The identity and parentage of the variety known in California as Petite Sirah

DNA marker analysis was used to determine the varietal identity of Petite S irah in public collections and commercial vineyards in California. Twenty-o ne vines analyzed from public collections at the University of California a t Davis included accessions labeled Petite Sirah, Durif, Syrah and Serine. Fifty-three vines from 26 private Petite Sirah vineyards in four California counties were also analyzed. Several accessions each of Durif, Peloursin, and Syrah obtained from Montpellier, France and an accession of Pinot noir from the University of California at Davis were used as controls for variet al identification. Samples were analyzed with four to eight simple sequence repeat (SSR) DNA markers. Some samples were first analyzed with four DNA p robes to detect restriction fragment length polymorphisms (RFLPs). Davis ac cessions labeled Petite Sirah were found to include vines that we determine d to be Durif, Peloursin, Syrah, and Pinot noir. Accessions labeled Durif' included vines identical to Durif and Peloursin. The Syrah accessions were identical to the Syrah controls. The Serine accession was found to be Pinot noir. Forty-nine of the 53 Petite Sirah vines from private vineyards were identical to Durif. Four vines, from three vineyards in two counties, were Peloursin. Comparison of the SSR genotypes of Durif and Peloursin indicates that Durif is probably a seedling of Peloursin as reported and cannot be a selection of Peloursin (as also reported). The other parent of Durif is mo st probably Syrah. SSR genotypes of Durif, Peloursin, and Syrah at 25 loci are consistent with this relationship and likelihood analysis of SSR allele frequencies supports the relationship with a very high degree of probabili ty.