Genetic variability among Alternaria solani isolates from potatoes in Southern Germany based on RAPD-profiles

One of the problems encountered when studying the population genetics of fungal plant pathogens is defining what constitutes a "population". Potato early blight is a major disease of potatoes and other species of the Solanaceae. The causal agent is the ascomycete Altemaria solani, which infects leaves and stems of potato plants leading to premature defoliation. In this study, spatial genetic diversity within A. solani populations from potato leaves were investigated using RAPD markers in order to reveal the degree of homo- or heterogeneity. Analysis of RAPD profiles revealed distinct genetic diversity among isolates originating from the same field. In addition, pronounced genetic variability was found for isolates from different years. These results indicate a surprising genetic heterogeneity within the population of A. solani, which must be kept in mind when designing protective measures for agriculture.