进境美国加州脐橙中丁香疫霉Phytophthora syringae的截获

从产自美国加利福尼亚州的新鲜脐橙样品中发现多个腐烂病果,通过分离培养得到3个疑似丁香疫霉Phytophthora syringae菌株,对3个菌株进行形态学研究、致病性测定和分子序列比对分析。结果表明病菌在V8A培养基上菌落稀疏、平铺,呈星状,菌丝紧贴培养基生长或埋于基质内生长;在PDA培养基上菌落呈菊花花瓣状,菌丝致密,乳白色;游动孢子囊和菌丝膨大体在无菌水和土壤浸出液中黑暗条件下48h后产生;菌株为同宗配合,卵孢子在带有新鲜脐橙果实组织或杜鹃叶片的V8A培养基中大量产生;创伤接种脐橙果实,7d后接种脐橙出现典型的褐腐症状;通用引物ITS1/ITS4扩增测序,Blastn分析表明序列与GenBank中P.syringae序列相似性为99%。依据上述研究结果,将分离获得的3株菌鉴定为丁香疫霉Phytophthora syringae,系国内首次截获的一种植物检疫性真菌病害。

Interception of Phytophthora syringae on Citrus fruits imported from California, USA

Several brown rot fruits have been found from Californian fresh orange sample. Three isolates similar to Phytophthora syringae were obtained from these rot fruits. The colonies grew slowly on PDA and V8 juice agar (V8A). They were stellate, tiled and thin on V8A, but on PDA, the margin was chrysanthemum petaloid; mycelia dense, milk-white-colored. Sporangia and catenulate hyphal swellings formed in sterilizing water and soil extract water in 48h. The isolates were homothallic. Oospores were produced abundantly on PDA and V8A mixed with fresh Citrus fruit tissue or leaf of rhododendron. The isolates were wounded-inoculated on fresh Citrus fruits. Typical brown rot symptoms are apparent on inoculated fruits in 7d. DNA of hyphae was amplified with ITS1/ITS4 primers. In comparision with P. syringae from NCBI GenBank databases, the sequences had 99% identity. All the results of tests showed that the isolates were Phytophthora syringae.