Impact of Vein-Banding on Vine Performance: Interaction Between Grapevine

Molecular characterization of the grapevine viroids associated with the yellow speckle (YS) and vein-banding (VB) disease syndrome as well as “mystery” disease tissues has identified specific grapevine yellow speckle viroid (GYSVd) variants associated with symptomatic tissues. Zinfandel-1 A from the UCD Foundation Vineyard and a yellow speckle Mission source from the Virus Collection at UCD were found to harbor homogeneous populations of’type 1′ (non-symptomatic) and ‘type2’ (symptomatic) GYSVd-1 variants. With the utilization of apple scar skin viroid (ASSVd) generic primers, capable of identifying members of the ASSVd group, RT-PCR amplification and nucleotide sequencing detected a previously unknown ‘type 3’ symptomatic GYSVd-1 variant in Italian sources. Heterogeneous mixtures of GYSVd-1 variants have been detected in vein-banding and ‘mystery’ diseased vines in Lodi and Napa Valley comprising of all of the above variants. All available viroid-free materials have been propagated for planting in an isolated site at UC Davis. Vines are available for grafting for the Viroid-free Performance Trial when a suitable location at Oakville field station is determined. Materials are being collected for the rootstock germplasm sensitivity study.