Abstract: The SSR markers linked tightly with opaque-2 (o2) can be used effectively in the quality protein maize (QPM) breeding. In this study, the SSR primer phi057 was used in the evaluation of inbred lines developed in recent years, and QPM breeding program to convert the elite normal lines into QPM. Mutation on o2 was found during the improvement of the QPM populations CPop13 and CPop14 after detection of o2 gene frequency with the marker. The o2o2 genotypic frequency in CA, CD, CB, and R series derived from the improved populations was detected as 91.7%, 80.0%, 0.0, and 100%, respectively. It was indicated that homozygous o2o2 genotype in QPM could not be ensured in conventional breeding efforts. In order to enhance the QPM germplasm basis and convert elite normal lines into QPM, the markers were used to detect o2 gene in backcross generations, and it has proved that it is a powerful tool in the breeding.

Key words: Quality protein maize (QPM), Marker assisted selection, Simple sequence repeat (SSR), AFLP (Amplified fragment length polymorphism)