In this study, we identified the causative agent of stem-end rot in potatoes that were grown in Gangwon alpine areas of Korea in 2013. The disease symptoms included appearance of slightly sunken circular lesion with corky rot on the potato surface at the stem-end portion. The fungal species isolated from the infected potatoes were grown on potato dextrose agar and produced white aerial mycelia with dark violet pigments. The conidiophores were branched and monophialidic. The microconidia had ellipsoidal to cylindrical shapes and ranged from 2.6~11.4 × 1.9~3.5 µm in size. The macroconidia ranged from 12.7~24.7 × 2.7~3.6 µm in size and had slightly curved or fusiform shape with 2 to 5 septate. Chlamydospores ranged from 6.1~8.1 × 5.7~8.3 µm in size and were present singly or in pairs. The causal agent of potato stem-end rot was identified as Fusarium oxysporum by morphological characterization and by sequencing the internal transcribed spacer (ITS1 and ITS4) regions of rRNA. Artificial inoculation of the pathogen resulted in development of disease symptoms and the re-isolated pathogen showed characteristics of F. oxysporum. To the best of our knowledge, this is the first study to report that potato stem-end rot is caused by F. oxysporum in Korea.

中文翻译：

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韩国尖孢镰刀菌引起马铃薯茎端腐烂的首次报道。

在这项研究中，我们确定了 2013 年在韩国江原道高山地区种植的马铃薯茎端腐烂的病原体。疾病症状包括在马铃薯茎端表面出现轻微凹陷的圆形病灶和软木腐病部分。从受感染的马铃薯中分离出的真菌在马铃薯葡萄糖琼脂上生长，并产生带有深紫色色素的白色气生菌丝体。分生孢子梗是分枝的和单核的。小分生孢子为椭圆形至圆柱形，大小为 2.6~11.4 × 1.9~3.5 µm。大分生孢子大小为 12.7~24.7 × 2.7~3.6 µm，略弯曲或纺锤形，有 2 至 5 个隔膜。厚壁孢子的大小范围为 6.1~8.1 × 5.7~8.3 µm，单独或成对存在。通过形态学表征和对 rRNA 的内部转录间隔区（ITS1 和 ITS4）区域进行测序，马铃薯茎端腐烂的病原体被确定为尖孢镰刀菌。病原体的人工接种导致疾病症状的发展，并且重新分离的病原体显示出尖孢镰刀菌的特征。据我们所知，这是韩国首次报道马铃薯茎端腐烂是由尖孢镰刀菌引起的研究。