Genetic variability and fumonsin production by Fusarium proliferatum isolated from durum wheat in Argentina

PALACIOS, S. A.; SUSCA, A; STEA, G; HAIDUKOWKI, M.; RAMIREZ, M.L.; CHULZE, S. N.; FARNOCHI, M.C; MORETTI, A.; TORRES, A.M.

Rotterdam

Simposio; 7th Conference of The World Mycotoxin Forum and XIII th IUPAC International Symposium on Mycotoxins and Phycotoxins; 2012

IUPAC

Fusarium proliferatum is one of the main pathogens associated with maize ear rot worldwide and can produce fumonisins that contaminate this cereal. This fungus has a wide range of host plants besides maize, such as wheat and barley among oathers. Recently, studies in our laboratory have detected natural fumonisins contamination in durum wheat kernels; mainly F. proliferatum were isolated from these kernels. The objectives of this study were to analize (i) the genetic variability through a phylogenetic analysis and (ii) the fumonisin producing ability of F. proliferatum strains isolated from durum wheat in Argentina. The phylogenetic study was performed based on partial sequence of EF-1a and CL genes. The fusarium species evaluated in this study (n=62) were identified using  morphological markers and were from diverse geographic origin, hosts (wheat and maize) and year of isolation. By molecular markers, strains of F. verticillioides (6) and F. proliferatum (51) were identified. To determine their fumonisin producing ability, the isolates were grown on autoclved whe Aftyer 3 weeks of incubation in the dark at 25 ºC, grains were dried and ground. Non-inoculated wheat grains were used as controls. Quantitation of fumonisins (FB1, FB2 and FB3) was done by HPLC with o-phthalaldehyde precolumn derivatization. The phylogenetic study performed revealed the presence  of two main clusters, one grouped all the F. proliferatum strains while the other contained 7 F. verticilloides strains. Moreover, F. proliferatum isolates were separated in groups showing a high intraespecific variability, however, a correlation to geographic origin, host or year of harvest was not observed. Out of 51 F. proliferatum strains evaluated for fumonisin production in durum wheat grains, 49 showed fumonisins production in levels ranging from 1.1 to 2,072.4 ug/g. Seven strains produced more FB2 than FB1 and 11 strains produced more FB3 than FB2. Six F. verticcilloides strains pproduced fumonisins in levels ranging from 30.1 to 301.1 ug/g. Three strains produced more  fB3 than FB1. These results indicate that, among the fumonisin producing species, durum wheat grains are contaminated mainly by F. proliferatum; however, F. verticcillioides can alsoo found in this cereal, presenting a high risk for human and animal health.