Abstract: In order to understand the pathogenic mechanism of the black rot leaf diseases of sainfoin(Onobrychis viciaefolia Scop.),diseases were investigated from field specimens obtained in Lanzhou,Dingxi district of Gansu provinces.The pathogen was identified by isolating cultures with separation and purification,and pathogenicity tests.Separation of the pathogenic toxins was incubated in PSK culture medium by ethyl acetate extraction,and toxin activities were tested by biological assay.Pure toxin specimens were obtained by concentration and purification from crude toxin.The chemical structures of toxin components were determined by gas chromatograph-mass spectrometer(HP6890-5973I).Results show that the black rot disease of sainfoin was caused by the fungus Alternaria tenuis.The crude toxin of the pathogen show strong virulence to seminal root elongation,leaves in vitro and leaf disks of sainfoin.The main chemical structure of the toxin component is acetic acid 2,5-dioxo-1-pyrrolidinyl ester.The molecular formula is C₆H₇NO₄,and the relative content is 67.02%.

Key words: Pathogenic mechanism, Extraction, Chemical structure, Bioassay

摘要： 为明确红豆草(Onobrychis viciaefolia Scop.)黑腐病的病原及其病菌的主要制病机理,对甘肃省兰州、定西等地红豆草黑腐病进行调查,通过对病叶进行组织分离得到病菌,经纯化培养、致病性测定后进行病原鉴定;病菌用PSK培养液在适宜条件下培养,经乙酸乙酯萃取,获得粗毒素液,进行生物测定后,经过浓缩、纯化,得到较纯的毒素样品,利用气相色谱-质谱联用仪(HP6890-5973I)测定了该毒素组分。结果表明:该病菌属半知菌亚门极细链格孢菌(Alternaria tenuis Nees.),病菌粗毒素液对红豆草种子根伸长、离体叶片和叶圆片具有较强的毒性;红豆草细链格孢菌毒素的主要组成成分为乙酸-N-羟基琥珀酰亚胺酯(C₆H₇NO₄),相对含量为67.02%。

关键词: 制病机理, 萃取, 毒素组分, 生物测定