Banking on Seeds

by | Aug 1, 2003 | Conservation

DURING THE WINTER OF 1941-42, while Hitler’s troops were blockading Leningrad, nine Russian seed biologists gave their lives to protect the contents of the Vavilov Institute of Plant Industry, the world’s first and oldest seed bank. As thousands starved during the terrible winter, the dedicated seed biologists prepared a sample collection of plant seeds that was later smuggled out of Leningrad to a safe storage facility in the Ural Mountains.

The remaining collection was prepared for long-term storage and placed in only the most secure rooms of the institute. Keys to those rooms were securely locked in a safe. As the winter went on, the seed biologists succumbed one by one to starvation, each refusing to eat from any of the secured seed collections. When the siege ended in January 1944, the bulk of the collection was preserved.

Today, the Vavilov Institute (established in 1894 and named for the famed botanist and geneticist Nikolai I. Vavilov) represents more than 380,000 gene types of 2,500 plant species. Many of today’s crops are the result of cross-breeding with the seed varieties saved during that long, brutal siege – seeds the Russian biologists gave their lives to protect.

With nearly as much fervor, the 110-year-old tradition of seed banking continues today. Seeds are so much a part of our daily lives that we tend not to give them a second thought. Yet seeds – in the form of corn, rice, wheat, and other grains – provide as much as 75 percent of the food consumed by humans worldwide. It is hard to imagine what would happen if an environmental disaster destroyed all the plants native to a particular area and with them the priceless genetic information held in their seeds.

As repositories for this genetic information that comes from thousands of generations of evolution and breeding, seed banks are insurance that in the event of such a disaster we still can access the seeds of plants needed for human health and survival.

Plant Insurance
In the absence of a natural crisis, seed banks still are critical for conservationists. Seed banking is of specific interest to organizations that work with endangered species and threatened habitats because it allows conservationists to store seeds for study or safekeeping – seeds that could be used in the future to help restore damaged or destroyed habitats, or to increase numbers of rare and endangered plants in the wild. In fact, for many rare and endangered native plant species, seed banks are an insurance policy against possible extinction in the wild. Stored seeds also can be used in scientific research to find new ways for plants to benefit society such as in medicine, agriculture, or local industry.

Seed banking is a relatively simple and inexpensive way to preserve the important genetic diversity of plants. Seeds are collected from the wild and placed in paper bags. The collections are returned to the lab, where they are sorted, cleaned, and dried. They are then placed in aluminum foil bags, sealed, and stored in freezers. Larger seed-storage facilities employ a more sophisticated approach to these steps, but in general the process of cleaning, drying, and freezing seeds is the same.

This process of safeguarding seeds is an important conservation method at the Wildflower Center. “Seed banking gives us a hedge against possible extinction in the wild,” Flo Oxley, the Center’s conservation officer, explains, “If a species becomes extinct in its natural habitat, we have the genetic resources available for possible reintroduction.”

There are other benefits of seed banking, especially as a backup to the preferred in situ (on-site) method of conservation. Pressures on the environment are so great in many areas that it is not always possible to conserve plants in their natural habitats. While we cannot always guarantee the safety of a plant in even the best-protected nature reserve, plant seeds can be kept safely for hundreds, sometimes thousands, of years in a seed bank.

Project for the Millennium
For conservationists and to the world of seed banking, the new millennium brought with it a project of unprecedented significance and magnitude. The Millennium Seed Bank Project at the Royal Botanic Garden, Kew is a global plant conservation initiative with collaborators from developed and developing nations throughout the world. So far there are 16 countries involved in the project.

The Wildflower Center is among the participants. Its partnership with RBG Kew forms part of the national Seeds of Success program, established by the Bureau of Land Management, the Plant Conservation Alliance, and RBG Kew under the MSB project. The role of Seeds of Success is to coordinate seed collecting in the United States and in the future to make available seed samples for restoration.

After approximately 30 years of work by RBG Kew, the MSB now holds the largest and most diverse collection of wild species in the world, including 90 percent of the flora of the U.K. The MSB currently holds some 13,000 collections of more than 5,000 wild species from all over the world. Seeds are brought to the Wellcome Trust Millennium Building at Wakehurst Place, United Kingdom, where they are stored ex situ (off-site). The MSB aims to safeguard 24,000 additional plant species from around the globe and to have collected seeds of 10 percent of the world’s flora by 2010.

A staff of 40 RBG, Kew conservation experts oversees the project at Wakehurst. When seed collections arrive at the MSB’s multi-room facility, they undergo an intensive, high-tech seed banking process that helps ensure that – depending on the plant species – seed collections will last hundreds to thousands of years.

Before being dried and then frozen, seeds are meticulously cleaned – often by hand with the use of sieves to reduce damage to the seed and also by using an aspirator to winnow debris from heavier, filled seeds. Seeds then undergo X-ray analysis to determine the proportion of malformed or insect-damaged seeds.

