Just about any crop you can think of has a wild relative. Sugar, rice, sorghum, sunflowers, Echinacea, various berries, nuts, peaches and cherries along with food staples like beans, squash, tomatoes, sugarcane and grapes have native gene pools in the U.S. Researchers have used the crop wild relatives not only to breed resistance to pests and disease but in some cases to actually create new crops. Not all of them are native Texans, but they got here as fast as they could, as the saying goes.
Botanists, geneticists and plant breeders have studied the crop wild relatives for decades, often quietly and behind the scenes, and averted many a disastrous harvest by finding traits from the wild relatives that helped the domesticated species to survive.
In the 1970s, when the rice harvests in Asia were decimated by a virus, scientists studied some 10,000 wild species and found one with a resistance to the virus; the rice crops were saved. In 1996, a wild sunflower in Kansas was found to be resistant to ALS inhibitors in weed killers.
“Almost every crop has one of those kinds of stories,” says David Baltensperger, head of the soil and crop sciences department at Texas A&M University. “They are a valuable source for research on many crops.”
Baltensperger said one of the most important crop wild relatives is sunflowers, which is estimated to be a $384 million industry in the U.S. It's one of the few food crops (blueberries, squash and pecans are also on the very short list) that originated in this country but they were commercialized in, of all places, Russia.
A study that inventoried crop wild relatives in the United States, part of an international effort by the Global Crop Diversity Trust, was published last month in the journal Crop Science. The study, the first of its kind ever done in the U.S., found 4,600 wild relatives of agricultural crops in the U.S., many more than researchers expected.
The number of crop wild relatives was a surprise because the general consensus has always been the Mediterranean Basin or the Fertile Crescent of the Middle East hold a lot of these plants but that North America lacks numbers and variety.
Bill Rooney, a researcher and professor at Texas A&M University, has worked to develop grain sorghum hybrids for feed, food and forage. He has published extensively on his research that applies genetics to improved sorghum varieties. Nearly every crop has a wild relative, he said, and every one of them has been studied.
“As a rule of thumb, if a crop has wild relatives, somebody has messed with it,” Rooney said. “The most obvious benefits are pest and disease control, but you also find some that improve yields and quality, too. More recently, during the drought, more of them have been documented for both yield and quality.”
He said that wheat researchers have found rust-resistant genes in wild varieties, and oat researchers have had similar results. Triticale, for example, is a hybrid of wheat and rye, combining the yield potential and grain quality of wheat with the disease and environmental tolerance, including soil conditions, of rye
Lead author of the U.S. crop wild relatives study was Colin Khoury of the International Center for Tropical Agriculture in Cali, Colombia. He noted that 30 percent of the U.S. plants are of “conservation concern” and might be at increased risk since they tend to be overlooked by the conservation community. Seventeen percent of the plants inventoried are listed as either non-native or noxious, and others are threatened or endangered. This is where the battle to get rid of invasive and noxious plants runs headlong into efforts to save crop wild relatives.
Stephanie Greene of the University of Washington, who started and contributed heavily to the U.S. inventory, said she believes that crop wild relatives should be the “poster child” for plant conservation, yet most people have never heard of them or their contributions to their domesticated cousins.
“We always say that crop wild relatives are important and that they're threatened,” Khoury said. “I think what this study does is takes those general statements and puts some good evidence and documentation behind them.”
Baltensperger said the importance of crop wild relatives cannot be underestimated.
“Remember,” he said. "The Green Revolution started with a semi dwarf trait in a wild relative of wheat. Those kinds of things always make for interesting stories.”