Bartz Faith E, Cubeta Marc A, Toda Takeshi, Naito Shigeo, Ivors Kelly L
Department of Plant Pathology, North Carolina State University, Raleigh 27695.
Faculty of Bioresource Science, Akita Prefectural University, Shimo-shinjo, Akita 010-0195, Japan.
Plant Dis. 2010 May;94(5):515-520. doi: 10.1094/PDIS-94-5-0515.
A tomato (Solanum lycopersicum) foliar blight disease of unknown etiology was observed in North Carolina (NC) during 2005 to 2006. Symptoms included necrotic lesions and blighted leaves, with signs of white mycelial growth on abaxial leaf surfaces. The morphology of isolates from symptomatic leaves was consistent with that of Rhizoctonia solani. Because the pattern of symptom expression suggested that basidiospores were the primary inoculum source, Koch's postulates were fulfilled using a method to generate basidiospores in planta. Isolates were characterized by morphology, DNA sequence analysis, hyphal anastomosis, and somatic hyphal interactions. Phylogenetic analyses and hyphal anastomosis criteria support placement of the isolates in R. solani anastomosis group 3 (AG-3). Tomato foliar blight isolates from NC form a single phylogenetic group with tomato isolates of R. solani AG-3 from Japan and are more closely related to R. solani AG-3 isolates from potato than tobacco. Isolates exhibited both compatible and incompatible hyphal interactions when paired in vitro. To our knowledge, this is the first detailed report of tomato foliar blight caused by R. solani AG-3 in North America. A comprehensive description of the technique employed for producing basidiospores is presented with potential utility for understanding foliar disease etiology in other Rhizoctonia pathosystems.
2005年至2006年期间，在北卡罗来纳州（NC）观察到一种病因不明的番茄（Solanum lycopersicum）叶枯病。症状包括坏死斑和枯萎叶片，叶背表面有白色菌丝生长迹象。从有症状叶片分离出的菌株形态与立枯丝核菌（Rhizoctonia solani）一致。由于症状表现模式表明担子孢子是主要接种源，因此采用在植物体内产生担子孢子的方法满足了科赫法则。通过形态学、DNA序列分析、菌丝融合和体细胞菌丝相互作用对分离菌株进行了鉴定。系统发育分析和菌丝融合标准支持将分离菌株归入立枯丝核菌融合群3（AG-3）。来自北卡罗来纳州的番茄叶枯病分离菌株与来自日本的立枯丝核菌AG-3番茄分离菌株形成一个单一的系统发育组，并且与来自马铃薯的立枯丝核菌AG-3分离菌株的亲缘关系比与烟草的更近。分离菌株在体外配对时表现出相容和不相容的菌丝相互作用。据我们所知，这是北美关于立枯丝核菌AG-3引起番茄叶枯病的第一份详细报告。本文介绍了用于产生担子孢子的技术的全面描述，该技术对于理解其他丝核菌病害系统中的叶部病害病因具有潜在用途。
