ACTION BIOSCIENCE
Bookmark and Share

Plant Genebanks: Food Security

Geoffrey C. Hawtin and Jeremy Cherfas

articlehighlights

Genebanks are like an insurance policy for the future of agriculture, for they:

  • conserve the diversity of plant species
  • offer resources for breeding of hardier crop varieties
  • provide food solutions in times of disaster
  • safeguard food supplies for future generations

April 2003


Genetic Resource Center personnel inspect shelves of rice germplasm in a genebank. Photo: International Rice Research Institute.

They sit, on shelves, in drawers, stacked in massive walk-in refrigerators. In paper bags, metal canisters, and aluminum foil pouches. Some live brief lives in glass test tubes under artificial lights. Others are all but immortal, bathed in liquid nitrogen at 196 degrees below freezing. A few take their chances in wide-open spaces.

Plant genebanks aim to safely conserve plant diversity.

They are the deposits in the world’s plant genebanks, living samples of the plants that humanity depends on, as precious as life itself. The simple word genebank covers many possibilities, from massive collections stored in elaborate buildings to a simple field of a few labeled plants. Genebanks are ex situ collections. That is, they comprise samples stored off site, away from the environments in which they naturally grow. The primary purpose of all genebanks is the safe conservation of plant diversity. For example:

Over 100,000 rice varieties are stored in genebanks.
  • It may be the diversity of a single species and its wild relatives, for example the 100,000 or more samples of rice and its relatives, gathered from around the world and maintained by the International Rice Research Institute in the Philippines.
  • Or it could be a small collection of a few locally important fruit trees, like those being assembled by schoolchildren in Sarawalk, Borneo.
The Russian N.I. Vavilov pioneered plant genetic collections.

It is impossible to say exactly when the world’s plant genetic resources collections began: people have been collecting and conserving plants in botanical gardens for many hundreds of years. The greatest pioneer of the modern era was the Russian Academician Nikolai Ivanovich Vavilov (1887-1943). In a series of extraordinary and intrepid expeditions, mainly between 1916 and 1933, Vavilov and his many disciples collected more than 250,000 plant accessions from around the world. Vavilov fell foul of Stalin’s regime but his name has long been properly honored in the N. I. Vavilov Institute of Plant Industry (VIR) in St Petersburg, which houses one of the world’s most important genebanks.

Globally, genebanks maintain millions of plant samples.

Today, the Food and Agriculture Organization of the United Nations’ (FAO) World Information and Early Warning System on Plant Genetic Resources (WIEWS) lists about

  • 1,460 genebanks worldwide
  • including 465 in Europe, 468 in the Americas, and 298 in Asia

Between them, the world’s genebanks maintain more than 5.4 million samples — although many are duplicates, so the total of genuinely distinct accessions is considerably lower.

Food staples are prized crops for genebanks.

How genebanks work

Our most valuable food crops — wheat, rice, and maize, which together provide all humanity with half the calories needed — produce seeds that are easy to store. So do many other prized crops. For genebanking,

  • the seeds are merely cleaned, dried, and placed in a sealed jar or packet
  • for medium term storage (20 to 30 years), the seeds are maintained at the modest temperature of 5°C
  • for long-term storage (up to 100 years) they are kept at -18 to -20°C
Seeds, if cooled and dried properly, can remain viable for many years.

Cool, dry seed should remain viable (capable of germination) for many years, and in some cases for decades or even centuries. But viability does decline over time, so the seed must be planted and grown out every few years to provide a fresh stock. The plants need to be cultivated carefully, and isolated so that they do not pick up pollen from any surrounding plants and so become genetically ‘polluted.’ All this is technically straightforward but, of course, adds to the expense of conservation.

With some plants, however, including some of the crops most important to people in developing countries, the technical problems are not so easy to solve.

