7种景天科多肉植物白粉病病原种类鉴定

Identification of the pathogen of powdery mildew of 7 species Crassulaceae succulents

为确定7种景天科多肉植物白粉病的病原菌,本研究通过显微形态观察、致病性测定和分子生物学的方法对其进行鉴定,并构建系统发育树。结果表明:该病原菌闭囊壳暗褐色至黑色,球形或扁球形,壁细胞呈不规则多边形;附属丝5~18根,丝状不分枝,上下近等粗或顶端略细,褐色或基部褐色,向上渐无色;子囊3~5个,卵形或长卵形,无色,有短柄或无柄;子囊孢子3~5个,长卵形或椭圆形;分生孢子梗直立或稍弯曲,分生孢子单生,长筒柱形、长椭圆形;病原菌接种叶片症状与自然发病状态叶片一致。病原菌rDNA-ITS序列的系统发育树显示,该菌与八宝属(Hylotelephium sp.)、景天属(Sedum sp.)和伽蓝菜属(Kalanchoe sp.)叶片白粉病的病原菌景天白粉菌(Erysiphe sedi)聚在一支上。据此确定景天科多肉植物白粉病的病原为景天白粉菌(Erysiphe sedi)。

In order to determine the pathogen of powdery mildew of 7 species of Crassulaceae succulents,the pathogen of powdery mildew is identified by microscopic observation,pathogenicity determination and molecular biology methods. In addition,a phylogenetic tree is constructed in this paper. The results show that the color of the closed capsule ranges from dark brown to black,spherical or oblate. The shape of parietal cells is irregular polygon;there are 5-18 accessory filaments,unbranched,upper and lower subequal thick or apically slightly thin,brown or base brown,colorless upward;there are 3-5 ascus,ovate or long ovate,colorless with short stalk or sessile;there are 3-5 ascospores with long oval or elliptical shape;conidiophores are straight or slightly curved;conidia are solitary with long cylindrical and long oval shape;the symptoms of the pathogen inoculation leaves are the same as natural pathogenetic leaves;phylogenetic tree of pathogen r DNA-ITS sequence shows that the pathogen is clustered in one branch with the pathogen Erysiphe sedi of Hylotelephium sp.,Sedum sp. and Kalanchoe sp. powdery mildew. Therefore,Erysiphe sedi is identified as the pathogen which causes powdery mildew of Crassulaceae succulents.