Characterization of the genetic diversity contained within the genus Arachis
Newman, Melanie Leigh
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The genus Arachis contains both the cultivated peanut, A. hypogaea and its wild relatives. Although many investigations into the genetic diversity and relationships of species within the genus have been conducted, there is still a need to better characterize the genetic diversity in the genus by studying a larger sampling of species with a common set of molecular markers. By understanding the genetic structure of A. hypogaea and its wild relatives, breeding programs will be better informed as to how one might introduce wild ancestry into the cultivated peanut for crop improvement. This research has focused on understanding the genetic diversity and its partitioning in the wild species contained within the genus Arachis using Amplified Fragment Length Polymorphisms (AFLP) and on the genetic structure and diversity within A. hypogaea using Simple Sequence Repeats (SSR). In the wild species, the results indicate that there is a great deal of diversity within the genus that is partitioned mainly within individual sections as opposed to among taxonomic sections. This is important to both plant breeders and germplasm curation alike by highlighting the potential benefits from choosing plants within a particular section as opposed to broadly sampling plants across different taxonomic sections. The AFLP data also support the idea that A. monticola is the tetraploid precursor of A. hypogaea and A. batizicoi is the B genome donor. In the cultivated peanut, genetic diversity is much more limited and the availability of markers to assess genetic diversity is wanting. However, SSR analysis has revealed that the diversity within the species is partitioned better according to geographic distribution of the plants rather than by taxonomic grouping. This information can be used in germplasm collection and by plant breeders by suggesting that more diversity may be gained when selecting plants from diverse geographic regions rather than basing selection on taxonomy alone.