Expression difference of P450–1 and P450–4 between G- and F-groups of Fusarium fujikuroi

Abstract

Fusarium fujikuroi is the pathogen of rice bakanae disease and has been intensively studied for gibberellin (GA) production. F. fujikuroi is phylogenetically subclassified into G- and F-groups, which differ in GA and fumonisin production. A higher amount of GA is produced by the G-group than the F-group. A previous study found that the GA production difference between the G-group strain Gfc0801001 and the F-group strain Gfc0825009 was due to the GA gene cluster. In this study, higher expression of P450–1 and P450–4 in the GA gene cluster were detected in G-group strains than in F-group strains. The nucleotide sequence of the bidirectional promoter region between P450–1 and P450–4 and expression of P450–1 and P450–4 were compared between G- and F-group strains. The promoter sequence was identical among G-group strains while nucleotide substitutions were detected at various locations in F-group strains. Most F-group strains did not share the same substitutions. These results combined with the ancestral position of the F-group in the phylogenetic tree suggest that the population carrying highly expressed sequence generates the G-group rather than the low expression of P450–1 and P450–4 in the F-group due to a specific mutation occured in G-group.