Submitted to: Plant Genome Analysis Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 10/24/2007
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: A retrospective analysis of the USDA-ARS Canal Point bredding history was undertaken to search for the determinants of yield and quality traits in sugarcane (Saccharum spp.). The fact that progress is being realized implies that relevant genomic reions are being targeted by selection. This study follows the temporal changes in genetic diversity parameters (allele frequency, Fst expected heterozygosity, and linkage disequilibrium) to find associations between molecular markers (as target region amplification polymorphism or TRAP) and quantitative traits, and to detect the signatures of selection. Sixty-one genotypes, including early progenitors and cultivars released fro 1950 to 2000,were divided into decades and genotyped with 24 TRAP primer combinations. A bottleneck was observed based on reductions in number of alleles and % polymorphism. Allele frequencies diverged since the progenitor population with the distribution changing from anL-shaped (progenitor poluation) to a U-shaped therafter. An excess of low frequency alleles suggested the effect of balancing selection shaping the patterns of polymorphism and diversity in the CP bredding polulation. Testing for evidence of selection yielded 15 TRAP marker-loci as the strongest candidates, with these loci falling outside the expected distribution of simulated neutral loci. As expected, stabilizing or balancing selection was operating in the CP poluation to preserve these polymorphisms. Our expectation is that these 15 markers correspond tp disease and/or sucrose contact loci, given that the most stringent selection intensity is imposed on these two traits in Florida. A high research priority is to determine their associations with quantitative traits which will be discussed in details.