Tasty and good for you
By EMILIE LORDITCH, MICHIGAN STATE UNIVERSITY
The mint family of herbs, encompassing sage,
rosemary, basil, and even woody plants like teak, provides a stimulating burst
to our sense of smell and taste. Researchers at Michigan State University have discovered that
the evolution of these plants have diversified their specialized natural
characteristics through the evolution of their chemistry, opening up the
possibility of future uses in fields such as medicine and pesticide production.
“People easily recognize members of the mint family for their specialized metabolites,” said Björn Hamberger, an associate professor and James K. Billman Jr., M.D., Endowed Professor in the College of Natural Science. “Metabolites are an efficient way for plants to defend themselves because they can’t run away.”
Since 2016, Hamberger has been studying
specialized metabolites in plants called terpenoids, which are essential in protecting
plants from predators and pathogens and are also common ingredients in green
and sustainable agrochemicals, antioxidants, cosmetics, and fragrances.
Hamberger worked with Robin Buell, a former
MSU genomics researcher now at the University of Georgia, who sequenced several mint
plant genomes. This collaboration with Buell’s team led Hamberger’s graduate
students, Abigail Bryson and Emily Lanier, to discover how several genomes of the
mint family have evolved and how these chemistries have emerged over the past
60 million to 70 million years.
“Over millions of years, plants have adapted
and evolved for their particular niches where they thrive, and that means that
these chemistries are diverse and have clearly adjusted to their environment,”
Hamberger said. “So, we try to identify and discover pathways to these
specialized metabolites that plants make.”
Taking an interdisciplinary approach, Bryson
identified the genomic organization of terpenoid biosynthesis, and Lanier
analyzed the chemical pathways. Together, Lanier and Bryson discovered
something highly unusual in the beautyberry genome from the mint family. It has
a large biosynthetic gene cluster. A BGC is a group of genes located close
together in the genome that are involved in the same metabolic pathways. These
genes are like the individual pearls on a necklace — separate and yet
connected. Additionally, Bryson and Lanier found variants of this BGC in six
other species in the mint family.
“We are learning that the physical location
of genes within the genome is important,” Bryson said. “It can drive the
evolution of specialized metabolic pathways in the plant, leading to a vast
diversity of interesting natural plant compounds.”
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.
“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,” Lanier said.
Hamberger describes it like a recipe that
everyone has a copy of and changes to suit their requirements and preferences.
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 repellants.”
Reference: “Uncovering a miltiradiene
biosynthetic gene cluster in the Lamiaceae reveals a dynamic evolutionary
trajectory” by Abigail E. Bryson, Emily R. Lanier, Kin H. Lau, John P.
Hamilton, Brieanne Vaillancourt, Davis Mathieu, Alan E. Yocca, Garret P.
Miller, Patrick P. Edger, C. Robin Buell and Björn Hamberger, 20 January
2023, Nature Communications.
DOI: 10.1038/s41467-023-35845-1
