Molecular identification of Fusarium spp. associated with bakanae disease of rice in Italy and assessment of their pathogenicity

Between 2006 and 2008, 146 isolates of Fusarium spp. were obtained from bakanae-diseased rice plants and seeds from the major rice-growing regions of Italy. These isolates were identified based on translation elongation factor (EF-1 alpha) sequence and pathogenicity tests were used to assess their aggressiveness against the susceptible rice cultivar Galileo. Use of the EF-1 alpha sequence gave reliable identification and showed that Fusarium fujikuroi, the causal agent of bakanae disease, was the most abundant Fusarium spp. isolated. These data were confirmed by inoculation of the isolates to rice seeds which were then germinated in the greenhouse, showing that only F. fujikuroi isolates were able to cause bakanae disease. Pathogenic isolates were identified with different levels of aggressiveness. Phylogenetic analysis based on EF-1 alpha sequences generated a tree which separated the various Fusarium species into different clusters with high bootstrap values.