Abstract
Total nucleic acids were isolated from leaves collected from symptomatic tomato, and indigenous weeds Merremia quinquefolia and M. aegyptia in Puerto Rico from 1992-1995. All plants exhibited yellow mosaic symptoms characteristic viruses in the genus Begomovirus. These Merremia species have long been recognized as hosts of the Merremia mosaic virus (MeMV), but the associated virus(es) have not been characterized molecularly. The genomic components were amplified by PCR cloned, and sequences were determined. Preliminary comparisons indicated the core CP for all isolates examined shared 98-100% nt identity. Comparison of genomic components for M. quinquefolia and tomato isolates shared 99.2% nt identity, suggesting that MeMV has only recently become adapted to tomato. The nucleotide sequence for the MeMV DNA-A (2557 nt) shared 91% nt identity with its closest relative, Tomato mosaic leaf curl virus (TMLCuV) from Venezuela. In contrast, the MeMV DNA-B (2492 nt) shared only 72% nt sequence identity with TMLCuV, suggesting that MeMV possibly is a reassortant. The experimental host range for MeMV includes Datura stramonium, Lycopersicon esculentum, Malva parviflora, and Nicotiana tabacum, in addition to indigenous hosts M. quinquefolia and M. aegyptia.