白莲腐败病病原菌的分离鉴定

Isolation and Identification of Pathogens Causing Rhizome Rot of Lotus

莲腐败病是白莲种植区发生最普遍、为害最严重的病害之一。本试验对发病白莲上的病原茵进行分离鉴定。该病原分离物在PSA培养基上气生茵丝由白色渐变成深紫色，并产生大小两种孢子。大型分生孢子镰刀形，无色，稍呈弯曲，两端尖细，大小为（39．1-55．2）μm×（2．8～4．6）p,m，多为3个隔膜，少部分为1-2隔或4~5隔；小型分生孢子椭圆形。无色，无隔膜，大小为（5．0～9．2）μm×（2．0～3．5）μm。致病性测定表明分离物能100％引起白莲出现典型的白莲腐败病的症状。ITSl／ITS4的PCR扩增产物与GenBank中Fusariumoxysporum￡sp．nelumbicola的序列同源性为99％。研究结果表明。分离到的病原物为尖孢镰刀茵莲专化型Foxysporum f.sp．ndumbicola。

Rhizome rot was the most common disease of lotus. We isolated six isolates from diseased roots of lotus from Guangchang county of Jiangxi province in July 2011, and identified the isolates through their morphological and molecular characteristics. On PSA medium, the aerial mycelium was white firstly, and then changed to dark purple. Their macroconidia were fusiform, slightly curved, pointed at two ends, （39.1-55.2）μm×（2.8-4.6） μm in size, and mostly had three septa. Microconidia were colourless, ellipsoidal or cylindrical, never in chains, mostly non-septate, straight or curved, with the size of （5.0-9.2） μm×（2.0-3.5） μm. The typical symptoms of rhizome rot occurred on all louts seedlings infected with the isolates. To verify the pathogen, we sequenced rDNA-ITS fragments of the isolates amplified by primers ITS1 and ITS4, and 99% of sequences were homologous with those of Fusaffum oxysporum f. sp. nelumbicola in GenBank. The above results showed the isolates were F. oxysporum f. sp. nelumbicola.