Genetics of Frankia

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Actinorhizal Plants Frankia Induced Nodulation Root Nodules Caused by Frankia Actinorhizal Symbiosis Cross Inoculation Experiments Isolation and Characteristics of Frankia Cultural Characteristics of Frankia Taxonomy of Frankia Entry of Frankia to the Host Plant Structure of Actinorhizal Nodule

Genetics of Frankia

Genetics of Frankia
The genome size of Frankia is twice that of E. coli and like Streptomyces measures 10,000 kilo bases. The G + C per cent of Frankia strains so far quantified lie between 68 and 72 which is rather high. In some strains of Frankia sp., plasmids ranging from 8kb to 190kb have been detected. It has been shown that in Frankia sp., isolated from Alnus glutinosa, at least some of the nif genes are located on a large indigenous plasmid of 190kb.

Comparisons with nif H sequences of other nitrogen-fixing microorganisms such as Anabaena, K. Preumoniae and Azotobacter suggest that Frankia nif genes are similar to these microorganisms.

Of late, DNA probes have been used to study the competitiveness for nodule formation of Frankia strains in Alnus glutinosa and A. incana. Applying the analytical data of 165 r RNA sequence from several Frankia strains, two major Frankia divisions have been distinguished-those infective on Elaeagnus and those infective either on Alnus or Casuarina. One particular strain from Purshia tridenta was however grouped outside these two divisions. This information has also helped in confirming the identity of several atypical non-infective isolates of Frankia and also in grouping of strains infective on Casuarina equisetifolia.

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Nitrogen Fixation and Assimilation Field Experiments on the Benefit of Frankia Inoculation Mycorrhizae and Actinorhizal Plants Proteoid Roots Genetics of Frankia Rhizobium Induced Root Nodulation of Parasponia Leaf Nodules Gymnosperm Nodules

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