GoKawiilIt was a routine day in the laboratory belonging to Cameron Peace on the campus of Washington State University, Pullman, in the high, dry hills close to the Idaho border. Peace is a tree-fruit geneticist, and on this warm September afternoon, as on most days, he was running programs that tease out the DNA profiles of apples. Apples are Peace’s passion and the focus of his professional expertise. He maintains a backyard collection of unusual varieties and runs a project called MyFruitTree, which lets members of the public send in leaves from unidentified apple trees and matches those trees’ genetic fingerprints to entries in a database of known types.
Washington State University is a land-grant university, founded to research and support agriculture, and Peace was honoring that mission. The samples he was examining had come from a team on the other side of the country at the Maine Organic Farmers and Gardeners Association (MOFGA), a long-standing agricultural nonprofit. The group wanted to identify trees it had found on old and abandoned farms, hoping to salvage valuable rarities before high winds or harsh winters killed them.
Peace does this work because every analysis he runs benefits his central project, a literal family tree of North American apples that traces the distribution of distinctive traits—flavor, color, hardiness, disease resistance—through siblings, parents and forebears. He plugged the data from a Maine sample coded AMHO-504 into a spreadsheet tool that would compare it against his collection. Then he sat back, agape. High up in the continental pedigree the entire DNA fingerprint matched a predicted empty space. The Maine team had found a living lost progenitor to hundreds of varieties—a tree that had been contributing its characteristics to American apples for hundreds of years.
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A lost piece of apples’ history had suddenly been discovered in North America.
That afternoon three years ago was the culmination of a detective story that spanned continents, collapsed centuries and linked the unlikeliest collaborators. Two quests drove their efforts. They wanted to identify a mystery tree on a property that dates back to the American Revolutionary War. But they also wanted to uncover what the possibly oldest living apple tree in the U.S. contributed to generations of apple varieties—and, equally, what traits it might still harbor that could be bred back into apples today to protect them against new threats in the future. “Maybe there are aspects that people didn’t value in the past and, 200, 300 years ago, selected against,” Peace says. “But these days, actually, we do need them.”
Scientists such as Peace, and detectives such as the team that brought the mystery apple to him, agree that retrieving those genetic resources is a vital task. For one thing, apples are valuable. They are the fruit Americans eat the most and one of the top commercial crops in the U.S., which grows more apples than any other country outside China. Apple harvests are rising in volume all the time, but in genetic terms, the base of that towering, crunchy mountain is narrowing. Although about 2,500 varieties exist in the U.S. and roughly 100 are raised commercially, most of the market depends on just 15 of them.
And apples are under threat. When small numbers of varieties are planted very widely, the crop becomes more vulnerable to diseases such as fire blight, powdery mildew and scab. Having near-monocultures in the field means disease organisms don’t have to rely on the evolution of new mechanisms to overcome the diverse genetic protections collectively carried by many apple varieties; once they settle genetically on a strategy, they can attack. And they do, very successfully. A U.S.-wide estimate made more than 20 years ago put the annual cost of fire blight, a bacterial disease, in excess of $100 million. Since then, outbreaks in various parts of the country have cost producers $16 million to $42 million at a time.
Apple varieties on display at the Maine Organic Farmers and Gardeners Association Common Ground Country Fair. Grant Delin
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