IDENTIFICATION OF SOME LOCAL FRANKIA STRAINS BASED ON PHYSIOLOGICAL AND MOLECULAR VARIATION

Abstract

In this investigation, set of five Frankia strains were isolated from root nodules of Casuarina
trees from five different regions in Egypt and were identified based on their physiological and
molecular genetic variations. Results showed that growth parameters of C. glauca inoculated with
the five Frankia strains grown in loamy sandy soil were both significantly higher than those of
plants grown in clay soil. The effect of the Frankia strains under study on number of nodules,
percentages of seedling that formed root nodules (nodulation frequency) and activity of acetylene
reduction in clay soil as well as loamy sandy soil was addressed. The numerical analysis of the
investigated parameters was found to be a useful tool for differentiation between the Frankia strains.
We have analyzed 9 randomly amplified polymorphic DNA (RAPD) primers against five Frankia
strains. Results showed that the number of amplified fragments differed between the strains. Some
primers were useful in identifying unique DNA polymorphisms of all strains tested. Some fragments
were found to be polymorphic (not common). These unique fragments could be recommended as
markers for distinguishing between the applied strains of Frankia. Statistical analysis of RAPD-PCR
polymorphisms showed similarities between Frankia strains ranged from 67.3 to 85%. The
phylogenetic tree confirmed the genetic diversity between the Frankia strains under investigation.
Genomic fingerprinting assay using RAPD-PCR was excellent methodology for differentiating
between the Frankia strains. The correlation between the phylogenetic and the phylophenetic trees
of the five Frankia strains were also discussed.