Abstract: In order to clarify the types of Amorphaphallus konjac rot disease and the casual pathogens in Shiyan city of Hubei province, the symptoms of A. konjac rot disease in Shiyan city were investigated, the isolation frequency of each kind of bacteria was determined as well as the classification and pathogenicity of the dominant bacteria. The results showed that the disease incidence and symptoms varied with field sites. The disease symptoms were classified into six types containing circle soft rot on stem base, yellowing and stem base black rot, yellowing and stem split and black, yellowing and stem dry soft, yellowing and external stem base black while interior red, upper stem and whole plant black rot. The most serious disease occurred at Liubei, and the incidences of the first two types of A. konjac rot disease were 13.0% and 26.9%, respectively, and the lowest disease incidence was 4.8% at Yunxi county. Two kinds of fungi, Sclerotium rolfsii and Fusarium sp., and 11 kinds of bacterial strains were isolated from 28 A. konjac samples. The three dominant bacterial isolates were Pectobacterium carotovorum subsp. carotovorum, Stenotrophomonas maltophilia and Klebsiella oxytoca with high isolation frequency of 27.6%, 17.6% and 12.1%, respectively. Pathogenic test indicated that Pectobacterium carotovorum subsp. carotovorum was pathogenic to A. konjac, and specific DNA band was only amplified from the total DNA of isolates B12, B16 and B17. In a conclusion, complex infection was found in A. konjac rot disease, and P. carotovorum subsp. carotovorum was the important pathogen. These results were valuable for the management of A. konjac rot disease.

Key words: Amorphaphallus konjac rot, isolation frequency, disease symptom, disease incidence, pathogens

摘要： 为了明确湖北省十堰市魔芋腐烂病的发病类型及重要致病菌，调查了十堰市不同地点魔芋腐烂病的发病类型，研究了不同地区病原菌的分离频率、优势菌种类及致病性。结果表明，魔芋发病率和发病症状因地点而异，可分为茎基环状软腐型、黄化茎基黑烂型、黄化茎黑裂型、黄化茎干软型、黄化茎基外黑内红型、茎上部或整株黒烂型六大类症状。柳陂基地魔芋发病率最高，茎基环状软腐型和黄化茎基黑烂型发病率分别为13.0%和26.9%；郧西乡魔芋发病率最低，为4.8%。从28个样品中共分离到2种真菌和11种细菌，其中真菌为齐整小核菌和镰刀菌，优势细菌为胡萝卜软腐果胶杆菌胡萝卜亚种（Pectobacterium carotovorum subsp. carotovorum）、嗜麦芽寡养单胞菌（Stenotrophomonas maltophilia）和产酸克雷伯氏菌（Klebsiella oxytoca），分离频率分别为27.6%、17.6%和12.1%。致病性测定表明，胡萝卜软腐果胶杆菌胡萝卜亚种为魔芋软腐病的致病菌。利用胡萝卜软腐果胶杆菌特异性引物仅从被鉴定为该种的B12、B16、B17菌株中扩增出特异DNA条带。上述结果表明：魔芋腐烂病存在复合侵染，胡萝卜软腐果胶杆菌为魔芋腐烂病的重要致病菌，为魔芋腐烂病的防控提供了依据。

关键词: 魔芋腐烂病, 分离频率, 症状, 发病率, 致病性