Koike S T, Cintas N A, Bull C T
University of California Cooperative Extension, Salinas 93901.
U.S. Agricultural Research Station, Salinas 93905.
Plant Dis. 2000 Mar;84(3):370. doi: 10.1094/PDIS.2000.84.3.370B.
In 1998 and 1999, a new disease was detected in commercial broccoli (Brassica oleracea var. botrytis) grown in the Salinas Valley, Monterey County, CA. Initial symptoms consisted of large, water-soaked, dark green, angular leaf sections that were bordered by major leaf veins. Diseased areas were as large as 10 × 3 cm. As the disease developed, affected areas turned tan and papery, and leaf margins sometimes became tattered. The numerous small (<1 cm diameter), round to angular spots that also were present retained their size and did not develop into larger lesions. A blue-green fluorescing pseudomonad was consistently isolated from both types of lesions on King's medium B. Strains were levan positive, oxidase negative, and arginine dihydrolase negative. Strains did not rot potato slices but induced a hypersensitive reaction in tobacco (Nicotiana tabacum L. 'Turk'). Fatty acid methyl ester analysis (MIS-TSBA version 4.10, MIDI, Inc., Newark, DE) indicated that the strains were highly similar (similarity ≥0.843) to Pseudomonas syringae. Biolog GN (version 3.50, Biolog, Inc., Hayward, CA) profiles also identified the strains as P. syringae. Therefore, the bacterium associated with the disease was identified as P. syringae. Pathogenicity of 13 strains was demonstrated by greenhouse tests. The strains were grown as nutrient broth shake cultures for 48 h at 24°C, diluted to 10 CFU/ml, and misted onto broccoli (cvs. Patriot and Titleist) and broccoli raab (B. rapa subsp. rapa cv. Spring). Control plants were misted with sterile nutrient broth. After 4 to 5 days in a greenhouse (24 to 26°C), large angular leaf lesions developed on all inoculated broccoli and broccoli raab plants. Strains were reisolated from symptomatic tissue and identified as P. syringae. Control plants remained symptomless. The results of two sets of pathogenicity tests were the same. Unlike most P. syringae strains, those isolated from broccoli were sensitive to a bacteriophage recovered from a P. syringae pathovar that infects broccoli raab. These results suggest that the broccoli pathogen may be related to the bacterial blight pathogen of broccoli raab (1). This is the first report of this pathogen causing a disease on commercially grown broccoli. Reference: (1) S. T. Koike et al. Plant Dis. 82:727, 1998.
1998年和1999年，在加利福尼亚州蒙特雷县萨利纳斯山谷种植的商业西兰花（甘蓝变种花椰菜）中发现了一种新病害。最初症状表现为大的、水渍状、深绿色、呈角状的叶片部分，其边缘以主要叶脉为界。患病区域大小可达10×3厘米。随着病害发展，受影响区域变为棕褐色且呈纸质，叶边缘有时变得破烂。同时存在的众多小的（直径<1厘米）、圆形至角状斑点保持其大小，未发展成更大的病斑。在King氏培养基B上，始终能从这两种类型的病斑中分离出一种蓝绿色荧光假单胞菌。菌株产levan呈阳性，氧化酶呈阴性，精氨酸双水解酶呈阴性。菌株不会使土豆片腐烂，但会在烟草（烟草品种‘Turk’）中引发过敏反应。脂肪酸甲酯分析（MIS - TSBA版本4.10，MIDI公司，特拉华州纽瓦克）表明，这些菌株与丁香假单胞菌高度相似（相似度≥0.843）。Biolog GN（版本3.50，Biolog公司，加利福尼亚州海沃德）分析谱也将这些菌株鉴定为丁香假单胞菌。因此，与该病害相关的细菌被鉴定为丁香假单胞菌。13个菌株的致病性通过温室试验得以证实。将菌株在营养肉汤中于24°C振荡培养48小时，稀释至10 CFU/ml，然后喷雾接种到西兰花（品种Patriot和Titleist）和青花菜（芜菁亚种芜菁品种Spring）上。对照植株用无菌营养肉汤喷雾处理。在温室（24至26°C）中放置4至5天后，所有接种的西兰花和青花菜植株上都出现了大的角状叶斑。从有症状的组织中重新分离出菌株，并鉴定为丁香假单胞菌。对照植株保持无症状。两组致病性试验结果相同。与大多数丁香假单胞菌菌株不同，从西兰花中分离出的菌株对从感染青花菜的丁香假单胞菌致病变种中回收的一种噬菌体敏感。这些结果表明，西兰花病原体可能与青花菜的细菌性叶枯病病原体有关（1）。这是关于这种病原体在商业种植的西兰花上引发病害的首次报道。参考文献：（1）S. T. Koike等人，《植物病害》82:727，1998年。
