Rapid varietal authentication of oolong tea products by microfluidic-based SNP genotyping.

Oolong tea is one of the most popular Chinese teas, and its quality is significantly affected by the variety of tea plant. The growing demands lead to the adulteration of premium oolong tea products, e.g., Tieguanyin oolong tea. In this study, microfluidic technology and single-nucleotide polymorphism (SNP) biomarkers were used to authenticate the varieties of oolong tea products. Forty-eight pairs of primers were screened, and they can be used to authenticate Tieguanyin oolong tea via high-throughput microfluidic SNP chips. Through the combination of the NJ tree and PCoA plot methods, the study found that the most frequent adulterant of Tieguanyin oolong tea on the market is Benshan. For the first time, the commercial behavior of using Fuyun6 and Jinguanyin as adulterants or contamination in the production of Tieguanyin oolong tea was reported. This research has proposed rapid authentication technology for oolong tea to provide food quality supervision and promote consumer trust.

Light control of catechin accumulation is mediated by photosynthetic capacity in tea plant (Camellia sinensis).

BACKGROUND: Catechins are crucial in determining the flavour and health benefits of tea, but it remains unclear that how the light intensity regulates catechins biosynthesis. Therefore, we cultivated tea plants in a phytotron to elucidate the response mechanism of catechins biosynthesis to light intensity changes. RESULTS: In the 250 µmol·m- 2·s- 1 treatment, the contents of epigallocatechin, epigallocatechin gallate and total catechins were increased by 98.94, 14.5 and 13.0% respectively, compared with those in the 550 µmol·m- 2·s- 1 treatment. Meanwhile, the photosynthetic capacity was enhanced in the 250 µmol·m- 2·s- 1 treatment, including the electron transport rate, net photosynthetic rate, transpiration rate and expression of related genes (such as CspsbA, CspsbB, CspsbC, CspsbD, CsPsbR and CsGLK1). In contrast, the extremely low or high light intensity decreased the catechins accumulation and photosynthetic capacity of the tea plants. The comprehensive analysis revealed that the response of catechins biosynthesis to the light intensity was mediated by the photosynthetic capacity of the tea plants. Appropriately high light upregulated the expression of genes related to photosynthetic capacity to improve the net photosynthetic rate (Pn), transpiration rate (Tr), and electron transfer rate (ETR), which enhanced the contents of substrates for non-esterified catechins biosynthesis (such as EGC). Meanwhile, these photosynthetic capacity-related genes and gallic acid (GA) biosynthesis-related genes (CsaroB, CsaroDE1, CsaroDE2 and CsaroDE3) co-regulated the response of GA accumulation to light intensity. Eventually, the epigallocatechin gallate content was enhanced by the increased contents of its precursors (EGC and GA) and the upregulation of the CsSCPL gene. CONCLUSIONS: In this study, the catechin content and photosynthetic capacity of tea plants increased under appropriately high light intensities (250 µmol·m- 2·s- 1 and 350 µmol·m- 2·s- 1) but decreased under extremely low or high light intensities (150 µmol·m- 2·s- 1 or 550 µmol·m- 2·s- 1). We found that the control of catechin accumulation by light intensity in tea plants is mediated by the plant photosynthetic capacity. The research provided useful information for improving catechins content and its light-intensity regulation mechanism in tea plant.