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

Yan Wang,Chaochao Zhou,Huimin Jia,Zhongshan Gao,Guoyun Wang,Yun Jiao,Changqing Zhu,Yifan Zhu,Huijuan Jia,Lan Zhao,Pengju Ju,Qinsong Yang

doi:10.3389/fpls.2021.798086

Abstract

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 β-caryophyllene and α-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 β-caryophyllene and α-pinene synthesis, respectively, by qRT-PCR. Subcellular localization and enzyme activity assay showed that MrTPS3 was responsible for β-caryophyllene (sesquiterpenes) production and MrTPS20 for α-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 β-caryophyllene production. Our results lay the foundation to study volatile organic compounds (VOCs) in red bayberry and provide potential genes for molecular breeding.

Highlights

Red bayberry (Morella rubra, formerly Myrica rubra), an evergreen plant belonging to Myricaceae, Fagales, is one of the most economically important fruits in southern China, with a production of over one million tons each year
As β-caryophyllene is synthesized in cytoplasm and α-pinene is produced in chloroplasts, the results indicate that MrTPS3 is responsible for β-caryophyllene synthesis, while MrTPS20 produced α-pinene in red bayberry
The results showed that MrTPS3-BD could convert FPP to β-caryophyllene, while β-caryophyllene was not detected by MrTPS3-XY catalytic reaction (Figure 6B)

Summary

Introduction

Red bayberry (Morella rubra, formerly Myrica rubra), an evergreen plant belonging to Myricaceae, Fagales, is one of the most economically important fruits in southern China, with a production of over one million tons each year. It is distributed in Korea, Japan, Southeast Asia and Australia (Chen et al, 2003). Cheng et al (2016) identified the component of VOCs and their content in 11 cultivars of red bayberry fruit by headspace solid-phase extraction. They found that the main aroma components in red bayberry were β-pinene, α-pinene (monoterpenes), D-limonene and β-caryophyllene (sesquiterpenes), with different cultivars having different kinds of terpenoids (Cheng et al, 2016)

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Discussion

Conclusion