Nature designed tubers to be storage organs.
  • Many vital crops — among them potatoes, yams and cassava — are not generally propagated by seeds. Instead, farmers grow them from tubers or rhizomes or other storage organs. Potatoes, yams, cassava and others can reproduce sexually, as well, to produce true seed; but when they do, they shuffle their genes so that the potatoes or yams that grow from true seed are not genetically identical to the plants that produced them. The particular qualities of a particular variety are lost unless the tubers themselves are stored. Nature designed tubers to be storage organs, and although it is not technically difficult to keep them, albeit for the short term, tubers take up much more space than true seed and must, in general, be regenerated (replanted) much more often.
In vitro genebank: cells, grown on a gel, give rise to entire plants.
Cryopreservation: freezing cells in liquid nitrogen.
  • Other plants raise even greater difficulties. Many cultivated bananas and plantains produce no seed at all — they are sexually sterile. And they do not produce natural storage organs either. They are propagated by some form of cutting or offshoot. Traditionally, farmers simply keep their preferred varieties of bananas and plantains in the field by propagating them year after year. Varieties can also be conserved as whole plants in field genebanks. But, if only for safety’s sake, keeping them ex situ is desirable, too. Although it is clearly a challenge to store plants that produce neither seed nor natural storage organs, the technical problems have largely been solved. Since the 1960s, it has been possible to keep plants in an in vitro genebank: cells are grown on a gel and fed with suitable nutrients and hormones to give rise to entire plants. In addition, it is becoming more and more possible to store cells for long periods by cryopreservation, a specialized form of freezing in liquid nitrogen at -196°C.
Some plant seeds require sophisticated methods of genebanking.
  • Finally, a wide range of plants and particularly tropical trees produce seeds that are in various ways ‘recalcitrant.’ For example, the seeds of some tropical trees germinate while still on the parent: the ‘seed’ that drops to the ground is already a seedling. Recalcitrant seeds cannot be stored simply by drying and cooling. Indeed, they regard such treatments as a severe insult and quickly die. They require more sophisticated methods, which to a large extent must be tailored individually to their needs. The special problems associated with conserving these species adds to the expense.

Why are genebanks so important?

Genebanks remain necessary as the loss of biodiversity continues.

One reason to conserve crop diversity in genebanks is that crops are under threat elsewhere. Habitats continue to be destroyed by unsustainable human activity, and along with the habitats go the plants. One of the threats to diversity is advanced agriculture. As new varieties become available, and are taken up by farmers because they offer genuine benefits, they may displace the diversity that was there before. This is especially ironic because all advanced breeding is built on existing diversity, which makes it imperative that this diversity be conserved and remains available somewhere.

There are many, many instances of breeders finding the solution to some problem besetting agriculture in a genebank. One example: the Hessian fly is an insect pest that can devastate wheat crops worldwide. Estimates of the cost of damage vary widely.

Plant breeders use genebank resources to cultivate hardier plant varieties.
  • In one year, wheat farmers in the United States lost an estimated $100 million.
  • In Morocco, a hotspot for Hessian fly attacks, damage costs total more than $300 million a year, which the country can ill afford.

Resistant varieties can reduce the damage to less than 1%. To create them, breeders in the U.S. and Syria explored samples of wheat and its relatives held in genebanks. They found 15 new sources of resistance, and used them to generate new resistant varieties of wheat that help farmers in Morocco, the U.S., and everywhere else that the Hessian fly is a problem.

Genebanks also provide resources in times of agricultural disaster.

Meeting the needs of breeders is thus one important function of genebanks. But increasingly genebanks are fulfilling additional roles. In the aftermath of disaster, natural and human, they are a repository not only of the seeds farmers need, but also of essential skills and knowledge. Take the case of Rwanda:

  • Seeds of Hope was a coalition of 16 international and 9 national research centres, which moved in to help restore agriculture after the end of the genocide in Rwanda. At one point in 1994, when the war escalated, 800,000 people were killed and another 2,000,000 displaced in just two months.

  • Agriculture, the occupation of more than 90% of the Rwandan people, was acutely affected, with the disruptions peaking at the height of the growing season. The world worried about the loss of the harvest, estimated at 60%, and the hunger that would follow.

  • But concern also focused on the risk to one of Rwanda’s unique national treasures: the diversity of its beans. Rwandans grew the greatest range of varieties anywhere in the world: at least 600 different types in a country no larger than Switzerland. In their genebanks, some members of the Seeds of Hope consortium held collections of Rwandan bean varieties. Among many other activities, Seeds of Hope prepared to restore crop varieties to the farmers from whom it had been collected in the first place. The consortium multiplied 1.5 tons of seed of more than 275 different varieties.

