Fragrant garden staples part of the sprawling mint family like thyme, basil and lavender are hiding some super-sized secrets with big applications, according to Spartan researchers.\u202f\u202f\u202f<\/p>\n
While unraveling the genetic makeup of a mint relative called ground oak, MSU biochemists discovered it sported a truly massive genome \u2014 nearly as large as our own \u2014 as well as an extra-large gene cluster and four sets of chromosomes.<\/p>\n
Mint plant family members are known for their natural anti-cancer, anti-pest and anti-viral properties and by unraveling ground oak\u2019s genetic mysteries, researchers are one step closer to reproducing these naturally powerful plant chemicals in the lab.<\/p>\n
MSU biochemist Bj\u00f6rn Hamberger is an expert in specialized metabolites known as terpenes. These compounds have long been used by humanity for their medicinal, cosmetic and flavoring properties. Credit: Matthew Wisniewski\/GLBRC <\/p>\n
\u201cWhat if we could spray our veggies with a natural product that makes a hungry deer or insect say, \u2018No thank you,\u2019\u201d MSU researcher Bj\u00f6rn Hamberger<\/strong><\/a> said, noting potential uses in large-scale agriculture.\u202f\u202f<\/p>\n \u201cThese plants also have exciting antimicrobial properties, which could help with the trouble we see nowadays concerning antibiotic resistance,\u201d he added.\u202f\u202f<\/p>\n The team\u2019s findings, which appear in the journal Plant Communications<\/strong><\/a>, were made possible by funding from the National Science Foundation, the National Institutes of Health and the U.S. Department of Energy-supported Great Lakes Bioenergy Research Center.\u202f\u202f<\/p>\n \u201cThis project was like many others where we walked in thinking we knew just what to do,\u201d Hamberger said. \u201cWe\u2019ve learned again that plants always have something more up their sleeves.\u201d\u202f\u202f<\/p>\n A family reunion\u202f\u202f\u202f<\/p>\n Humans have made the most of the mint family\u2019s dazzling chemical diversity for millennia, from medicine and fragrances to well-known culinary uses.\u202f\u202f<\/p>\n At MSU, Hamberger studies these eclectic chemicals, better known as specialized metabolites \u2014 and particularly a group of molecules called terpenoids.\u202f\u202f<\/p>\n Specialized metabolites are molecules that plants evolve to give them an extra edge in their environment. These are different from primary metabolites, which are the molecules a plant needs for basic survival processes like growth and reproduction.\u202f\u202f<\/p>\n You might think of this molecular mix as the ingredients needed to bake a cake.\u202f\u202f\u202f<\/p>\n If primary metabolites are the flour, butter and sugar that form the cake\u2019s foundation, specialized metabolites are flavors like chocolate or vanilla that make it totally unique for each occasion.\u202f\u202f<\/p>\n When a plant finds its ecological niche and inhabits it for tens of millions of years, it\u2019ll evolve a treasure trove of specialized metabolites to adapt and thrive.\u202f\u202f\u202f<\/p>\n These highly unique molecules are the sources of exciting chemical properties seen across the mint family, whether its Indian Coleus\u2019s ability to treat glaucoma, or Texas sage, whose antimicrobial chemistry can be used against tuberculosis.\u202f\u202f\u202f<\/p>\n \u201cPlants don\u2019t have the luxury of running away from pests or pathogens, so they turn to chemistry to get the job done,\u201d said Hamberger, the James K. Billman Endowed Professor in the Department of Biochemistry & Molecular Biology<\/strong><\/a>.\u202f\u202f<\/p>\n Previously, the Hamberger Lab made major breakthroughs by exploring this genetic and chemical variety.\u202f\u202f\u202f<\/p>\n In 2023, his team unpacked the genome of American beautyberry<\/strong><\/a>, a shrub with bright magenta berries whose native chemistry repels mosquitoes and ticks. This helped shed light on how the mint family had diversified its chemistry across the ages.\u202f\u202f\u202f<\/p>\n The research, which ultimately looked to synthesize compounds that could be used as cost-effective pesticides, earned Hamberger lab members Abigail Bryson and Nicholas Schlecht MSU\u2019s Neogen Land Grant Prize<\/strong><\/a>.\u202f\u202f\u202f<\/p>\n Awarded by my MSU\u2019s Office of Research and Innovation, the prize highlights graduate students whose research will contribute to the scientific and economic improvement of society.\u202f\u202f<\/p>\n On the hunt for further scientific surprises in the mint family, Bryson chose the understudied ground oak as the lab\u2019s next target. Found throughout the Mediterranean basin, this mounded shrub with pinkish purple flowers earned its name for the shape of its tiny leaves.