Detection of Grapevine leafroll-associated virus 7 using real time qRT-PCR and conventional RT-PCR.

Nine isolates of Grapevine leafroll-associated virus 7 (GLRaV-7) from diverse geographical regions were sequenced to design more sensitive molecular diagnostic tools. The coat protein (CP) and heat shock protein 70 homologue (HSP70h) genes of these nine isolates were sequenced. Sequences were then used to design more sensitive molecular diagnostic tools. Sequence identity among these isolates ranged between 90 to 100% at the nucleotide and amino acid levels. One RT-PCR and two qRT-PCR assays were used to survey 86 different grapevines from the University of California, Davis Grapevine Virus Collection, the Foundation Plant Services collection and the USDA National Clonal Germplasm Repository, Davis, CA with primers designed in conserved regions of the CP and HSP70h genes. Results revealed that qRT-PCR assays designed in the HSP70h gene was more sensitive (29.07% positives) than that designed in the CP gene (22.09% positives) and both qRT-PCR assays proved to be more sensitive than RT-PCR.