In 1994, a sweet potato sample showing leaf curl symptoms was collected from the field in Louisiana. When graft-inoculated, Ipomoea nil cv. Scarlett O'Hara reacted with severe leaf distortion and chlorosis symptoms. I. aquatica reacted with a bright yellow mottle. The virus isolated was designated the United States isolate of sweet potato leaf curl virus (SPLCV-US). It was transmitted to I. nil by the sweet potato whitefly, Bemisia tabaci biotype B. DNA probes prepared with component A of pepper Huasteco geminivirus, with an isolate of bean golden mosaic geminivirus from Guatemala, with an isolate of tomato mottle geminivirus from Florida, and with an isolate of tomato yellow leaf curl geminivirus from the Dominican Republic (TYLCV-DR) hybridized with a 2.6-kb DNA band present in DNA extracts from plants infected with SPLCV-US. Probes prepared with the B component of these geminiviruses did not hybridize with these DNA extracts. We were unable to amplify SPLCV-US DNA products by polymerase chain reaction (PCR) in quantities that could be visualized by ethidium bromide staining. However, Southern blots from amplifications with primers AV494/AC1048 revealed PCR products of approximately 600 bp and 550 bp when hybridized with the TYLCV-DR probe. These results were consistently obtained from infected I. cordatotriloba and less consistently from I. aquatica or I. setosa. Fibrillar inclusions were occasionally seen, and granular aggregates of viruslike particles were observed in the nucleus of infected I. cordatotriloba. These results suggest that the virus isolated from sweet potato with leaf curl symptoms belongs to the geminivirus group.

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A viral disease causing severe leaf malformation and yellow mottle on Tabasco (Capsicum frutescens) and Habanero (C. chinense) pepper plants was observed in 1997 on farms in southwestern Costa Rica. Whiteflies (Bemisia tabaci) were present on affected farms and transmitted the putative virus. Total DNA was extracted from a whitefly-transmitted isolate, and polymerase chain reaction (PCR) was performed using degenerate primers. The expected PCR product (550 bp) was obtained, suggesting the presence of a geminivirus. This was confirmed by Southern analysis using a geminivirus-specific probe. The virus was mechanically transmitted from pepper to pepper. Electron microscopy of ultrathin sections from infected Tabasco pepper plants revealed fibrillar rings and viruslike particles in the nucleus of the vascular parenchyma cells. The sequence of DNA A was obtained from three overlapping PCR fragments amplified using three pairs of degenerate primers; PAL1v1978/PAR1c496, PCRc1/AV494, and PCRv181/ AC1048. The complete sequence of DNA A of this begomovirus consisted of 2,619 bp (GenBank accession number: AF149227) containing four open reading frames (ORF). The nucleotide sequence of the virus was 92.3% identical to DNA A of the Tamaulipas strain of Texas pepper virus (TPV-TAM). Phylogenetic analyses using AC1 and AV1 nucleotide sequences also indicated a close relationship between this virus and TPV. Based on the biological characteristics, the high percentage of nucleotide and derived amino acid sequence identities, and phyloge-netic analyses, we concluded that this virus is a distinct strain of TPV, and designated it as the Costa Rica strain. This is the first report of TPV in Costa Rica.

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