Heterofertilization of the opaque-2 endosperm in maize

Selection on endosperm traits among individual kernels is very important in maize because the characteristics of the kernel, especially the endosperm, are directly related to quality and yield. However the accuracy of the selection according to endosperm phenotype may be affected by heterofertilization. The objective of this work was to investigate the frequency of heterofertilization of opaque-2 (o2) kernels in maize. Three BC(1)F(1) populations using o2 lines as recurrent parents and some BC(1)F(2) progenies were used to investigate endosperm phenotypes and plant genotypes. The plant genotypes were determined using simple sequence repeat (SSR) markers, phi057 or phi112, which are sequences located within the Opaque-2 (O2) gene; the endosperm phenotypes were observed visually. In the BC(1)F(1) populations, the frequency of heterofertilization was 0 approximately 4.545%. This result indicates that there may be up to a 5% difference between the selections based on endosperm phenotype and plant genotype in a backcross breeding program. Molecular marker assisted selection should be a more accurate selection procedure. In addition, we discuss the relationship between the endosperm heterofertilization of o2 maize and the variations within the O2 locus.