<\/p>\n \u201cWe thought: let\u2019s sequence ground oak, find out how the plants achieve their useful chemical products and get a blueprint to build plant-derived therapeutics in the lab,\u201d Hamberger said.\u202f\u202f<\/p>\n \u201cThis was all good, until Abby found out ground oak had an unexpectedly massive surprise in store for us,\u201d he added.\u202f\u202f<\/p>\n Puzzles and clusters\u202f\u202f\u202f<\/p>\n In the commonly studied plant Arabidopsis, you\u2019ll find a modest 135 million base pairs of DNA.\u202f\u202f<\/p>\n So, imagine Bryson and Hambergers\u2019 surprise when it was revealed their ground oak contained some three billion base pairs \u2014 nearly as many as the human genome.\u202f\u202f<\/p>\n To wrangle these massive genetic sums, Bryson honed her bioinformatic skills working alongside Robin Buell, a former MSU Research Foundation Professor and current Georgia Research Alliance Eminent Scholar Chair in Crop Genomics at the University of Georgia.\u202f\u202f<\/p>\n \u201cWhen you assemble a genome, it’s like you have parts of sentences of a book and you are trying to figure out what the story says, line by line, chapter by chapter,\u201d Bryson said, the paper\u2019s lead author and a current postdoctoral researcher at the Donald Danforth Plant Science Center.\u202f\u202f<\/p>\n \u201cSomething about genomes that is difficult to picture is the size of the data we are working with. If the genome was the size of an actual book, the thickness of that book would be hundreds of feet and the human and ground oak genomes would be around the size of world\u2019s fifth tallest building,\u201d she added.\u202f\u202f<\/p>\n The group\u2019s research efforts further benefited from Department of Plant Biology<\/strong><\/a> collaborators Kevin Childs and Jiming Jiang and made use of MSU\u2019s Max T. Rogers Nuclear Magnetic Resonance facility<\/strong><\/a>.\u202f\u202f\u202f<\/p>\n On top of the eye-watering size of the ground oak genome, the team encountered extra surprises that helped fill in the picture of just how the mint family evolved its potent natural chemistry.\u202f\u202f\u202f<\/p>\n \u201cWe found that ground oak is a tetraploid, meaning it has four copies of its genome. By comparison, we humans are diploid, so we have two \u2014 one from mom and one from dad,\u201d Bryson said.\u202f\u202f<\/p>\n \u201cImagine if you have to sort through and solve four puzzles dumped into the same box \u2014 that\u2019s what Abby achieved,\u201d Hamberger added, noting the challenges of sequencing such a complex genetic landscape.\u202f\u202f\u202f<\/p>\n There was also the revelation that ground oak contained an incredibly large gene cluster. This is a genomic region where genes with similar functions are located close together.\u202f\u202f<\/p>\n The Hamberger Lab found a similar, smaller cluster in their earlier study of American beautyberry, leading them to believe this cluster is evolving dynamically across many mint family plants.\u202f\u202f<\/p>\n But why double or group up your genes in the first place? Hamberger says it comes down to plain old evolutionary efficiency.\u202f\u202f\u202f<\/p>\n If one set of genetic information is already performing an important duty, its duplicate is free to evolve newer functions.\u202f\u202f\u202f<\/p>\n As for having similar genes grouped together, Hamberger compares it to having your checked luggage reach the correct destination after multiple flights.\u202f\u202f\u202f\u202f<\/p>\n \u201cOnce materials are packed together tightly, it\u2019s easier to move them onto the next generation,\u201d he explained.\u202f\u202f\u202f\u202f<\/p>\n With these latest findings, the Spartan biochemists are taking the next step toward reproducing powerful, naturally occurring molecules in the lab in useable quantities.\u202f\u202f\u202f<\/p>\n So, the next time you encounter a mint relative on your table or in the garden \u2014 whether it\u2019s oregano, rosemary or even catnip \u2014 remember you\u2019re looking at a plant whose chemistry could help us take on the world\u2019s grand challenges.<\/p>\nA member of the mint family, ground oak is native to the Mediterranean region. This plant has unique chemical properties that drive off hungry pests and dangerous microbes, making it an exciting target for scientists. Credit: Hamberger Group <\/p>\n
As graduate students in the Hamberger Group, Abigail Bryson (right) and Emily Lanier helped reveal numerous genetic surprises in the mint family of plants. Credit: Bj\u00f6rn\u202fHamberger Genetic luggage\u202f\u202f\u202f<\/p>\n
A close-up of chromosomes created by a single ground oak cell. Researchers discovered the plant had several genetic surprises in store for them, including four sets of its genome and a massive gene cluster. Credit: Hamberger Group <\/p>\n