Banking on Seeds
The Millennium Seed Bank Project and Other Projects Worldwide
By Steven Foster

Seed banks are a survival strategy for humans and the plants on which we depend. They allow the opportunity for reintroduction of species should a catastrophic natural event affect a key ecosystem somewhere in the world.

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What is the difference in the needs of a human in a space capsule bound for Mars and a simple seed? Besides the obvious, the creation of a seed by a living plant and its dispersal to the earth beneath is little different in the basic requirements for survival than that of the astronaut. The living embryo of the seed is encased in a capsule suitable to the environment, much like an astronaut tucked away in a space. The astronaut and the seed have similar survival needs – water, oxygen, and food stores.

Seeds are so much a part of our daily lives that we tend not to give them a second thought, yet seeds provide as much as 75 percent of the food consumed by humans worldwide, in the form of corn, rice, wheat, and other grains. What would happen if an asteroid or other catastrophic event hit a particular part of the world and destroyed all the genetic information held within the seeds for native plants that might be endemic to that region?

Seed scientists have been asking that basic question and the solution, created only within the last 110 years, is the seed bank. Seed banks are repositories of the genetic information held in plant species of specific interest to organizations or institutions that collects and stores the seed. The world’s first and oldest seed bank is the N.I. Vavilov All-Russian Scientific Research Institute of Plant Industry.

Begun in 1894, the Institute became a repository of the seed collections of the botanist and geneticist for whom the Institute is named— Nikolai I. Vavilov, who became a famed collector of food plant seeds from around the world. He was regarded as the leading plant geographer and food plant geneticist of his day, collecting seed of food plants in over sixty countries and laying the foundation for the world’s first seed bank. He became the Institute’s director in 1917.

Vavilov is a Russian national hero and a tragic victim of the Stalinist Soviet Union. He fell into disfavor with Stalin, when Stalin’s protégé and Vavilov’s former student, Trofim D. Lysenko, denounced him. Stalin imprisoned Vavilov in 1940 and he died in the Soviet prison at Saratov, the town in which he was born.

Today, the institute’s collection represents over 380,000 gene types of 2,500 plant species. The seed bank at the Vavilov Institute set the stage for a development of new scientific disciplines of seed storage and germination theory in practice eventually leading to development of seed banks worldwide holding genetic information for food plants, ornamentals, and native plants. Seed banks are a survival strategy for humans and the plants on which we depend. They allow the opportunity for reintroduction of species should a catastrophic natural event affect a key ecosystem somewhere in the world.

"If the comet comes and knocks out the National Wildflower Center," Flo Oxley, the Center’s Conservation Officer, explains, "We have the seeds stored elsewhere for possible reintroduction."

The Austin, Texas-based National Wildflower Research Center is sending seed collections of Texas native plants to the U.K. for safekeeping. According to Flo Oxley, the "Wildflower Center is a partner with the Millennium Seed Bank Project (MSBP) at the Royal Botanical Garden at Kew. The species collected are not the rare and endangered species, but the more common plants such as Texas Blue Bonnet (Lupinus texensis) and Indian paint brush (Castilleja indivisa). The collection represents more common species typical of the habitat that they occupy."

The Millennium Seed Bank Project is an international plant conservation initiative with collaborators throughout the world. The aim is to safeguard 24,000 plant species from around the globe against extinction by collecting and storing seed ex situ at the Project’s headquarters at the Wellcome Trust Millennium building at Wakehurst Place in West Sussex, England. The Royal Botanical Gardens, Kew, Seed Conservation Department staff the project.

The first part of the effort focused on collecting native plants of the UK, and to date, seed has been collected and preserved from over 90 percent of the UK’s flowering plants, representing the largest national collection of its type anywhere in the world.

Dr. Oxley states, "In addition to storing seeds, they are also researching seed biology and physiology, as well as conservation. They are the world leaders, the leading experts in seed biology and seed physiology studies. The goal is to collect seeds of 10 percent of the world’s flora by 2010."

The National Wildflower Research Center is a collaborating organization for the MSBP international program to collect seeds from arid and semi-arid lands throughout the world. Arid lands cover as much as one third of the earth’s land surface. The MSBP is collaborating with institutions and organizations in Australia, Chile, Egypt, India, Jordan, Kenya, Lebanon, Madagascar, Mexico, Namibia, South Africa, the U.S., and other countries. Collaborating institutions share duplicate seed storage, data exchanges, and technology transfer especially for collaborators in the developing world.

Carol Spurrier of the Bureau of Land Management is spearheading an effort with Kew to collect seeds from other parts of the U.S. for the seed bank. The program, ‘Seeds for Success’ brings government and non-governmental partners together through the Plant Conservation Alliance to collect seeds for possible future restoration efforts. Student conservation teams are working out of five western BLM offices to collect seeds. The goal is to provide duplicate collections of at least 4,400 native American plant species to the MSBP collections.

The Federal government established programs in the early 20th century to address plant genetic resources issues. The United States Department of Agriculture is involved in national and international efforts aimed at storing important genetic resources, through The National Center for Genetic Resources Preservation, a USDA Agricultural Research Service facility located on the campus of Colorado State University in Fort Collins. The Center’s mission is "to acquire, assess, preserve, and provide a collection of genetic resources to secure the biological diversity that underpins economic and environmental sustainability of agriculture through research, stewardship, and communications."

