Technician Remi Bonnart (foreground) flash-freezes plant shoot tips.
Technician Remi Bonnart (foreground) flash-freezes plant shoot tips.

U.S. Department of Agriculture scientists are depositing citrus germplasm in a deep-freeze bank to preserve it for future breeding efforts.

The process, known as cryopreservation, involves small buds or shoot tips, according to a news release.

Some genebanks maintain living citrus trees in groves or screenhouses.

But with the onset of citrus greening, also known as huanglongbing or HLB, sciences are concerned that the disease may infect these repositories.

One such grove is in Riverside, Calif., which is managed along with the University of California, Riverside.

Although citrus greening has not been found in Riverside, it has been found in one residential tree in nearby Los Angeles County.

The plant material, which is plunged into liquid nitrogen, will be stored inside state-of-the-art vaults at the National Center for Genetic Resources Preservation in Fort Collins, Colo.

So far, ARS plant physiologist Gayle Volk and colleagues have cryopreserved shoot tips from 30 different citrus cultivars taken from the Riverside collection.

The facility, sometimes called the Fort Knox of plant and animal germplasm, is designed to withstand tornadoes, floods and the impact of 2,500-pound objects traveling at 125 mph.