Molecular reagents have been developed for virus-specific and simultaneous
(virus-non-specific) detection of Grapevine fleck virus (GFkV) and allied v
iruses, ie. Grapevine asteroid mosaic-associated virus (GAMaV) and Grapevin
e red globe virus (GRGV). Degenerate primers designed on nucleotide sequenc
es of the RNA-dependent RNA polymerase (RD) and methyltransferase (MTR) dom
ains of the GFkV genome, were able to give amplification products of the ex
pected size from total nucleic acid extracts of: (i) vines infected with GF
kV, GAMaV, and GRGV; (ii) a Californian grapevine accession infected by a m
arafi-like virus; (iii) Greek grapevine accessions infected by an unidentif
ied agent that induced symptoms reminiscent of those elicited by GAMaV in V
itis rupestris, Degenerate primers designed on the nucleotide sequence of t
he helicase (HEL) domain of the GFLV genome recognized all the above viruse
s except for GAMaV and the unidentified Greek viral agent. RD primer set wo
rked well also with crude grapevine cortical scrapings, thus constituting a
useful universal reagent for the non-specific molecular identification of
GFkV-like viruses in Vitis, The marafi-like virus from California was ampli
fied by all sets of primers, but was recognized only by the GRGV-specific p
robe, suggesting that it is a likely isolate of GRGV: Likewise, the unident
ified virus from Greek vines shared sequence homology with GFkV and allied
viruses (GAMaV and GRGV) but exhibited differences relevant enough that cal
l for further investigations to establish its taxonomic position. While GRG
V was identified, though with a very low incidence, in some 11 southern Ita
lian grapevine cultivars, no evidence was obtained for infection by GAMaV i
n any of 50 cultivars analyzed.