Identification, mycotoxin risk and pathogenicity of Fusarium species associated to fig endosepsis in Apulia.

In a survey carried out on 87 rotted fig fruits samples collected in the Apulia region of Italy, the authors isolated 126 Fusarium strains identified as F. ramigenum (69 strains), F. solani (49), F. proliferatum (five) and three not identified. Investigation on the fertility of the strains belonging to F. proliferatum and F. ramigenum revealed that only strains of F. proliferatum were fertile. The identity of F. ramigenum strains was confirmed by sequencing a portion of the translation elongation factor-1 gene. When Fusarium species were analysed for their toxigenicity, 37/69 strains of F. ramigenum produced fusaric acid (FA) up to 525 mg kg-1; 30 strains produced beauvericin (BEA) up to 190 mg kg-1; 60 strains produced fumonisin B1 (FB1) and fumonisin B2 (FB2) up to 1575 mg kg-1 of total FBs; and two strains produced fusaproliferin (FUP) up to 345 mg kg-1; all five strains of F. proliferatum produced FA at low levels; two strains produced BEA up to 205 mg kg-1; one strain produced FB1 and FB2, 1100 and 470 mg kg-1, respectively; and one strain produced FUP, 820 mg kg-1; F. solani (30 strains) produced FA, 13 strains up to 215 mg kg-1. Few fungal extracts showed high toxicity toward brine shrimp larvae and in some cases in relation to BEA and FA content. A pathogenic assay on fig fruits showed that all three species were pathogenic, with higher virulence of F. ramigenum. These data report for the first time the production of BEA and FB1/FB2 by F. ramigenum and show that it is a main agent of fig endosepsis in Apulia and can contribute to fumonisin contamination of fresh and dried figs.