The 2012 ASHS Annual Conference

Microsatellite DNA marker analysis was used to characterize 62 Vitis californica and 31 V. girdiana candidate selections that are currently maintained by the Department of Viticulture and Enology at the University of California, Davis, and 83 vines of “wild” V. californica (selected based on phenotype) from diverse geographic areas in Northern California that were not located near current commercial vineyards.  Final analysis was based on nine markers from nine different linkage groups that were polymorphic in the study set.  From 50 V. californica vines collected in Sonoma County, CA, 10 were F₁ hybrids with either ‘Cabernet Sauvignon’, ‘Merlot’, or ‘Zinfandel;’ and several others were the same clone as other wild vines, even if the vines were separated by 20–40 m.  The final reference population of 83 wild V. californica vines was selected from diverse geographic areas in northern California.  Thirty-eight of these vines were chosen because they were growing > 400 m apart to eliminate clonal duplication and were collected from areas removed from commercial grape cultivation.  The other 47 candidate selections were also included in the reference population for V. californica allele frequencies, since they were collected as V. californica based on phenotype in diverse areas of the state.  The reference population for V. girdiana consisted of 25 candidate selections.  Allele frequencies for V. vinifera were based on the available profiles of 45 diverse cultivars.  Based on likelihood analysis, the populations of V. californica and V. girdiana contained hybrids with V. vinifera as well as pure forms of both wild species.  Selections from the wild, non-hybrid populations will be added to the grape collection of the National Clonal Germplasm Repository in Davis, CA.