Variations in oolong tea key characteristic floral aroma compound contents among tea (Camellia sinensis) germplasms exposed to postharvest stress

Tea (Camellia sinensis) germplasm affects the tea aroma quality, especially in oolong tea. However, the mechanism underlying the diversity in aroma formation induced by postharvest stresses among different tea cultivars remains unclear. In this study, correlation analyses between sensory evaluation scores and aroma compound contents of oolong teas made from 12 different cultivars was carried out. The results confirmed the contribution of three characteristic aroma compounds [i.e., indole, jasmine lactone, and (E)-nerolidol] to the oolong tea floral aroma quality. However, only the indole was positively correlated with the jasmonic acid (JA) in the simulated withering (wounding stress due to plucking) and turnover (continuous wounding stress) stages. Furthermore, the expression levels of transcription factor CsMYC2c and structural genes for the three aroma compounds were positively correlated in the simulated withering stage. Transient transcriptional activation analyses in tobacco revealed that CsMYC2c regulated the promoter activity and expression of structural genes. However, yeast one-hybrid assay showed that CsMYC2c did not directly bind to the gene promoters. The information has expanded our understanding of the causes for the variations in aromas among diverse tea cultivars in response to postharvest stress. Furthermore, it may provide the basis for breeding and selection of high-aroma tea cultivars.