INFECTIVITY OF IN VITRO TRANSCRIPTS FROM A FULL-LENGTH cDNA CLONE OF PELARGONIUM FLOWER BREAK VIRUS IN AN EXPERIMENTAL AND A NATURAL HOST

Abstract

To carry out reverse genetics experiments with Pelargonium flower break virus (PFBV), one of the most important viruses affecting Pelargonium spp., cDNA clones were constructed from which RNA transcripts can be synthesized in vitro. Two populations of overlapping RT-PCR products encompassing the complete PFBV RNA were ligated into pUC18 with the T7 RNA polymerase promoter fused to the 5’ extremity of the viral cDNA. The RNA transcripts derived from one of the resulting clones were infectious when mechanically inoculated to the experimental host Chenopodium quinoa and to the natural host P. zonale inducing local and systemic infections, respectively. The sequence of the infectious cDNA was almost 98% identical to that determined previously for a Spanish isolate of PFBV. This is the first description of a biologically active PFBV cDNA clone, an essential tool for detailed analyses of the viral genome.