Discrimination between alfalfa and potato isolates of Verticillium albo-atrum using RAPD markers

Random amplified polymorphic DNA (RAPD) of total DNA was used to study genetic variability within 35 alfalfa and potato isolates of Verticillium albo-atrum, the causal agent of Verticillium wilt. With five selected RAPD primers, patterns were clearly different between the alfalfa and the potato isolates. A significant (37%; P < 0.002) portion of the total genetic variance was attributable to differences between the potato and the alfalfa isolates. These results suggest that these alfalfa and potato isolates are genetically distinct. Combined with previous inoculation studies these results are in agreement with the presence of host adaptation in V. albo-atrum and support the creation of a distinct taxonomic entity for alfalfa isolates. In addition, one avirulent potato isolate and one alfalfa isolate were tested and found divergent according to RAPD patterns.