An amino acid ester of menthol elicits defense responses in plants

Abstract

Terpenoids, including menthol, exhibit potent abilities as plant defense potentiators in agriculture and horticulture. In the current study, we developed new terpene derivatives that consisted of menthol and various amino acids and that were expected to act as powerful plant defense potentiators. We used 6 amino acids possessing low-reactive sidechains to synthesize an array of amino acid ester of menthol (ment-aa) compounds. Transcript levels of two defense genes (pathogenesis-related 1 [PR1] and trypsin inhibitor [TI]) were evaluated in leaves of soybean plants 24 h after application of aquatic solution of menthol or menthol-aa, and revealed that the menthol menthyl ester of valine (ment-Val) alone elevated the transcript level of defense genes, and it did so only at the low dose of 1 µM, not at higher or lower doses tested. Moreover, it appeared that histone acetylation was involved in this effect. Application of ment-Val enabled soybean plants to sustain the increased transcript levels in their leaves for up to 3 days. Moreover, when ment-Val was additionally applied at day 4, at which time the transcript level had declined to the basal level, the transcript level was re-elevated, indicating the possibility that ment-Val could be repeatedly used to sustain pest control. Ment-Val was found to be chemically stable and effective for defense of several crop species. Collectively, these data show that terpenoid conjugates are useful for pest control instead of or in addition to pesticides.

Novel Potential of Rose Essential Oil as a Powerful Plant Defense Potentiator

“…Otherwise, the data shown with a p value are marginally different from those of Ct. reported for valine menthyl ester, a previously developed plant defense potentiator for crops, such as soybean, which was effective only at 1 μM. 14 It is possible that higher doses of REO may be harmful to plants and, thus, ineffective as a plant defense potentiator. For example, it has been shown that elevated levels of menthone from peppermint EO can disrupt microtubules and rapidly permeabilize the plasma membrane, leading to plant mortality.…”

“…10−13 In addition, our studies on the properties of peppermint VOCs, especially menthol, have led to the development of valine menthyl ester, a remarkably effective plant defense potentiator for soybean plants. 14 However, there is still a lack of sufficient examples that adequately address this important issue. Therefore, our research focused on investigating the efficacy of 11 different EOs in stimulating defense responses in tomato plants.…”

“…In the fields of agriculture and horticulture, there is an urgent need for extensive research and implementation of plant defense potentiators. A promising candidate in this regard is prohydrojasmon (PDJ), which has shown the ability to enhance insect resistance. − In addition, our studies on the properties of peppermint VOCs, especially menthol, have led to the development of valine menthyl ester, a remarkably effective plant defense potentiator for soybean plants . However, there is still a lack of sufficient examples that adequately address this important issue.…”

Sustaining nitrogen dynamics: A critical aspect for improving salt tolerance in plants

“…These AMTs might aid in delivering NH Organic compounds in the soil can also aid plant N nutrition (Geisseler et al, 2022). Amino acids account for the majority of low molecular weight dissolved organic N in soil (Tsuzuki et al, 2022). Evidence suggests that Arabidopsis has a single target of rapamycin (TOR) kinase gene (AtTORC) which is known to be involved in the maintenance of N metabolism including accumulation of amino acids thereby, influencing plant growth and metabolism (Caldana et al, 2013;Dobrenel et al, 2016).…”

Molecular biology of chemical defenses

“…Wound and UV-B-inducible patterns of their genes are consistent with the general defensive roles of flavonoids. Tsuzuki et al (2021) proposes the application of a menthol derivative, called ment-Val, that can boost the expression of defense genes to reduce pest damage in soybean plants and other crops. Their findings could usher in a change from harmful chemical pesticides to sustainable and environment-friendly alternatives.…”