Genetic diversity of oolong tea (Camellia sinensis) germplasms based on the nanofluidic array of single-nucleotide polymorphism (SNP) markers

As one of the most popular Chinese tea products, oolong tea involves the most complicated manufacturing process and the most abundant tea germplasm resources. However, the unclear genetic backgrounds of oolong tea germplasms have been biological limitations for tea breeding and quality control. In this study, high-throughput SNP technology was used to analyze the genetic diversity of 100 oolong tea landraces and cultivars. Ninety-six pairs of primers were selected and validated from the expressed sequence tag (EST) database of Camellia sinensis. The results verified 75 SNP loci that are able to accurately and efficiently determine the genetic relationships among Chinese oolong tea germplasms. The DNA fingerprints of 4 main oolong tea-producing areas were constructed by tracing the information of each site of the SNP. The Guangdong oolong tea germplasms were a relatively distinct group, while the genotypes of Taiwan oolong tea were similar to those of populations in Fujian. The tea germplasms in Southern and Northern Fujian had the largest intersections, and they also showed their own characteristics. Our results provide guidance for the identification, integration, and selection of parents for tea plant germplasms. Moreover, our study provides an effective tool to protect the diversity of tea germplasms and to assist in future breeding work.