Identification and distribution of a single nucleotide polymorphism responsible for the catechin content in tea plants

Catechins are the predominant products in tea plants and have essential functions for both plants and humans.Several genes encoding the enzymes regulating catechin biosynthesis have been identified,and the identification of single nucleotide polymorphisms(SNPs)resulting in nonsynonymous mutations within these genes can be used to establish a functional link to catechin content.Therefore,the transcriptomes of two parents and four filial offspring were sequenced using next-generation sequencing technology and aligned to the reference genome to enable SNP mining.Subsequently,176 tea plant accessions were genotyped based on candidate SNPs using kompetitive allelespecific polymerase chain reaction(KASP).The catechin contents of these samples were characterized by highperformance liquid chromatography(HPLC),and analysis of variance(ANOVA)was subsequently performed to determine the relationship between genotypes and catechin content.As a result of these efforts,a SNP within the chalcone synthase(CHS)gene was shown to be functionally associated with catechin content.Furthermore,the geographical and interspecific distribution of this SNP was investigated.Collectively,these results will contribute to the early evaluation of tea plants and serve as a rapid tool for accelerating targeted efforts in tea breeding.

Effects of Soil Characters on the Tea Quality in the Tea Region of Qin-Ba Mountain,Hubei Province,PR China

Based on the analysis of physical and chemical properties of soil,nutrient elements and biochemical compositions of tea leaves,the relationship between soil characters and tea quality was studied.The results showed that soil total phosphorus,potassium,available potassium,copper and zinc were the main factors which affected and limited the content of nutrient elements of tea leaves.Furthermore,soil pH,organic matter,total nitrogen,potassium,exchangeable calcium,magnesium,available copper and zinc were the main factors affecting and limiting the content of biochemical compositions in tea leaves.Tea quality could be improved by controlling these soil factors.

The Tea Tree Genome Provides Insights into Tea Flavor and Independent Evolution of Caffeine Biosynthesis

Tea is the world＇s oldest and most popular caffeine-containing beverage with immense economic, medicinal, and cultural importance. Here, we present the first high-quality nucleotide sequence of the repeat-rich （80.9%）, 3.02-Gb genome of the cultivated tea tree Camellia sinensis. We show that an extraordinarily large genome size of tea tree is resulted from the slow, steady, and long-term amplification of a few LTR retrotransposon families. In addition to a recent whole-genome duplication event, lineage-specific expansions of genes associated with flavonoid metabolic biosynthesis were discovered, which enhance catechin production, terpene enzyme activation, and stress tolerance, important features for tea flavor and adaptation. We demonstrate an independent and rapid evolution of the tea caffeine synthesis pathway relative to cacao and coffee. A comparative study among 25 Camellia species revealed that higher expression levels of most flavonoid- and caffeinebut not theanine-related genes contribute to the increased production of catechins and caffeine and thus enhance tea-processing suitability and tea quality. These novel findings pave the way for further metabolomic and functional genomic refinement of characteristic biosynthesis pathways and will help develop a more diversified set of tea flavors that would eventually satisfy and attract more tea drinkers worldwide.

METABOLIC AND TRANSCRIPTOME ANALYSIS REVEALS METABOLITE VARIATION AND FLAVONOID REGULATORY NETWORKS IN FRESH SHOOTS OF TEA(CAMELLIA SINENSIS)OVER THREE SEASONS

Metabolites,especially secondary metabolites,are very important in the adaption of tea plants and the quality of tea products.Here,we focus on the seasonal variation in metabolites of fresh tea shoots and their regulatory mechanism at the transcriptional level.The metabolic profiles of fresh tea shoots of 10 tea accessions collected in spring,summer,and autumn were analyzed using ultra-performance liquid chromatography coupled with quadrupole-obitrap mass spectrometry.We focused on the metabolites and key genes in the phenylpropanoid/flavonoid pathway integrated with transcriptome analysis.Multivariate statistical analysis indicates that metabolites were distinctly different with seasonal alternation.Flavonoids,amino acids,organic acids and alkaloids were the predominant metabolites.Levels of most key genes and downstream compounds in the flavonoid pathway were lowest in spring but the catechin quality index was highest in spring.The regulatory pathway was explored by constructing a metabolite correlation network and a weighted gene co-expression network.