Managing self-pollinated germplasm collections to maximize utilization

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-lined accessions for self-pollinated species not only eliminates the problems associated with genetic drift and natural selection, but also enhances the accuracy of the evaluations and fosters effective germplasm utilization. Neither the current potential to characterize entire germplasm collections with tens of thousands of DNA markers nor the future potential of whole genome sequencing to completely characterize the diversity of all accessions in collections can be fully realized for self-pollinated species 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.

Characterization of Morphological Diversity of Jute Mallow (Corchorus spp.)

“…Germplasm collections from underutilized traditional vegetables such as Jute mallow can be an important step in breeding for improvement of the crop [23,24]. Accessions, particularly those from East and Southern Africa, remain unexploited.…”

Grain Legumes

“…landraces) within an accession. Pure lining accessions and creating a new pure-line accession has increased the utility of germplasm collections (Nelson 2011). Consequently, precision in phenotyping is achievable and high-throughput genotyping is feasible.…”

Systems for making NIAS Core Collections, single-seed-derived germplasm, and plant photo images available to the research community

“…Each line derived by single-seed descent is registered as a new accession. This approach could result in considerable increase in the genebank's accession size and presents the risk of losing a rare allele in a heterogeneous accession (Nelson 2011). However, an advantage of this approach is that the genebank can supply seeds with a known genotype that can be phenotyped to allow more accurate genotype-phenotype association analysis (such as Genome Wide Association Analysis (GWAS)).…”