How MhMYB1 and MhMYB2 Genes Affect Menthol Production in Mint Plants

Jenn Hoskins
20th May, 2024

How MhMYB1 and MhMYB2 Genes Affect Menthol Production in Mint Plants

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Jiangsu University identified two transcription factor genes, MhMYB1 and MhMYB2, in Mentha haplocalyx
  • MhMYB1 and MhMYB2 regulate key enzymes in the monoterpenoid biosynthesis pathway, affecting essential oil composition
  • Knocking down MhMYB1 and MhMYB2 reduced (-)-menthol and (-)-menthone levels, confirming their role in essential oil production
Mentha haplocalyx Briq., commonly known for its medicinal and edible uses, is particularly valued for its essential oils, which have distinct aromatic flavors and functional activities. The biosynthetic pathways for the primary monoterpenes in mint are well-documented, but the regulatory mechanisms for different chemotypes, especially the l-menthol chemotype, remain underexplored. Recent research from Jiangsu University provides new insights into these regulatory mechanisms by identifying and characterizing two transcription factor genes, MhMYB1 and MhMYB2, from the MYB family[1]. Transcription factors (TFs) are proteins that help turn specific genes on or off by binding to nearby DNA. In this study, the researchers focused on understanding how MhMYB1 and MhMYB2 influence the biosynthesis of monoterpenoids, which are the primary components of mint essential oils. Bioinformatics analysis revealed that MhMYB1 contains two conserved MYB domains, while MhMYB2 has a conserved SANT domain. These domains are critical for the transcription factors' ability to bind DNA and regulate gene expression. The researchers employed yeast one-hybrid (Y1H) analysis to demonstrate that both MhMYB1 and MhMYB2 interact with the promoter regions of MhMD and MhPR. These genes encode key enzymes in the monoterpenoid biosynthesis pathway, specifically (-)-menthol dehydrogenase (MD) and (+)-pulegone reductase (PR). The interaction between these transcription factors and the promoter regions suggests that MhMYB1 and MhMYB2 play significant roles in regulating these enzymes' expression levels. To further validate their findings, the researchers used virus-induced gene silencing (VIGS) to knock down the expression of MhMYB1 and MhMYB2 in M. haplocalyx. They observed a significant reduction in the expression levels of MhMD and MhPR genes in the VIGS-treated plants, accompanied by a notable decrease in the contents of (-)-menthol and (-)-menthone in the essential oil. These results strongly indicate that MhMYB1 and MhMYB2 positively regulate (-)-menthol biosynthesis, thereby influencing the essential oil composition in the l-menthol chemotype of M. haplocalyx. This study builds on previous research that identified transcription factors as crucial regulators of various plant processes. For instance, the R2R3-MYB sub-family has been implicated in phenylpropanoid and lignin pathways, which are involved in cork biosynthesis in Quercus suber L.[2]. Similarly, other studies have shown that MYB transcription factors are highly correlated with key enzymes in different chemotypes of Mentha plants, affecting the biosynthesis of monoterpenoids[3]. The current study adds to this body of knowledge by elucidating the specific roles of MhMYB1 and MhMYB2 in the l-menthol chemotype of M. haplocalyx. Moreover, the findings align with broader research on transcription factors' roles in regulating complex biological processes. For example, the regulation of leaf senescence in various crops involves multiple transcription factor families, including MYB[4]. Additionally, the regulation of patchoulol biosynthesis in Pogostemon cablin involves the interaction of MYB-related transcription factors with other proteins, demonstrating the intricate regulatory networks that govern essential oil production[5]. In summary, this study from Jiangsu University provides crucial insights into the regulatory mechanisms of monoterpenoid biosynthesis in the l-menthol chemotype of Mentha haplocalyx. By identifying and characterizing the roles of MhMYB1 and MhMYB2 transcription factors, the research lays a foundational understanding that could pave the way for more targeted breeding and metabolic engineering strategies to optimize essential oil composition in mint plants.

GeneticsBiochemPlant Science

References

Main Study

1) Effects of MhMYB1 and MhMYB2 transcription factors on the monoterpenoid biosynthesis pathway in l-menthol chemotype of Mentha haplocalyx Briq.

Published 20th May, 2024

Journal: Planta

Issue: Vol 260, Issue 1, May 2024

Related Studies

2) Molecular characterization of Quercus suber MYB1, a transcription factor up-regulated in cork tissues.

https://doi.org/10.1016/j.jplph.2012.08.023

3) Transcriptome analysis of transcription factors and enzymes involved in monoterpenoid biosynthesis in different chemotypes of Mentha haplocalyx Briq.

https://doi.org/10.7717/peerj.14914

4) Transcription Factors-Regulated Leaf Senescence: Current Knowledge, Challenges and Approaches.

https://doi.org/10.3390/ijms24119245

5) PatDREB Transcription Factor Activates Patchoulol Synthase Gene Promoter and Positively Regulates Jasmonate-Induced Patchoulol Biosynthesis.

https://doi.org/10.1021/acs.jafc.2c01660


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