Integrating Transcriptomic and GC-MS Metabolomic Analysis to Characterize Color and Aroma Formation during Tepal Development in Lycoris longituba

Abstract

Lycoris longituba, belonging to the Amaryllidaceae family, is a perennial bulb bearing flowers with diverse colors and fragrance. Selection of cultivars with excellent colored and scented flowers has always been the breeding aim for ornamental plants. However, the molecular mechanisms underlying color fading and aroma production during flower expansion in L. longituba remain unclear. Therefore, to systematically investigate these important biological phenomena, the tepals of L. longituba from different developmental stages were used to screen and analyze the metabolic components and relevant genes. Utilizing the Illumina platform, a total of 144,922 unigenes were obtained from the RNA-Seq libraries. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that the phenylpropanoid biosynthesis and flavonoid biosynthesis pathways might play important roles during color and aroma changes. Metabolomic analysis identified 29 volatile organic components (VOCs) from different developmental stages of L. longituba tepals, and orthogonal partial least-squares discriminate analysis (OPLS-DA) revealed that trans-β-ocimene—a terpene—was the most important aroma compound. Meanwhile, we found the content of anthocyanin was significantly reduced during the tepal color fading process. Then, we identified two dihydroflavonol-4-reductase (DFR) and three terpene synthase (TPS) genes, for which expression changes coincided with the production patterns of anthocyanins and trans-β-ocimene, respectively. Furthermore, a number of MYB and bHLH transcription factors (TFs) which might be involved in color- and aroma-formation were also identified in L. longituba tepal transcriptomes. Taken together, this is the first comprehensive report of the color and fragrance in tepals of L. longituba and these results could be helpful in understanding these characteristics and their regulation networks.

Analysis of flavonoids and anthocyanin biosynthesis-related genes expression reveals the mechanism of petal color fading of Malus hupehensis (Rosaceae)

“…It is proven by many authors that transcription factors are regulating anthocyanin biosynthesis pathway, such as R2R3-MYB, basic helix-loop-helix (bHLH) and WD40repeat (WD40) (Zhao et al 2013;Liu et al 2015). These transcription factors activate or suppress the transcription and expression of target genes by binding to specific DNA sequences and affecting protein-protein interactions, thereby regulating anthocyanin biosynthesis (Yue et al 2019). Many studies have shown that the MYB transcription factors primarily regulate flavonoid pathway genes, while bHLH and WD40 transcription factors play roles in the anthocyanin biosynthesis pathway by binding to MYB transcription factors (Zhao et al 2013;Liu et al 2015).…”

“…(Zhang et al 2017), Lycoris longituba Lycoris radiata Herb. (Yue et al 2019) and Silene littorea Silene littorea Brot. (Casimiro-Soriguer et al 2016).…”

How the Color Fades From Malus halliana Flowers: Transcriptome Sequencing and DNA Methylation Analysis

“…Flower color is a major characteristic of ornamental value, but the petal color of M. halliana clearly changes from red to pale pink during flower development ( Figure 1A), which affects its ornamental value. This fading of flower color is widespread in Malus plants and other ornamental plants (Jiang et al, 2014;Yue et al, 2019). The phenotype change of flower color of M. halliana presents distinct visible phases, so M. halliana is considered as an excellent model plant for research on flower color.…”

Transcriptome Analysis of Different Tissues Reveals Key Genes Associated With Galanthamine Biosynthesis in Lycoris longituba

“…Among them, 85,622 unigenes were successfully annotated. Recently, a transcriptome report of this specie was published by using 12 tepals samples at different stages as materials, and a large number of unigenes were also obtained (Yue et al, 2019). Although our study only use nine samples, we focused on diverse tissues including leaves, roots, and bulbs at vegetative growth stages.…”