Association Mapping of Leaf Traits of Spinach

Spinach (Spinacia spp.) is a cool-season and economically important crop and it was produced on about 18,000 ha in the U.S. in 2012 valued at $224 million, according to USDA NASS. As the latest application of next-generation sequencing technology, Genotyping by Sequencing (GBS) has relatively low cost and provides for rapid discovery of SNPs (Single Nucleotide Polymorphisms) in different crop species. In this study, 518 spinach lines, including 388 from USDA-GRIN germplasm originally collected from 24 countries, 60 commercial cultivars or F1 hybrids, and 70 advanced lines developed by University of Arkansas were field-planted near Kibler, AR in October 2013. Leaf traits including texture, shape, petiole color and edge attributes were phenotyped in December 2013. Leaf variations included: smooth 82.0% vs semi-savoy or savoy leaf 18.0%; oval 67.3% vs long leaf 32.7%; green 76.2% vs purple petiole 23.8%; entire 73.6% vs lobed leaf 26.4%. Additionally, leaf tissue was sampled from each individual line and freeze dried. Genomic DNA was extracted using the cetyltrimethyl ammonium bromide (CTAB) method. DNA sequencing is underway on each line using GBS by Illumina HiSeq 2000 Sequencing System. GBS data will be analyzed for SNPs using the DNASTAR Lasergene Genomics Suite, TASSEL, and/or the AMtools pipeline. The SNP markers associated with specific leaf traits will be identified and these markers will provide breeders with the ability to select different leaf types of spinach through marker assisted selection in spinach breeding programs.