1株具抑菌活性除虫菊内生真菌的菌种鉴定

Identification of Endophytic Fungi in Pyrethrum cinerariifolium Trev.

【目的】明确1株具抑菌活性的除虫菊内生真菌（编号为Y2）的种属分类地位。【方法】将在PDA培养基上培养7 d的Y2菌株,转接于PDA、PSA、Czapek（CA）、DYPA、WA、CLA、PA、VBC、CMA等9种培养基培养,并结合25℃间歇光照培养、变温培养、紫外线照射与黑暗交替培养等方法诱导产孢,进行形态学初步鉴定;采用分子生物学方法对Y2菌株rDNA的ITS基因（ITS-5.8 S rDNA）进行PCR扩增、测序,利用相关软件对PCR产物序列进行分析。【结果】该菌株在CLA、PA和VBC 3种培养基上产生了大型分生孢子堆,大型分生孢子着生在分生孢子梗顶端,呈镰刀形,微弯曲,具5-7个横隔,小型分生孢子具0-1个横隔,初步鉴定为镰刀菌;其rDNA的ITS基因序列分析结果表明,其基因序列与尖孢镰刀菌（Fusarium oxysporum）的同源性达到100%。【结论】根据形态学和分子生物学方法鉴定可知,Y2菌株为尖孢镰刀菌（Fusarium oxysporum）。

[Objective] Endophytic fungus strain Y2 was isolated from the leaf of Pyrethrum cinerariifolium Trev. [Method] By comparising morphological characters and sequence of ITS regions,the mycelia sterilia were inoculated onto plates containing CLA,PA,VBC et al. nine culture media and treated with changing temperature incubation and then incubated under UV-light so as to form conidia. The complete 5. 8 S rDNA sequence of Y2 strain was cloned and sequenced respectively, and phylogenetic tree was constructed based on 5.8 S rDNA sequences and the sequence homology was analysed. [Result] The characteristics of morphology showed that the macroconidium was falciform with five or seven diaphragms while microconidium had zero or one diaphragm. The analysis of DNA sequences showed that the sequence homology of Y2 strain was 100% with Fusarium oxysporum. [Conclusion] The characteristics of morphology and the analysis of DNA sequences suggest that the strain of Y2 is identified as Fusarium oxysporum.