进境美国大豆中大豆茎褐腐病菌的截获

 从进境的美国大豆豆秆样品中分离到2株疑似大豆茎褐腐病菌Phialophora gregata的分离物247-8和8300-5,2株分离物在PGM培养基上菌落圆形,边缘规则,白色至暗褐色,表面隆起,粗糙,轮纹状。分生孢子卵形至椭圆形,无色,平滑,单胞,平均大小4.3 μm×1.9 μm。分生孢子梗具有瓶梗状结构,无色,无隔膜或有隔膜,大小(5~16)μm×(2~3) μm,呈桶型或长颈瓶型。特异性引物BSRIGS1/2、BSR1/2和Pgl/4分别扩增分离物247-8的DNA得到预期1 022 bp、483 bp和499 bp的产物;分离物8300-5的DNA经PCR扩增分别得到834 bp、483 bp和499 bp的预期条带。2株分离物的ITS区序列完全一致,与GenBank中大豆茎褐腐病菌(登录号AB190396、DQ459387、DQ459386和AF132804)的序列相似性为100%。人工接种大豆幼嫩植株茎基部均产生大豆茎褐腐病菌的典型症状。根据分离物形态特征、PCR检测、序列分析以及致病性测试结果,将进境美国大豆样品中的分离物247-8和8300-5鉴定为大豆茎褐腐病菌P. gregata。

Interception of Phialophora gregata in soybean samples from USA

Two isolates 247-8 and 8300-5 were intercepted from soybean stem samples imported from USA with the PDA plate method. These isolates with similar morphological characteristics to Phialophora gregata showed slow growth on PGM medium with regular margin of round colony, white to dark brown, rough and swell surface with physalospora shape. The conidia produced on GBA medium were ovoid to elliptical, hyaline, smooth, aseptate with the average size of 4.3 μm×1.9 μm. Conidiophore with phialide-like structure, were hyaline, aseptate or uniseptate, (5-16)μm×(2-3) μm, long vasiform or long bottleneck-shaped. The result of PCR detection showed that the isolate 247-8 can be amplified by P. gregata-specific primer BSRIGS1/2 with a product of 1 022 bp and the isolate 8300-5 got PCR product of 834 bp. The expected bands from the two isolates were 483 bp and 499 bp by primers BSR1/2 and Pgl/4, respectively. The sequence analysis revealed that ITS sequences of the two isolates shared 100% sequence identity with P. gregata (Accession No. AB190396, DQ459387, DQ459386 and AF132804) in GenBank. Pathogenicity was confirmed on young soybean stem by artificial inoculation with typical symptoms of brown stem rot. Based on the morphological characteristics, PCR detection, sequence analysis and the results of pathogenicity test, the isolates 247-8 and 8300-5 from soybean samples were identified as P. gregata.