ARS | Publication request: Association analysis of beet curly top disease resistant genes in sugarbeet

Submitted to: Journal of Sugarbeet Research
Publication Type: Abstract Only
Publication Acceptance Date: November 18, 2008
Publication Date: February 25, 2009
Citation: Eujayl, I.A., Simko, I., Strausbaugh, C.A. 2009. Association analysis of beet curly top disease resistant genes in sugarbeet [Abstract]. Proceedings of 35th Biennial Meeting of American Society of Sugar Beet Technologists: Section B&E. Paper No. 1.

Technical Abstract: Association mapping is a novel approach to overcome common bi-parental genetic linkage mapping limitations. This linkage-disequilibrium based approach was successfully applied in other crops, thus allowing for detection of markers linked to genes of resistance. The objectives of this study were to analyze population structure (estimate K) of a large collection of experimental and commercial varieties from six seed companies and elite germplasm from USDA-ARS, and to use this population to identify markers associated with resistance to curly top. A pool of 168 diploid hybrids and germplasm were genotyped with 39 polymorphic SNP and 30 SSR markers and phenotyped for curly top reaction in the field and the greenhouse for two seasons. To compare performance of the two marker systems, the population structure analysis was performed on a subset of 62 genotypes that were analyzed with both SSR and SNP makers. The estimated number of subpopulations was affected by marker system, and varied from K=2 to 4. Analysis of population structure based on K=3 indicated clustering of varieties from Betaseed and American Crystal, while varieties from Hilleshog and Seedex formed a different cluster. Varieties from Holly Hybrids were distinctly separated from other clusters with a notable exception of accession HH06. Analysis of the complete population of 168 accessions, confirmed clustering detected on a subset of individuals. The USDA-ARS germplasm showed similarity to the Hilleshog – Seedex cluster, while a population from KWS clustered separately. The association analysis revealed several genomic regions associated to the disease reaction and putative alleles associated with SNP markers located on chromosomes 2, 5, 7, and 9.