苜蓿镰刀菌根腐病病原菌的分离鉴定与致病性分析

为了解河北廊坊、内蒙古临河和山西阳高县紫花苜蓿根腐病的病原,于2013年采集疑似感染镰刀菌根腐病的苜蓿病株,在PSA和MGA等培养基上分离纯化后观察菌落、菌丝和大小孢子等形态特征。在形态学观察的基础上,筛选各地具有代表性的菌株,克隆其rDNA-ITS和TEF-1α序列。通过形态学观察和分子生物技术相结合,对分离出的代表性菌株进行快速鉴定,并通过回接试验确定其致病性。共分离6个菌株,分别命名为C1、C2、C3、C4、C5和L1。根据形态和分子共同鉴定:C1和C2为三线镰刀菌(Fusarium tricinctum),C3、C4和C5为腐皮镰刀菌(F.solani),L1为层出镰刀菌(F.proliferatum)。L1和C4菌株的致病性较强,发病率均大于80%,病害严重指数分别为61.35%和59.26%。C2株系致病性最弱(DI 54.44%,DSI 29.63%)。C1、C3和C5菌株的发病率和致病性均无显著差异,发病率分别为66.66%,62.22%和65.55%;病害严重指数分别为42.59%,40.37%和38.89%。

Identification and Pathogenicity Test of Pathogenic Fusarium of Alfalfa Root Rot

Samples of root rot disease of Medicago sativa were collected from Langfang of Heibei,Linhe of Inner Mongolia and Yanggao of Shanxi in 2013,to determine the dominant pathogens of alfalfa in these places.Pathogens were isolated from the samples and purified in PSA and MGA plate.Representative strains were selected based on biological characteristics,and then rDNA-ITS and TEF-1α sequences of the fungi were amplified and sequenced.Morphological and molecular biological methods were used for identification of the representative fungi,and then determined pathogenicity by back infestation test.We isolate 6 representative strains,named C1,C2,C3,C4,C5 and L1.The results showed that:C1 and C2 were identified to be F.tricinctum,C3,C4 and C5 were F.solani,L1 was F.proliferatum,which revealed that F.tricinctum was the main pathogens of alfalfa root rot in Langfang of Hebei province,F.tricinctum and F.solani were the dominant pathogens of this disease in Linhe of Inner Mongolia,and F.solani and F.tricinctum were the chief pathogens of Yanggao County of Shanxi province.The results of inoculation showed that L1 (DI 80.88％,DSI 61.35％) and C4 (DI 82.22％,DSI 59.6％) strains had higher pathogenicity,and C2 showed weakest pathogenicity (DI 54.44％,DSI 29.63％).There were no significant differences at disease incidence and disease severity index in C1,C3 and C5 strains,the disease incidence was 66.66％,62.22％ and 65.55％ respectively;Disease severity index was 42.59％,40.37％ and 38.89 ％,respectively.