Q&A with Stephanie Greene, seed curator at preservation facility

While pursuing a doctorate in agronomy, Stephanie Greene became aware of the need to conserve genetic resources — materials plant breeders use to improve crops.

Greene, now retired from her position as a supervisory plant physiologist with the USDA Agricultural Research Service, managed the laboratory at the Agricultural Genetic Resources Preservation Research facility in Fort Collins, Colorado, where she was in charge of processing thousands of seed samples received each year. She also coordinated U.S. efforts to send seed material to the Svalbard Global Seed Vault in Norway. She is currently working as a consultant for the Alliance of Bioversity and CIAT, providing training to national genebanks.

SF: What is the Agricultural Genetic Resources Preservation Research facility's mission? How did it get its start?

SG: The facility dates back to the 1950s when it was recognized that Colorado was a great place to store seed because we had relatively low humidity — good for long-term seed storage. One of the best management practices for gene banking is to have a collection backed up at another geographic location in the event that something happens to your primary collection.

The role that the National Laboratory for Genetic Resources Preservation (NLGRP) plays is to store this duplicate collection for USDA. We have one of the largest collections in the world. We also store collections for other organizations including other countries, international ag research centers, and botanical gardens.

SF: Why is work in your field important for agriculture?

SG: Constant challenges are facing farmers as they try to produce food: pests, insects, diseases, and environmental changes. Climate change is a big challenge right now. In order to keep up with these challenges, plant breeders need to focus on breeding crops that have traits to help us overcome challenges. Plant breeders need to turn to our collections in order to find the traits that they're looking for. They then get seed samples of what they think has a good trait, and they'll incorporate it into their breeding programs. It's essential to improve crops to ensure food security as the world changes.

These collections provide a resource for scientists who are studying a whole host of things. For example, taxonomists who are interested in understanding the evolution of a certain crop can turn to our collections to find material to study. These collections are important for conserving diversity because a lot of our material is collected in a farmer's field.

In the past, USDA would have extensive collection trips where they would collect seed. If you go back to these places now, it's quite likely that these original traditional varieties are no longer being grown. These collections are simply a way to conserve this diversity because out in the wild, so to speak, farmers frequently will no longer grow this material. We also have a lot of wild species. Those are important resources because many of them are related to crops, so they're of interest for plant breeders to use. There's a lot of habitat loss and genetic erosion occurring in the landscape, so our collections serve to conserve this material.

SF: Can you describe the pro-cess in which you acquired and maintain the seed genetic material?

SG: When we think about a genetic resource collection for crops, there are different types of material that make up the collection. There are obsolete cultivars that have developed through breeding, but perhaps are no longer used. There's also landrace material that hasn't been bred by a plant breeder.

It's mainly selections that farmers have made over a long period of time, so the material's very unique to a specific location. We have wild species re-lated to crops. Then we also will have more undeveloped materials like breeding lines, germplasm, and genetic stocks.

Our collections date back to the late 1800s when USDA recognized they needed to expand agriculture in the U.S. They sent plant explorers around the world to collect seed and plant material. When the explorers came back, the seed was sent off to Extension agents, farmers, and other scientists around the country to see how well they grew in particular locations. Our collections started from that point. What we have now are Ph.D-level curators responsible for a given collection.

Before I came to Fort Collins, I curated the temperate forage legume collection, alfalfa and clover, and my responsibility as a curator — and this is a responsibility shared by all the curators — is to put together a collection that represents the diversity and meets the needs of our users: plant breeders.

In my collection, there was a gap for crop wild relatives of alfalfa, which are important in the breeding of alfalfa. I went to Kazakhstan, Ukraine, and Crimea, and also did some collecting in the U.S. for wild clover species. Basically a curator identifies the gaps and then goes out and fills those.

Once the materials are in the collection, then of course we have to maintain it. The seeds are kept in a freezer, and in the case of apples and clonally propagated crops — a lot of our fruit and nut trees — we keep individual trees in an orchard to preserve them.

You have to take care of the trees and grow out seed as a tree loses viability. There's this whole piece of maintaining the collection that's critical because we want to keep this material alive and maintain its unique characteristics. If we do grow it out in the field, we will isolate plots in cages and introduce bees into the cages so that we're not getting cross-contamination.

We do what we need to do to ensure the genetic integrity of the material as we go through the maintenance process. We work with our users to help them use and try to evaluate the collection, because the more we know about it, the more useful it becomes.

SF: What is the average shelf life of these seeds?

SG: Our goal is to keep the seed alive as long as possible. What we found is that the colder and drier the storage conditions, the longer the seed will survive. Wheat and barley seeds, for example, are stored at –18°C, and we expect that they'll last hundreds of years in storage. Species that are naturally short-lived — for example, lettuce and onion — are stored in liquid nitrogen vapors at about –156°C.

SF: How did climate change affect your work in recent years?

SG: The need to develop climate-resilient crops has been ongoing in probably more than the past decade. This is just my observation, there's no data behind it, but there is a large focus on developing crops that are climate-resilient. Our collections have been used for that purpose — they're a major source around the world. We distribute about 250,000 seed packets every year to both breeders and scientists in the U.S., but also to other countries as well. There's been a real recognition we need to develop crops that are more drought-tolerant and resistant to high heat.

SF: Can you share more about your work with the Svalbard Global Seed Vault in Norway?

SG: The U.S. has been sending seed to Svalbard since it opened in 2008, and we now have about 20% of our collection backed up in Norway. We're lucky because the U.S. has Fort Collins to serve as our primary backup location, so we consider Svalbard as basically a next level of backup. A lot of gene banks have duplications, so what we're focusing on sending to Svalbard is material that's really unique to the U.S.

SF Bio

Name: Stephanie Greene

Background: Greene is a retired supervisory plant physiologist with the USDA Agricultural Research Service. She managed the lab at the Agricultural Genetic Resources Preservation Research facility in Fort Collins, Colorado, where they conserve plant species for future generations.

Education: Greene has a Ph.D from Kansas State University in agronomy, with an emphasis on plant breeding. She earned her bachelor's at University of Idaho in horticulture science.