Application of SSR Markers for Purity Testing of Commercial Hybrid Soybean (Glycine max L.)

Exploitation of the full potential of any hybrid requires the possessing of genetically high-purity seeds. Commercial soybean hybrids have been developed using a cytoplasmic male sterility (CMS) system. In order to avoid reduction in yield caused by using lowpurity seeds, development of a simple, rapid, and accurate method for hybrid purity assessment is of great essence and significance. Therefore, the parental lines of HybSoy 1 to 5 were screened using 160 Simple Sequence Repeat (SSR) makers, of which 8 markers exhibited polymorphism. A PCR-based assay with these markers detected both alleles of the parental lines in pure hybrids, proving their heterozygosity, whereas impurities were identified by the presence of only one parental allele. The confirmation of hybrid purity indicated that a single polymorphic marker was sufficient for detection of contaminations of these hybrids from their parents. It was also found that if a hybrid seed lot was contaminated by another hybrid or its parental lines, two or more appropriate markers could be used to easily detect such contamination. This method could accurately and effectively identify the hybrid purity in a predetermined sample of soybean hybrids constituted by deliberately mixing seeds of parental lines. This is the first report that demonstrates the utility of SSR markers for assessment of genetic purity of soybean hybrids.