Why does seed longevity matter?

Genebanks are at the forefront of conserving the world’s genetic diversity. They provide agricultural researchers with the PGRFA they need to address problems of food security and climate change. For these reasons alone, genebanks expend an enormous amount of effort to ensure the survival of seeds in their care.

Watch this video, in which scientists and genebank managers discuss the measures they have adopted to secure the longevity of seeds in their genebank. The video was filmed in two particular genebanks, IRRI and IITA, but the underlying biological mechanisms that are referred to are common to many crops and relevant to many other settings, including yours.

The video considers how to minimize aging reactions while seeds are in storage. As you watch, think about what underlying chemical reactions the scientists are attempting to control in their bid to maximize seed longevity.

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Transcript: Video 1: Securing seed longevity

Narration:

At the heart of the genebank, these seeds being conserved for the future. The conditions in the base store aren’t comfortable for humans. But for the seeds, the low temperatures are key to their survival.

Fiona Hay:

So there are a number of things that genebanks do to ensure the longevity of the seeds in the genebank. So the first thing they have to think about is the quality of the seeds, the initial quality of the seeds when they first put them into storage. And there are various things for them to think about in that context, for example the maturity of the seeds.

Olaniyi Oyotomi:

Seed quality matters a lot for gene banks because the essence of this conservation is to make them to be available, to make them to be alive and to make them to be useful for breeders, for farmers, for improvement of crop, for food security. So the management is essential in that they have to be maintained in such a way that they can maintain their longevity and be useful at any point in time.

Fiona Hay:

The other thing is then the storage environment, how they're storing the seeds in the gene bank. So a very important part of what the gene bank process is, is to dry the seeds. We have to dry the seeds to reduce the rate of aging and extend the longevity of the seeds.

Narration:

This is the active collection of IITA genebank. The legumes and maize inside have been dried and packed in airtight containers, to prevent moisture from getting in.

Jeffery Ihenacho:

Materials are maintained in perpetuity for distribution to researchers, to scholars, to breeders, for crop improvement. So this is where we store seeds for regeneration, characterization, for evaluation. So we check their viability every ten years, to ensure the materials are still alive.

Narration:

This is the active collection of IRRI genebank. Here too, they monitor the condition of the rice being stored.

Marionette Alana:

The active collections are the materials that we use to give to our seed requestors, and this is also where we get the materials for regeneration. The seeds are stored in the active collection at two to four degrees Celsius, they are dried to about six to seven percent moisture content, and they are packed using hermetic aluminum foil packets.

Narration:

There are many reasons why, without all this care, seeds may age, lose vigor and die over time.

Fiona Hay:

Seeds lose viability mainly due to the effect of damaging reactions that are going on inside the seeds. And a lot of those are caused by reactive oxygen species. So these have very high energy and they oxidize other molecules within the seeds. They oxidize proteins, they oxidize lipids and they oxidize nucleic acids. So DNA, which is the genetic material, which we're particularly interested in conserving as it is.

Narration:

The airtight packaging not only prevents water from getting in, it also prevents oxygen-rich air from reaching the seeds. This helps prevent the ageing reactions in the seeds.

Fiona Hay:

I think we've got a fairly good idea now of the main drivers of seed aging and then how we can turn it around so that we can extend the longevity of the seeds. So for example, we could consider putting silica inside the packets. And that's good for absorbing any excess moisture just as a security, just as a, a safety measure.

Narration:

If it’s a challenge too keep seeds viable in the active collection, it’s even more critical for the base collection, where seeds must survive for decades.

Jeffery Ihenacho:

The difference between the seeds in the base collection and the active collection is that material in the base collection serve as a back-up of what we have in the medium-term collection. Most of the time we don’t source seed from the base collection, except when we run out of stock.

Marionette Alana:

In the base collection, seeds are stored negative eighteen to negative twenty degrees Celsius, and we’re using vacuum-sealed cans for packing the seeds.

Narration:

Understanding the science of seed ageing means you can give the seeds in your base collection a helping hand.

Fiona Hay:

As scientists we’re still trying to understand the ageing process and how we can slow it down more, how we can better store seeds.

Narration:

The genebank’s collections must withstand the passage of time, and even the risk of fire, civil unrest or emergencies. If the staff needs to leave the building in an emergency, the cold stores are extra-resilient – so the seeds in the genebank remain safe.

Olaniyi Oyotomi:

Maintaining this longevity of seeds in the gene bank, it is essential, and this can only be achieved when the seeds are well monitored right from the planting stage, the harvesting stage, the seed processing stage, such that every condition around the seed in every stage of conservation proceedings are managed very well, such that they maintain the temperature around the seeds, relative humidity around the seeds are properly maintained at optimum level, that will allow the seeds to be alive.

End transcript: Video 1: Securing seed longevity

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Video 1: Securing seed longevity