An Update on the Function, Biosynthesis and Regulation of Floral Volatile Terpenoids

Abstract

Floral volatile terpenoids (FVTs) belong to a group of volatile organic compounds (VOC) that play important roles in attracting pollinators, defending against pathogens and parasites and serving as signals associated with biotic and abiotic stress responses. Although research on FVTs has been increasing, a systematic generalization is lacking. Among flowering plants used mainly for ornamental purposes, a systematic study on the production of FVTs in flowers with characteristic aromas is still limited. This paper reviews the biological functions and biosynthesis of FVTs, which may contribute a foundational aspect for future research. We highlight regulatory mechanisms that control the production of FVTs in ornamental flowers and the intersection of biosynthetic pathways that produce flower fragrance and color. Additionally, we summarize the opportunities and challenges facing FVT research in the whole genome and -omics eras and the possible research directions that will provide a foundation for further innovation and utilization of flowering ornamental plants and their germplasm resources.

Integrated volatile metabolomic and transcriptomic analysis provides insights into the regulation of floral scents between two contrasting varieties of Lonicera japonica

“…Monoterpenes and diterpenes represent important classes of aromatic compounds responsible for floral scents ( Qiao et al, 2021 ). Increased accumulations of geraniol (sweet rose odor) and alpha-terpineol (lilac floral terpenic odor), i.e., monoterpenes, and geranylgeraniol, i.e., a diterpene, in ‘Yujin2’, may contribute to the stronger aroma ( Figure 8 ).…”

“…Monoterpenes and diterpenes are generated by the plastid-localized MEP pathway. Beginning with pyruvate and glyceraldehyde-3-phosphate, DXS, DXR, and 2-C-methyl-D-erythritol 4-phosphate cytidylyltransferase (ispD) catalyze the first three reactions of the MEP pathway ( Qiao et al, 2021 ). In this study, we found three DXS genes that were upregulated, while a DXS gene, a DXR, and an ispD were downregulated in ‘Yujin2’ ( Figure 8 ; Supplementary Table 12 ).…”

“…Orchestrated production of VOCs from these independent pathways requires coordinated transcriptional regulation of the floral scent biosynthetic network. To date, a number of TF families have been reported to regulate the production of VOCs in various plants, including MYB, bHLH, WRKY, ERF/ AP2, bZIP, and NAC-type TFs (Qiao et al, 2021;Mostafa et al, 2022). For instance, ODORANT1 (DOD1), a member of the R 2 R 3 -type MYB family, regulates the synthesis of precursors in the shikimate pathway and the entry points to the phenylpropanoid and benzenoid biosynthetic pathways (Verdonk et al, 2005;Yoshida et al, 2018).…”

Volatile organic compounds as mediators of plant communication and adaptation to climate change

“…Farnesyl pyrophosphate synthase (FPPS) condenses two IPP molecules and one DMAPP molecule in the MVA pathway to generate FPP. Lastly, cytosolic FPPS catalyzes the formation of FPP into sesquiterpenes (Pichersky et al, 2006; Qiao et al, 2021; Ramya et al, 2020). Monoterpenes are generated from GPP, sesquiterpenes, and triterpenes from FPP, diterpenes from GGPP, and hemiterpenes from DMAPP (Tholl, 2015; Tholl & Lee, 2011).…”

Insights into the Cytochrome P450 Monooxygenase Superfamily in Osmanthus fragrans and the Role of OfCYP142 in Linalool Synthesis

“…Various volatile terpenoids are formed directly by catalysis using terpenoid synthases (TPSs). Previous studies provided evidence that cytochrome P450 enzymes involved in monoterpenoid metabolism are usually co-expressed with TPSs [ 14 , 15 ]. Gene co-expression analysis was used to predict which P450 genes were involved in monoterpenoid metabolism [ 16 ].…”