|Mullet, John - TEXAS A&M UNIV|
|Jordan, David - DWF, QUEENSLAND, AU|
|Miller, Frederick - MMR GENETICS|
|Ronney, William - TEXAS A&M UNIV|
|Menz, Monica - SYNGENTA SEEDS SAS FRANCE|
|Klein, Patricia - TEXAS A&M UNIV|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 28, 2007
Publication Date: March 8, 2008
Citation: Klein, R.R., Mullet, J.E., Jordan, D.R., Miller, F.R., Rooney, W.L., Menz, M.A., Franks, C.D., Klein, P.E. 2008. The effect of tropical sorghum conversion and inbred development on genome diversity as revealed by high-resolution genotyping. Crop Science. 48(S1):S12-S26. Interpretive Summary: Major advancements in science hinge on the identification of genes controlling plant and animal traits that are critically important to agriculture. Genes are tiny packets of genetic blueprint material that are found inside the cells of all plants and animals and control all of the physical characteristics of these organisms. Our work focuses on improving major grain crops and, with gene sequences, the genetic blueprint will be visible and this information can make improving the plants more efficient. This study is a detailed genetic analysis in sorghum of height and maturity genes, which are central to sorghum adaptation to temperate climates. The detailed mapping of these genes will permit more efficient conversion of tropical sorghum to high yielding grain varieties in temperate climates, and will allow scientists to understand those key features of the genetic blueprint that make sorghum the desired height and maturity for US producers. Information will be primarily used by fellow scientists but the work will ultimately result in better adapted, higher producing crop varieties available to American farmers.
Technical Abstract: With the development of saturated genetic maps and high-throughput marker systems, it is now feasible to detail the genetic diversity for defined chromosomal regions by constructing high-resolution graphical genotypes for any number of selected cultivars. This analysis can identify genomic regions with great allelic diversity and other regions, often quite large, which have been fixed due to selection pressure, genetic hitchhiking, or genetic drift. To this end, graphical genotypes have been generated for a set of sorghum germplasm, which includes selected public inbreds, germplasm from the world collection, and ancestral lines central to the early breeding efforts of sorghum. We have focused our present examination on sorghum chromosome SBI-06 that encodes ma1 and dw2, two genes critical to sorghum improvement dating to the original introduction of tropical sorghums into the U.S. Utilizing the pedigree relationship between sorghum cultivars, the patterns of genetic variation were detailed within segmental chromosomal blocks of SBI-06. Segmental genomic blocks were traced back through multiple generations of a pedigree, often back to founder tropical accessions. The graphical genotypes reveal genomic signatures of historical breeding decisions, especially evidence of directional selection during the conversion of tropical accessions to temperate adaptation. This information is central to our efforts to understand those crop improvement processes that have shaped the genomic diversity of elite sorghum cultivars.