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Hot Potato: Global Warming Threatens Spuds and Peanuts

Wild cousins have provided the genes to boost nutrition in domesticated potatoes and other crops, but they face trouble as the climate changes
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© A.LANE/BIOVERSITY
Climate change will not be kind to wild potatoes, and even less so to wild peanuts. Temperature shifts in the South American highlands, which many varieties of wild potatoes call home, will drive them further up the mountainsides. Meanwhile, the wild peanut, which thrives in the hot, flat savanna, will find itself increasingly subjected to droughts and extreme temperatures, potentially leading to the extinction of as many as 31 out of 51 species and a range reduction of as much as 94 percent by the 2050s, according to Bioversity International, a Cali, Colombia–based research organization devoted to the conservation of agricultural biodiversity.

"What was interesting is that you could see that the geography was very important," says Andy Jarvis, senior scientist at Bioversity International and the International Center for Tropical Agriculture, also in Cali. "Wild peanuts are the worst hit because they have long distances they would need to migrate in order to track their climate [due to the fact they are] on flat lowlands."

This is not just bad news for wild peanuts and potatoes, but also for their domesticated brethren. From their many sizes and colors (vibrantly demonstrated by the potatoes on offer at the Bolivian market pictured above) along with genes that resist drought, wild relatives represent a genetic storehouse of potentially useful traits, such as the genes that allowed potatoes to recover from the blight that precipitated the Irish potato famine. "Wild species typically have more resistance to pests," Jarvis notes. "Wild relatives are becoming more and more useful for plant breeding," especially given advanced genetic techniques. For example, wild cousins provided the genetic basis for boosting the calcium content of potatoes.

In this study, the researchers probed how Arachis (peanuts), Solanum (potatoes) and Vigna (cowpeas, a nutritious legume common in Africa) fared under various climate scenarios that took into consideration the plants ability to migrate. Peanut and potato species unable to migrate suffered drastic reductions in number as well as in the amount of land available to them. In fact, 80 percent of all three species—including those able to migrate completely and partially—experienced range reductions, even Vigna, which was least impacted because it is the most widespread.

Other studies have found that plants prove more resilient in the face of climate change than anticipated, so further field experiments will be needed to determine if this gloomy prognosis is correct. But Jarvis says it would be prudent to catalogue and store the genetic materials of various wild relatives of important crops—and set up suitable protected reserves—before climate change forces them to pack up and move 300 kilometers to find a suitably hospitable region again. "The gene banks are drastically underrepresenting wild relatives," he warns. "Species ranges are highly likely to change and therefore you need to account for that; that needs to be taken into account in conservation plans."

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