Mentha piperita L demonstrates a potential tolerance at molecular and biochemical level to Pb stress: New perspectives

Mentha piperita L., belonging to Lamiaceae, is widely cultivated to extract one of the most invaluable compounds, such as menthol used in the pharmaceutical and food industries. However, abiotic stress adversely affects high yields, compelling researchers to utilize biotechnological approaches to improve tolerance in this plant. Therefore, this study aimed to investigate stress responses at biochemical, molecular, and metabolic levels under four Pb concentrations:0, 100, 300, and 600 ppm. The results indicated that the relative abundance of menthofuran synthase (MFS) was downregulated, whereas menthol reductase (MR) and pule gone reductase (PR) were upregulated. Accordingly, GC-MS data have demonstrated an increasing tendency of menthol content with intensifying Pb stress. Moderate stress decreased the total chlorophyll, chlorophyll a/b, and carotenoid content and increased the oxygen peroxide content compared to the control. Although the total protein level was unaffected, the plant antioxidant system, especially the enzymatic system, showed high activity at Pb levels of 600 and 300 ppm, respectively. In conclusion, the correlation between menthol content and the relative expression level of genes involved in biosynthetic pathways under Pb stress demonstrates the contribution of this metabolite in withstanding such abiotic environmental factors. These findings pave the way for further metabolomic studies of medicinal plants of interest to cultivate them under severe conditions.& COPY; 2023 SAAB. Published by Elsevier B.V. All rights reserved.

Automated summary

This study aimed to investigate the stress responses of Mentha piperita under different lead concentrations. The results showed that the relative abundance of menthofuran synthase gene was downregulated, while the relative abundance of menthol reductase and pule gone reductase genes were upregulated under lead stress. Moreover, the menthol content also increased with intensifying lead stress. Moderate stress decreased chlorophyll and carotenoid content, and increased hydrogen peroxide content. Overall, these findings revealed the adaptation mechanisms of Mentha piperita under lead stress.