Wen Zhaohui, Duan Tingyu, Christensen Michael J, Nan Zhibiao
State Key Laboratory of Grassland Agro-Ecosystems; College of Pastoral Agricultural Science and Technology, Lanzhou University; and Central Laboratory of Technical Center, Gansu Exit-Entry Inspection and Quarantine Bureau; Lanzhou 730010, P. R. China.
State Key Laboratory of Grassland Agro-Ecosystems; College of Pastoral Agricultural Science and Technology, Lanzhou University.
Plant Dis. 2015 Jan;99(1):87-92. doi: 10.1094/PDIS-10-13-1048-RE.
A crown and root rot complex was detected in the alfalfa (Medicago sativa 'Longdong') fields of Huanxian County. The symptoms of the diseased plants were characterized, and 11 fungal species were obtained from the roots. These fungi included isolates that resembled the genus Microdochium. An isolate of this type, designated MP313, was proven to infect alfalfa, fulfilling Koch's postulates. Isolate MP313 was examined by microscopy and the morphological characteristics indicated that it was similar to members of the genus Microdochium. Sequence analyses of the 28S large subunit as well as the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA) of MP313 revealed 98 to 100% similarity to the corresponding regions of M. tabacinum. A polymerase chain reaction assay based on the ITS region of the rDNA was developed to amplify a 304-bp fragment from DNA concentrations as low as 20 fg/μl, which was sensitive enough to detect isolate MP313 in diseased root samples. Taken together, these results confirmed that M. tabacinum was one of a complex of fungi associated with crown and root rot in the alfalfa samples collected in Gansu Province. This is the first report of M. tabacinum being a pathogen of alfalfa in China.
在环县的紫花苜蓿（Medicago sativa 'Longdong'）田中检测到一种冠根腐病复合体。对患病植株的症状进行了表征，并从根部获得了11种真菌。这些真菌包括类似微座孢属的分离物。其中一种名为MP313的分离物被证明可感染紫花苜蓿，满足柯赫氏法则。通过显微镜检查MP313分离物，其形态特征表明它与微座孢属的成员相似。对MP313核糖体DNA（rDNA）的28S大亚基以及内部转录间隔区（ITS）区域进行序列分析，结果显示与烟草微座孢（M. tabacinum）的相应区域有98%至100%的相似性。基于rDNA的ITS区域开发了一种聚合酶链反应检测方法，可从低至20 fg/μl的DNA浓度中扩增出一个304 bp的片段，该方法灵敏度足以检测患病根样本中的MP313分离物。综上所述，这些结果证实烟草微座孢是甘肃省采集的紫花苜蓿样本中与冠根腐病相关的真菌复合体之一。这是中国首次报道烟草微座孢是紫花苜蓿的病原菌。
