Gibberellin biosynthesis and gibberellin oxidase activities in Fusarium sacchari, Fusarium konzum and Fusarium subglutinans strains (original) (raw)

Several isolates of three Fusarium species associated with the Gibberella fujikuroi species complex were characterized for their ability to synthesize gibberellins (GAs): Fusarium sacchari (mating population B), Fusarium konzum (mating population I) and Fusarium subglutinans (mating population E). Of these, F. sacchari is phylogenetically related to Fusarium fujikuroi and is grouped in the Asian clade of the complex, while F. konzum and F. subglutinans are only distantly related to Fusarium fujikuroi and belong to the American clade. Variability was found between the different F. sacchari strains tested. Five isolates (B-12756; B-1732, B-7610, B-1721 and B-1797) were active in GA biosynthesis and accumulated GA3 in the culture fluid (2.76–28.4 μg/mL), while two others (B-3828 and B-1725) were inactive. GA3 levels in strain B-12756 increased by 2.9 times upon complementation with ggs2 and cps-ks genes from F. fujikuroi. Of six F. konzum isolates tested, three (I-10653; I-11616; I-11893) synthesized GAs, mainly GA1, at a low level (less than 0.1 μg/mL). Non-producing F. konzum strains contained no GA oxidase activities as found for the two F. subglutinans strains tested. These results indicate that the ability to produce GAs is present in other species of the G. fujikuroi complex beside F. fujikuroi, but might differ significantly in different isolates of the same species.Gibberellin biosynthesis is present in Fusarium sacchari and Fusarium konzum, two species of the Gibberella fujikuroi complex, although this ability can differ significantly in different isolates. GA3 or GA1, respectively, are the main gibberellins synthesized. By contrast, Fusarium subglutinans is inactive in gibberellin biosynthesis.