Abstract
Tomato plants showing leaf curling and yellow mosaic symptoms, together with reduced yield, were observed for the first time in Puerto Rico (PR) in 1991. Nucleic acids isolated from tomato samples collected from 1991-2001 were used as template for PCR amplification of the Potato yellow mosaic virus-Puerto Rico (PYMV-PR) genome. The DNA-A and DNA-B for PYMV-PR were cloned and sequenced. The DNA-A and DNA-B components were determined to be 2595 and 2545 nt, respectively. The PYMV-PR genome shared >98% nt identity with the isolate PYMV-GP, also from PR. The DNA-A component for both PR isolates were 90% identical to PYMV-VE, and thus are isolates of the prototype isolate, PYMV-VE. Molecular recombination analysis of the DNA-A component indicated that PYMV-PR resulted from an interspecies recombination event between PYMV-VE and PYMTV-TT. The major fragment (1597 nt) that comprises the AV1, AC2, AC3 ORFs and the AC1 3' end shared 97% nt identity with PYMTV-TT, while a smaller fragment (998 nt) containing the common region and the remainder of the AC1 ORF is 90.5% identical to PYMV-VE. Although PYMV-PR shares an identical REP binding motif with PYMV-VE, its DNA-B is 93.8% identical to yet another species, PYMTV-TT, suggesting that the DNA-B component has possibly resulted from multiple recombination and reassortment events.