AFLP characterization of Southern Europe population of Aspergillus Section Nigri from grapes.

Members of Aspergillus belonging to Section Nigri are distributed worldwide and are mainly responsible for the ochratoxin A accumulation in grapes and wine, particularly in Southern Europe. Limited information is available on the species composition and genetic variability of black Aspergilli strains occurring on grapes. We analyzed 283 representative strains from the main wine producing European countries collected in 2001-2002 (Italy, France, Spain, Portugal, Greece and Israel) using amplified fragment length polymorphisms (AFLP) technique. Four main groups were obtained by AFLP clustering analysis of these strains and three of them showed a well defined homogeneous population/species with intraspecific homology higher than 48%: Aspergillus carbonarius (105 strains), Aspergillus tubingensis (69 strains), and Aspergillus "uniseriate" (56 strains) with a similarity less than 20% to the Aspergillus japonicus type strain. The fourth cluster, that we called "A. niger like" (44 strains), showed low homology with A. niger type strain (35%) and high internal heterogeneity. Finally, nine strains could not be assigned readily to any of the type strain of the A. nigri Section. These findings indicate that the Aspergillus Section Nigri strains occurring on grapes in Southern Europe represent a complex of species, and some of these are peculiar to grapes.