IMPROVED MICROSATELLITE MARKERS FOR QUINCE (CYDONIA OBLONGA) GENETIC ANALYSIS

The USDA National Clonal Germplasm Repository (NCGR) maintains a diverse living collection of 149 European quince (Cydonia oblonga) individuals with origins from 16 countries. The collection is represented by one tree per accession on a 0.5-ha orchard in Corvallis, Oregon, USA. We previously used nine apple-derived simple sequence repeat (SSR) primer pairs to determine genetic relationships in 92 European quince clones, but were unable to differentiate several groups of accessions. In this study, we replaced four of the less informative SSRs with four SSRs reported to amplify at least four alleles. This new fingerprinting set improved the power of differentiation, was amplified in two multiplex PCR reactions and was used to identify 106 European and four Chinese (Pseudocydonia sinensis) quince accessions. Some previously suspected synonyms were confirmed including several clones identical to the Quince A rootstock, cultivars that grouped with ‘Portugal’, and a ‘Meech’s Prolific’/‘Bourgault’ group. Unlike the previous SSR set, this improved panel distinguished a ‘Tevloskaya’ seedling from the ‘Quince A’ group. ‘Gamboa’ is the Portuguese cultivar known as ‘Portugal’ elsewhere, and their SSR fingerprints were identical. ‘Champion’, ‘Smyrna’ and ‘Van Deman’ at NCGR had the same fingerprint as ‘Portugal’ and are likely mislabeled. ‘Lisle’ from a nursery source had the same fingerprint as ‘Pineapple’. Assorted seedlings and clones from Bulgaria formed a clade, and other seedlings from the same seed lot grouped close to each other and to their parent cultivar. Several quince cultivars have phenotypes consistent with putative polyploidy such as very large fruit and very large and thick leaves. However, flow cytometry showed all NCGR quince accessions to be diploid. The SSR fingerprints revealed large genetic diversity in the USDA Cydonia genebank and will be very useful management tools for eliminating mislabeled and redundant accessions.