Differential gene expression between cross-fertilized and self-fertilized kernels during the early stages of seed development in maize

In maize, cross-fertilization advantage was observed during the early stage of embryo development and grain filling. In this study, we performed screening of differentially expressed genes between maize cross-fertilized and self-fertilized kernels at 5, 10, and 15 days after pollination (DAP) by differential display technique. The results indicated that the patterns of gene expression altered obviously in cross-fertilized kernels as compared to self-fertilized kernels. Both quantitative and qualitative differences were observed. Four differentially expressed cDNAs were cloned and sequenced, their expression patterns were confirmed by reverse-Northern blot. Sequence analysis and database search revealed that two of them were new sequences; the other two were methyl-binding domain protein (MBD) and phosphoenolpyruvate carboxylase (PEPC), respectively, and it is concluded that the altered gene expression may be responsible for the observed maize heterosis.