The mission of the work of the Seed Viability and Storage Research Unit, within the NCGRP’s National Seed Storage Laboratory is "to effectively document, preserve, and maintain viable seed and propagules of diverse plant germplasm in long-term storage, to develop and evaluate procedures for determining seed quality of accessions, and to provide administrative support to allow for effective operation of this Unit. The mission also includes the distribution of seed, when not available from the active collections, for crop improvement through the world."

The National Seed Storage Laboratory is like a combination between a hospital neonatal intensive care unit and a high tech bank vault. The NNSL receives seed and plant materials from all over the United States and foreign countries. The collection is the foundation of the U.S. National Plant Germplasm System. When seeds or other propagules arrive at the center, they are held in a quarantine center, inspected, and treated for any suspected disease microorganisms or insect infestations before they enter the vaults or a distributed to other sites. After passing through the quarantine process, seed samples are assigned accession numbers, germination cards and bar-coded labels. They are then placed in a special equilibration room for a few weeks in order to stabilize the moisture content at 25 percent relative humidity at a temperature of 5° C (41°F). Once stabilized, seeds are cleaned with special seed blowers that help to separate chaff, weed seeds or other contaminants, so that only pure seed remains in the lot.

Next, lab technicians perform standard tests to determine how many of the seeds are alive, followed by tests for viability. All samples are also tested for the seed lots’ ability to survive storage in a liquid nitrogen cooled environment where temperatures dip to –160° C (-320°F). Once all these tests have been performed, information on moisture content, cleanout and seed counts are recorded and the results are uploaded to the Genetic Resource Information Network (GRIN) at USDA. Depending upon the type of seed, size of seed, number of seeds in each lot, and the viability of the sample, they are tagged for storage in the facility’s conventional vault or its deep-freeze cryogenic storage facility. Seeds to be stored in the conventional vault are transferred to heat sealable, moisture-proof, foil-laminated bags. The bags are marked inside and out with a barcode for their location and a serial number for the lot. They are then heat sealed and ready for storage.

Seeds that are destined for cryogenic storage are placed in clear tubes made of a special plastic, and closed with plugs made of birch wood. The filled tubes are labeled with serial numbers and bar codes then placed in metal boxes, ready for a trip to the deep freeze.

The seeds are now ready for placement in the conventional vault or cryogenic storage vaults. The 5000 sq ft. vault which holds the bulk of America’s national seed collections is a self-contained structure in Fort Collins built to withstand flooding, tornados, and a 2500 pound object traveling at 125 miles per hour. The facility also has a special air handling unit and electrical generator in case of emergencies. The vaults have a capacity to store 1.5 million seed samples. Half of the facility has conventional vaults used to store seeds at –18°C (-64°F). Here, a moveable rack system, which increases the effective storage space by 60 percent, has plastic shelves on which samples are stored. The other half of the facility is designed for cryogenic storage, in which up to 224 storage tanks hold up to 330 metal containing tubes of seed samples.

Periodic testing and retesting is performed on the samples to make sure they remain viable. Despite the laborious steps taken to store the seeds, the life expectancy of the viable seeds is estimated at only 20 to 50 years. Scientists have conducted seed viability and longevity experiments since the mid 1800s. Stories abound of seeds from ancient Egyptian tombs germinating after thousands of years of storage, though most are discredited because of lack of clear scientific evidence of the seed’s age or origin.

Not surprisingly, claims for the oldest viable seeds are hard-coated seeds of the legume family. Seeds of the arctic lupine (Lupinus arcticus) found buried and frozen in the Yukon and later in Alaska were carbon-dated to an age in excess of ten thousand years. This is the rare exception, rather than the rule, however, where unusual right conditions have persisted over a long period of time. Longevity of seed viability is determined by factors in storing seed such as temperature, moisture content, possible insect or microbial infestations, and the simple passage of time.

Flo Oxley adds, "Seed banking is a relatively new tool in the conservation tool box. It’s relatively inexpensive and effective. What this means is that people in a particular region can store genetic information relatively inexpensively for a long period of time. You’re creating a genetic insurance policy for the flora over a long period of time and that’s a good thing."

Guidelines for Gardeners to Collect and Store Seeds

1. Collect seeds only after they have matured and ripened. Most seeds will continue to develop, if harvested early, but proper timing of harvest improves viability and vigor.
2. Dry and clean seeds. Chaff and other extraneous matter should be carefully removed. This can be done in the kitchen with different size sieves. You have to experiment to get seeds cleaned. If you wash them, make sure they are air dried before storage.
3. Storing Seeds: Seeds are best stored in a cool, dry place, with relatively low humidity. Typically a refrigerator will suffice for storing seeds for a year or two. There are a few rules of thumb to keep in mind for seed storage.
• A) Storage life of seeds is doubled for each 1 percent decrease in seed moisture.
• B) Storage life of seeds is also doubled for each 10° F decrease in temperature.
• C) Do not exceed 100 percent of the sum of the relative humidity and the storage temperature in degrees Fahrenheit. Most household refrigerators store food at about 40° F, so the relative humidity should not be more than 60 percent. If stored at room temperature of 72°F, the relative humidity would have to be a dry 28 percent maximum.

A simple, easy way to store seeds? Simply put cleaned, dried seeds in a paper envelope, then seal them in a freezer bag (after squeezing out the air) and stick them in the back of the refrigerator for the next season. If available, add a little silica gel desiccant to help wick away moisture.

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