Seed Banks​—A Race Against Time


OUR lives depend on plants. They are sources of food and clothing. They provide fuel, building materials, and lifesaving medicines. Animals, birds, and insects depend on them too. Yet, according to some researchers, a quarter of the world’s plants are in danger of becoming extinct within the next 50 years. A leader in the race against time is the Millennium Seed Bank Project.

Hailed as a “Noah’s Ark for plants” and “an insurance policy for the planet,” the $120 million building in southern England will safeguard hundreds of millions of seeds gathered from some of the world’s most endangered species.

What Is a Seed Bank?

Have you ever deposited your valuables in a bank for safekeeping until you need them again? A seed bank performs a similar function for plants. It is an easy, economical way of preserving any plant life bearing seed, from the tiniest herb to the tallest tree. Once banked, the seeds need very little attention. Most do not take up much space. A tiny glass vial holds a million orchid seeds! For numerous other species, as many seeds fit into an ordinary pickling jar as there are people in a city. After specialized treatment, these potential new plants can be safely preserved for decades or even for centuries, far longer than they would survive in the wild.

Seed banks are not new, though in the past they were used mainly for commercial crops. In 1974, scientists of the Royal Botanic Gardens, at Kew, in London, began studying how to conserve wild plant seeds at their branch at Wakehurst Place in the Sussex countryside. Having stored 4,000 different species from around the world, they realized that they needed a far larger enterprise to ensure against the earth-wide loss of plants and their habitats. So in 1998, Kew started building a larger seed bank on the grounds of Wakehurst Place.

Meeting the Goals

The first goal, even before completion, was to bank the seeds of all Britain’s trees, brambles, grasses, shrubs, and wildflowers by the year 2000. Out of 1,440 native species, 317 are threatened with extinction. Kew already had 579 species in the bank, and a team of over 250 professional and amateur botanists scoured the land to find the remainder. Enthusiasts climbed mountains, lowered themselves down cliffs, and waded through icy waters searching for elusive  plants. The deadline was met for all except a handful of rare specimens.

Since the year 2000, the main objective has been to collect and bank 1 in 10, or over 24,000 species, of the world’s seed-bearing flora by 2010, particularly those from the dry lands. A fifth of the world’s human population live in these hot, arid regions and depend on plants for survival, yet vast areas are being lost to deserts each year. Seed-collecting expeditions started in some countries at the beginning of 1997, and by February 2001, Kew’s seed hunters had collected 300 million seeds from 122 countries, leaving nearly 19,000 species still to bank.

Banking the Seeds

Gardeners and farmers have long collected seeds and stored them. However, seeds treated in the Millennium Seed Bank will live far beyond their natural life span. The secret lies in the way they are dried and frozen.

After seeds are collected in sufficient numbers and separated from surrounding material, they are placed in paper or cloth bags or even in soft-drink bottles to dry out before being sent to Britain. At the same time, the collectors prepare pressed specimens of the actual plants so that they can be formally identified at Kew, and the precise location where they were found is recorded by means of navigation satellites.

On arrival at Wakehurst Place, the seeds go through two vital drying stages separated by a cleaning session. Spending time in two rooms that have a successively lower relative humidity and are both drier than most deserts reduces their moisture content from at least 50 percent to about 5 percent. This ensures that they will not be damaged when they are frozen, and it slows their biological processes right down to a kind of suspended animation in which they can remain for a very long time. Before the seeds are banked, a few are X-rayed to see if they are healthy or have been damaged by insects. Another sample is  tested to see if they will germinate. In fact, every ten years samples will be nudged back to life to see if they are still viable. If fewer than three quarters of them germinate, new seeds will need to be collected.

Knowing how seeds respond to long-term storage and understanding how to germinate them later are key areas of research. Finally, the seeds are packed in airtight glass jars and taken below ground to one of two room-size freezers in a large concrete vault. There, stacked neatly on shelves, they begin their long sleep at a temperature of minus 4 degrees Fahrenheit [-20° Celsius].

Does the process work? Indeed it does. A few years ago, when 3,000 seeds of different plants that had been banked for a decade were tested, 94 percent of them germinated.

Some species present a problem. Their seeds die if their moisture content drops too low. Some oak (Quercus), cacao (Theobroma cacao), and rubber tree (Hevea brasiliensis) seeds are examples. But freezing them moist kills them because water expands and ruptures cell walls when it turns to ice. Scientists are researching techniques to overcome this hurdle. One possible solution is to extract the seed’s embryo, dry it rapidly, and store it in liquid nitrogen at an ultralow temperature.

Who Share the Dividends?

Like a financial bank, the Millennium Seed Bank makes payments. Samples of seeds are used for research. A quarter of medicines are derived from plants, but four fifths of the world’s flora have not yet been studied. What new remedies are waiting to be found? A Mediterranean species of vetch (Vicia faba) has provided a blood-clotting protein that helps detect rare human blood disorders. Perhaps new foods, fuels, or fibers will be discovered too.

