患病植株的茎中重新分离出尖孢镰刀菌，证实了柯赫氏法则。对照幼苗没有症状。已知尖孢镰刀菌在新疆会引起棉花和番茄的萎蔫病（3）。然而，据我们所知，这是中国首次关于商业种植田由尖孢镰刀菌引起枣树自然发生萎蔫病的报道。参考文献：（1）G. M. Arruda等人，《植物病理学》54:53，2005年。（2）J. F. Leslie和B. A. Summerell，《镰刀菌实验室手册》，Blackwell出版社，艾姆斯，爱荷华州，2006年。（3）F. X. Tian等人，《植物病理学报》11:27，1981年。
