Differentiation of normal and giant Vicia faba populations of the stem nematode Ditylenchus dipsaci : agreement between RAPD and phenotypic characteristics

Two main race groups of the stem nematode, Ditylenchus dipsaci, attack Vicia faba. The aim of this work was to evaluate random amplified polymorphic DNA (RAPD) as a source of markers for race identification and variability analysis of D. dipsaci. Thirteen populations of D. dipsaci were tested and one population of both D. myceliophagus and D. destructor as outgroup species. Sufficient levels of variation were detected to allow a clear distinction between the two D. dipsaci groups. This result was in agreement with the characterization based on morphological differences among races and on the type of faba bean disease symptoms. The intraspecific variation within D. dipsaci populations associated with V. faba was low and no strong correlation could be found between the geographical origin and molecular or morphological characterization. RAPDs are a powerful tool for identification of D. dipsaci races and/or populations.