Scientists from overseas stay at the Bank while learning about seed storage and germination techniques so that they can set up seed banks back home. Each country providing seeds retains a substantial proportion of them, and it will have an equal share in any research benefits and profits.

With seed samples being used to restore degraded lands and increase stocks of critically endangered species, the hope is that these conservation strategies will help to turn the tide of the world’s fast-disappearing flora and the many life-forms dependent on it.

 How Will the Race Be Won?

No one can doubt the serious situation mankind faces. Roger Smith, head of Kew’s seed conservation department, gives three reasons for the project: “The first is direct use. Do we know so much about every plant that if one is lost, we know what has gone in terms of its potential for food or medicine? The second is the web of life. Imagine all the world’s species forming a net, with each species a knot in the net. How many knots can you cut out before the net ceases to function? The strongest argument is stewardship. What right does the current generation have to take options away from future generations by not handing on the species it inherited?”

The challenges for the future are formidable. Project coordinator Steve Alton says: “You can have all the seeds in the world, but if there’s no habitat for those plants to go back to there’s no point in storing them.” Will it be possible to save these vanishing species as well as ensure responsible care of our planet?

The reassuring answer is yes. The Creator promises: “There will be the seed of peace; the vine itself will give its fruitage, and the earth itself will give its yield, and the heavens themselves will give their dew; and I shall certainly cause the remaining ones of this people to inherit all these things.”​—Zechariah 8:12.

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Kew Gardens is just one of the 1,300 seed banks around the world that are busily preserving seeds in deep freezers. Steve A. Eberhart, head of the National Seed Storage Laboratory in Colorado, describes that facility as a sort of “Fort Knox for plants.”


Millennium Seed Bank Project

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An important function of seed banks is to collect diverse forms of a crop and its relatives. This collection then provides a genetic pool from which to draw when combating outbreaks of new diseases or pests in that crop. By selectively breeding plants, scientists can improve the yield, nutritional value, and disease and insect resistance of crops. This genetic pool is becoming increasingly important.

Worldwide, more than 90 percent of mankind’s calorie requirements are now met by just 103 plant species, and more than half the global energy intake comes from only three major crops​—rice, wheat, and maize. Why is this a problem?

When a widespread crop is genetically similar, it becomes uniformly susceptible to a single disease or pest. The most famous example of the danger of genetic uniformity occurred in the 1840’s in Ireland. Back then the potato crop was wiped out by potato blight (Phytophthora infestans). This fungus triggered what is sometimes called the Great Famine and led to the death of 750,000 people.

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Dr. Peter H. Raven warned delegates at the XVI International Botanical Congress, held in the United States: “As many as 100,000 of the estimated total 300,000 species may be gone or on the way to extinction by the middle of the [21st] century.” A report from the Food and Agriculture Organization of the United Nations (FAO) states that the loss of diversity in our food crops already “has been substantial.” The major threat to plant diversity comes from an unlikely source.

The FAO report noted: “The chief contemporary cause of the loss of genetic diversity has been the spread of modern, commercial agriculture. The largely unintended consequence of the introduction of new varieties of crops has been the replacement​—and loss—​of traditional, highly variable farmer varieties.”

In China nearly 10,000 wheat varieties were in use in 1949. Today fewer than 1,000 are still in use. In the United States, nearly 6,000 varieties of apple trees have disappeared over the past 100 years, and 95 percent of the cabbage varieties as well as 81 percent of the tomato varieties have apparently vanished.

Warfare also causes the extinction of crop species when farmers are forced off their land for many years and local crop varieties die out. The UNESCO Courier noted: “Wars . . . have affected every country in the West African coastal zone of ancient rice agriculture. This region is a key centre for genetic diversity in African rice (Oryza glaberrima), which . . . can now be cross-bred with Asian rice, one of the world’s key food crops. It will be of global significance if this . . . little-studied African crop is a casualty of the regional warfare.”

Safer Than Seed Banks

John Tuxill, a researcher for the Worldwatch Institute, warned: “We are increasingly skillful at moving genes around, but only nature can create them. If a plant bearing a unique genetic trait disappears, there is no way to get it back.” Thus, millions of dollars are invested in keeping seeds safe in seed banks.

Safer still is the promise made by the Creator of these miracles of packaging, who long ago gave this assurance: “All the days the earth continues, seed sowing and harvest . . . will never cease.”​—Genesis 8:22.

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Seed collecting in Burkina Faso

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Storing at subzero temperature

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A botanist from Kenya learns how to check the moisture content of seeds

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All pictures on pages 24-7: The Royal Botanic Gardens, Kew