|Stewart, James mcd.|
Submitted to: Genetica
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/25/2008
Publication Date: 5/1/2009
Citation: Kantartzi, S.K., Ulloa, M., Sacks, E., Stewart, J.McD. 2009. Assessing genetic diversity in Gossypium arboreum L. cultivars using genomic and EST-derived microsatellites. Genetica 136: 141-147. Interpretive Summary: Genetic diversity, or the variation in genetic makeup among individuals, is desirable for long-term crop improvement and reduction of vulnerability to important crop stresses such as pests, diseases, and unfavorable environments. An old world cotton, Gossypium arboreum, which is one of the ancestors of the modern cultivated cottons, possesses many favorable traits which the modern cottons lack. For example, G. arboreum is well adapted to dry land conditions and low input production practices. One of the important advancements in DNA technology is the ability to use molecular markers as a tool for crop improvement. A molecular marker is a small piece of DNA that can be detected chemically. Molecular markers have already proven useful for studying genetic diversity and genetic relationships in different crops. In this paper, we evaluated the usefulness of more than 1600 markers of three types by assessing them in a collection of G. arboreum specimens. The results from this research allowed us to select a set of 25 markers that were useful in distinguishing specimens or groups of specimens, and to clarify genetic relationships among specimens of G. arboreum from different geographic areas. Outcomes of this research should be useful in decreasing redundancy of effort by the scientific community and in constructing a collection of G. arboreum specimens that will be important for efficient use of this genetic resource in cotton breeding.
Technical Abstract: The cultivated diploid, Gossypium arboreum L., (A genome) is an invaluable genetic resource for improving modern tetraploid cotton (G. hirsutum L. and G. barbadense L.) cultivars. The objective of this research is to select a set of informative and robust microsatellites for studying genetic relationships among accessions of geographically diverse G. arboreum cultivars. From more than 1,500 previously developed simple sequence repeat (SSR) markers, 115 genomic (BNL) and EST-derived (MUCS and MUSS) markers were used to evaluate the allelic diversity of a core panel of G. arboreum accessions. These SSR data enabled advanced genome analyses. A set of twenty-five SSRs were selected based both upon their high level of informativeness (PIC=0.50) and the production of clear PCR bands on agarose gels. Subsequently, ninety-six accessions representing a wide spectrum of diversity of G. arboreum cultivars were analyzed with these markers. The 25 SSR loci revealed 75 allelic variants (polymorphisms) ranging from 2 to 4 alleles per locus. The Neighborjoining (NJ) method, based on genetic dissimilarities, revealed that cultivars from geographically adjacent countries tend to cluster together. Outcomes of this research should be useful in decreasing redundancy of effort and in constructing a core collection of G. arboreum, important for efficient use of this genetic resource in cotton breeding.