Floral scent: Regulation and role of MYB transcription factors

Osmanthus fragrans is widely grown for the purpose of urban greening and the pleasant aroma emitted from its flowers. The floral scent is determined by several monoterpenoid volatiles, such as linalool and its oxides, which are a few of the most common volatiles and the main components of the essential oils in most sweet osmanthus cultivars. In addition, the relative contents of cis- and trans-linalool oxide (furan) may affect the aromas and quality of the essential oils. MYB proteins represent the largest family of transcription factors in plants and participate in regulating secondary metabolites. Several cis-elements, especially AC-rich regions, are known to be bound by 2R-MYBs and could be found in the promoter of the enzyme genes in the terpenoid metabolic pathway. However, there has to date been no investigation into the 2R-MYB family genes involved in regulating terpenoid biosynthesis in O. fragrans. Here, 243 non-redundant 2R-MYB proteins were grouped into 33 clusters based on the phylogeny and exon-intron distribution. These genes were unevenly distributed on 23 chromosomes. Ka/Ks analysis showed that the major mode of 2R-MYB gene evolution was purifying selection. Expression analysis indicated that 2R-MYB genes in O. fragrans exhibited varied expression patterns. A total of 35 OfMYBs representing the highest per kilobase per million mapped reads in the flower were selected for quantitative real-time PCR analysis. The correlation analysis between the expression level and the contents of fragrant compounds at different flowering stages suggested that OfMYB19/20 exhibited remarkably positive correlation with the accumulation of cis-linalool oxides. OfMYB51/65/88/121/137/144 showed significantly negative correlations with one or more linalool oxides. Characterization of these proteins revealed that OfMYB19 and OfMYB137 were localized in the nuclei, but did not show transcriptional activation in the yeast system, which suggested that they may be bound to other transcription factors to exert regulatory functions. These findings provide useful information for further functional investigation of the 2R-MYBs and offer a foundation for clarifying the 2R-MYB transcription factors involved in the molecular mechanism of the regulation of monoterpenoid biosynthesis in Osmanthus fragrans.

Download Full-text

Genome-Wide Analysis Reveals the Potential Role of MYB Transcription Factors in Floral Scent Formation in Hedychium coronarium

Frontiers in Plant Science ◽

10.3389/fpls.2021.623742 ◽

2021 ◽

Vol 12 ◽

Author(s):

Farhat Abbas ◽

Yanguo Ke ◽

Yiwei Zhou ◽

Yunyi Yu ◽

Muhammad Waseem ◽

...

Keyword(s):

Transcription Factors ◽

Gene Family ◽

Floral Scent ◽

Expression Patterns ◽

Acid Methyl Ester ◽

Regulatory Elements ◽

Composition Analysis ◽

Myb Gene ◽

Hedychium Coronarium

The MYB gene family is one of the largest groups of transcription factors (TFs) playing diverse roles in several biological processes. Hedychium coronarium (white ginger lily) is a renowned ornamental plant both in tropical and subtropical regions due to its flower shape and strong floral scent mainly composed of terpenes and benzenoids. However, there is no information available regarding the role of the MYB gene family in H. coronarium. In the current study, the MYB gene family was identified and extensively analyzed. The identified 253 HcMYB genes were unevenly mapped on 17 chromosomes at a different density. Promoter sequence analysis showed numerous phytohormones related to cis-regulatory elements. The majority of HcMYB genes contain two to three introns and motif composition analysis showed their functional conservation. Phylogenetic analysis revealed that HcMYBs could be classified into 15 distinct clades, and the segmental duplication events played an essential role in the expansion of the HcMYB gene family. Tissue-specific expression patterns of HcMYB genes displayed spatial and temporal expression. Furthermore, seven HcMYB (HcMYB7/8/75/79/145/238/248) were selected for further investigation. Through RT-qPCR, the response of candidates HcMYB genes toward jasmonic acid methyl ester (MeJA), abscisic acid (ABA), ethylene, and auxin was examined. Yeast one-hybrid (Y1H) assays revealed that candidate genes directly bind to the promoter of bottom structural volatile synthesis genes (HcTPS1, HcTPS3, HcTPS10, and HcBSMT2). Moreover, yeast two-hybrid (Y2H) assay showed that HcMYB7/8/75/145/248 interact with HcJAZ1 protein. In HcMYB7/8/79/145/248-silenced flowers, the floral volatile contents were decreased and downregulated the expression of key structural genes, suggesting that these genes might play crucial roles in floral scent formation in H. coronarium by regulating the expression of floral scent biosynthesis genes. Collectively, these findings indicate that HcMYB genes might be involved in the regulatory mechanism of terpenoids and benzenoid biosynthesis in H. coronarium.

