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Scanning Electron Microscopy of Mycoplasmalike Organisms After Freeze Fracture of Plant Tissues Affected with Clover Phyllody and Aster Yellows. G. H. Haggis, Chemistry and Biology Research Institute, Research Branch, Agriculture Canada, Ottawa, Ontario, K1A 0C6, Canada; R. C. Sinha, Chemistry and Biology Research Institute, Research Branch, Agriculture Canada, Ottawa, Ontario, K1A 0C6, Canada. Phytopathology 68:677-680. Accepted for publication 12 September 1977. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-677.

Scanning electron microscopy (SEM) of freeze-fractured root and petiole tissues of aster yellows and clover phyllody-affected aster (Callistephus chinensis) plants revealed the presence of mycoplasmalike organisms (MLO). The identification of MLO was based on the presence of polymorphic bodies such as filamentous branching forms, ‘dumbells’, and budding spherical bodies in the phloem cells, presumbably the sieve elements; these were not observed in healthy plants. The sizes and polymorphic forms of the MLO found in aster yellows- and clover phyllody-affected plants were not significantly different. The advantages and disadvantages of freeze-fracture SEM are discussed.