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United States Department of Agriculture

Agricultural Research Service

Research Project: RESEARCH, ACQUISITION, MANAGEMENT, AND DOCUMENTATION OF PLANT GENETIC RESOURCES

Location: Plant Germplasm Introduction and Testing

Title: Isolation Distance, Inflorescence Sampling, and Population Size: Maintaining Genetic Diversity in the U.S. Temperate Grass Germplasm Collection

Author
item Bradley, Vicki

Submitted to: International Symposium on Forage, Turfgrass and Biofuel Germplasm Research
Publication Type: Proceedings
Publication Acceptance Date: June 30, 2010
Publication Date: October 9, 2010
Citation: Bradley, V.L. 2010. Isolation Distance, Inflorescence Sampling, and Population Size: Maintaining Genetic Diversity in the U.S. Temperate Grass Germplasm Collection. International Symposium on Forage, Turfgrass and Biofuel Germplasm Research p.100-103.

Interpretive Summary: The Western Regional Plant Introduction Station (WRPIS) at Pullman, Washington is a major germplasm repository within the U.S. National Plant Germplasm System (NPGS) and holds more than 85,000 accessions representing 4,084 plant species from 819 genera. There are 20,499 accessions in the cool-season grass collection at the WRPIS. When accession seed quantities are of good quality and of sufficient quantity, they are distributed free of charge to scientists and educators worldwide. Seed regenerations must be performed when original seed samples are small or of poor quality, when seed quantities are diminished, or when seed quality has deteriorated. It is critical that the genetic diversity of the accessions in the collection is maintained as well as possible. Researchers at the WRPIS have performed studies on proper isolation distance and how inflorescence sampling may influence effective population size. Using these research findings as a guide; germplasm managers at the WRPIS have revised the methods used in regenerating the U.S. cool-season grass collection to maintain the genetic diversity of cross-pollinated grasses in the collection.

Technical Abstract: During the regeneration of cross-pollinating accessions, genetic contamination from foreign pollen and reduction of the effective population size can be a hindrance to maintaining the genetic diversity in the temperate grass collection at the Western Regional Plant Introduction Station (WRPIS). These problems have been addressed in several studies by researchers at the WRPIS. Genetic contamination by windborne pollen was studied using pubescent and glabrous smooth bromegrass (Bromus inermis Leyss.) strains. This study indicated that an isolation distance of 22 to 27m results in a relatively low level of pollen contamination between accessions of the same species. Other studies focused on how sampling methods affect genetic structure, development, and morphology in three model annual ryegrass (Lolium multiflorum Lam.) accessions over three regeneration cycles, and showed that sampling a constant number of inflorescences improves the effective population size in a regeneration plot. A fourth study used three perennial grass species to predict the optimum number of inflorescences per plant to most efficiently increase the effective population size. Using these research findings as a guide; germplasm managers at the WRPIS have revised the methods used in regenerating the U.S. temperate grass collection.

Last Modified: 7/28/2014
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