Download Full-text

Role of Arabidopsis MYB transcription factors in osmotic stress

Plant Tolerance to Abiotic Stresses in Agriculture: Role of Genetic Engineering ◽

10.1007/978-94-011-4323-3_13 ◽

2000 ◽

pp. 181-194 ◽

Cited By ~ 2

Author(s):

Eleonora Cominelli ◽

Giuliana Gusmaroli ◽

Lucio Conti ◽

Domenico Allegra ◽

Katia Petroni ◽

...

Keyword(s):

Transcription Factors ◽

Osmotic Stress ◽

Myb Transcription Factors

Download Full-text

Expression pattern analysis of three R2R3-MYB transcription factors for the production of anthocyanin in different vegetative stages of Arabidopsis leaves

Applied Biological Chemistry ◽

10.1186/s13765-020-00584-0 ◽

2021 ◽

Vol 64 (1) ◽

Author(s):

Yeonjong Koo ◽

R. Scott Poethig

Keyword(s):

Transcription Factors ◽

Developmental Stages ◽

Myb Transcription Factors ◽

Expression Pattern Analysis ◽

Myb Genes ◽

R2r3 Myb ◽

Post Transcriptional Regulation ◽

Anthocyanin Production ◽

R2r3 Myb Transcription Factors

AbstractAnthocyanin is a type of flavonoid that appears purple in plants. PAP1, PAP2, and MYB113 are the three major R2R3-MYB transcription factors that regulate flavonoid biosynthesis in Arabidopsis thaliana. In this study, we found that the three MYB genes regulate anthocyanin accumulation in different leaf stages. Under limited nutrient conditions, PAP1 and PAP2 genes were highly induced in juvenile leaves. Conversely, MYB113 was expressed mainly in adult leaves. In addition, we investigated the role of trans-acting siRNA4 (TAS4) in the post-transcriptional regulation of anthocyanin expression in Arabidopsis leaves. In plant growth, the inhibition of PAP1 and PAP2 gene expression by TAS4 was observed only in juvenile leaves, and MYB113 inhibition was observed in adult leaves. In conclusion, we found that transcription and transcript repression of the three MYB genes is differentially regulated by TAS4 in leaf developmental stages. Our results improve the understanding of the regulation of plant anthocyanin production under stress conditions.

Download Full-text

Auxin-Responsive R2R3-MYB Transcription Factors HcMYB1 and HcMYB2 Activate Volatile Biosynthesis in Hedychium coronarium Flowers

Frontiers in Plant Science ◽

10.3389/fpls.2021.710826 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yanguo Ke ◽

Farhat Abbas ◽

Yiwei Zhou ◽

Rangcai Yu ◽

Yanping Fan

Keyword(s):

Transcription Factors ◽

Floral Scent ◽

Terpene Synthase ◽

Auxin Signaling ◽

Myb Transcription Factors ◽

Protein Protein Interaction ◽

Hedychium Coronarium ◽

Aroma Production ◽

R2r3 Myb ◽

R2r3 Myb Transcription Factors

Auxin, an important plant hormone, induces the biosynthesis of various secondary metabolites by modulating the expression of auxin-responsive genes. In the ornamental plant Hedychium coronarium, linalool and methyl benzoate are biosynthesized by the terpene synthase (TPS) HcTPS5 and the benzoic/salicylic acid methyltransferase (BSMT) HcBSMT2, respectively. However, the transcriptional regulation of this process remains unclear. Here, we identified and functionally characterized the R2R3-MYB transcription factors HcMYB1 and HcMYB2 in regulating the biosynthesis of these floral aroma compounds. HcMYB1 and HcMYB2 are specifically expressed in flowers, their expression is correlated with the emission of volatile compounds in flowers, and is induced by auxin. Moreover, HcMYB1 and HcMYB2 interact with the HcBSMT2 promoter region. HcMYB2 activates the expression of the linalool synthase gene HcTPS5. In flowers with HcMYB1 or HcMYB2 silenced, the levels of floral scent compounds were significantly reduced, and HcBSMT2 and HcTPS5 were downregulated compared with the wild type. Moreover, HcMYB1 form protein-protein interaction with key scent-related HcIAA4 protein to regulate floral aroma production. Taken together, these results indicate that HcMYB1 and HcMYB2 play crucial roles in regulating the formation of scent compounds in Hedychium coronarium (H. coronarium) flowers in response to auxin signaling.

Download Full-text