Association analysis for oxalate concentration in spinach

Reducing oxalate content of spinach is a major breeding objective. The aim of this research was to conduct association analysis and identify SNP markers associated with oxalate concentration in spinach germplasm. A total of 310 spinach genotypes, including 300 USDA germplasm accessions and ten commercial cultivars, were used for the association analysis of oxalate concentration. Genotyping by sequencing was used to identify 841 SNPs among the genotypes examined for the association analysis. The distribution of oxalate concentration showed a near normal distribution with a wide range in concentrations from 647.2 to 1286.9 mg/100 g on a fresh weight basis and 53.4 to 108.8 mg/g on a dry weight basis. The range in oxalate concentration in spinach suggests that it is a complex quantitative trait which may be controlled by multiple genes, each with a minor effect among the tested spinach panel. Association analysis indicated that six SNP markers (AYZV02031464_116, AYZV02031464_117, AYZV02031464_95, AYZV02283363_2707, AYZV02287123_2830, and AYZV02296293_852) were associated with the oxalate concentration. The SNP markers may be useful for breeders to select germplasm for reduced oxalate concentrations in spinach breeding programs through marker-assisted selection.