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Isolation of the DNA of Various Plant Pathogenic Mycoplasmalike Organisms from Infected Plants. A. Kollar, Biologische Bundesanstalt, Institut fur Pflanzenschutz im Obstbau, D-6915 Dossenheim, Federal Republic of Germany; E. Seemüller(2), Françoise Bonnet(3), Colette Saillard(4), and J. M. Bové(5). (2)Biologische Bundesanstalt, Institut fur Pflanzenschutz im Obstbau, D-6915 Dossenheim, Federal Republic of Germany; (3)(4)(5)INRA, Laboratoire de Biologie Cellulaire et Moleculaire et Université de Bordeaux II, F-33140 Font de la Maye, France. Phytopathology 80:233-237. Accepted for publication 20 April 1989. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-233.

DNA from apple proliferation-diseased periwinkle plants and apple trees and from periwinkles infected with mycoplasmalike organisms (MLOs) causing a virescence (chloranty) of rape, a virescence of periwinkle, and a phyllody of Diplotaxis erucoides was extracted by using two different methods. Repeated bisbenzimide-CsCl buoyant density gradient centrifugations were used to separate MLO DNA from host plant DNA. MLO DNA was obtained as a well-resolved band showing a lower buoyant density than the host plant DNA due to its low G + C content. This band was highly enriched in MLO DNA and comprised 0.1–3.0% of the total DNA extracted from diseased plants. The DNA of the apple proliferation agent was cloned in Escherichia coli and the specificity of the cloned MLO DNA was confirmed by dot and Southern blot hybridization.