GENETIC VARIABILITY OF GRAPEVINE FANLEAF VIRUS ISOLATES WITHIN GENES 1B(HEL) AND 1E(POL)

The genetic variability of six isolates of Grapevine fanleaf virus (GFLV) from South Moravia (Czech Republic) and Italy was investigated by RT-PCR and sequencing within part of the RNA-1-encoded genes 1B(Hel) (379 nts) and 1E(Pol) (365 nts). Sequence analyses showed 96-100% and 91.4-100% identity at the amino acid level for genes 1B(Hel) and 1E(Pol), respectively, among Czech, Italian and other isolates for which sequence information is available. As expected, some of the conserved motifs of the helicase and polymerase proteins were found in the deduced amino acid sequences, although isolates PN33 from Czech Republic, and isolates 55TK and UR11 from Italy had a Ile to Val subtitution in the helicase motif B. Phylogenetic analyses confirmed the close relationship among GFLV isolates and the relatedness of GFLV isolate WAPN173 with Arabis mosaic virus (ArMV) in protein 1B(Hel). Two distinct phylogenetic clusters were identified for protein 1E(Pol), with isolates from California and the French reference strain F13 grouping together, and isolates from the Czech Republic, Italy, New Zealand, and USA grouping in a different lineage. This study provides new insights into the genetic variability of GFLV RNA-1-encoded genes 1B(Hel) and 1E(Pol).