Are You Getting What You Ordered from Your Genebank? Fingerprinting of the Clonal Potato and Sweetpotato Collections at the International Potato Center

Quality assessments using morphological descriptors of germplasm collections are usually not done except during regeneration for seed accessions or during field grow-out for clonal crops.  Genetic analyses are rarely available, even for clonal crops maintained as vegetatively propagated genetically stable unique genotypes.  The International Potato Center (CIP) maintains one of the largest in vitro clonal collections with over 11,000 accessions.  Accessions are also maintained as field plantings from original material providing an exceptional opportunity to assess if the tissue culture accessions are the same genotype after 30+ years.  The SolCAP SNP Array was used to fingerprints 4,350 accessions in the active potato collection while simple sequence repeats (SSRs), followed by DArTseq was used for the over 5,000 accessions in the active sweetpotato collection.  The original mother plants and original descriptor data was used for comparison to confirm in vitro material was true-to-type.  These studies found approximately 85% of the accessions in the in vitro collections were true-to-type and the original material generally matched primary descriptors from the original collections.  Although our working hypothesis is that mistakes were made early in the isolation of accessions in vitro, the work clearly highlights the need for such studies.  The generation of unique fingerprints has already yielded unanticipated results by highlighting errors in determining the ploidy levels of the potato germplasm (2X, 3X, 4X, and 5X).  Long-term, genetic fingerprints will be a critical component of the CIP quality management system to ensure genetic integrity of genebank accessions now and into the future.