Detection and characterization of an elm yellows (16SrV) group phytoplasmainfecting virginia creeper plants in southern Florida

The polymerase chain reaction (PCR) employing phytoplasma-specific ribosoma l RNA primer pair P1/P7 consistently amplified a product of expected size ( 1.8 kb) from 29 of 36 symptomless Virginia creeper (Parthenocissus quinquef olia) plants growing in southern Florida. Restriction fragment length polym orphism analysis of P1/P7-primed PCR products indicated that most phytoplas mas detected in Virginia creeper were similar to phytoplasmas composing the elm yellows (16SrV) group. This relationship was verified by reamplificati on of P1/P7 products using an elm yellows (EY) group-specific rRNA primer p air fB1/rULWS1. rDNA products (1,571 bp) were generated by group-specific P CR from 28 phytoplasma-positive plants and I negatively testing plant ident ified by earlier P1/P7-primed PCR. Analysis of 165 rDNA sequences determine d the Virginia creeper (VC) phytoplasma to be phylogenetically closest to t he European alder yellows (ALY) agent, an established 16SrV-C subgroup stra in. However, presence or absence of restriction sites for endonucleases Alu I, BfaI, MspI, RsaI, and TaqI in the 16S rRNA and 16-23S rRNA intergenic sp acer region of the VC phytoplasma collectively differentiated this strain f rom ALY and other 16SrV group phytoplasmas. Failure to detect the VC phytop lasma by PCR employing nonribosomal primer pair FD9f/FD9r suggests that thi s newly characterized agent varies from known European grapevine yellows (f lavescence doree) phytoplasmas previously classified as 16SrV subgroup C or D strains.