Title: Managing self-pollinated germplasm collections to maximize utilization Author
Submitted to: Plant Genetic Resources
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 7, 2011
Publication Date: April 1, 2011
Citation: Nelson, R.L. 2011. Managing self-pollinated germplasm collections to maximize utilization. Plant Genetic Resources. 9:123-133. Interpretive Summary: Historically germplasm collections have provided the raw material for plant breeders to use to improve cultivars. Advances in genetics and genomics have greatly expanded the number and types of scientists using germplasm collections. How germplasm collections are managed can impact how successfully they are used. Using the USDA Soybean Germplasm Collection as a model, the advantages of having all self-pollinating entries in a germplasm collection represent a single genetic type (pure lines) rather than maintaining entries as they were collected, even if they are mixed seed lots, is discussed. Maintaining pure lines reduces the risks of genetic loss. It also makes evaluation more accurate and affordable. The presentation of distribution statistics over the last 15 years demonstrates the how intensively and broadly the USDA Soybean Germplasm Collection is used. This information will be of use to all scientists involved in maintaining and utilizing plant genetic resources.
Technical Abstract: The primary mission of germplasm collections is to preserve genetic diversity, but germplasm is preserved so that it can be used. Historically the standard practice is that all germplasm accessions should be maintained as collected so that even self-pollinated accessions are maintained as heterogeneous seed lots. In theory, this seems like an ideal strategy for preserving genetic diversity, but in practice it is simply not workable. Heterogeneous accessions are in constant risk of change and loss. It is possible to mitigate the risk factors but they can only be lessened and not eliminated. Maintaining pure line accessions for self-pollinated species not only eliminates the problems associated with genetic drift and natural selection, but enhances the accuracy of the evaluations and fosters effective germplasm utilization. Neither the current capacity to characterize entire germplasm collections with tens of thousands of DNA markers and the future potential of extensive whole genome sequencing can be realized unless accessions are homogeneous and homozygous. In this manuscript, the case is made for pure lining self-pollinated germplasm accessions using the USDA Soybean Germplasm Collection, which has maintained pure lined accessions for over 50 years, as an example. There is also an analysis of the extensive seed distribution from this collection to indicate the value of a diverse collection of genotypes.