Analysis of intraspecific and interspecific variation in the genus Alternaria by the use of RAPD-PCR

The RAPD-PCR profiles of 13 phytopathogenic Alternaria species and two closely related outgroups were examined using six different primers. Each species produced a distinct pattern of DNA fragments which were used as a measure of the degree of relatedness between species. A. brassicae isolates of diverse origin showed high levels of similarity but little similarity was noted between other species. The closest interspecific genetic distances were recorded between A. citri, A. alternata and A. longipes. The outgroup genera Embellisia and Stemphylium, which are recognised as distinct, could not be clearly separated using RAPD banding criteria, suggesting a high level of genetic diversity amongst these groups of fungi.