The experiences in Rwanda have guided more recent efforts to restore agriculture, for example in Afghanistan. After war and the worst drought in 40 years, a new consortium was established to supply seeds and know-how. Much of the seed came from genebanks holding varieties collected in Afghanistan. Genebanks are now an important component of the response to wars, hurricanes, drought, and disaster.

Genebanks promote agricultural growth and exchange.

Genebanks are also finding a role in improving the livelihoods of poor farmers directly. Diversity is one of farmers’ great strategies for survival. Farmers who grow a diversity of species buffer themselves against a disaster that destroys one species. And a diversity of varieties of a single species makes better use of different environmental conditions. Having sometimes lost their local varieties, for example after adopting new and improved crops, farmers can turn to genebanks for new material to try. This has been a factor in the spread of better varieties of taro, a starchy root crop that is also grown for its leaves, across the many small island states of the Pacific. Genebanks have organized diversity fairs at which farmers gather to exchange varieties and the know-how associated with them.

All is not well

There remain major gaps in collections and global management standards.

On the face of it, the state of the world’s collection of crop plant genes seems encouraging. Growth has been rapid over the past two decades (there were only about 54 genebanks worldwide at the end of the 1970s) and the total number of accessions under conservation, which runs into millions, seems impressive. But there are major gaps in the present collections, particularly among crops that need to be stored as tubers, such as cassava. Furthermore, many existing genebanks fall short of world standards for genebank management.

Ideally, genebanks should meet three criteria — they should be able to:

  • store accessions over the long term
  • duplicate and regenerate the material as required
  • have the capacity to document and store information about the plant material in the collections
Technical storage problems persist in some areas.

However, in 1998:

  • 75 countries said they had facilities to store seed in the medium or long term — but fewer than half (35) of these were able to meet agreed-upon international management standards.
  • The rest reported a lack of facilities for drying seeds, problems in maintaining equipment, and unreliable power supplies.
  • Another 56 countries said that their facilities were suitable only for short to medium-term storage.
Global agricultural resources are not as secure as they should be.
Conclusion: Countries need to unite to ensure that genebanks remain a solid insurance policy for the future of agriculture.

In short, the world’s most important agricultural asset is nowhere as secure as it should be. The work needed to conserve plant diversity must be given assured and unassailable financial underpinning forever. Unfortunately, this has proven politically difficult. Support for long-term caretaker activities can be precarious and difficult to justify, especially from a narrow-minded and short-term economic standpoint. Yet when it comes to rebuilding a shattered country’s economic base, or when a single sample among 50,000 contains exactly the traits that farmers need, the value of genebanks is almost literally impossible to calculate. From that point of view, genebanks are like an insurance policy for the future of agriculture, and that is part of the problem. When times are hard, skimping on insurance can seem a good idea. Indeed, some people choose not to insure their possessions at all. That may be fine if their possessions are easily replaced and their children have no expectations. But crop diversity, once lost, is impossible to replace.

Fortunately, countries have come together under the Food and Agriculture Organization of the United Nations (FAO) to endorse a plan to create an endowment, the Global Conservation Trust, which provides a permanent source of funding support for the precious deposits of diversity held in genebanks. Funding for the endowment is still needed, but the Trust has at least made a start at protecting the genebanks that protect our future.

Jeremy Cherfas, Ph.D., is a biologist, science writer, and broadcaster with an involvement in several organizations, including the Documentation, Information And Training Group for IPGRI headquarters, Italy, the Biotechnology and Biological Sciences Research Council of the UK, and Elm Farm Research Centre, UK. His books include The Hunting of the Whale: A Tragedy That Must End (1990), Seed Saver’s Handbook (1996), and Essential Science: Human Genome (2002, with John Gibbon).

