Evaluation of resistance of popcorn maize genotypes to fumonisin accumulation and fusarium ear rot

ABSTRACT Fusarium ear rot, caused by the fungus Fusarium verticillioides, is one of the major diseases of popcorn maize (Zea mays) in Brazil and, besides reducing productivity, the action of the pathogen results in the contamination of grains by mycotoxins of the fumonisin group. The aim of this study was to evaluate the resistance of popcorn genotypes to fusarium ear rot and to the accumulation of fumonisins in the grains. The experiment was conducted in the field by adopting a randomized block design. Pathogen inoculation in the ear was artificial. Among the 22 evaluated genotypes, which included 16 progenitor lines and 6 varieties, there were significant differences (p = 0.05) in relation to the levels of fusarium rot and the accumulation of fumonisins B1, B2 and B3 in the grains. Spearman’s correlation for these variables was positive, but the correlation coefficients were low (r = 0.53; p < 0.0002), showing that for this group of genotypes the quantification of fusarium ear rot has a small predictive value in relation to fumonisin content in the grains. This piece of information is believed to be useful for breeding programs of popcorn maize in Brazil.

摘要 由轮枝镰孢菌（Fusarium verticillioides）引发的镰孢穗腐病（Fusarium ear rot）是巴西爆米花玉米（Zea mays）的主要病害之一，该病害不仅会降低作物产量，还会因病原菌的侵染导致籽粒被伏马菌素类真菌毒素污染。本研究旨在评估爆米花玉米基因型对镰孢穗腐病的抗性以及籽粒中伏马菌素的积累水平。试验采用随机区组设计在田间开展，通过人工方式对果穗进行病原菌接种。供试的22份基因型材料包含16个亲本自交系与6个品种，其镰孢穗腐病发病程度及籽粒中伏马菌素B1、B2和B3的积累水平均存在显著差异（p=0.05）。上述性状的斯皮尔曼相关性（Spearman’s correlation）呈正相关，但相关系数较低（r=0.53；p<0.0002），表明对于该组基因型材料而言，镰孢穗腐病的量化指标对籽粒伏马菌素含量的预测价值有限。该研究结果可为巴西爆米花玉米的育种项目提供参考依据。