Molecular identification, mycotoxin production and comparative pathogenicity of Fusarium temperatum isolated from maize in China.
A recently isolated Fusarium population from maize in Belgium was identified as a new species, Fusarium temperatum. From a survey of Fusarium species associated with maize ear rot in nineteen provinces in 2009 in China, ten strains isolated from Guizhou and Hubei provinces were identified as F. temperatum. Morphological and molecular phylogenetic analyses based on the DNA sequences of individual translation elongation factor 1-alpha and β-tubulin genes revealed that the recovered isolates produced macroconidia typical of four-septate with a foot-shaped basal cell and belonged to F. temperatum that is distinctly different from its most closely related species F. subglutinans and others within Gibberella fujikuroi complex species from maize. All the strains from this newly isolated species were able to infect maize and wheat in field, with higher pathogenicity on maize. Mycotoxin determination of maize grains infected by the strains under natural field condition by ultra-high-performance liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry analyses showed that among fifteen mycotoxins assayed, two mycotoxins fumonisin B1 and B2 ranging from 9.26 to 166.89 µg/g were detected, with massively more FB2 mycotoxin (2.8- to 108.8-fold) than FB1. This mycotoxin production profile is different from that of the Belgian population in which only fumonisin B1 was barely detected in one of eleven strains assayed. Comparative analyses of the F. temperatum and F. subglutinans strains showed that the highest fumonisin producers were present among the F. temperatum population, which were also the most pathogenic to maize. These results suggested a need for proper monitoring and controlling this species in the relevant maize-growing regions.