Molecular identification of variety purity in a cotton hybrid with unknown parentage using DNA-SSR markers.

Molecular identification of hybrid purity is difficult in regional trials of cotton varieties and hybrid trials. In particular, the molecular detection of hybrid purity has not yet been reported in the case of unknown parentage. In this study, we screened 5000 pairs of primers and chose 17 pairs of core simple sequence repeat (SSR) primers to determine the F1 purity of Han6402. The results showed that the purity based on SSR markers reached 100%. Twelve of the 17 pairs of primers exhibited co-dominant banding patterns, and 5 showed non-co-dominant banding patterns. Moreover, we constructed an F1 SSR fingerprinting profile that enabled the identification of the authenticity of Han 6402. Using these primers, we subsequently detected 44 individual F2 seedlings, and the results exhibited different extents of separation, in which the majority of genotypes were heterozygous with co-dominance at most of the loci that differed from each other. The results validated the underlying heterozygous status of the F2 population at the molecular level. Therefore, we conclude that the set of core SSR primers can be used for the laboratory identification of the authenticity and purity of cotton hybrids, not only for distinguishing Fl hybrids or segregating F2 populations, but also for detecting volunteer seeds as fake F1 hybrids in the cotton hybrid industry, based on the hybrid fingerprinting.