While pursuing a PhD in agronomy, Stephanie Greene realized the need to conserve genetic resources—the materials plant breeders use to improve crop yields.
Greene, now retired from his position as supervising plant physiologist at the USDA Agricultural Research Service, managed the laboratory at the Agricultural Genetic Resources Conservation Research Facility in Fort Collins, Colorado, where he was responsible for processing thousands of seed samples received every year . He also coordinated US efforts to send seed material to the Svalbard Global Seed Vault in Norway. He currently works as a consultant for the Alliance of Bioversity and CIAT, providing training to national gene banks.
SF: What is the mission of the Agricultural Genetic Resources Conservation Research Facility? How did it start?
SG: The facility dates back to the 1950’s when it was recognized that Colorado was a great place to store seeds because we had relatively low humidity which was great for long term seed storage. One of the best gene bank management practices is to back up a collection to another geographic location in case something happens to your main collection.
The role played by the National Laboratory for Genetic Resources Preservation (NLGRP) is to archive this duplicate collection for the USDA. We have one of the largest collections in the world. We also archive collections for other organisations, including other countries, international agricultural research centers and botanical gardens.
SF: Why is work in your field important to agriculture?
SG: Constant challenges farmers face as they try to produce food: pests, insects, diseases, and environmental changes. Climate change is a big challenge right now. To keep up with these challenges, plant breeders need to focus on breeding crops that have characteristics to help us overcome the challenges. Plant breeders should turn to our collections to find the traits they are looking for. They then get seed samples of what they think has a good trait and will incorporate that into their breeding programs. Improving crop yields is essential to ensure food security as the world changes.
These collections provide a resource for scientists who are studying a variety of things. For example, taxonomists interested in understanding the evolution of a certain crop can turn to our collections for material to study. These collections are important for conserving diversity because so much of our material is harvested in a farmer’s field.
In the past, the USDA made long harvest trips where they collected the seeds. If you go back to these places now, it is very likely that these original traditional varieties are no longer grown. These collections are simply a way to conserve this diversity because in the wild, so to speak, farmers often no longer cultivate this material. We also have many wildlife species. These are important resources because many of them are related to crops, so they are interesting for plant breeders to use. There is much habitat loss and genetic erosion in the landscape, so our collections serve to conserve this material.
SF: Can you describe the process in which you acquired and maintained the genetic material of the seed?
SG: When we think of a collection of genetic resources for crops, there are different types of material that make up the collection. There are obsolete cultivars that have developed through breeding, but are perhaps no longer used. There is also native material that has not been bred by a plant breeder.
These are mostly selections that farmers have made over a long period of time, so the material is very unique to a specific location. We have crop-related wildlife. Then we will also have more undeveloped materials such as breeding lines, germplasm and gene stock.
Our collections date back to the late 1800’s when the USDA recognized the need to expand agriculture in the United States. They sent plant scouts all over the world to collect seeds and plant material. When the explorers returned, the seed was sent to Extension agents, farmers, and other scientists around the country to see how well it grew in particular locations. Our collections started from that point. What we have now are Ph.D level curators responsible for a given collection.
Prior to coming to Fort Collins, I curated the temperate forage legume, alfalfa and clover collection, and my responsibility as curator – and this is a responsibility shared by all curators – is to put together a collection that represents diversity and meeting the needs of our users: plant growers.
There was a gap in my collection for alfalfa’s wild relatives, which are important in alfalfa breeding. I went to Kazakhstan, Ukraine and Crimea, and also collected wild clover species in the United States. Basically a curator identifies the gaps and then goes out and fills them.
Once the materials are in the collection, of course we have to keep it. The seeds are stored in a freezer, and in the case of apples and clonally propagated crops – many of our fruit and nut trees – we keep the individual trees in an orchard to preserve them. You have to take care of trees and grow seeds while a tree loses vitality. There’s this whole part of maintaining the collection that’s key because we want to keep this material alive and keep its unique characteristics. If we grow it in the field, we will isolate the plots in cages and introduce the bees into the cages so as to avoid cross-contamination.
We do what we have to do to ensure the genetic integrity of the material during the maintenance process. We work with our users to help them use and try to rate 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 for as long as possible. What we have 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 them to last hundreds of years in storage. Naturally short-lived species, such as lettuce and onion, are stored in liquid nitrogen vapors at about -156°C.
SF: How has climate change affected your work in recent years?
SG: The need to develop climate-resilient crops has probably been going on for more than the last decade. This is just my observation, there is no data behind it, but there is a big focus on developing climate resilient crops. Our collections have been used for that purpose: they are an important source worldwide. We distribute approximately 250,000 packets of seeds each year to both breeders and scientists in the United States, as well as in other countries. There has been real recognition that we need to develop crops that are more resistant to drought and high heat.
SF: Can you share more about your work with the Svalbard Global Seed Vault in Norway?
SG: The US has been sending seeds to Svalbard since it opened in 2008 and we now have about 20% of our collection in Norway. We’re lucky because the US has Fort Collins as our primary backup location, so we look at Svalbard basically as a next level backup. Many gene banks have duplicates, so what we are focusing on sending to Svalbard is material that is very unique to the US
First name: Stephanie Greene
Background: Greene is a retired supervising plant physiologist at the USDA Agricultural Research Service. He managed the laboratory at the Agricultural Genetic Resources Conservation Research Facility in Fort Collins, Colorado, where they conserve plant species for future generations.
Education: Greene holds a PhD in agronomy from Kansas State University with a focus on plant breeding. He received his BA from the University of Idaho in horticultural science.