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Neil Holt and Leslie Schichtel/MEDILL

Data based on the threat status of 3,512 (76.4%) taxa in the Inventory of NatureSecure. Data courtesy of Colin K. Khoury et al., “An Inventory of Crop Wild Relatives of the United States.”

Wild ancestors of crop plants call for conservation attention

by Leslie Schichtel
May 2, 2013

Researchers have compiled the first-ever list of wild ancestors of domesticated crop plants, called crop wild relatives, in the U.S. This will be useful not only in recognizing available resources and collecting them for plant breeders, but also in conserving at-risk species.

“People know the species are here, but no one had ever compiled a list to see just how many,” said Stephanie Greene, a plant geneticist at the U.S. Department of Agriculture-Agricultural Research Service.

A study taking the inventory of the diversity of crop wild relatives in the U.S. was published this week in the journal, Crop Science. The research explains how crop wild relatives can be used for crop improvement and points to a need for strengthened conservation efforts to prevent certain species from becoming extinct.

Active conservation is at work on many levels, but there hasn’t been much effort devoted to conservation of native genetic resources, said co-author Colin Khoury, a researcher at the International Center for Tropical Agriculture in Cali, Colombia.

“This has proved extremely important to the productivity of crops such as sunflower and corn, and will continue to be important in the future,” he said.

Identifying the highest-priority species to collect for future pursuits in agriculture is an important undertaking, said Brian Dilkes, a biochemical and molecular genetics professor at Purdue University in West Lafayette, Ind.

“We don’t really know how much diversity is actually there for many of the crop wild relatives, and identifying the highest-priority for conservation is important to do before we lose that diversity,” he said.

Crop wild relatives’ conservation and protection will charge divided communities with fostering a partnership. The two communities are those who focus on conserving the rare and endangered species and those who focus on protecting the crop plants’ wild ancestors.

“A challenge that we are facing to effectively conserve crop wild relatives is to foster communication among conservation organizations of traditional thought and what we are doing now,” Greene said. “It would be wise to conserve crop wild relatives, and so we are working to foster communication to help them recognize their importance.”

The list enables people to collect germplasms to make sure there’s enough material in genebanks. Plant breeders have ready access to the material in the genebanks.

“The initial work suggests we have gaps, even though we have everything in our own backyard,” Greene said. “We just haven’t adequately collected it, so it’s not available to breeders yet.”

The crop wild relatives are also beneficial in furthering certain forms of study and research.
When studying a crop’s adaptation to harsh environments or pest resistance, often wild species are the best sources of new alleles since wild species have a larger populations than cultivated varieties, Dilkes said.

“Being able to tap that diversity and provide a source for novel resistance genes can be extremely important,” he said. “Many of the genes that can improve yield and economic properties of plants were not captured during the domestication of crops. Returning to wild relatives and getting these advantageous properties back into cultivation can prove extremely important.”

This can be especially essential to plant breeders.

Some plant breeders engage in exploratory efforts to identify genes in wild growth that can be important for improvement, Dilkes said. “For identifying resistance to pathogens, wild relatives will be a critical resource,” he said.

“The next steps are to understand exactly where the species are distributed and how well they have been collected and stored in genebanks so that breeders can access them as well as how well-protected they are in their natural habitats so that they may continue to evolve,” Khoury said.

He said he plans to do this analysis in the coming year and “feed the work” directly into actions, specifically actions by the USDA-Agricultural Research Service and the U.S. Forest Service  in collecting and protecting native crop wild relatives.

“It’s a very timely study,” Dilkes said. “We are beginning to see how the expansion of agriculture, climate change and climate variability affect habitat and populations. Now would be the time to re-collect and catalogue the crop wild relatives to make them available to future plant breeders.”