北京地区大白菜黄萎病的病原鉴定

 对北京地区大白菜发生的叶片黄化、维管束变色的新病害进行了鉴定，通过形态学观察、致病力检测和rDNA-ITS序列分析，确定该病是由大丽轮枝菌（Verticillium dahliae）引起的大白菜黄萎病。从4个发病大白菜材料中分离获得的4个真菌分离物，均在寄主大白菜三叶一心期接种后表现出叶片黄化、维管束变色等症状；PDA培养菌落为白色，1周后中心变黑，显微镜下可观察到明显的轮枝状分生孢子梗，长椭圆形孢子大小3.5 ~ 5.6 μm × 1.5 ~ 2.5 μm，在22 ℃菌丝生长最快。4个菌株的rDNA-ITS序列一致性达100%，序列已在GenBank上登录，登录号为JN564038。

Pathogen Identification Causing Verticillium Wilt on Chinese Cabbage in Beijing Area

The pathogen causing verticillium wilt on Chinese cabbage in Beijing area was identified by morphological characteristics,pathogenicity test,and the sequence of ribosomal DNA-ITS in this study. Four isolates from diseased plants of four different varieties were obtained. Seedlings showed symptoms of yellowing,wilting of leaves,discoloration in vascular tissue of the stem and death after inoculating with isolates,which were consistent with the symptoms in the field. The fungus showed dark colonies that produced verticillate conidiophores with two to three layers with colorless,ovoid,conidia and small,black microsclerotia on PDA medium. When cultured under the temperature ranged from 14 ℃ to 32 ℃,hyphae showed fastest growth at 22 ℃;The rDNA-ITS sequence of the fungi which was 100% identity of the four isolates has been submitted to GenBank(GenBank accession number:JN564038).