Soylu S, Dervis S, Soylu E M
Department of Plant Protection, Mustafa Kemal University, Agriculture Faculty, 31034, Hatay, Turkey.
Plant Dis. 2011 Feb;95(2):219. doi: 10.1094/PDIS-10-10-0770.
Chinese wisteria, Wisteria sinensis (Sims) DC., is a woody, twining vine and is commonly cultivated as an ornamental for its foliage and striking, drooping racemes of white, pink, or lavender sweet pea-like flower. Distinct leaf spots were observed in several gardens, retail nurseries, and parks located in Hatay Province since May 2009. The primary infection zones are frequently observed on the leaf margins and apices, brown, up to 2 mm in diameter, and often surrounded by a yellow zone. Foliar symptoms are characterized by grayish, round, semicircular or irregular-shaped, numerous spots (up to 9 mm in diameter) with dark brown borders and the appearance of black, granular structure within the dead leaf tissues. A fungus was consistently isolated from symptomatic tissues on potato dextrose agar (PDA). Fungal colonies were initially white, becoming light to dark gray with the onset of sporulation with black, spherical to subspherical single-celled conidia (15 to 18 × 12 to 15 μm), which were borne on a hyaline vesicle at the tip of the conidiophore. These characteristics agree with published descriptions of Nigrospora sphaerica (Sacc.) E.W. Mason 1927 (1,3). To fulfill Koch's postulates, a conidial suspension (10 conidia per ml) collected from PDA cultures was used to spray inoculate leaves of potted 3-year-old Chinese wisteria plants. Inoculated plants were kept for 48 h in polyethylene bags and maintained in a controlled environment chamber at 20°C with a 12-h photoperiod. The bags were removed after 3 days. In addition, five 3-year-old plants were sprayed with sterile water to serve as controls. After 14 to 20 days, inoculated leaves showed infection symptoms similar to those observed on naturally infected leaves with N. sphaerica. The pathogen was reisolated from the margins of necrotic tissues, but not from the controls. Although N. sphaerica is frequently encountered as a secondary invader or as a saprophyte on many plant species, this fungal agent is also known as a leaf pathogen on several hosts worldwide (2,4). To our knowledge, this is the first report of N. sphaerica as a leaf pathogen of Chinese wisteria in Turkey or worldwide. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory. Online publication. ARS, USDA. Retrieved 28 October from http://nt.ars-grin.gov/fungaldatabases/ , 2010. (3) P. M. Kirk. IMI Descr. Fungi Bact. 106:1056, 1991. (4) E. R. Wright et al. Plant Dis. 92:171, 2008.
紫藤，即中华紫藤（Wisteria sinensis (Sims) DC.），是一种木质缠绕藤本植物，常因其叶片以及下垂的总状花序上醒目地开着白色、粉色或淡紫色类似香豌豆的花朵而作为观赏植物栽培。自2009年5月以来，在哈塔伊省的多个花园、零售苗圃和公园中观察到了明显的叶斑。最初感染区域常见于叶缘和叶尖，呈褐色，直径达2毫米，且常被黄色区域环绕。叶片症状表现为灰色、圆形、半圆形或不规则形状，有许多斑点（直径达9毫米），边缘深褐色，在枯死的叶片组织内出现黑色颗粒状结构。在马铃薯葡萄糖琼脂（PDA）培养基上，从有症状的组织中始终能分离出一种真菌。真菌菌落最初为白色，随着产孢开始变为浅灰色至深灰色，有黑色、球形至近球形的单细胞分生孢子（15至18×12至15微米），这些分生孢子着生于分生孢子梗顶端的透明小泡上。这些特征与已发表的球形黑孢霉（Nigrospora sphaerica (Sacc.) E.W. Mason 1927）的描述相符（1,3）。为了验证科赫法则，从PDA培养基培养物中收集的分生孢子悬浮液（每毫升10个分生孢子）用于喷雾接种3年生盆栽中华紫藤植株的叶片。接种后的植株在聚乙烯袋中放置48小时，然后置于温度为20°C、光周期为12小时的可控环境箱中。3天后取出袋子。此外，对5株3年生植株喷洒无菌水作为对照。14至20天后，接种的叶片出现了与在自然感染球形黑孢霉的叶片上观察到的类似感染症状。病原菌从坏死组织边缘重新分离得到，但对照植株未分离到。尽管球形黑孢霉在许多植物物种上常作为次生入侵者或腐生菌出现，但这种真菌病原体在全球范围内的几种寄主植物上也被认为是叶部病原菌（2,4）。据我们所知，这是球形黑孢霉作为中华紫藤叶部病原菌在土耳其或全球范围内的首次报道。参考文献：(1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory. Online publication. ARS, USDA. Retrieved 28 October from http://nt.ars-grin.gov/fungaldatabases/, 2010. (3) P. M. Kirk. IMI Descr. Fungi Bact. 106:1056, 1991. (4) E. R. Wright et al. Plant Dis. 92:171, 2008.
