Abstract:
The population structure and genotypic diversity of Septoria tritici Rob ex Desm. from two crop field
populations in Buenos Aires Province were studied with DNA restriction fragment length polymorphism. Hierarchical
samples were taken from different cultivars. A total of 120 single spore isolates was subject to molecular analysis to
compare the genetic structure of Los Hornos and Balcarce populations separated by 500km. Eight RFLP loci and 1DNA
fingerprinting were used. Among the total of the isolates, 24 RFLP alleles were detected from the first population and 22
from the second. Gene and genotype diversity were high in both populations. Different haplotypes for each region were
identified. Identical haplotypes were clustered in the same location in the field. The mean gene diversity and the mean
genotypic diversity were high for the 8 loci of RFLP. This means that Balcarce and Los Hornos were significantly
different. The X2 was significant (P>0.005) only for two RFLP locus, then both populations were not independant. They
had to be compared with an European and an American populations. Balcarce population was very different to all of
them. Both Argentine populations were very similar at regional level but strongly different at a continental level. The
greatest genetic variability between continents belonged to Argentine population. The amount of gene flow was high
when all the populations were compared.