Beschreibung:
<p>Until recently, the identification of <italic>Armillaria</italic> species relied upon morphological characteristics and mating tests, but now molecular techniques based on polymorphisms in the IGS region of the fungal rDNA are more commonly used, since these are more rapid and reliable. Differences found in RFLP patterns identifying <italic>Armillaria</italic> species have suggested the existence of intraspecific variation. In this work, 185 <italic>Armillaria</italic> isolates from different plant species (including fruit trees, broadleaf and coniferous trees, ornamental shrubs, kiwifruit and grapevine) affected by white root rot were analyzed by RFLP-PCR, in order to study intraspecific variation in <italic>Armillaria</italic> and the relationship with the plant host. <italic>Armillaria mellea</italic> was found in the majority of samples (71%), and was the most frequent <italic>Armillaria</italic> species in symptomatic ornamental shrubs, kiwifruit, grapevine, fruit trees and broadleaf trees. In conifers however white root rot was generally caused by <italic>Armillaria ostoyae. Armillaria gallica</italic> was identified, although with low incidence, in ornamental, coniferous, broadleaf and fruit hosts. Intraspecies variation was recorded only in <italic>A. mellea</italic>, for which RFLP patterns mel 1 and mel 2 were found. Most plants infected with <italic>A. mellea</italic> showed the mel 2 pattern. Further research is needed to study whether <italic>Armillaria</italic> RFLP patterns are specific to certain plant hosts, and whether intraspecific variation is related to differences in pathogenicity.</p>