Identification of frankia strains by direct DNA hybridization of crushed nodules.
A hybridization procedure was developed to identify Frankia strains inside actinorhizae by direct probing of crushed root nodules. The probe consisted of an indigenous cryptic plasmid. This well-conserved, 8-kilobase plasmid was detected in Frankia isolates that were very close taxonomically (they possessed a very high DNA sequence homology). The probe did not hybridize to the DNA of Frankia isolates which did not carry the plasmid. Endophyte DNA was extracted by a modification of a technique originally developed for the detection of plasmids in Frankia isolates. The hybridization procedure applied to nodules collected in a stand of alder permitted determination of a distribution map of the plasmid-bearing Frankia strains.
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Laboratoire de Biologie des Sols, U.A. Centre National de la Recherche Scientifique 697, Bâtiment 741, Université Lyon 1, Villeurbanne F-69622 Cedex, and Station d' Amélioration des Arbres Forestiers, Institut National de la Recherche Agronomique, Orléans, Ardon F-45160 Olivet, France.
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Du Cros
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Bardin
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