Nov. 5 (UPI) -- At least 36 percent of endangered plant species can't be conserved in seed banks because the seeds can't be frozen, according to a new study.
If scientists can't freeze the seeds, they can't bank the seeds, they said, which could lead to the extinction of some important plant varieties.
The study -- conducted by researchers at the Kew Botanical Gardens in the UK and published this month," in the journal Nature Plants -- examined the inability of scientists to preserve certain plant seeds, ultimately posing a threat to those species existence.
The unbankable, or "recalcitrant," seeds include 35 percent of "vulnerable" species and 27 percent of "endangered" species, in addition to 33 percent of all tree species. The "recalcitrant" seeds can't endure the drying process required before freezing, so they ultimately can't be frozen.
But some scientists are exploring other options to keep these plants from almost certain extinction.
Kew Garden fertility lab at the Millennium Seed Bank in the UK houses 40,000 wild plants and 2.2 billion seeds.
"Today, 60,000 to 100,000 species of plant are faced with the threat of extinction. Plants provide the air we breathe, clean water and we all rely on plants for food. We aim to save plants world wide with a focus on plants most at risk and most useful for the future," a Kew spokesperson told The Telegraph. "Together with our partners in more than 95 countries worldwide, we have already successfully saved seeds from over 13 per cent of the world's wild plant species."
Kew scientist John Dickie, former Kew scientist Sarah Wyse and former director of science at Kew Kathy Willis, the authors of the study, support an alternative technique called cryopreservation that uses liquid nitrogen to freeze otherwise recalcitrant seeds. Scientists hope this technique can help the Global Strategy for Plant Conservation reach its goal of conserving 75 percent of the world's endangered plants.
For the conventional process, a seed must be dried before it is frozen at -20 degrees. Under the cryopreservation technique, a seed needs to have its embryo removed before being frozen with liquid nitrogen at -196 degrees. This enables otherwise unbankable seeds to be stored, and some scientists believe it could extend the lifespans of other seeds.
Scientists rely on seed banking as an "insurance policy" to protect plants from around the world from extinction by keeping them alive outside of their natural habitat. Scientists are looking to freeze avocado seeds, coffee beans, cocoa plant, as well as oak tree seeds.
"Ex-situ conservation of plants is more critical than ever, with many threats to plant populations including climate change, habitat conversion and plant pathogens," John Dickie, head of Seed & Lab-based Collections at Kew's Millennium Seed Bank and one of the authors of the paper, said in a press release. "This paper shows that we need greater international effort to understand and apply alternative techniques like cryopreservation which have the potential to conserve many more species from extinction."