MORE THAN JUST SAVING SEEDS
Purpose
To discuss and evaluate the methods used by seedbanks in the conservation of endangered plants.
Seed banks
Students use video about the Millennium Seed Bank (MSB) that accompanies this activity, the Student Book and the MSB website to explore the role of seedbanks. Students should realise that as well as storing seeds, the seedbanks have a role in scientific research, in reintroducing species to the wild and in education. See the weblinks section for this activity.
The initial questions focus on viability and longevity. Crop plants have much greater longevity than wild species; the longevity of wheat has been predicted to be about 10 000 years. There have been claims that 3000-year old seeds found in Egyptian tombs remained viable. But there are doubts about the true age of these seeds.
Answers
Q1 Flowchart should appear similar to the one below.
Q2 Research has suggested that changes to the cell structure in seeds with ageing may lead to a loss of viability, for example, increased membrane permeability due to loss of phospholipids and fatty acids, reduced enzyme activity, DNA damage and degeneration of cell organelles, such as mitochondria, endoplasmic reticulum and Golgi apparatus.
Seeds cleaned
Seeds unpacked and checked Transfer to seedbank by courier
Seed collection
Seed identification checked
Seeds dried and packed
Seeds stored at –20 °C
Periodic germination trials to check on seed viability.
Salters-Nuffield Advanced Biology Resources
Activity 4.28 Teacher SheetQ3 a Seeds remain on, or buried in, the soil or associated litter and provide a natural seedbank. These seeds can replace adult plants that have been lost due to adverse conditions, disease, grazing or disturbance. Seeds must remain viable in the soil seedbank for long periods if they are going to be able to germinate when conditions are favourable – which may not be frequently. For example, in woodlands, some tree seeds may only germinate when a tree falls, creating a gap in the canopy and allowing light to enter to break the seed dormancy.
b Identifying those species with short-lived seeds allows better management of seedbank collections. Short-lived species viability may be tested more often. For some species, it may be decided that conventional seedbanking is not a suitable conservation method.
Q4 a The shortest-lived species on the graph is St John’s wort (Hypericum perforatum). The longest-lived is oil-seed rape (Brassica napus).
b The buttercup (Ranunculus sceleratus) has 95% germination at the start of the experiment compared with only 40% for the chrysanthemum (Chrysanthemum leucanthemum). Germination falls rapidly for the buttercup, with 50% germination after only four days of storage. Chrysanthemum had low viability at the start of the experiment, but it lost viability at quite a slow rate, taking 20 days to drop by half to 20% germination.
Q5 Seeds are collected that are endangered in the wild and/or endemic to their country or region, or are of economic use to people.
Q6 Several examples of seeds being used for reintroduction programmes are included in the MSB website. In the UK, the grass interrupted brome was last seen in the wild in 1971. A seed collection made in 1963 has been used to re-introduce the grass into the wild. In August 2004, 200 000 seeds were sown in a field in Oxfordshire where the plant successfully established and flowered. Damasonium alisma (star fruit), an aquatic herb found at muddy pond margins, is classified as endangered and was not recorded in the wild at all in 2006. The MSB holds seeds from four different UK sites. In 2001, Kew horticulturalists used seed to grow plants at Wakehurst Place, resulting in the harvesting of about 29 000 seeds. These have been used to re-introduce star fruit to pond margins on Greenham Common, Berkshire.
In South Africa, Erica margaritacea is classed as endangered and is restricted to one small area within a race course. Seed was collected in February 2004 and is being used in a reintroduction programme by the Cape Section of the Millennium Seed Bank project.
Q7 Capacity building is an important feature of conservation and reintroduction programmes. Global initiatives rely on local knowledge and expertise for identification and collection of seeds and, increasingly, for their storage locally. The economic and scientific priorities of each country must be considered alongside those of the MSB, so the process serves both local and international priorities. If the project did not serve an important and immediate local role, it might be more difficult to engage international resources and the sustainability of the project would be threatened.
Q8 A wide range of research is carried out by the MSB staff across the world. This includes seed studies to help understand seed storage and germination requirements. The seed collections have been used in plant biology and conservation research, including much applied research in medicinal and environmental applications.
The Millennium Seed Bank project educates professionals in the techniques of seedbanking and plant conservation. This is to allow other countries to participate in helping to protect their threatened plant species. Seedbanks also have a role in educating the public about the large number of threatened plant species and the threats to plant survival.
Q9 There are concerns that many of the animals in zoos are not endangered, but kept for crowd- pleasing reasons. There are also concerns raised about the success of animal reintroductions and suggestions that it would be better to use in situ conservation strategies rather than using zoos (ex situ). Concerns have also been raised about research on animals kept in zoos not mirroring the wild situation. These concerns are not apparent for seedbanks, assuming that the initial seed collection does not damage the plants and their habitat, and that the number of seeds collected does not threaten the survival of plants growing in the wild. Any reasonable arguments can be included.