Summary of Ancient Plant Family, New Medicine:
Michigan State University researchers have discovered the evolution of the chemistry of the mint family of herbs, including sage, rosemary, basil, and teak. The family is comprised of over 7,000 species and their chemistry may have medical and pesticide production uses in the future. The researchers studied specialized metabolites in plants called terpenoids, which protect plants from predators and pathogens and are common in green and sustainable agrochemicals, antioxidants, cosmetics, and fragrances. The researchers discovered a biosynthetic gene cluster (BGC) in the beautyberry genome from the mint family, which is involved in the same metabolic pathways. The team found these terpenoids accumulate in various parts of the plant and may play distinct roles in adaptation. The team believes plant-natural products could be made in the lab, including natural good-smelling mosquito repellents. Previous research has led to unique medical uses for mint plants, such as natural treatments for glaucoma and antimicrobial properties.
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The Diverse Evolution of the Mint Family: Implications for Medicine and Pest Control
The mint family of herbs, which includes popular varieties such as sage, rosemary, basil, thyme, mint and oregano, have been used for centuries for culinary, medicinal and ornamental purposes. Now, findings from researchers at Michigan State University suggest that the evolution of the chemistry of these plants has diversified their specialized natural characteristics, opening up the possibility of future uses in fields such as medicine and pesticide production.
Specialized Metabolites and Chemical Defense Mechanisms of the Mint Family
“People easily recognize members of the mint family for their specialized metabolites,” says Björn Hamberger, an associate professor and James K. Billman Jr., M.D., Endowed Professor in the College of Natural Science at Michigan State University. “Metabolites are an efficient way for plants to defend themselves because they can’t run away.” Terpenoids are a type of specialized metabolite in plants that serve to protect them from predators and pathogens. They are also used in a variety of products such as green and sustainable agrochemicals, antioxidants, cosmetics and fragrances.
Evolutionary Pathways to Specialized Metabolites
Hamberger has been studying terpenoids since 2016, and his work has revealed that the evolution of these plants has diversified their specialized natural characteristics through the evolution of their chemistry. In collaboration with former MSU genomics researcher Robin Buell, now at the University of Georgia, who sequenced several mint plant genomes, Hamberger’s team discovered the molecular adaptations of these plants and how their chemistries evolved over the past 60 million to 70 million years.
Through Bryson’s identification of the genomic organization of terpenoid biosynthesis and Lanier’s analysis of the chemical pathways, the team discovered something highly unusual in the beautyberry genome from the mint family. It has a large biosynthetic gene cluster (BGC), which is a group of genes located close together in the genome that are involved in the same metabolic pathways. Bryson and Lanier found variants of this BGC in six other species in the mint family.
The Role of BGCs in Plants
BGCs are well known in the bacterial world, but their role in plants is not fully understood. The BGC cluster of the beautyberry plant contains genes that encode two distinct terpenoid pathways. The team found these terpenoids accumulate in various parts of the plant, such as the leaves and roots, and may play distinct roles in adaptation.
Moreover, “It’s the same base molecule, but each species is making its own version and modifying it in different ways to fit their survival needs,” according to Lanier. Hamberger describes it like a recipe that everyone has a copy of and changes to suit their requirements and preferences.
Implications for Future Uses
Previous research has led to unique medical uses for mint plants. For example, Indian Coleus can be used as a natural treatment for glaucoma and Texas sage is a natural antimicrobial that is effective against tuberculosis. The new molecular adaptations Hamberger and his team have found open the door for future applications of natural plant products from the mint family.
“Our team has been excited about the opportunities within the mint family,” said Hamberger. “Those mint enzymes, as in the American beautyberry plant, give us the ability to make plant-natural products in the lab, including — hopefully in the future — natural good-smelling mosquito repellents.”
Conclusion
The evolution of the chemistry of the mint family has diversified their specialized natural characteristics, opening up the possibility of future uses in medicine and pest control. Hamberger and his team’s findings offer a glimpse into the molecular adaptations that occurred over millions of years, leading to the vast diversity of interesting natural plant compounds. The discovery of BGCs in mint plants suggests that we are only beginning to understand the role of these gene clusters in plants, and future studies may uncover more valuable insights on how we can harness the power of these plants for practical applications.
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