Plant Genebanks: Food Security

BioScience Article

“A Century of Crop Improvement: From Vavilov to Biotechnology.”
In this May 2009 article, BioScience author, Carol Auer, reviews two books that present very different stories about crop improvement over the last century; however, they explore similar themes, such as the role of science in food security, the concept of food democracy, the role of government in food production, and the importance of public trust in agriculture. Free to read.
http://caliber.ucpress.net/doi/full/10.1525/bio.2009.59.5.11

Bioversity International (formerly IPGRI)

“Bioversity is the world’s largest international research organization dedicated solely to the conservation and use of agricultural biodiversity.”
http://www.bioversityinternational.org/

Food and Agriculture Organization of the United Nations (FAO)

“FAO is one of the largest specialized agencies in the United Nations system …and has worked to alleviate poverty and hunger by promoting agricultural development, improved nutrition, and the pursuit of food security.”
http://www.fao.org

Consultative Group on International Agricultural Research (CGIAR)

“CGIAR is an association of public and private members supporting a system of 16 Future Harvest Centers that work in more than 100 countries to mobilize cutting-edge science to reduce hunger and poverty, improve human nutrition and health, and protect the environment.”
http://www.cgiar.org

The Global Diversity Trust

An activist site with information about the importance of plant genebanks.
http://www.croptrust.org/main/

Gene Conserve

“An electronic journal devoted to conservation of crop genetic resources with emphasis on cassava.”
http://www.geneconserve.pro.br/

Local Harvest

Here is a way for the food buying public in the U.S. to create a relationship with a farm and to receive a weekly basket of produce. Click on the map to find a participating farm in your area.
http://www.localharvest.org/csa/

Visit a botanical garden

Botanique is “a portal to over 2400 botanical gardens, arboreta, and nature sites” in Canada and the United States. Visit and learn more about plants and their benefits.
http://www.botanique.com/

ActionBioscience.org original lesson

This lesson has been written by a science educator to specifically accompany the above article. It includes article content and extension questions, as well as activity handouts for different grade levels.

Lesson Title: Maintaining Plant Genebanks
Levels: high school - undergraduate
Summary: This lesson explores the benefits and problems of maintaining plant genebanks globally. Students can plan a genebank or agricultural cryopreservation business venture, write a biography about a famous botanist, present views at a genebank symposium for developing nations… and more!

Download/view lesson. (To open the lesson’s PDF file, you need Adobe Acrobat Reader free software.)

Lessons for middle school

The following links will take you to middle school lessons available on other web sites:

Useful links for educators

  • » APSnet Education Center
    The APSnet Education Center is free and has sections for K-12, Introductory and Advanced Plant Pathology, which include materials with broad applications in biology and microbiology. The K-12 section includes monthly “News and Views” and complete lab exercises.
    http://www.apsnet.org/edcenter/Pages/default.aspx

Useful links for student research

In addition to the links in the “learn more” section above:

General References:

  • » Cooper H.D., C. Spillane and T. Hodgkin. 2001. Broadening the Genetic Base of Crop Production. CABI (Cab International ), FAO (Food and Agricultural Organization of the United Nations), GRST (Genetic Resources Science and Technology Group), IPGRI (International Plant Genetic Resources Institute).
  • » Engelmann, Florent and Hiroko Takagi, ed. 2000. “Cryopreservation of tropical plant germplasm: current research progress and application.” Proceedings of the JIRCAS/IPGRI Joint International Workshop, Tsukuba, Japan, 20-23 October 1998. International Plant Genetic Resources Institute, pub.
  • » Engels J.M.M., et al. 2002. Managing Plant Genetic Diversity. The proceedings of the conference on Science and Technology for Managing Plant Genetic Diversity in the 21st Century. Pub. By GRST (Genetic Resources Science and Technology Group), IPGRI (International Plant Genetic Resources Institute).
  • » Johnson R.C., T. Hodgkin (eds.) Core collections for today and tomorrow. 1999. GRST (Genetic Resources Science and Technology Group).
  • » Richards, Paul and Guido Ruivenkamp. 2001. “Seeds and survival: crop genetic resources in war and reconstruction in Africa.” A report commissioned by the International Plant Genetic Resources Institute (IPGRI) and the Joint Working Group on Technology and Agrarian Development, Agricultural University, Wageningen. Revised version.
  • » Vavilov, N.I. 1996. Five Continents. IPGRI (International Plant Genetic Resources Institute).

Advertisement



Understanding Science