Aspergillus sección Flavi isolated from peanut fields in Argentina: molecular characterization. Barros, G., Chiotta, M., Reynoso, M., Torres, A., Chulze, S.

BARROS, G.G; CHIOTTA, M.L; REYNOSO, A.M.; TORRES, A.M; CHULZE, S.N

Villa Carlos Paz, Cordoba

Congreso; Advances in research on toxigenic fungi and mycotoxins in South America ensuring food and feed safety in a myco-globe context.; 2006

European Commission-UNRC

Aflatoxins are highly toxic secondary metabolites that naturally contaminate peanut and their presence cause important economic losses. Peanuts are often invaded before harvest by Aspergillus flavus and A. parasiticus, both members of section Flavi. A. flavus produces aflatoxin B and cyclopiazonic acid (CPA), while A. parasiticus produces aflatoxin B and G. Atypical A. flavus strains aflatoxin B, G and CPA producer salso have been isolated in Argentina. In this study eighty-two strains belonging to the section Flavi isolated from the peanut agroecosystem were analyzed by AFLP to assess the genetic relationship between A. flavus/A. parasiticus. Fungal DNA extraction was done with by cetyltrimethylammnonium bromide (CTAB) method of Murray and Thompson (1980) as modified by Kerényi et al. (1999). AFLPs reactions were performed as described by Vos et al. (1995), as modified by Zeller et al. (2000). The selective primers combinations analysis produced a complex fingerprint pattern. We identified 174 polymorphic AFLP bands among a total of 204 bands genereted following amplification with three different primers pairs, as follow: (number of polymorphic bands/total number of bands): EcoRI + TG / MseI + CG, 49/56; EcoRI + TG / MseI + G, 59/69; EcoRI + GG / MseI + A, 66/79. Based on cluster analysis, it is clear that the isolates can be readlly assigned into two groups. The group A was composed by 48 A. flavus strains and the group B by 34 A. parasiticus strains. This separation agree with previous morphological and physiological characterization. The atypical SBG strains were included into group A. Both A. flavus and A. parasiticus strains examinated displayed a high degree of similarity. The average similarity among the 48 A. flavus strains was 82% (range= 64?97%). Among the 34 A. parasiticus the average similarity was 78% (range= 52?100%) There was no clear association between the genetic similarity and the potential of the strains to produce aflatoxin, CPA and VCG affiliation.