Varietal identification of tea (Camellia sinensis) using nanofluidic array of single nucleotide polymorphism (SNP) markers. (30th July 2014) - Fang, Wan-Ping
Abstract: Apart from water, tea is the world's most widely consumed beverage. Tea is produced in more than 50 countries with an annual production of approximately 4.7 million tons. The market segment for specialty tea has been expanding rapidly owing to increased demand, resulting in higher revenues and profits for tea growers and the industry. Accurate varietal identification is critically important to ensure traceability and authentication of premium tea products, which in turn contribute to on-farm conservation of tea genetic diversity. Using a set of single nucleotide polymorphism (SNP) markers developed from the expressed sequence tag (EST) database of Camilla senensis, we genotyped deoxyribonucleic acid (DNA) samples extracted from a diverse group of tea varieties, including both fresh and processed commercial loose-leaf teas. The validation led to the designation of 60 SNPs that unambiguously identified all 40 tested tea varieties with high statistical rigor ( p <0.0001). Varietal authenticity and genetic relationships among the analyzed cultivars were further characterized by ordination and Bayesian clustering analysis. These SNP markers, in combination with a high-throughput genotyping protocol, effectively established and verified specific DNA fingerprints for all tested tea varieties. This method provides a powerful tool for variety authentication and quality control for the tea industry. It is also highly useful for the management of tea genetic resources and breeding, where accurate and efficient genotype identification is essential. Molecular markers: Authenticating specialty teas: DNA fingerprinting now enables quality control, more effective breeding and conservation of the genetic diversity of specialty tea varieties. A team led by Dapeng Zhang of the United States Department of Agriculture analyzed both fresh and processed tea leaves to identify 60 discrete single-letter changes in the DNA sequences of expressed genes. This set of variants reliably discriminates between each of the 40 tea varieties that they tested. The demand for specialty tea, which comprises an ever-increasing segment of the $40 billion-a-year global tea market, has created an urgent need for highly reproducible methods to authenticate premium tea products. These cannot be distinguished from inferior varieties on the basis of morphological or biochemical features, especially after processing. Additional markers should refine the ability to reliably discriminate between premium teas not included in the study.