Relationship between resistance of tropical maize inbred lines for resistance to ear rot and fumonisins accumulation caused by Fusarium verticillioides

Maize infection by Fusarium verticillioides, the causal agent of Fusarium ear rot, can result in the production of mycotoxins of the fumonisin group. Genetic resistance is the most effective way to control this disease. Thus, the aim of this study was to evaluate tropical maize inbred lines as potential sources of resistance to F. verticillioides and production of fumonisins. Six maize inbred lines, three previously classified as resistant and three as susceptible to F. verticillioides, were inoculated with the pathogen and subsequently evaluated for ear rot severity, incidence of symptomatic grain and fumonisin concentration. Results showed that the lines R1 and R3 exhibited high resistance to the pathogen infection. However, only R3 was resistant to the accumulation of fumonisins. Therefore, it is suggested that absence of relationship between disease intensity and fumonisin production is inherent to this pathosystem. Thus, asymptomatic grains infected by F. verticillioides cannot be ensured to be free of contamination by fumonisins.

玉米感染镰孢穗腐病（Fusarium ear rot）致病菌轮枝镰孢菌（Fusarium verticillioides）后，可产生伏马菌素（fumonisin）类真菌毒素（mycotoxin）。遗传抗性（genetic resistance）是防控该病害最为有效的手段。因此，本研究旨在评估热带玉米自交系（tropical maize inbred line）作为抗轮枝镰孢菌侵染及伏马菌素产生的潜在抗源的潜力。本研究选取6份玉米自交系，其中3份此前被鉴定为抗轮枝镰孢菌材料，另外3份为感病材料，经人工接种该病原菌后，对其穗腐病严重度、显症籽粒发病率及伏马菌素含量进行了评价。结果显示，自交系R1与R3对病原菌侵染表现出高抗性，但仅R3能够抑制伏马菌素的积累。由此表明，病害严重程度与伏马菌素产生之间不存在关联，这是该病害体系（pathosystem）所固有的特性。因此，即便被轮枝镰孢菌侵染的无症状籽粒（asymptomatic grain），也无法确保其未受伏马菌素污染。