甘肃玉米穗腐病样品中轮枝镰孢菌的分离鉴定及生物学特性

 为了明确甘肃玉米穗腐病的病原种类, 于2009年9月在甘肃省四大生态区采集玉米穗腐病样品, 以组织分离法进行病原物的分离培养, 对分离得到的镰孢菌菌落进行纯化和单孢分离后, 以形态学为基础, 参照Leisle分类系统进行鉴定。结果表明:共分离到271株镰孢菌菌株, 其中以轮枝镰孢菌(Fusarium verticillioides)和黄色镰孢菌(F. culmorum)出现频率高, 属优势种。按照柯赫氏法则对沈单16和金穗96832进行致病性测定, 证实了轮枝镰孢菌对玉米果穗的致病性。选取2株轮枝镰孢菌菌株进行EF-1α(tef) 基因序列分析, 将PCR产物回收测序后在GenBank上比对, 菌株GSLT4-3-2与GenBank中登记的轮枝镰孢菌FN179339、FN179345和FN179338;GSTS24-2-1与轮枝镰孢菌FN179343、FN179346、FN179340、FN179344和 FN252384亲缘关系最近, 序列同源性达100%。轮枝镰孢菌GSYC17-2-1的生长温度范围为15～35℃, 最适温度为28℃, pH 值为8;菌落在pH值为4～10的培养基上能够迅速扩展, pH值为7时产孢量最大;碳源对轮枝镰孢菌菌丝生长影响相对稳定, 而氮源对其营养生长影响的变幅较大;完全黑暗条件下, 菌丝扩展最快, 12 h光暗交替对产孢量有明显的促进作用;病原菌菌丝致死温度为70℃, 10 min。

Isolation,identification and biological characteristics of Fusarium verticillioides from maize ear rot samples in Gansu Province

In order to know the pathogens of maize ear rot in Gansu Province, samples were collected from 4 ecological zones in september, 2009. The pathogens were isolated by tissue isolation method from cankered maize ear on standard medium. Fusarium colonies obtained were identified according to the taxonomic system of Leisle after being subcultured and single-spored . The results showed that the total 271 Fusarium isolates were obtained from the sampling sites, and the dominant species were F. verticillioides and F. culmorum. According to Koch's Postulate, the pathogenicity of isolate GSYC17-2-1 was tested with mixed isolates on maize varieties Shendan 16 and Jinsui 96832 and verified that F. verticillioides was pathogenic to maize ear. The two F. verticillioides isolates were selected randomly for sequence analysis of EF-1α (tef) gene. The PCR products of the three isolates were collected, purified and sequenced. The sequences were aligned in GenBank. It was showed that a very close relationship of isolates GSLT4-3-2 with the FN179339, FN179345 and FN179338; and that of GSTS24-2-1 with FN179343, FN179346, FN179340, FN179344 and FN252384 downloaded from GenBank, their max similarity were 100% similar with F. verticillioides. The results also indicated that The Fusarium could grow under15～35℃, pH 4～10, with optimal condition at 28 ℃, pH 8, and the largest conidia germination at pH 7. Vegetative growth of F. verticillioides was found to be significantly influenced by nitrogen source compared with carbon source. The best cultural condition for mycelial was 24 h under dark while the largest sporulation quantity was alternating light and dark. The lethal temperature was 70 ℃ for 10 min for hypha of F. verticillioides.