Characteristic volatile components and transcriptional regulation of seven major tea cultivars (Camellia sinensis) in China

The volatiles in the young shoots of tea cultivars are the important material basis for the formation of tea aroma, but the cultivar-specific aroma and its molecular regulation are still lacking in research. In this study, the characteristic volatiles of seven tea cultivars in China were detected, and the results showed that the green tea cultivars 'Fuding Dabaicha' (FDDB), 'Longjing43' (LJ43), 'Shuchazao' (SCZ), and 'Baihaozao' (BHZ) were rich in ( E )-3-hexenol, phenylethyl alcohol, phenylacetaldehyde, and β -ionone. For oolong tea cultivars, the characteristic volatiles of 'Tieguanyin' (TGY) were heptanal and eugenol, while the contents of ( E )- β -ocimene, geraniol, and methyl salicylate were significantly increased in 'Jinxuan' (JX). In addition, 'Fujian Shuixian' (FJSX) has the highest content of esters, mainly jasmonolactone and dihydrojasmonolactone. Transcriptomic analysis showed that the different tea cultivars were significantly enriched in different levels of gene transcription in the three pathways related to aroma biosynthesis. Potential regulatory modules and genes of several characteristic volatiles were identified by WGCNA, among which CsbHLH (CsTGY12G0001520) may regulate the expression of CsTPS (CsTGY05G0001285) to directly affect the accumulation of β -caryophyllene in young shoots, while CsMYB (CsTGY01G0001203, CsTGY04G0001918, CsTGY06G0002545) may affect the synthesis of ( Z )-3-hexenol and ( E )-3-hexen-1-ol acetate by regulating the CsADH (CsTGY09G0001879). In addition, the transcription factors bHLH, WRKY, ERF, and MYB may be involved in the biosynthesis of linalool by regulating the expression of CsLIS/NES (CsTGY08G0001704, CsTGY08G0000359) genes individually or through interaction. These results revealed the characteristic volatiles and their key regulatory genes of seven tea cultivars, which will provide a theoretical basis for breeding and suitability research of tea cultivars.