Department of Plant Pathology, University of Georgia, Coastal Plain Experiment Station, Tifton 31793
University of Georgia Cooperative Extension Service, Colquitt County
Department of Plant Pathology, University of Florida, Gainesville 32611
University of Georgia Cooperative Extension Service, Grady County
University of Georgia Cooperative Extension Service, Brooks County
University of Georgia Cooperative Extension Service, Pierce County
Department of Horticulture, University of Georgia, Coastal Plain Experiment Station, Tifton 31793
Cabbage and collard greens were inflicted with a previously undescribed virus-like disease during the fall 2000. Symptoms on leaves were yellow spots, vein clearing, mosaic, curling, and puckering. Symptomatic plants were widespread in Brooks, Colquitt, Grady, and Pierce counties in Georgia. Disease incidence ranged from 10 to 20% in the majority of the fields surveyed but some fields had 100% incidence. Fields were heavily infested by Bemisia argentifolii and the symptoms were suggestive of a whitefly-transmitted geminivirus infection. A polymerase chain reaction (PCR)-based diagnostic test for geminivirus was conducted. Total DNA was extracted from symptomatic cabbage and collard green plants collected from commercial fields. The two primers, 5'-GCCCACATYGTCTTYCCNGT-3' and 5'- GGCTTYCTRTACATRGG-3' (2,3), are “universal” for genus Begomovirus of family Geminiviridae. The primer pair could amplify a part of the replicase-associated protein and coat protein and the complete common region of DNA-A. The PCR gave a DNA band of expected size (1.1 kb) from both symptomatic cabbage and collard green samples, whereas no such product was obtained from healthy samples, suggesting that the causal agent could be a geminivirus. To establish the identity of the virus, the 1.1 kb PCR product was cloned into pGEM-T Easy (Promega) and sequenced. GenBank search showed that the geminivirus isolated in Georgia was most closely related (98% sequence identity) to Cabbage leaf curl virus (accession number U65529) reported from Florida (1). The virus was mechanically transmitted to healthy cabbage and collard green plants under experimental conditions. To our knowledge, this is the first report of Cabbage leaf curl virus from Georgia.
References: (1) A. M. Abouzid et al. Phytopathology 82:1070, 1992. (2) S. S. Pappu et al. Plant Dis. 84:370, 2000. (3) M. R. Rojas et al. Plant Dis. 77:340--347, 1993.