TaqMan-MGB SNP genotyping assay to identify 48 citrus cultivars distributed in the Japanese market

Abstract

A citrus cultivar identification system using CAPS marker has been developed on nursery trees, but this needs to be extended to include various product types, such as imported fruits and processed products. Here, we developed a new cultivar identification system using TaqMan-MGB SNP genotyping assay. Eight probe and primer sets were designed to amplify PCR fragments <100 bp to enable the genotyping of fresh and processed fruits in which predicted that insufficient quantities of DNA and residual impurities in the DNA extracts. The TaqMan-MGB SNP genotyping assay was stable and reproducible, and were confirmed to apply various sample sources, including leaves, fresh fruit, juice, canned fruit, and dry fruit. They could provide at least a single differentiating SNP to discriminate any paired combination among 48 citrus cultivars. Minimal marker subsets to identify the target cultivar were listed for each of 18 registered cultivars with valid patent. The allelic SNP genotypes of 48 citrus cultivars, which cover more than 98% of all citrus fruit shipment produced in Japan, is valuable for the referencing information in the DNA-based identification for fresh and processed fruits. This identification system will help protect registered cultivars and facilitate food fraud inspections.