Welcome to the Plant Germplasm Preservation Research Unit
The research team at NCGRP is called the Plant Germplasm Preservation Research Unit (PGPRU). PGPRU is an integral part of the National Plant Germplasm System (NPGS) infrastructure. PGPR’s role is to support collections activities by developing strategies and technologies that:
- improve the efficiency of ex situ genebanks and
- expand the potential uses of genebanked samples
Genebanking is really an investment for the future. The investment will pay off if we can anticipate the needs of tomorrow’s ever-expanding genebank users and develop genebank strategies that satisfy those needs in an economical way. Successful genebanking requires linking a physical sample with accurate information about it, and then making sure that the stored sample retains the same properties as the material from which it originated.
Five strategies pursued within the PGPRU group aimed at improved genebanking include:
- Maintaining biological integrity
- Sampling representatively to accommodate current and anticipated uses and multiple conservation targets
- Providing annotation that authenticates, calibrates and characterizes samples
- Integrating information systems
- Providing germplasm with validated phenotypic and genetic descriptions
Genebanked samples are used for a variety of reasons by diverse
customers:![Understanding the critical parameters of wild rice seed production](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-2lisa.jpg)
- Genetic “improvement”
- Conservation of biodiversity
- Mechanistic studies of adaptation
- Systematics and taxonomy
- Environmental monitoring
- Epidemiology
- Forensics
- New questions in new disciplines
PGPR also has provided many innovations that have been implemented to improve genebanking worldwide.
Some current projects are described below.
The PGPR team is charged with trouble-shooting key NPGS operations to ensure cost-effective procedures today and relevance and impact of NPGS collections in the future:
1) Maintaining biological integrity![Freeze fracture image of embryo cells damaged during the preservation process.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-5ff2.jpg)
![Freeze fracture image of embryo cells that have been successfully preserved.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-4ff1.jpg)
This requires that the physical structure and chemical composition of the stored material remains unchanged through time so that future researchers can test for the presence of compounds or evaluate the appearance of plant cells and organs. Preserving biological integrity usually requires cooling, drying or applying chemical fixatives to samples – all of which can be lethal.
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2) Sampling representatively to accommodate current and anticipated uses and multiple conservation targets
Conservation targets for a genebank include particular genes, genotypes or gene frequencies. Genetic diversity embodied by these different conservation targets should be available to future users without oversampling and unnecessary duplication.
![Cacao embryos are desiccation sensitive.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-8cacao.jpg)
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3) Providing annotation that authenticates, calibrates and characterizes samples
Genebank users need information about where, how and when a sample was collected in order to understand why the sample is the way it is. The information must be standard to avoid misinterpretations and must have a traceable history to ensure accountability.
![DNA samples are gathered in the field during collection trips.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-10DNA.jpg)
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4) Integrating information systems
Databases that describe holdings of repositories from all parts of the world must be interoperable to ensure that users have access to the full breadth of available material and information.
![The GRIN database provides access to annotation.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-12GRIN.jpg)
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5) Providing germplasm with validated phenotypic and genetic descriptions
Germplasm repositories differ from other genebanks or repositories in that they provide living samples that can be grown out and used further. Providing living samples introduces the risk of change through mortality during the genebanking process or through drift or selection when material is regenerated.
![Diverse lettuce cultivars in field plot.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-14lettuce.jpg)
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Innovations
Innovations developed by the PGPR team have directly improved germplasm repository operations at NCGRP and at genebanks around the world. Innovations that are now implemented in routine operations include:
![Lettuce seeds stored at -12C for 40 years germinate vigorously.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-1710C.jpg)
![Bags, tubes, and vials are compared for water vapor transmission and suitability in liquid nitrogen.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-23storage.jpg)
- new ways to evaluate genetic diversity within collections
![Diversity of wild apples.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-26apples.jpg)
![Relationships among molecular tables in GRIN.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-28gobs.jpg)
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Current research projects build on past accomplishments with additional focus on:
![Gas chromatography of head space volatiles reveal chemical changes during seed aging.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-28GC.jpg)
Gas Chromatography of head space volatiles. |
![Differential scanning calorimetry is used to measure motion of molecules in dry cold cells.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-29DSC.jpg)
Differential scanning calorimetry. |
![Dynamic mechanical analysis is used to measure elasticity and yield of seeds.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-30DMA.jpg)
Temperature-controlled Dynamic mechanical analysis.
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![Shoot tips vitrified in cryoprotectant solution.](https://webarchive.library.unt.edu/web/20120916041718im_/http://www.ars.usda.gov/sp2userfiles/Place/54020500/images/H3-36vitrificationshoots.jpg)
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For further information about NCGRP research contact PGPR principal investigators:
Dr. Christina Walters (Lead)
Christina.Walters@ars.usda.gov
- Seed: development, storage, germination
- Biophysics of cellular stabilization
Dr. Gayle Volk
Gayle.Volk@ars.usda.gov
- Vegetative propagules: acclimation and growth
- Cellular responses to preservation stress
Dr. Chris Richards
Chris.Richards@ars.usda.gov
- Population and Conservation Genetics
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