Spearmint plants are resistant to the wilt, but produce an oil with a different chemical composition.
Peppermint oil is more commercially valuable.
Research WSU researchers have examined the biosynthetic origins of peppermint and spearmint oils. In spite of their distinct flavors and odors, the formation of the two oils differs in only one biosynthetic step. The enzyme catalyzing this step has been purified and the gene that codes for the enzyme has been isolated. The next step is to develop a way to transfer this key peppermint gene into spearmint. Then the genes will be transferred, a test breeding program started, and plants evaluated for oil production and disease resistance.