5 October 2023
The Millennium Seed Bank as the Noah’s Ark of global wild useful plants.
The coevolution between plants and people is a remarkable process that has shaped human life across the centuries. But how do we conserve and benefit from plant resources without jeopardizing them?
Plants are the backbone of world ecosystems. The services they provide us play a fundamental role in supporting animal and human life – from helping keep our climate stable to providing the medicines that keep us healthy.
Throughout history, plants have always constituted an irreplaceable source for livelihoods, which made them a key means of economic and socio-cultural development for human societies.
What are Useful Plants?
Useful Plants are defined as plants with at least one reported human use, although there are many plants with multiple uses: for instance, plants mainly used as a food source often also possess medicinal properties. The list of uses is long: environmental use, social use, use as material, fuel, fibre, fodder, poison, etc.
According to The World Checklist of Useful Plants (WCUP), there are around 40,239 species of Useful Plants globally, representing 11% of the global vascular flora. The top three Useful Plant families are Fabaceae, Asteraceae, and Poaceae, which include many well-known cultivated species, such as beans (Fabaceae), sunflowers (Asteraceae), and wheat (Poaceae).
These are just examples of popular Useful Plants that have been domesticated and cultivated over centuries, but there are countless wild or semi-domesticated Useful Plants that have been overlooked, known as Neglected and Underutilised Species.
The conservation of underutilised species is key to addressing hunger and food insecurity, as well as to pass on local ethnobotanical knowledge.
Wild Useful Plants under threat
The global awareness of the effects of urbanisation, farming and climate change on biodiversity has been growing, and the calls to action have never been louder.
It is estimated that nearly half of all known plant taxa are threatened with extinction, but there are still many questions about how to implement effective ways to conserve them.
Plants can be conserved either in situ (“on site” – protecting plants directly in their natural ecosystems) or ex situ (“off-site” – protecting plants through storing seeds in seed banks or as living plants in botanic gardens): both strategies are useful and work best when working in tandem, as both present advantages and limitations.
Seeds from most plants can be stored long-term after being dried to ~5% moisture content and kept at around −20°C: this way, a considerable amount of genetic diversity can be safeguarded long-term in a relatively small and secure space.
Seed banks constitute ever-changing sources of seeds and genetic material useful for research, food security, and reforestation.
The Millennium Seed Bank Collection
The Millennium Seed Bank (MSB) is the biggest seed conservation facility for wild species in the world. Managed by the Royal Botanic Gardens, Kew at Wakehurst, the MSB currently houses the seeds of ~ 40,000 species from 190 different countries and territories. Many of these species are useful, threatened, and rare.
Two major Kew Science projects have contributed to the conservation of Useful Plants through seed banking: the “MGU–Useful Plants Project” (2007-2015) and “Adapting agriculture to climate change“ (2013–2023).
The first promoted the conservation and sustainable use of 110 wild multipurpose Useful Plants from sub-Saharan Africa and Mexico, while the second conserved the Crop Wild Relatives of 28 crops fundamental to food security.
A recently published article by Liu et al. (2023) showcases the main accomplishments of the MSB for the conservation of Useful Plants. It assesses the breadth of species conserved, the number of locations over which seeds were collected, the number of plant uses among the stored plants, and conservation status of all Useful Plants within the Millennium Seed Bank collections.
The MSB conserves over 10,000 Useful Plant species, and there are many interesting facts about its remarkable plant conservation impact: it stores the seeds of a third of the global known Useful Plant species; its seed collections come from every single biome and continent; 90% of the known useful species with more than 10 identified uses are conserved here; 8% of the Useful Plant species stored are globally threatened; it holds the seeds of 3 hyper-rare species now extinct in the wild, such as the Angel’s trumpet (Brugmansia arborea (L.) Sweet).
The most common uses among the Useful Plant species conserved at the MSB were medicinal uses, followed by environmental, material, and human food uses.
Thanks to this exhaustive study, it is possible to appreciate the outstanding effort of the MSB to safeguard the future of the next generations through seed conservation.
However, there are still many challenges and limitations to seed conservation, as some seeds, known as “recalcitrant”, do not survive standard seed banking conditions.
It is estimated that around 8% of all seed plants produce recalcitrant seeds, the majority of which are trees. Most of these plants live in highly biodiverse wet tropical habitats that are threatened by human activities.
But there is hope, as seed biologists are researching new techniques for storing recalcitrant species (e.g., cryopreservation), even though there is still a long way to go because different species have varied responses to cryopreservation.
Therefore, broadening scientific research on seed conservation is fundamental to secure Useful Plants and therefore our future, in line with the United Nations Sustainable Development Goals and the new Kunming-Montreal Global Biodiversity Framework.
Undoubtedly, the conservation of Useful Plants in seed banks can help to address food insecurity and to build a more sustainable future.
This blog is based on a scientific paper published in Biodiversity and Conservation by Kew’s scientists and collaborators from Mexico.
Liu, U., Gianella, M., Dávila Aranda, P., Diazgranados, M., Flores Ortíz, C.M., Lira-Saade, R., Bacci, S., Mattana, E., Milliken, W., Mitrovits, O., Pritchard, H., Rodríguez-Arévalo, I., Way, M., Williams, C., Ulian, T. (2023). Conserving useful plants for a sustainable future: species coverage, spatial distribution, and conservation status within the Millennium Seed Bank collection. Biodiversity and Conservation, 1-49. DOI: https://doi.org/10.1007/s10531-023-02631-w; Shareable link: https://rdcu.be/dlyqp