Differential metabolites and their transcriptional regulation in seven major tea cultivars (Camellia sinensis) in China

Various genetic and biochemical characteristics exist in tea plant cultivars, which largely determine production suitability and tea quality. Here, we performed transcriptomic and metabolomic analyses of young shoots of seven tea cultivars and identified major regulatory transcription factors (TFs) for the characteristic metabolites in different cultivars based on WGCNA. Phenotypically, we found that TGY and FJSX suitable for oolong tea had higher catechin contents. The metabolites of JX were more prominent, especially the contents of phenolic acids, flavonoids, terpenes, and tannins, which were higher than those of the other six cultivars. Moreover, FDDB suitable for white tea was rich in amino acids, linolenic acid, and saccharides. At the molecular level, it was found that HCT (CsTGY12G0001876, CsTGY06G0003042) led to the accumulation of chlorogenic acid in TGY. The main reason for the higher l-ascorbic acid content in FJSX was the high expression of GalLDH (CsTGY13G0000389) and MIOX (CsTGY14G0001769, CsTGY14G0001770), which were regulated by WRKY (CsTGY11G0001197). Furthermore, FDDB, LJ43, SCZ, and BHZ had higher free fatty acid contents, among which MYB (CsTGY14G0002344) may be a hub gene for the regulation of palmitoleic acid accumulation. More importantly, we found that the shoots of TGY were green with purple, mainly due to the accumulation of anthocyanins and the downregulation of the MPEC (CsTGY10G0001989) gene that affected chlorophyll synthesis. These results will provide a theoretical reference for tea cultivar breeding and suitability.