Amplified fragment length polymorphism (AFLP) was used to analyze the genetic diversity of 14 strains
of Xanthomonas arboricola pv. pruni and seven strains of X. axonopodis pv. phaseoli, which are used in
xanthan production studies. Relationships identified by the AFLP profiles were assessed for xanthan
production capacity, geographical location and host plant. Strains were isolated from 10 different
geographic regions in South and Southeast States in Brazil. Data were analyzed for genetic similarity using
the Dice coefficient and subjected to UPGMA cluster analysis. A total of 128 AFLP fragments were
generated from four primer combinations: EcoRI+C/MseI+0, EcoRI+A/MseI+0, EcoRI+G/MseI+T and
EcoRI+G/MseI+A. Of these, 96.1% were polymorphic. X. axonopodis pv. phaseoli (SD = 0.27) was shown
to be more polymorphic than X. arboricola pv. pruni (SD = 0.58). All 14 pathovar pruni strains were
included in a single main group (SD = 0.58), while the pathovar phaseoli strains were divided into three
separate groups, with one group containing five strains (SD = 0.38) and two isolated groups (SD = 0.31 and
0.27) composed of only one strain each. Species were distinguished by three and eight specific AFLP
markers present in the pathovar phaseoli and the pathovar pruni, respectively. For the unique strain
without xanthan production capacity (X. axonopodis pv. phaseoli str. 48), nine specific AFLP bands were
found. There was no evidence that geographic area or host plant influenced genetic heterogeneity.
Correlations between AFLP patterns and xanthan production capacity were found in some strains, but were
not consistent enough to establish a relationship.