7 November 2024
Monkeys at the Millennium Seed Bank
Conserving the UK's threatened orchids through seed banking and DNA sequencing
Take a close look at the monkey orchid (Orchis simia) and you’ll understand why it was named that – its petals are shaped like little monkeys!
These stunning plants are native to the UK, but it’s unlikely that you would have the chance to see one of these beautiful flowers in real life unless you were specifically searching for them. They are a threatened species here, only found in isolated spots in Kent and Oxfordshire.
Conserving the monkey orchid
A group of Kew scientists went searching for these orchids in deepest Kent, with a mission: to collect their seeds and take them back to Kew’s Millennium Seed Bank (MSB) at Wakehurst. There, seeds from across the world are stored so they can be regrown and reintroduced if their species go extinct in the wild. The collections are also made available for scientific research.
The UK’s native flora is very well represented in the MSB’s collections – over 98% of native bankable plant species' seeds are stored there. This impressive breadth of collection is the result of a great deal of time and effort from scientists.
Some of the UK seed collections currently in the MSB have come from just one location which means they may not capture the full genetic diversity of a species.
The UK Threatened Flora Project aims to add to the existing collections, by collecting seeds from populations of threatened plants in different locations to maximise the genetic diversity conserved in the MSB.
What is genetic diversity?
Every species has a lot of diversity within it – each individual is different. This is easier for us to recognise in humans – we're all the same species but have different heights, hair colour, eye colour etc. This is largely due to slight differences in our genetic code – genetic diversity.
The same principle applies to monkey orchids and every other species – a population found in Oxfordshire might be very genetically different to one found in Kent!
Higher genetic diversity enables a species to adapt to different environments. If we want to reintroduce or conserve a threatened plant, then growing individuals from seeds collected from different populations could increase the ability of the species to survive.
Sequencing the monkey orchid genome
To make the best use of genetic diversity in our conservation work, we need to understand where that diversity arises from and what it looks like. To do that, we have to study the DNA of the species we’re interested in.
The team’s search for the monkey orchid was not just for seed collection, but also to collect living tissue for DNA sequencing.
A challenge here is that the monkey orchid has been found to hybridise with closely-related orchid species – either the ‘lady orchid’ (Orchis purpurea) or the ‘military orchid’ (Orchis militaris) – if they are growing near each other.
The Kew team wanted to make sure that the DNA they sequenced was just that of the monkey orchid, so they had to find a population that was far away from these other species. This is, thankfully, true of the population in Kent, although not in Oxfordshire.
The sequencing effort is part of the Darwin Tree of Life project, which aims to sequence the DNA of all c. 70,000 UK species. The data will be made free to use by all, providing scientists with an open access resource for more research, and helping catalogue and conserve the biodiversity that exists in the UK.
Monkeying around at the MSB
Once the monkey orchid seeds make it to the MSB, they must be cleaned and assessed before storage. Orchid seeds are tiny, with some as small as a speck of dust, so cleaning them is a difficult task!
When clean, they are tested for viability using a fluorescent dye – if the seeds glow green under ultraviolet light, then they’re alive and capable of growing up into the next generation.
This sample of monkey orchid seeds was found to be 86% viable, which is a good result. Collectors were careful not to sample more than 20% of the available seed from the plants; this amounted to ~42500 viable seeds.
The seeds were then gently dried and frozen, some at -20°C and some at a whopping -196°C, before being placed in the MSB’s vaults. This treatment extends their lifetime, so they can be defrosted many years down the line and grown up into new monkey orchids.
Beyond the monkey orchid
So far, over 1,480 genomes have been sequenced as part of the Darwin Tree of Life, and since 2020 the UK Threatened Flora project has made 503 new collections of priority threatened species, totalling almost 4 million seeds.
Sixty of these collections are from plants that can only be found in the UK, and fifty-four species have now been comprehensively sampled, meaning the MSB holds seeds from every area of the UK they grow in.
The scientists do not only collect seeds, they also research how to germinate and propagate these threatened species. The majority of collections are germinated in the laboratory as part of routine viability assessments, and some have also been grown on in the nursery at Wakehurst.
So far, the team have put together detailed protocols for growing twelve of these threatened species from seed, which are available here, under 'UKTFP propagation protocols'.
Some of the seedlings grown at Wakehurst as part of this research have been donated to conservation practitioners working to protect these threatened species.
Field wormwood (Artemisia campestris) is an endangered species in the UK, growing only in one region of East Anglia, and is the only food source of the nocturnal wormwood moonshiner beetle.
In March 2024, field wormwood plants which had been grown from seed by MSB horticulturalists were donated to a conservation project managed by Natural England, Plantlife and Buglife. These plants have been reintroduced into areas where they used to grow, ensuring the survival of both the plant itself and the beetle that relies on it for food.
Kew has also donated seedlings of petty whin (Genista anglica) – a spiny shrub with beautiful yellow flowers and nitrogen boosting properties for the soil it grows in – to Natural England in Cornwall, where they will be planted in the same locations the seeds were originally taken from to enhance the populations there.
You can spot a few of these plants in Kew’s alpine meadow!
Looking to the future
The UK is one of the most nature-depleted countries on earth, with only half of its native biodiversity remaining (compared to a world average of 75%), but with a concerted effort to catalogue and conserve the biodiversity that remains, we can turn the situation around.
The Kew team is hard at work collecting seeds and DNA samples from hundreds of UK species, so that we can protect and conserve plants like the monkey orchid for years to come.
.jpg0084.webp "A closeup of Steveniella satyrioides flowers from a day of more pleasant weather © Anush Nersesyan")