苜蓿根腐病病原菌的分离鉴定及苜蓿品种的抗性评价

Isolation and Identification of Pathogens Causing Root Rot Disease in Alfalfa and the Evaluation of Resistant Ability of Alfalfa Varieties to Fusarium equiseti and F.tricinctum

苜蓿根腐病病原菌较为复杂,因此明确不同生态环境下苜蓿根腐病病原菌的种类和优势菌株,对于苜蓿根腐病的防治非常重要。利用柯赫氏法则对采自内蒙古三个不同地点苜蓿田中疑似根腐病的病样进行了分离和鉴定。结果表明,从供试病样中共分离得到6个不同种的镰刀菌:木贼镰刀菌(Fusarium equiseti)、锐顶镰刀菌(F.acuminatum)、产黄色镰孢菌(F.thapsinum)、变红镰刀菌(F.incarnatum)、尖孢镰刀菌(F.oxysporum)和三线镰刀菌(F.tricinctum)。其中,木贼镰刀菌是上述三个供试地点苜蓿根腐病的优势致病菌。在室内条件下,利用优势菌株木贼镰刀菌以及三线镰刀菌对32个苜蓿品种的抗根腐病水平进行了评价,结果表明供试的品种间对根腐病的抗性水平呈现出一定的差异,其中品种康赛对两种不同的镰刀菌种表现出最高的抗性水平,其病情指数分别为26.07和26.81;按照抗性水平的划分标准,32份供试材料中对三线镰刀菌呈现中抗水平的品种18份,占供试品种的56.25%;表现为中感水平的品种14份,占43.75%,未见高感品种。对木贼镰刀菌而言,呈现中抗水平的苜蓿品种9份,占28.13%;呈现中感品种14份,占43.74%;呈现高感水平的苜蓿品种9份,占28.13%。本研究中未发现针对上述两种根腐病病原菌呈现免疫和高抗水平的苜蓿品种。

Pathogens caused alfalfa root rot disease(ARR)are very complicated that it is important to identify dominant species of pathogens induced ARR to control this disease in different ecological environments.In this study,ARR suspected samples were collected from three different locations in Inner Mongolia region,in which pathogens were isolated and identified by Koch’s method.The results showed that 6 different fusarium species were identified,including XAMG-6(Fusarium equiset),XAMG-2(F.acuminatum),XAMJ-4(F.thapsinum),CYSG-3(F.equiseti),CYSG-1(F.incarnatum),CYS1-3(F.oxysporum)and MX-1(F.tricinctum).Among them,F.quiseti is the dominant fusarium species in three different locations.Furthermore,the resistance of 32 alfalfa varieties against both MX-1(F.tricinctum)and MX-2(F.equiseti)were evaluated under greenhouse conditions.Our results suggested that the resistance of tested alfalfa varieties was variable.Among the 32 varieties,‘KangSai’showed the highest resistance against both MX-1(F.tricinctum)and MX-2(F.equiseti).Based on the classification of resistant ability,18 of 32 varieties showed moderate resistant ability to F.tricinctum;14 varieties showed moderate susceptible level,no high susceptible variety was identified in this study.For F.equiseti,9 varieties showed moderate resistant ability and 14 varieties exhibited moderate susceptibility,while 9 varieties were identified as high susceptibility.None of tested varieties was identified as either high ARR immunity or resistant ability to both fusarium species in this study.