New Technique to Clone Hemlock Trees May Save the Species from Extinction

Cloning trees may help fight off a nasty pest. Scientists have successfully cryogenically frozen germplasm from hemlock trees that are being wiped out across the eastern U.S. by an invasive insect, and believe that cloning trees that are fighting off the pest could save the species as a whole.

There are only two native hemlocks species in the eastern U.S.: eastern and Carolina. Both of these species are currently at risk from an insect called the hemlock woolly adelgid, which is a pest native to East Asia. This insect kills hemlocks by injecting a toxin into the trees while feeding on sap. Unfortunately, it's spread from Virginia and exploded in the Appalachians.

"It looks like a bomb went off where there were once pure hemlocks," said Scott Merkle, one of the researchers, in a news release. "It's just dead trees because there doesn't seem to be much natural resistance."

In this case, the researchers managed to generate hemlock tissue cultures, cryogenically store them and then grow plants from the cultures after thawing them several months later. They also developed a method that will allow them to clone hemlocks, which is particularly important since it could allow them to clone individuals that do well against the insect destroying the trees.

The ability to cryostore and recover hemlock cultures provides a practical approach for storing germoplasm of a large number of trees indefinitely. Once a system is found to deal with the invasive insect, hemlocks can then be repopulated. In addition, the ability to clone trees that are potentially more resistant to the insect could be a huge boon to the species.

Scientists are still working on ways to preserve this species of trees. Some hemlocks seem to be naturally resistant and currently, researchers are working on determining whether the resistance is genetically based. That said, it will take some times before this pest can be properly handled.

The findings are published in the journal Tree-Structure and Function.

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