Isozyme Variation among 40 Frankia Strains.

Forty Frankia strains belonging to the Alnus and Elaeagnus host specificity groups and isolated from various plant species from different geographical areas were characterized by the electrophoretic separation of isozymes of eight enzymes. All the enzyme systems that were investigated showed large variation. Diaphorases and esterases gave multiple band patterns and confirmed the identification of specific Frankia strains. Less variability was observed with enzymes such as phosphoglucose isomerase, leucine aminopeptidase, and malate dehydrogenase, which allowed for the delineation of larger groups of Frankia strains. Cluster analysis, based on the pair-wise similarity coefficients calculated between strains, delineated three large, dissimilar groups of Frankia strains, although each of these groups contained a large amount of heterogeneity. However, numerous Frankia strains, mainly from the Alnus host specificity group, demonstrated a perfect homology for all the enzymes tested.