The genetic building blocks of the mint plant may hold the key to defeating the crop’s longtime enemy — verticillium wilt.

Oregon State University researcher Kelly Vining has sequenced roughly 25 to 50 percent of the genetic data contained in a mint species, Mentha longifolia.

Vining said she is still conducting “quality control” work that will determine how much of the mint genome has actually been sequenced.

However, the hereditary data currently available can already help researchers look for genes that confer resistance to the fungal pathogen, she said.

The species of mint that Vining is studying is resistant to verticillium wilt, but it’s a wild relative of commercial varieties and doesn’t have the desired yield or oil characteristics.

By comparing the species’ genetic data with that of other crops, like tomatoes and grapes, she is able to identify genes that are unique to mint.

The next step is examining genes that are activated when the mint encounters the fungus and comparing them with genes of susceptible plants.

Imparting resistance into commercial varieties will depend on how many genes are involved in resistance, Vining said.

“We really can’t answer that question until we know how many,” she said.

The issue is a double-edged sword.

If only a small number of genes confer verticillium wilt resistance, it would be easier to genetically transform commercial varieties to include them.

On the other hand, if the plant has many modes of resistance, it’s more likely to withstand the pathogen over time.

“What we hope for in agriculture is durable resistance,” Vining said. “More genes means more durable resistance, potentially.”

It’s unlikely that researchers would be able to use classic breeding to confer resistance to peppermint, she said.

As a hybrid, peppermint is sterile, so the focus would be on a transgenic approach, Vining said.

The mint genome study may also boost other research, such as the work of Washington State University researcher Mark Lange.

Lange is currently studying a spearmint plant that is resistant to verticillium wilt. His goal is to coax it into producing oil with characteristics similar to peppermint oil.

“It’s more commercially valuable,” said Vining.

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