Kwon J-H, Kim J
Gyeongsangnam-do Agricultural Research and Extension Services, Jinju 660-360, Korea.
Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju 660-701, Korea.
Plant Dis. 2013 Apr;97(4):559. doi: 10.1094/PDIS-08-12-0801-PDN.
Lily of China (Rohdea japonica Roth) is a flowering plant native to eastern Asia. In the summers of 2010 and 2011, suspected anthracnose disease was observed on R. japonica plants in the exhibition field of Jinju Agriculture Technology Center, Jinju, South Korea. Symptoms began as yellow to brown spots on leaves and darkened as the spots expanded. The lesions subsequently became dark brown, and bristled acervuli were observed on the dark brown areas. Leaf spots led to leaf shriveling and eventual death. Fresh leaf specimens were collected from infected plants and the putative causal pathogen was isolated on potato dextrose agar (PDA). The fungus formed a dark brown colony, irregularly shaped black sclerotia, and abundant setae in PDA cultures. Conidia were colorless, falcate, fusiform, and 21 to 26 × 2 to 3 μm. Appressoria were clavate to circular and 8 to 12 × 6 to 8 μm. Amplification of the internal transcribed spacer was conducted as described previously (2) and generated a 577-bp sequence (GenBank Accession No. JQ677042) with 99% identity to sequences of C. liriopes strain CBS 119444 (GU227804), identified previously as C. dematium from Agavaceae (1). In the phylogenetic tree, the representative strain was placed within a clade comprising a reference strain of C. liriopes (data not shown). A representative isolate of the pathogen was used to inoculate R. japonica leaves for pathogenicity testing. Five 4-month-old R. japonica plants were sprayed to runoff with a conidial suspension (10 conidia/ml) and 0.025% Tween. Three plants were sprayed with sterilized distilled water and 0.025% Tween as a control. The plants were kept in a moist chamber with >90% relative humidity at 25°C for 48 h and then moved to a greenhouse. After 7 days of incubation, necrotic spot symptoms similar to those observed in the field developed on the inoculated leaves. Control plants remained asymptomatic. The pathogenicity test was repeated twice with similar results and the causal fungus was reisolated from the lesions of inoculated plants to satisfy Koch's postulates in each test. On the basis of observed symptoms, morphology, pathogenicity, and molecular characterization, this fungus was identified as Colletotrichum liriopes. The recent outbreak of leaf spot on R. japonica plants suggests that C. liriopes is spreading and poses a serious threat to these plants in Korea. References: (1) U. Damm et al. Fungal Diversity 39:45, 2009. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications, M. A. Innis et al., eds., Academic Press, Inc., New York, 1990.
万年青（Rohdea japonica Roth）是一种原产于东亚的开花植物。2010年和2011年夏季，在韩国晋州农业技术中心的展览场地上，万年青植株上观察到疑似炭疽病症状。症状最初表现为叶片上的黄色至褐色斑点，随着斑点扩大颜色变深。病变随后变为深褐色，在深褐色区域观察到具刚毛的分生孢子盘。叶斑导致叶片枯萎并最终死亡。从受感染植株上采集新鲜叶片标本，并在马铃薯葡萄糖琼脂（PDA）上分离出假定的致病病原体。该真菌在PDA培养基上形成深褐色菌落、不规则形状的黑色菌核和大量刚毛。分生孢子无色，镰刀形，梭形，大小为21至26×2至3μm。附着孢棒状至圆形，大小为8至12×6至8μm。按照先前描述的方法（2）进行内转录间隔区的扩增，得到一个577bp的序列（GenBank登录号JQ677042），与之前鉴定为来自龙舌兰科的炭疽菌（Colletotrichum dematium）菌株CBS 119444（GU227804）的序列具有99%的同一性。在系统发育树中，代表性菌株位于包含炭疽菌参考菌株的一个分支内（数据未显示）。使用该病原体的一个代表性分离物接种万年青叶进行致病性测试。用分生孢子悬浮液（10个分生孢子/ml）和0.025%吐温喷洒五株4个月大的万年青植株至径流状态。三株植株喷洒灭菌蒸馏水和0.025%吐温作为对照。将植株置于相对湿度>90%、温度25°C的保湿箱中48小时，然后转移至温室。培养7天后，接种叶片上出现了与田间观察到的类似的坏死斑症状。对照植株保持无症状。致病性测试重复两次，结果相似，并且从接种植株的病变部位重新分离出致病真菌，以在每次测试中满足柯赫氏法则。根据观察到的症状、形态、致病性和分子特征，该真菌被鉴定为炭疽菌。最近万年青植株上叶斑病的爆发表明炭疽菌正在扩散，并对韩国的这些植株构成严重威胁。参考文献：（1）U. Damm等人，《真菌多样性》39:45，2009年。（2）T. J. White等人，载于《PCR协议：方法与应用指南》，M. A. Innis等人编，学术出版社，纽约，1990年，第315页。