To maximize seed longevity, most seed banks (including the MSB) use a combined process of drying and freezing the seeds that is effective for most plant species. Many seed banks dry the seeds within fairly cool conditions that are made possible by chemically drying the air within the drying room. Moisture is thus pulled out of the seed into the “moisture-hungry” air (11-15 percent humidity and 59-64 F). At the point at which equilibrium is achieved with no net movement of moisture either into or out of the seed (usually less than one month), the seed is packaged into airtight containers and then transferred to the MSB’s cold rooms kept at -4 F.

Michael Way, of the RGB, Kew international team for the MSB, says what is most unique about the project is not the storage method but the level of cooperation involved. “Partners in the Seeds of Success program use common collecting protocols to make really high-quality seed collections that will be invaluable resources for the future, especially for restoration efforts,” Way says.

Oxley, who oversees the Wildflower Center’s participation in the project, says it has begun collecting plant species on its own land holdings and will progress to the wider Edwards Plateau and to the Texas Blackland Prairie.

“The species collected by the Center for this project are not the rare and endangered species, but the more common plants such as Texas bluebonnets (Lupinus texensis) and Indian paintbrush (Castilleja indivisa),” Oxley says. “The collection represents more common species typical of the habitat that they occupy.”

The Center collaborates in the MSB’s effort 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 MSB 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 send duplicates of the seed collections to the MSB and benefit from data exchanges, training opportunities, joint research, and technology transfer.

The Center – the only Texas garden to participate in the MSB – shipped its first batch of seeds in summer 2002. Seeds sent included common Texas plants such as prairie verbena (Glandularia bipinnatifida), black-eyed Susan (Rudbeckia hirta), agarita (Mahonia trifoliolata), pink evening primrose (Oenothera speciosa), Indian blanket (Gaillardia pulchella), annual pennyroyal (Hedeoma acinoides), Texas spear grass (Nassella leucotricha), stork’s bill (Erodium texanum), Texas thistle (Cirsium texanum), and zexmenia (Wedelia texana).

New partners for the Seeds of Success program are being sought as the project expands to collect seeds from 4,000 species within the United States by 2010. Other U.S. partnerships under development include the Chicago Botanical Garden, Virginia Native Plant Society, and the San Diego Zoo.

Under the Microscope
In addition to storing seeds from around the world, Kew scientists also research seed biology and physiology and storage techniques for difficult-to-store seeds. They also help their partners all over the world develop conservation strategies and techniques.

Currently they are conducting some seed viability and longevity studies through an artificial aging process, by which they hope to have conclusive evidence of their own within the next three years about the viability and longevity of numerous species.

Now scientists at Kew operate under the scientific evidence available that as much as 75 percent of the MSB collections will live more than 200 years. “Plenty, however,” says Way, “will endure thousands of years.”

It is a sensitive area of study though, because not only will each species vary in terms of seed longevity and viability, but each seed collection will vary as well.

While seeds are under their care, the MSB staff does everything possible to maintain viability by providing the best storage conditions for a particular seed collection. Way says the MSB’s germination approach is somewhat distinct.

“We put a sub-sample of 25-50 seeds in Agar (seaweed extract) jelly in Petri dishes so that the seeds take up moisture very gently. We then place the dishes in well-lit germination conditions in one of our 30 incubators that mimic the temperatures of many of the world’s environments.

“They are checked every day or two and then every week. If they are alive but have not germinated, we know we have to change the germination conditions to break their natural dormancy,” Way says. By this germination testing stage, seeds will have experienced drying and freezing, so if the sample germinates it is safe to conclude that the species involved produces seeds that are capable of long-term storage. Every 10 years, sub-samples are removed from storage to retest germination.

In the Bank Under the leadership of the BLM in the United States, the Seeds of Success program has identified both restoration and conservation target species. The BLM’s first priority is to collect the species needed for restoration, but other conservation targets will be collected over the next 10 years. Seed samples will be stored under internationally recommended conditions at the USDA’s National Seed Storage Laboratory and also at RBG Kew.

Way says the MSB is important to the world in so many different ways. He says the participation of conservation organizations from developing countries raises the awareness of plant conservation issues and provides the organizations with the know-how to conserve seeds effectively. In developed nations, he says, the importance of the MSB stems from the conviction of each of the partnering organizations.

“If we can help them reach their individual goals for conservation or restoration efforts, then with that alone we have been successful. And from our perspective, we are given access to a better understanding of the wonderful diversity of seeds. Only through this type of global project can we answer those important questions about seed behavior.”

For Oxley, seed banking is the perfect way to accomplish the Center’s ambitious goals. “Seed banking is a relatively inexpensive yet remarkably effective tool. This means that people in a particular region can easily store genetic information for long periods of time. You create a genetic insurance policy for the flora over a long period of time, and that’s a good thing. But this is just one tool. Let’s face it: the most successful seed bank in the world will be the one with no seeds in it because we will have restored the damaged habitats, grown all those seeds up into healthy plants, and placed them back into the wild where they belong.”