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Wild relatives of key crops not protected in gene banks, study finds

Phaseolus lunatus, a wild relative of the lima bean, is threatened by land use change in Costa Rica.

Daniel Debouck/CIAT

Wild relatives of key crops not protected in gene banks, study finds

The wild, sometimes scraggly cousins of grains and vegetables have a role to play in food security, but urgent action is needed to conserve them, says a new study published today in Nature Plants. The first global survey of the distribution and conservation of 1076 wild relatives of 81 crops finds that more than 95% are insufficiently safeguarded in the world’s gene banks, which store seeds and other plant tissues that can be used for future breeding efforts.

Some 70% of the wild populations examined by the study, including the relatives of banana, cassava, wheat, and sorghum, are considered high priority for collection; 300 could not be located in any gene bank.

Crop wild relatives are, in essence, evolutionary experiments. Without coddling from farmers, these hardy plants withstand drought, pests, and disease. As a result, they often evolve valuable traits that plant breeders could use to create varieties able to resist pests or maintain yields in the face of global warming. In the past, virus-resistant wild relatives of sugarcane and rice have helped produce new varieties that averted millions of dollars in losses.

“Our findings capture which critical regions around the world hold the wild diversity we need for the stability of global agriculture,” says study co-author Colin Khoury, a crop diversity specialist at the International Center for Tropical Agriculture (CIAT) in Cali, Colombia. Even though crop species have been moved all over the world, he says the historic home ranges of many crops are still relevant because wild relatives persist there.

Some of these crop diversity hot spots include the Mediterranean, Near East, Asia, and southern Europe, the researchers found. And plants in these regions are facing growing threats, ranging from dramatic land-use change to civil unrest. “It’s a race against time to collect in areas that are war-torn, or subject to deforestation or rapid development,” says study co-author Nora Castañeda-Álvarez, a postdoc at CIAT.

Because enhancing the conservation of crop wild relatives is one of the United Nations’s Sustainable Development Goals, the authors suggest that the study’s numbers could be used as a baseline for measuring progress toward meeting conservation goals.

Collecting crop wild relatives will require a massive global effort, the researchers suggest. In recent decades, however, seed conservation and sharing efforts have been hampered at times by concerns about biopiracy, as nations have negotiated numerous international treaties and agreements that regulate the collection, movement, and equitable use of seeds and other genetic resources. “This paper comes out of a global effort to reopen borders and share crop genetic resources,” Khoury says.

One effort—the largest to date to systematically collect wild gene pools—is already underway in 17 countries. It focuses on securing the wild relatives of 29 of 64 crops that are listed in an annex to the International Treaty on Plant Genetic Resources for Food and Agriculture. But crops not on that list, including the wild relatives of peanut, asparagus, or lettuce, are not included in the collecting effort, which is jointly run by the Kew Millennium Seed Bank in Wakehurst, U.K., and the Global Crop Diversity Trust (GCDT) in Bonn, Germany.

Organizers ultimately hope to expand the effort to more countries, says Hannes Dempewolf, project manager at GCDT. But plant collectors have had difficulty negotiating agreements in certain countries for a variety of reasons, including a lack of suitable institutions to coordinate collecting work and the absence of seed-sharing regulations.

Axel Diederichsen, curator of Plant Gene Resources of Canada in Saskatoon, says the new study’s effort to document and map missing wild diversity is valuable. Still, he questions whether the international gene bank system has the funding and infrastructure to absorb all of the at-risk populations. “Do we have the capacity to conserve, much less utilize, all this diversity?” he asks. “It’s not trivial.”