An…Attempt to Save the Reefs & Forests
http://NewYorker.com/magazine/2016/04/18/a-radical-attempt-to-save-the-reefs-and-forests Engineering the #chestnut tree to express OxO, a defense against its blight
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“Powell attended graduate school in the nineteen-eighties, around the same time as Gates, and, like her, he was fascinated by molecular biology. When he got a job at the forestry school, in 1990, he started thinking about how new molecular techniques could be used to help the chestnut. Powell had studied how the fungus attacked the tree, and he knew that its key weapon was oxalic acid. (Many foods contain oxalic acid—it’s what gives spinach its bitter taste—but in high doses it’s also fatal to humans.) One day, he was leafing through abstracts of recent scientific papers when a finding popped out at him. Someone had inserted into a tomato plant a gene that produces oxalate oxidase, or OxO, an enzyme that breaks down oxalic acid.
“I thought, Wow, that would disarm the fungus,” he recalled.
Years of experimentation ensued. The gene can be found in many grain crops; Powell and his research team chose a version from wheat. First they inserted the wheat gene into poplar trees, because poplars are easy to work with. Then they had to figure out how to work with chestnut tissue, because no one had really done that before. Meanwhile, the gene couldn’t just be inserted on its own; it needed a “promoter,” which is a sort of genetic on-off switch. The first promoter Powell tried didn’t work. The trees—really tiny
seedlings—didn’t produce enough OxO to fight off the fungus. “They just died more slowly,” Powell told me. The second promoter was also a dud. Finally, after two and a half decades, Powell succeeded in getting all the pieces in place. The result is a chestnut that is blight-resistant and—except for the presence of one wheat gene and one so-called “marker gene”—identical to the original Castanea dentata.”
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