Enhancement of plant variety protection and regulation using molecular marker technology

Plant variety protection is one of the important approaches for plant intellectual property protection. The distinctness, uniformity and stability (DUS) and essentially derived variety (EDV) are two major concepts in plant variety protection. DUS-EDV has been evaluated largely through morphological traits and pedigrees at the very beginning, to an integrated approach using morphological traits, pedigrees and molecular marker information and now to a stage largely driven by molecular diagnostics. Molecular diagnostic technology has been evolved from RFLP to SSR and SNP marker systems. The liquid SNP chip, represented by genotyping by target sequencing through capture in solution, has advantages of low cost, high flexibility in marker combinations and wide suitability for DUS-EDV evaluation across plant species. There are two important strategies in DUS-EDV evaluation, one being examined based on the analysis and comparison at the whole genome level and the other being examined at specific genomic regions for target functional loci associated with important phenotypes. Evaluation criteria should be established separately for DUS and EDV. The former can be evaluated based on the criteria constructed for specific fingerprint maps, haplotypes, unique alleles, genomic regions, target functional markers, minimum genetic homozygosity, and within-variety variation, whereas the latter can be examined by the genetic similarity between the potential EDV and check variety estimated using a large number of molecular markers evenly distributed across the genome, rather than by the number of markers. The number and the genomic coverage of molecular markers are two key factors affecting the efficiency and reliability in DUS and EDV assessment. Using only a small number of markers in such assessment will likely result in a large sampling error for the estimates. The threshold of genetic similarity required for distinguishing EDV and non-EDV can vary greatly across plant species and with the levels of plant variety protection. After reviewed the current status of plant variety protection across countries, the authors proposed that a national consultant expert committee should be established for consistent support to implement and improve DUS-EDV system, and an official database system should be constructed for public service and comparison of variety DNA fingerprint data to facilitate innovative activities in plant breeding.