Metabolite and Transcriptome Profiling Analysis Revealed That Melatonin Positively Regulates Floral Scent Production in Hedychium coronarium

Abstract

Melatonin is a pleiotropic molecule that regulates a variety of developmental processes. Floral volatiles are important features of flowers that facilitate flower–visitor interactions by attracting pollinators, structure flower–visitor communities, and play defensive roles against plant and flower antagonists. Aside from their role in plants, floral volatiles are an essential ingredient in cosmetics, perfumes, pharmaceuticals, and flavorings. Herein, integrated metabolomic and transcriptomic approaches were carried out to analyze the changes triggered by melatonin exposure during the Hedychium coronarium flower development stages. Quantitative analysis of the volatiles of H. coronarium flowers revealed that volatile organic compound emission was significantly enhanced after melatonin exposure during the half bloom (HS), full bloom (FB) and fade stage (FS). Under the melatonin treatment, the emission of volatile contents was highest during the full bloom stage of the flower. Variable importance in projection (VIP) analysis and partial least-squares discriminant analysis (PLS-DA) identified 15 volatile compounds with VIP > 1 that were prominently altered by the melatonin treatments. According to the transcriptome sequencing data of the HS, FB, and FS of the flowers, 1,372, 1,510, and 1,488 differentially expressed genes were identified between CK-HS and 100MT-HS, CK-FB and 100MT-FB, and CK-FS and 100MT-FS, respectively. Among the significant differentially expressed genes (DEGs), 76 were significantly upregulated and directly involved in the floral scent biosynthesis process. In addition, certain volatile organic compounds were substantially linked with various DEGs after combining the metabolome and transcriptome datasets. Moreover, some transcription factors, such as MYB and bHLH, were also significantly upregulated in the comparison, which might be related to the floral aroma mechanism. Our results suggested that melatonin increased floral aroma production in H. coronarium flowers by modifying the expression level of genes involved in the floral scent biosynthesis pathway. These findings serve as a foundation for future research into the molecular mechanisms underlying the dynamic changes in volatile contents induced by melatonin treatment in H. coronarium.

Metabolome and transcriptome analysis of terpene synthase genes and their putative role in floral aroma production in Litchi chinensis

“…Similar results were reported in the floral volatile profile of numerous species, including H . coronarium (Abbas, Zhou, et al, 2021; Zhou et al, 2021). To effectively screen various metabolites between different groups, a combination approach of OPLS‐DA and VIP analysis was applied (Figure 2).…”

“…Similarly, gene‐to‐metabolite study in H . coronarium revealed that MYB/bHLH were the key transcription factors interconnected with multiple nodes of important volatile components (Abbas, Zhou, et al, 2021). Likewise, similar findings were observed in Osmanthus fragrans (Zhou et al, 2017), Freesia x hybrida (Gao et al, 2018), Camellia oleifera (Yang et al, 2022), and Chrysanthemum dichrum (Liu et al, 2021).…”

“…“Siberia” (Abbas et al, 2019; Abbas, Ke, Zhou, Ashraf, et al, 2020; Abbas, Ke, Zhou, Waseem, et al, 2020; Abbas, Nian, et al, 2021), H . coronarium (Abbas et al, 2021b; Abbas, Zhou, et al, 2021; Ke et al, 2021; Zhou et al, 2021), Paeonia suffruticosa (Zhang et al, 2021), Citrus grandis (Zhang et al, 2017), Cananga odorata var. fruticose (Jin et al, 2015), Cymbidium faberi (Wang et al, 2021), and Freesia x hybrida (Gao et al, 2018).…”

“…The headspace floral substances were collected and GCMS analysis was performed as described earlier (Abbas, Zhou, et al, 2021; Ke et al, 2019). Briefly, flowers and fruit samples from each development stage were placed in a glass bottle supplemented with ethyl caprate (1.728 μg) as an internal standard.…”

Exogenous Methyl Jasmonate Application Improved Physio-Biochemical Attributes, Yield, Quality, and Cadmium Tolerance in Fragrant Rice

“…Similarly, Ashraf et al (2017) and Ashraf and Tang (2017) reported the deterioration in rice grain quality attributes under heavy metal toxicity. It has been demonstrated that exogenous hormone application improves plant fitness via maximizing the transcriptional level of related biosynthesis pathway genes in plants ( Abbas et al, 2021a , b ). Mineral elements contents were increased in treatments with applied MeJa, while under Cd stressed treatments, mineral elements contents reduced greatly.…”