Phytopathology. 2003 Mar;93(3):323-8. doi: 10.1094/PHYTO.2003.93.3.323.
ABSTRACT Spore germination fluid of Alternaria panax, the causal agent of Alternaria blight of American ginseng (Panax quinquefolius), collected from water droplets or aqueous ginseng leaf extracts produced visible water-soaked lesions on wounded, detached leaflets after incubation for 48 h. Maximum development of brown, necrotic spots occurred 4 to 5 days after inoculation on attached and detached ginseng leaflets. Of 15 plant species tested, only American ginseng was susceptible to applications of spore inoculum or spore germination fluid. The phytotoxic activity of the spore germination fluid was destroyed by heat and treatment with proteinase A. The phytotoxic factor was retained by an ultrafiltration membrane with a 30-kDa molecular mass cut-off. Purification of the phytotoxic protein, named AP-toxin, was performed by anion exchange and gel filtration chromatography. Bioactive fractions eluted as a single peak. By comparison with protein standards, a molecular mass of 35 kDa was estimated for the native protein. The denatured protein toxin also had a mass of 35 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. Production of the protein toxin was induced on American ginseng leaflets and water extracts of ginseng leaves but not on leaves of other nonhost plants and their water extracts. The results show that A. panax produces a host-specific, proteinaceous toxin during colonization and pathogenesis of ginseng leaves.
来自西洋参黑斑病菌（Alternaria panax）的孢子萌发液，从水滴或水提西洋参叶提取物中收集，在 48 小时孵育后，对受伤的、分离的小叶产生可见的水渍病变。在附着和分离的西洋参小叶上接种后 4 至 5 天，出现最大程度的棕色坏死斑点。在 15 种测试的植物物种中，只有西洋参容易受到孢子接种或孢子萌发液的应用。孢子萌发液的植物毒性活性被热和蛋白酶 A 处理破坏。具有 30 kDa 分子量截止值的超滤膜保留了植物毒性因子。通过阴离子交换和凝胶过滤色谱对有毒蛋白进行了纯化，命名为 AP-毒素。生物活性部分作为单个峰洗脱。与蛋白标准比较，估计天然蛋白的分子量为 35 kDa。变性蛋白毒素通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析也具有 35 kDa 的分子量。在西洋参小叶和西洋参叶的水提取物上，但不在其他非宿主植物及其水提取物上诱导产生蛋白毒素。结果表明，A. panax 在西洋参叶片的定殖和发病过程中产生一种宿主特异性的蛋白毒素。
