As the sun finally clears the horizon, signalling an end to the long winter night, the eyes of the world will be on the Global Seed Vault, dug into the mountainside above the town of Longyearbyen in Svalbard, Norway. The first boxes of 12 tonnes - a hundred million seeds - will be carried down the long tunnel to the deep freezers within, there to be kept in safety just in case. The specimens will all be what scientists call orthodox seeds, those that can be dried and stored at low temperatures without harm. Ironically, species that cannot be dried and stored have no place in the frozen Svalbard vault. They need cold, but they also need regular human attention. Where will they be secure?

For some, in the sunny south of France.

The first few hundred samples of banana and plantain from the International Musa Germplasm Collection, managed by Bioversity International and supported by the Belgian government, have been safely delivered from the International Transit Centre (ITC) at Katholieke Universiteit Leuven in Belgium to the French Research Institute for Development (IRD) in Montpellier, France.

The "black box" collection at IRD - in reality a large vat kept at an extremely chilly -196°C by liquid nitrogen - represents the same kind of safety backup that Svalbard offers for orthodox seeds. Should anything happen to the samples at Leuven, like the typhoon that damaged the Philippine rice genebank or the looters who wiped out the genebank at Abu Ghraib in Iraq, duplicates will be available at IRD.

"It's a mirror of the need for crop diversity itself," said Emile Frison, Director General of Bioversity International, which is working closely with the Global Crop Diversity Trust to secure important collections of agricultural biodiversity. "Just as humanity needs different varieties of different crops, so different crops need different kinds of long-term storage."

Like bananas and plantains, crops such as coconut, cassava, yam, potato, sweet potato and taro are vitally important foods that are best conserved in field genebanks and tissue culture. But those methods are expensive, so scientists are working to develop protocols for cryopreservation, long-term storage at very low temperatures. KULeuven is a leader in this area and has been designated a Global Centre of Excellence on Plant Cryobiology. The experts there have been working with the genebanks of the Consultative Group on International Agricultural Research and others to develop cryopreservation protocols and safety duplicates of important collections.

"The safety duplicates are at KULeuven in Belgium," Frison said. "But because the primary banana collection is already there, we had to put the safety duplicate somewhere else."

"We chose IRD to house the black box collection because of the expertise of their scientists in cryopreservation," said Professor Rony Swennen, Honorary Research Fellow at Bioversity and Director of the ITC. IRD researchers made an important contribution to cryopreservation by working out how many samples of each variety should be conserved.

"There is no guarantee that a thawed piece of plant tissue will regenerate into a fully viable plant," Swennen explained. "IRD scientists solved that problem by developing a method to calculate the number of samples needed to ensure a 95% chance that at least one of them will produce a plant."

The method is based on the survival rate of the accession, the risk level the genebank manager is willing to accept, and the time between regenerations. Armed with this information Bart Piette and Bart Panis, Belgian scientists at KULeuven, cryopreserved a batch of accessions three separate times, to minimise the risk that all might be contaminated. One of each repetition has gone to France while the other two remain in Belgium.

Just as the Trust is supporting the ongoing operations of the Global Seed Vault and the preparation and shipping of seeds to Svalbard, it is also supporting research into cryopreservation and safety backups for crops that need it. Tissue culture is expensive and time-consuming because fresh cultures must frequently be made, while field collections are vulnerable to environmental disasters. Research at the Global Centre of Excellence on Plant Cryobiology at KULeuven and elsewhere is delivering improved cryopreservation protocols that enable much longer storage without the need for human interference.

"The Trust's support in making sure that crops such as banana are safely stored for the global community is very much appreciated," said Frison. "But I think it is also important to recognize Belgium's contributions. The government has been a long-term supporter of research on the banana, from laboratory studies at KULeuven to field deployment of improved varieties and growing techniques. Without that, we might not have had any cryopreserved specimens to send to France."