Mint Plant Response and Chemical Changes to Stimuli

Jenn Hoskins
25th April, 2024

Mint Plant Response and Chemical Changes to Stimuli

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Payame Noor University studied how peppermint genes react to a defense-inducing treatment
  • The treatment increased peppermint's defensive enzymes and altered its essential oil composition
  • Despite changes in gene activity, the desired menthol content in the oil did not significantly increase
Peppermint (Mentha piperita) is a plant with a rich history in both the culinary and medicinal worlds, cherished for its refreshing flavor and potential health benefits. Researchers at Payame Noor University have taken a closer look at peppermint, aiming to understand how certain genes involved in the production of its essential oils respond to specific treatments[1]. This research could pave the way for enhancing the medicinal properties of peppermint, particularly its applications in treating a range of ailments from liver and prostate cancers to migraines. The study focuses on three genes: Pulegone reductase (Pr), Menthofuran synthase (Mfs), and Limonene synthase (Ls). These genes are part of the menthol biosynthesis pathway, which is responsible for creating the compounds that give peppermint its characteristic scent and therapeutic properties. By employing a technique called quantitative Polymerase Chain Reaction (qPCR), the researchers measured how the activity of these genes changed when the plants were treated with methyl jasmonate (MeJA), a substance known to induce plant defense mechanisms. MeJA, when applied at a concentration of 0.5 mM, was found to trigger a defensive response in peppermint, evidenced by an increase in the activity of enzymes like superoxide dismutase (SOD) and peroxidase (POD). These enzymes are part of the plant's protective arsenal, helping to neutralize potentially harmful oxidative molecules. The study observed the highest levels of Pr and Mfs gene activity 8 and 12 hours after the MeJA treatment, respectively. However, 24 hours post-treatment, the gene activity decreased. Further analysis revealed that the essential oil composition of peppermint was altered by MeJA treatment, with notable increases in compounds such as α-pinene, β-pinene, linalool, and methyl acetate after 48 hours. These compounds are known for their antimicrobial properties, suggesting that MeJA not only boosts the plant's defensive enzymes but also enhances its ability to produce substances that can fight off microbes. Interestingly, the increase in Pr and Mfs gene expression did not significantly correlate with the menthol content in the oil. The Pr gene is essential for directing the pathway towards the production of menthol, a compound highly valued for its sensory and therapeutic qualities. On the other hand, the Mfs gene influences the formation of menthofuran, which is considered an undesirable component in peppermint oil due to its potential toxicity. This finding implies that while MeJA can modify the expression of these genes, it does not necessarily increase the desired menthol content. This research at Payame Noor University builds on previous studies that have explored how plant growth and essential oil production can be influenced by natural compounds[2][3]. For example, earlier work showed that methyl jasmonate could affect the growth and polyamine metabolism in tobacco[2], while calliterpenone was found to enhance biomass and essential oil biosynthesis in Mentha arvensis[3]. The current study extends this knowledge by demonstrating that MeJA can modulate gene expression related to menthol production in peppermint. Moreover, the study ties into the understanding of peppermint's biosynthesis of monoterpenes, which includes menthol[4][5]. Prior research has established that the biosynthesis rate is a key factor in monoterpene accumulation within the plant[5], and the latest findings suggest that MeJA may influence this rate through gene expression. In summary, the study by Payame Noor University provides new insights into how MeJA can be used to manipulate the production of essential oils in peppermint by altering gene expression. While the treatment does not necessarily increase the menthol content, it does enhance the plant's defensive capabilities and the production of other beneficial antimicrobial compounds. These discoveries offer promising avenues for the metabolic engineering of peppermint to optimize its medicinal properties and oil composition.

GeneticsBiochemPlant Science

References

Main Study

1) Changes in Physiological Traits, Gene Expression and Phytochemical Profile of Mentha piperita in Response to Elicitor.

Published 23rd April, 2024

https://doi.org/10.1007/s10528-024-10805-6

Related Studies

2) Methyl jasmonate upregulates biosynthetic gene expression, oxidation and conjugation of polyamines, and inhibits shoot formation in tobacco thin layers.

Journal: Journal of experimental botany, Issue: Vol 52, Issue 355, Feb 2001

3) Effect of gibberellic acid and calliterpenone on plant growth attributes, trichomes, essential oil biosynthesis and pathway gene expression in differential manner in Mentha arvensis L.

https://doi.org/10.1016/j.plaphy.2013.02.011

4) (-)-Menthol biosynthesis and molecular genetics.

Journal: Die Naturwissenschaften, Issue: Vol 92, Issue 12, Dec 2005

5) Regulation of monoterpene accumulation in leaves of peppermint.

Journal: Plant physiology, Issue: Vol 122, Issue 1, Jan 2000


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