Abstract: In order to study the relationship between pathogenicity and toxin activity of Fusarium verticillioides, as well the effect of toxin on root protective enzymes of cotton seedlings, the cotton seeds and seedlings of variety ‘Xinluzao 82’ were treated with crude toxin solution of F. verticillioides hydroponically. Seed germination rate, radicle inhibition rate, seedling wilting degree, root conductivity, activities of superoxide dismutase (SOD), phenylalanine ammonia-lyase (PAL), peroxidase (POD), polyphenol oxidase (PPO) in root were measured. The results showed that the activities of F. verticillioides mycotoxin was positively correlated with the pathogenicity of cotton seedlings and the activities of root protective enzymes. Toxins extracted from different pathogenic strains and their different concentrations had significant effects on germination rate and radicle inhibition rate of cotton seeds. After being treated with pathogenic bacteria toxin solution, the activities of SOD, PAL, POD and PPO in cotton seedling roots all increased first and then decreased, with the highest activity occurring within 12~24 h after treated. This study provided reference for understanding the interaction between host and pathogenic bacteria, and for the application of toxins in disease resistance breeding and new methods of disease control.

Key words: cotton, Fusarium verticillioides, toxin, pathogenicity, enzyme activity

摘要： 为了研究拟轮枝镰孢霉(Fusarium verticillioides)的致病力与毒素活性之间的关系，以及毒素对棉苗根系保护酶的影响，选用棉花‘新陆早82号’品种，用拟轮枝镰孢霉粗毒素液水培处理棉种及棉花幼苗后，分别测定棉种发芽率、胚根抑制率、棉苗萎蔫程度、根系电导率、根系超氧化物歧化酶（superoxide dismutase, SOD）、苯丙氨酸解氨酶（phenylalanine ammonia-lyase, PAL）、过氧化物酶（peroxidase, POD）、多酚氧化酶（polyphenol oxidase, PPO）活性。结果表明：拟轮枝镰孢霉毒素活性与菌株致病力成正相关，与棉苗致萎程度、根系保护酶活性成正相关；不同致病力菌株所提取的毒素及其不同浓度溶液均对棉种萌发率及胚根抑制率有显著影响；经病原菌毒素溶液处理后，棉苗根系的SOD、PAL、POD、PPO活性均呈先增高后降低的趋势，其活性最高出现在处理后12～24 h。该研究对于了解寄主与病原菌相互作用关系，以及为毒素在抗病育种、病害防治新方法等方面的应用研究提供借鉴。

关键词: 棉花, 拟轮枝镰孢霉, 毒素, 致病力, 酶活性