Approaches for Updating the Peanut Core Collection.

A core collection should be dynamic.  Since the initial peanut core collection was selected, 821 accessions have been added to the U.S. germplasm collection of peanut.  The objective of this work was to evaluate various selection methods that could be used to select representative genotypes from these accessions to add to the peanut core collection.  Twenty selection methods were used to generate various core subsets.  These included simple random sampling, sampling after stratification by country of origin, sampling after stratification by country of origin and botanical variety, sampling after multivariate clustering, and sampling after multivariate clustering after stratification by country of origin.  These selection methods were evaluated based on their ability to identify sources of resistance to Tomato spotted wilt virus and the peanut root-knot nematode in the 821 accessions.  Multivariate clustering after stratifying by country of origin was superior to the other core collection selection methods in improving the success rate of identifying sources of resistance to these pathogens. These results will be used to update the peanut core collection to reflect changes in the entire germplasm collection.  These results also clearly demonstrate the improvements in efficiency that can be achieved using a core collection approach for evaluating germplasm.