Detecting seed purity of wheat varieties using microsatellite markers based on eliminating the influence of non-homozygous loci

Seed purity is an important criterion in assessment of wheat (Triticum aestivum) seed quality. The objective of this study was to establish a quicker and more precise method for testing wheat seed purity. It was found that SSR (simple sequence repeat) marker assay is more accurate and more efficient than the grain gliadin assay and phenotype identification methods used currently. However, inter-plant genotypic differences of SSR loci of a given variety are caused not only by contaminants but also by non-homozygous loci of the variety tested. To precisely identify contaminant individuals, we propose a method for distinguishing the two phenomena in self-pollinating and hybrid wheat varieties. On the basis of the preliminary work, 30 SSR markers and sample size of 100 individuals are recommended for official inspection, and a rapid estimation method is provided for internal tests by breeding, seed production and sales companies. On average for one variety, it takes only four working days to test a large number of samples based on the approach we have established. Estimation of seed purity is often necessary in seed production, market supervision and studies both on the genetics and breeding of crops. The methods proposed here will be beneficial for these purposes.