Straub’s Genome Research Aids Crop Cultivation   – Hobart and William Smith Colleges \
The HWS Update

Straub’s Genome Research Aids Crop Cultivation  

Assistant Professor of Biology Shannon Straub has co-authored a scientific journal article about the genetics of mint plants recently published in Molecular Plant.

The article, “Draft Genome Sequence of Mentha longifolia and Development of Resources for Mint Cultivar Improvement,” was featured on the cover of the February 2017 issue of the peer-reviewed journal, which publishes findings of high significance in plant biology.

Straub, who spent about a year working on the project with a group of researchers, was responsible for the complete chloroplast genome sequence assembly and characterization, as well as the evolutionary analysis of the plant, which is a South African strain of mint similar to peppermint and spearmint.

“Among members of the mint family with sequenced chloroplast genomes, the genome of our study species was most closely related to oregano (Origanum vulgare),” she says. “Other members of the family included in the study and known for their essential oils are rosemary, lavender and red sage.”

One of the complications of working with mint, Straub says, is that cultivated species of mint (like peppermint) have very complex genomes, featuring six sets of chromosomes (hexaploid) and are sterile, and thus must be grown by taking cuttings from existing plants. Finding a variety that had a less complex genome with two sets of chromosomes (diploid) and able to reproduce sexually, such as the South African strain, was key to the group’s ability to work successfully with the plant.

Often grown commercially for its oil, mint was chosen partly to take advantage of the crop improvement benefits that would result from a better understanding of its genome.

“My colleague Kelly Vining [the paper’s lead author], an assistant professor in the Department of Horticulture at Oregon State University, is interested in breeding mint and introducing desirable traits for disease resistance and oil composition into the cultivated species,” says Straub. “The paper provides resources for mint cultivar improvement by plant breeders to change the composition of the oils, including the amounts of different compounds that can change the smell and taste, and improve the plants’ resistance to diseases caused by fungal pathogens.”

Fungal diseases such as Verticillium wilt can be devastating for farmers of domesticated mint crops, and by exploring the genes and associated markers that indicate wilt resistance, the work of Straub, Vining and their colleagues can play a major role in the long-term health of this specialty crop.