Inside the Industry: Deriving new plants from DNA
By Taskeen Khan
Jon Mahoney (Photo Credit: Ball Horticultural Company)
If you have seen a unique flower at the garden center, you have likely thought, “That is amazing!” But, how often have you wondered, “How was that created? How did it come to be?” Jon Mahoney, a Cell Biology Scientist at Ball Horticultural Company, sat down to answer those very questions. What many people don’t know is that scientists, and breeders, work together to develop many of the plants we see in stores. And Jon has the inside scoop on this process. He is one of the scientists who helps create new flower varieties.He pulled back the curtain of ivy, and gave us an inside peek on how the techniques of genome doubling and mutagenesis are used to develop new flowers, and how he came to be a flower inventor.
Where it Begins
How does the process of developing a new plant variety begin? Jon explained that the cell biology team and plant breeders collaborate to develop ideas for new plants, or ways to improve an existing plant. For example, the team may decide they are interested in red roses with white specks across the petals, or a bee balm resistant to powdery mildew. Plant breeders have traditional methods available to them for creating these varieties. They can find existing plants with traits similar to what they are looking for, and breed those, or look for plants they can cross to create hybrids with the traits they are interested in. And this is where the cell biology team comes in. They work to provide plant breeders with even more “tools” for creating new varieties. Two of the “tools” that can be added to the plant breeders’ tool kits are mutagenesis and genome doubling.
It’s in the DNA
Both mutagenesis and genome doubling begin with a plant’s DNA. Each plant has DNA, instructions that determine almost everything about the plant, from the shape of its petals, to how it should react to drought conditions, to what chemicals it should produce to dissuade pests. And this DNA collectively is referred to as the plant’s genome.
Jon looking at a graph that shows the amount of DNA in a plant cell (Photo Credit: Taskeen Khan)
Genome Doubling
Genome doubling is exactly what it sounds like. The plant is exposed to chemicals, such as Colchicine (which is commonly used to treat gout), that cause the genome to double. This can produce changes such as larger flowers, more leaves, and thicker stems.
A regular angelonia (left) next to an angelonia with a doubled genome (right) (Photo Credit: Dr. Jiping Zhao)
Mutagenesis
In the process of mutagenesis, gamma radiation (the same radiation that created the Hulk), or chemical treatments are applied to the plant in order to induce random changes in the DNA. The DNA alterations can spur a variety of changes including flower color, variegation, and flower anatomy.
V1-V8 are variations of the Dreamland Zinnia, C, created through exposure to gamma radiation (Photo Credit: Smitha Hedge DOI:10.13128/ahs-20289)
Exciting as the possibilities are, neither genome doubling nor mutagenesis are exact processes. Altering a plant’s DNA can cause desirable changes, like larger flowers or disease resistance, but can also cause changes that decrease the plant’s health, cause it to die altogether, or cause no notable difference at all. For this reason, Jon and his team must apply these treatments to hundreds of plants to find the few that change in ways the breeders are interested in. Once successful, the cell biology team shares the plant with the plant breeding team. Together they determine if it can be sold as a product, or can serve as a parent plant to help breed new varieties.
The Path to Plants
So how did Jon become a cell biologist who focuses on flowers? Did he watch Little Shop of Horrors and decide he wanted to spend his life trying to create the next Audrey II ? Not quite.
Jon always enjoyed nature, plants, and gardening. Growing up, he worked in a local retail greenhouse, and watched his uncle, and great uncle, work in the horticulture industry. This led him to Iowa State University where he studied horticulture and developed an interest in plant genetics.
After graduation, he took part in internships focused on willow breeding, and the genetics and conservation of ornamental plants. Next, for his PhD at the University of Connecticut, he studied the genome of chokeberrys, a plant that is used both in the ornamental industry and as a food crop. After his PhD, Jon decided he wanted to focus on developing products that were available to consumers. This launched his transition from academia to the horticulture industry. Since then, he has been helping develop new varieties of plants to fill our gardens and homes.
So the next time you see a plant with interesting coloration, or disease resistance, take a moment to think about the exciting science that brought it to you!