Freezing seeds: an insurance policy for the future
We store the seeds collected from around the world at our Millennium Seed Bank (MSB). While most seeds can be stored dry in our freezers, some don't survive. The science of cryopreservation helps solve this problem.
Seeds that need cryopreservation by RBG KewRoyal Botanic Gardens, Kew
Please don't freeze me
Seeds that don't respond well to traditional preservation techniques are called recalcitrant seeds. We're talking about seeds like acorns and conkers. Freezing them is not an option because ice forms in the seed tissue, and that will destroy them. So what can be done?
Seeds that need cryopreservation by RBG KewRoyal Botanic Gardens, Kew
Cooling seeds
We extract the seed embryo. You'll be surprised to know that this rather small part of the seed can produce a plant.
Drying seeds during cryopreservation by RBG KewRoyal Botanic Gardens, Kew
Flash dryer
Once we extract the seed embryos we dry them. This is crucial. Water from the embryo tissues could freeze into ice and damage the embryo. How do we do this? We use a self-made “flash dryer”. (Don't try this at home).
An essential step during the cryopreservation of seeds by RBG KewRoyal Botanic Gardens, Kew
That's cool
Because the seed embryos are dry we can freeze them without worrying about the formation of ice. How do we do this? We use gases at very low temperatures.
Cryopreservation of seeds is a complex process by RBG KewRoyal Botanic Gardens, Kew
Storing the seeds
Surrounded by liquid nitrogen at about -180 °C, our seeds are frozen and safe. They are stored inside so-called cryo-vessels, ready to be brought back to life one day.
Storing seeds in nitrogen while carrying out the cryopreservation of seeds by RBG KewRoyal Botanic Gardens, Kew
Not your kitchen freezer
The seeds are stored at very cool temperatures. Think of the kitchen freezer, but 10 times colder.
In vitro culture of seeds by RBG KewRoyal Botanic Gardens, Kew
Back to life
It's amazing to think that seeds can be brought back or recovered and germinated after freezing them. When they are grown in test tubes, our scientists glean new insights about bringing plants back from seeds, protecting them from disease and for agriculture.
