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.

镰孢穗腐病（Fusarium ear rot）的致病菌为轮枝镰孢菌（Fusarium verticillioides），该病原菌侵染玉米后可诱导产生伏马菌素类真菌毒素。遗传抗性是防治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（maize inbred lines）作为抗轮枝镰孢菌侵染以及抑制伏马菌素（fumonisin）产生的潜在抗源材料。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，另外3份为感病材料，对其接种病原菌后，分别评估穗腐病病情严重度、病粒发生率与伏马菌素含量。结果显示，自交系R1与R3对病原菌侵染表现出较强抗性，但仅有R3能够抑制伏马菌素的积累。由此可见，病害严重程度与伏马菌素产生之间不存在关联是该寄主-病原互作系统（pathosystem）的固有特性。因此，被轮枝镰孢菌侵染但无症状的籽粒，并不能确保不会被伏马菌素污染。