| Detecting lysine content plays an important role in quality protein maize (QPM) breeding. Opaque-2 (o2) gene apparently increases the lysine content in maize endosperm. Marker assisted selection approach employing microsatellite markers developed in o2 gene was evaluated in the current study. The polymorphism at microsatellite marker loci, Phi057, Phil 12 and umcl066, was surveyed between quality protein maize and normal maize (CA335 and Hungzao4, CA335 and Qi319, and Qi205 and Qi319). The results indicated a clear polymorphism between CA335 and Huangzao4 by using the co-dominant marker Phi057 and dominant marker Phi 112, whereas no polymorphism was detected at o2 locus with umc 1066.Analysis with Phi057 showed recessively homozygous at o2 locus in the recycled QPM lines (R), while most of the CD lines derived from Pool34 were not homozygous. According to the heterotic patterns and the polymorphism at o2 locus, some elite normal inbreds (such as Mo 17, Dan340, Ye478, Zong31, etc) could be used to cross with QPM lines for development of new QPM lines. The test with the marker Phi057 revealed that the segregation ratio of two genotypes, o2o2 and O2o2, in the BCiF, families of (CA335×Huangzao4) ×CA335 with 224 individuals was 1:1.24 as it was expected according to Mendelian segregation. The kernels of o2o2 and O2o2 in the backcross population, as well as Recycled QPM lines (R) were harvested according to their genotypes, which were respectively bulked for the examination of lysine content. The results showed that the lysine contents of 0202 genotypes (0.428%) and R lines (0.377%) were significantly higher than mat of O2o2 genotypes (0.334%). It was suggested that the maize kernels with high lysine content could be effectively obtained by marker-assisted selection approach with the microsatellite marker Phi057. An efficient technique of QPM marker-assisted selection was established based on the adoption of Phi057.
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