山西省蒙古黄芪根腐病优势致病菌群分析

Analysis of dominant pathogen community causing Astragalus membranaceus var. mongholicus root rot in Shanxi Province

为明确山西省蒙古黄芪根腐病的优势致病菌群及其分布区域和症状差异性,采用组织分离法分离获得致病菌,按柯赫氏法则回接验证,结合形态学特征与EF-1α基因分子鉴定结果明确其分类地位,并分析不同地域和不同发病症状下致病菌的分离频率。结果表明,引起山西省蒙古黄芪根腐病的致病菌包括锐顶镰刀菌Fusarium acuminatum、腐皮镰刀菌F.solani、尖孢镰刀菌F.oxysporum、芬芳镰刀菌F.redolens、链格孢菌Alternaria sp.以及Ilyonectria torresensis,其中锐顶镰刀菌和腐皮镰刀菌为优势致病菌,平均分离频率为53.83%和26.42%。不同地区根腐病的优势致病菌具有明显差异,浑源县和应县为锐顶镰刀菌、腐皮镰刀菌,分离频率分别是42.86%、39.13%和62.50%、37.50%;五寨县为锐顶镰刀菌和尖孢镰刀菌,分离频率56.14%和35.96%。根腐病的症状具有一定地域差异,且引发不同症状的优势致病菌也不同,总体上引起纤维状腐烂的优势致病菌为锐顶镰刀菌、腐皮镰刀菌和尖孢镰刀菌,前二者平均分离频率分别为63.37%和20.50%,尖孢镰刀菌仅在五寨县检出,分离频率为21.98%;引起侧根发黑的优势致病菌主要是锐顶镰刀菌和腐皮镰刀菌,平均分离频率分别为35.50%和21.65%,但在浑源县未发现此类症状;引起皱缩软根的优势致病菌在各地差异明显,五寨县以尖孢镰刀菌最占优势,分离频率为43.48%,浑源县为链格孢菌,分离频率为32.79%,应县则是腐皮镰刀菌,分离频率为60.00%。

The study was designed to clarify the dominant pathogens that cause root rot disease of Astragalus membranaceus var. mongholicus and their distributive characteristics in different regions and symptoms in Shanxi Province. Pathogens were isolated from diseased root segments, their pathogenicity being tested applying Koch＇s postulates, and then identified with morphology and EF-1α sequences analysis.Follow-up analysis was made of the isolation frequency of the pathogens in terms of regions and symptoms. The result showed that a range of pathogens caused A. membranaceus var. mongholicus root rot in Shanxi Province, including Fusarium acuminatum, F. solani, F. oxysporum, F. redolens, Alternaria sp.and Ilyonectria torresensis, among which the dominant ones were F. acuminatum and F. solani, their average isolation frequency being 53.83% and 26.42% respectively. The composition and isolation frequency of dominant pathogen community showed regional differences： F. acuminatum and F. solani were dominant in both Hunyuan County and Ying County, their isolation frequency being 42.86%, 39.13% and62.50%, 37.50% respectively; F. acuminatum and F. oxysporum were dominant in Wuzhai County, their isolation frequency being 56.14% and 35.96%. The symptoms of root rot had some regional differences and were caused by different dominant pathogens. On the whole, fibrous decay was caused mainly by F.acuminatum, F. solani, and F. oxysporum, the average isolation frequency of the first two being 63.37%and 20.50% respectively, while F. oxysporum was found only in Wuzhai County, its isolation frequency being 21.98%. The lateral root turning black was caused mainly by F. acuminatum and F. solani, their average isolation frequency being 35.50% and 21.65% respectively; but no such symptom was found in Hunyuan County. The root of shrinking and softening was caused principally by F. oxysporum in Wuzhai County, its isolation frequency being 43.48%; Alternaria sp. in Hunyuan County, its isolation frequency being 32.79%; and F. solani in Ying County, its isolation frequency being 60.0%.