Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: RESEARCH TO DEVELOP STRATEGIES AND TECHNOLOGIES FOR PRESERVING PLANT GENETIC DIVERSITY IN EX SITU GENEBANKS

Location: Plant Germplasm Preservation Research Unit

Title: Modeling demographics and genetics in ex situ collections during seed storage and regeneration

Authors
item RICHARDS, CHRISTOPHER
item Lockwood, Dale -
item VOLK, GAYLE
item WALTERS, CHRISTINA

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 29, 2010
Publication Date: September 27, 2010
Citation: Richards, C.M., Lockwood, D.R., Volk, G.M., Walters, C.T. 2010. Modeling demographics and genetics in ex situ collections during seed storage and regeneration. Crop Science. 50:2440-2447.

Interpretive Summary: The goal of germplasm collections is to obtain representative samples of genetic variation and maintain them as living specimens that can be used in a variety of research applications. A key challenge in this objective is maintaining both genetic diversity and viability. The process of ex situ conservation involves a series of sampling events. Whether sampling directly from natural variation (in situ) or sampling during a seed increase, genetic drift can result in changes in diversity. We developed a computer simulation model to examine how the sampling process influences long term maintenance of genetic variation. In particular, we examine how two common regeneration strategies (parallel regeneration using the most original seed source or serial regeneration using the recent regeneration) influence the retention of neutral allelic variation over time. In addition we contrast highly heterogeneous accessions and highly uniform accession. Lastly we examine how changes in seed longevity influence drift indirectly through changes in viability. Our results indicate that regeneration methods and improvement in seed storage conditions can mitigate the loss of variation.

Technical Abstract: The goal of germplasm collections is to obtain representative samples of genetic variation and maintain them as living specimens that can be used in a variety of research applications. A key challenge in this objective is maintaining both genetic diversity and viability. The process of ex situ conservation involves a series of sampling events. Whether sampling directly from natural variation (in situ) or sampling during a seed increase, genetic drift can result in changes in diversity. We developed a computer simulation model to examine how the sampling process influences long term maintenance of genetic variation. In particular, we examine how two common regeneration strategies (parallel regeneration using the most original seed source or serial regeneration using the most recent regeneration) influence the retention of neutral allelic variation over time. In addition we contrast highly heterogeneous accessions (allele frequencies of 0.72, 0.2, 0.04, 0.02, 0.01, 0.005, and 0.005) and highly uniform accessions (allele frequencies of 0.95 and 0.05) that are either highly selfing or highly outcrossing. Lastly we examine how changes in seed longevity influence drift indirectly through changes in viability. Low frequency alleles were quickly removed from wild populations when 50 individuals were selected to regenerate the accession. Allele losses are minimized by performing regenerations in parallel, by improving seed longevity, by performing regeneration events before reductions in seed viability occur, and by increasing the number of individuals in regeneration events.

Last Modified: 9/10/2014
Footer Content Back to Top of Page