MrTPS3 and MrTPS20 Are Responsible for β-Caryophyllene and a-Pinene Production, Respectively, in Red Bayberry (Morella rubra)

Red bayberry is a sweet, tart fruit native to China and grown widely in the south. The key organic compounds forming the distinctive aroma in red bayberry, are terpenoids, mainly beta-caryophyllene and alpha-pinene. However, the key genes responsible for different terpenoids are still unknown. Here, transcriptome analysis on samples from four cultivars, during fruit development, with different terpenoid production, provided candidate genes for volatile organic compound (VOC) production. Terpene synthases (TPS) are key enzymes regulating terpenoid biosynthesis, and 34 TPS family members were identified in the red bayberry genome. MrTPS3 in chromosome 2 and MrTPS20 in chromosome 7 were identified as key genes regulating beta-caryophyllene and alpha-pinene synthesis, respectively, by qRT-PCR. Subcellular localization and enzyme activity assay showed that MrTPS3 was responsible for beta-caryophyllene (sesquiterpenes) production and MrTPS20 for alpha-pinene (monoterpenes). Notably, one amino acid substitution between dark color cultivars and light color cultivars resulted in the loss of function of MrTPS3, causing the different beta-caryophyllene production. Our results lay the foundation to study volatile organic compounds (VOCs) in red bayberry and provide potential genes for molecular breeding.

Automated summary

This study identified candidate genes regulating the production of volatile organic compounds (VOCs) in red bayberry through transcriptome analysis. The gene MrTPS3 was found to regulate the synthesis of β-caryophyllene, while MrTPS20 was found to regulate the synthesis of α-pinene. A single amino acid substitution between different cultivars resulted in the loss of function of MrTPS3 and led to differences in β-caryophyllene production.