Project description:Camellia sinensis var. sinensis, Camellia sinensis var. assamica, Camellia taliensis, Camellia taliensis var. bangwei, Camellia crassicolumna and Camellia tachangensis Targeted Locus (Loci)
Project description:Tea plants (Camellia sinensis) present an excellent system to study evolution and diversification of specialized metabolites due to their abundance in classes, numbers and contents. A large number of tea cultivars have been cultivated throughout the world not only because of their adaption to different environments but of selection for specific flavors. The chemical and genetic basis for unique taste and aroma of different tea cultivars remains largely unknown, but is critical for guiding genetic breeding of new cultivars. Using transcriptomic data from 136 representative tea accessions in China, we obtain 925,854 high-quality single-nucleotide polymorphisms (SNPs) useful for marker-assisted breeding. Phylogenetic and population structure analyses separate sampled tea accessions into five major groups. Different major alleles are identified on 1183 SNP sites for the two major types of tea, C. sinensis var. assamica (CSA) and C. sinensis var. sinensis (CSS), reflecting fixation of these alleles after population divergence. Non-targeted metabolomic analyses detect 2,818 and 2,311 metabolic features in tea samples in positive and negative ionization modes, respectively, including 355 and 286 metabolites respectively that are differentially accumulated in different tea groups. Each phylogenetic group contains signature metabolites. In particular, CSA tea accessions are featured with high accumulation of diverse classes of flavonoid compounds, such as flavanols, flavonol mono-/di-glycosides and proanthocyanidin dimers. Comparisons of gene expression profiles of different tea groups identify hundreds of differentially expressed genes with some involved in the biosynthesis of characteristic tea metabolites, reflecting a combinational effect of genetic and environmental factors. Taken together, our study provides new insights into the phylogenetic relationships, molecular markers, metabolite compositions, and gene expression profiles of representative cultivated tea accessions in China, which are beneficial for targeted tea breeding and improvement.
