Relationship Between Differential Gene Expression and Heterosis During Ear Development in Maize (Zea mays L.)

Maize (Zea mays L.) is one of the most important crops because of the remarkable properties of its hybrid, which is responsible for the high commercial value of hybrid maize. The genetic basis of heterosis (hybrid vigor) is not well understood. A differential display technique was performed to identify genes with differential expression across twelve maize inbred lines and thirty-three hybrids during ear development. An incomplete diallel design was used to investigate the relationship between the global framework of differential gene expression and heterosis. It was found that the genes belonging to MONO pattern (i.e., genes expressed in both parental lines and in hybrid) was the highest in percentage among the total five patterns and illustrated that the properties of differentially expressed genes are not entirely responsible for heterosis. Furthermore, a larger number of differentially expressed genes in hybrid, which serves as a major reservoir for generating novel phenotypes that exhibit heterosis of certain agronomic traits during early development and differentiation of maize ear. Moreover, there were some silent genesin hybrids that are responsible for the arrest or abortion of spikelets and for the increase in kernels weight.