Evaluation and Characterization of Germplasm: An Example Using Poa pratensis

摘要

Effective utilization of plant genetic resources is enhanced by characterization of germplasm collections. This is especially true when adapted germplasm is a limiting factor, as is often true for new sustainable agricultural systems. Characterization involves three basic steps: evaluation, analysis, and documentation. These steps were completed on the USDA collection of Poa pratensis L., a widely used forage and turf grass species. Seed production fields of P. pratensis provide a low soil erosion alternative to annual cropping systems. A collection of 228 accessions representing 26 countries, along with 17 commercial check cultivars, was characterized using 86 random amplified polymorphic DNA (RAPD) markers and 17 agronomic descriptors. Univariate analysis revealed differences in all agronomic factors measured, and accessions with high seed production and potentially high turf quality were identified. Cluster analysis of RAPD data revealed 11 accessions with particularly low similarity values. These were subsequently found to be misidentified Poa species. For RAPD and agronomic data the majority of accessions fell within a relatively few clusters, suggesting that unique genotypes were generally under represented in the collection. Correlation between the RAPD and agronomic-based distance matrices, excluding misidentified accessions, was highly significant (P<0.01) (n=234, r = -0.14). However, the correlation represented a relatively small fraction of the total variation, indicating that both molecular and agronomic characterizations were needed to assess overall diversity. For documentation, the agronomic data is available upon request and on the Germplasm Resources Information Network (GRIN).