Pounding the Genetic Diversity Trail

January 2, 2016 02:07 AM

Wild crop relatives are invaluable to the future of agriculture

Laura Marek and Gerald Seiler hunt with paper sacks. Each year, they pore over old records, locate their quarry and then cover thousands of miles across the U.S. to safeguard agriculture. Walking gravel roads, cutting through fields or boating to islands, the gumshoe pair follows the trail of wild sunflower crop relatives. When the prize is found on a back road or forgotten clearing, they break off sunflower heads and preserve the seeds in agriculture’s version of bag-and-tag.

Gerald Seiler collects narrow-leaf sunflower samples along a roadside ditch in Georgia. 

Wild crop relatives fight a cage match every day against disease, drought and pests. They endure by developing resistance and tolerance, and their genes hold invaluable lessons for cultivated crops. Simply, a scrawny sunflower clawing for space alongside a highway is hiding a mother lode of survival keys necessary for the future of agriculture.

Marek and Seiler have collected 2,200 unique populations and 53 genetically different wild sunflower species. They reference herbaria records and spend loads of time checking with botanists and land managers to get new location information or gain permission to access private land. 

“Our aim is to improve crop species with wild crop relatives,” says Seiler, botanist with USDA’s Sunflower and Plant Biology Research Unit in Fargo, N.D. “Sunflower is a highly managed crop and has overcome lots of pathogens and pests. How? We go back to the wild relatives and move their genes into cultivated sunflower.”

As with many crops, sunflower relies on a narrow genetic base—a precarious position when disease or environmental problems strike. 

Laura Marek collects sunflower samples in California’s Los Padres National Forest. 

Seiler performs long-term, high-risk research that can’t be done by major ag companies because of the lengthy turnaround. It can take 10 years to develop a hybrid sunflower, he says. 

When plant researchers request a particular trait, Seiler cross-references his collection with the environment for a promising match. “Every day is interesting as we test material,” he says. “All we need to find is one plant with resistance, and then we can transfer the gene to the cultivated side.”

Marek, curator of oil seed crops at USDA’s North Central Regional Plant Introduction Station in Ames, Iowa, ships collected seed back to her lab. Her crew hangs sunflower heads in mesh drying bags. After cleaning and viability tests, seeds are stored at the Ames gene bank and later distributed to plant breeders and scientists. Additional seed is sent to USDA’s National Seed Storage Lab in Fort Collins, Colo., and the Global Seed Vault in Svalbard, Norway, for storage. “We’ve found rust tolerance to downy mildew and some resistance to Sclerotinia white mold,” Marek says.

As a rare native plant in the U.S., sunflower offers a unique view into resistance and drought-tolerance not afforded by other crops. Marek and Seiler are grabbing while the getting is good, filling in gaps for each species. 

“Genetic diversity is the future of agriculture,” Seiler says. “Sometimes people think we’re collecting weeds. Weeds to them maybe—but a rare value to agriculture.” 

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