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Characterization and Electron Microscopy of a Potyvirus Infecting Commelina diffusa. F. J. Morales, Graduate Student, Department of Plant Pathology, University of Florida, Gainesville, FL 32611; F. W. Zettler, Professor, Department of Plant Pathology, University of Florida, Gainesville, FL 32611. Phytopathology 67:839-843. Accepted for publication 11 January 1977. Copyright 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-839.

A filamentous virus has been discovered that induces mosaic symptoms in Commelina diffusa distinguishable from those caused by cucumber mosaic virus (CMV). This virus, herein designated as commelina mosaic virus (CoMV), which appears to be a potyvirus, was readily transmitted mechanically to C. diffusa but not to 15 other species in nine plant families. Commelina mosaic virus was transmitted in a stylet-borne manner by Myzus persicae and Aphis gossypii. In leaf extracts stained with potassium phosphotungstate 84 of 100 particles measured 707-808 nm long (mode 734 nm). Thin sections of CoMV-infected tissue revealed the presence of laminated aggregate and pinwheel inclusions. The striated nature of these inclusions was revealed in leaf extracts stained with ammonium molybdate. The dilution end-point of CoMV was 101 to 102, its longevity in vitro was 12-20 hr, and the thermal inactivation point was 50-60 C. Leaf extracts from CoMV-infected plants did not react in immunodiffusion tests with antisera prepared to bidens mottle, blackeye cowpea mosaic, dasheen mosaic, lettuce mosaic, pepper mottle, potato Y, tobacco etch, or turnip mosaic viruses. This appears to be the first potyvirus reported infecting a member of the Commelinaceae. This study indicates that C. diffusa plants doubly infected with CoMV and CMV are better sources of CMV inoculum for aphids than are singly infected plants.

Additional keywords: Commelinaceae, potato virus Y group, cucumber mosaic virus, aphid transmissibility.