The seed bank is not an option for more than a third of endangered species

In an article published today in Plants Nature, researchers at the Royal Botanic Gardens, Kew, for the first time, detail the extent of endangered species that can not be kept in seed banks. The document reveals that when we look at endangered species, 36% of species "critically endangered" produce recalcitrant seeds. This means that they can not tolerate the drying process and therefore can not be frozen, key process they need to be "put in reserve" safely.

Kew scientist John Dickie, former Kew scientist Sarah Wyse and former science director Kew professor Kathy Willis, have discovered that other endangered species and the global list of tree species contain also high proportions of non-bank species including 35% of "vulnerable" species, 27% of species "endangered" and 33% of all tree species.

This comes after the publication of research last year that about 8% of the world's plants produce recalcitrant seeds. Among these species are important British heritage trees, such as oaks, chestnuts and chestnuts, as well as staple foods around the world, such as avocado, cocoa and cocoa. mango. This latest research reveals that the scale of plants that can not be kept in seed banks is much greater for endangered species. The problem is particularly serious for tree species, especially those in tropical rainforests where one-half of the tree species may not be available for bank use.

Seed bank

Currently, the seed bank is the most commonly used way to keep plants outside their natural habitats. The seed bank works as an "insurance policy" against the extinction of factories around the world – especially for those that are rare, endemic and economically important – so that they can be protected and used for the future.

This type of "ex situ" conservation is preferred for a number of reasons: it preserves high levels of genetic diversity at a relatively low cost in minimal space and can be conserved for relatively long periods of time.

However, this does not work for all the seeds and this new document suggests that there is a huge gap in knowledge about which of the world's rarest, most endemic and most important plants in terms of economics. not suitable for conservation in seed banks. To estimate for the first time the magnitude of the problem, Wyse and Dickie developed a set of models to predict the likely seed storage behavior of species. This analysis has highlighted the fact that the goal of the Global Strategy for Plant Conservation (GSPC) is to conserve 75% of the world's threatened plant species outside their natural habitat. 2020 is virtually impossible.

cryopreservation

Wyse, Dickie and Willis argue that other techniques are needed to reach the GSPC target, probably using cryopreservation, a form of conservation using liquid nitrogen that offers a potential long-term storage solution for recalcitrant seeds. In seed banks, the seeds are dried and frozen at -20 ° C, while cryopreservation consists of removing the embryo from the seed and then liquid nitrogen to freeze it at a much colder temperature from -196 ° C

Kew has been advocating for several years the use of cryopreservation in its famous Millennium Seed Bank (MSB) in Wakehurst and has described it as a key priority for the world's seed conservation in Kew's strategy on collections published earlier this year. Kew aims to develop a generic protocol for the banking of recalcitrant seeds and to revive the large-scale use of cryopreservation. Cryopreservation not only allows the storage of "non-bankable" species, but also helps to extend the life of orthodox seeds whose shelf life is too short at -20 ° C.

In 2010, Dr. Hugh Pritchard, Kew Scientist, and Professor of Botany at the Kunming CAS Institute of Botany, De-Zhu Li, called for an update of the Global Strategy for Plant Conservation in order to to set clear targets for cryopreservation in order to increase research efforts in the field of technology. This was not done subsequently and Kew now urgently calls for cryopreservation to be considered as an essential conservation tool after 2020, as it should enable us to achieve the greatest gains in the protection of human health. non-bankable species.

John Dickie, head of seed and laboratory collections at Millennium Seed Bank in Kew and one of the authors of the paper, said that "ex situ plant conservation is more essential than ever, with many threats to plant populations, including climate change, habitat transformation and plant pathogens, we must do everything in our power to conserve the most important and endangered species, as effective as seed storage. for some species, it is not suitable for all plants and we must invest This article shows that it is necessary to deploy more efforts at the international level to understand and apply alternative techniques such as cryopreservation, susceptible to preserve many other species of extinction. "

Explore further:
Researchers develop a new approach to the conservation of tree species

More information:
"The seed bank is not an option for many endangered plants" Plants Nature, www.nature.com/articles/s41477-018-0298-3