New Insights into Stress-Induced β-Ocimene Biosynthesis in Tea (Camellia sinensis) Leaves during Oolong Tea Processing

As the major contributors to the floral odors of tea products, terpenoid volatiles play critical roles in the defense response of plants to multiple stresses. Until now, only a few TPS genes in tea plants (Camellia sinensis) have been functionally validated. In this study, by comparative studies conducted at gene, protein, and metabolite levels during oolong tea processing, we isolated an ocimene synthase gene, CsOCS, which displays a low similarity to previously characterized tea ocimene synthases. Further prokaryotic expression and subcellular localization analysis showed that it is plastid-located and could produce (E)-beta-ocimene and (Z)-beta-ocimene using GPP as the substrate. The optimum temperature and pH of the enzyme were 30 degrees C and 7.5, respectively. Treatment with exogenous methyl jasmonate elevated the transcript level of CsOCS and enhanced the emission of ocimene from tea leaves. Collectively, CsOCS is implicated as a key enzyme for beta-ocimene synthesis during oolong tea processing.

Automated summary

Terpenoid volatiles play critical roles in the floral odors of tea products. A new ocimene synthase gene, CsOCS, has been isolated from tea plants, which produces (E)-beta-ocimene and (Z)-beta-ocimene in plastids. Treatment with exogenous methyl jasmonate enhances the emission of ocimene from tea leaves, indicating CsOCS as a key enzyme for beta-ocimene synthesis during oolong tea processing.