Correlations Between Maize (Zea Mays L.) The Differential Gene Expression And Heterosis

In maize, heterosis is particularly evident and has been used commercially with great benefit. And maize is a model crop for the investigation of genetic and molecular basis of heterosis. The molecular basis of heterosis or hybrid vigor is poorly understood despite its perceived importance in evolution and practical significance in breeding programs aimed to enhance yield of crop plants. Many studies have showed that gene expression in hybrid F₁ alters obviously as compared to their parental inbreds, but for further elucidation of the molecular mechanism of heterosis, those differentially expressed genes between hybrid F₁ and its parental inbreds need to be characterized.By using DDRT-PCR, 97 cDNA fragments that are differentially expressed between heterotic five maize hybrids and their parents were isolated at the stages of seeding, heading and grain filling.The results revealed that there were different expression patterns in both quantity and quality between hybrids and their parents. The quantitative differences included gene over—expression (QT₁, QT₂), under-expression (QT₃, QT₄) in hybrids. The qualitative differences are as follows: (1) bands observed only in hybrids (QL₁); (2) bands only present in one parent (QL₂); (3) bands present in one parent and F₁ but absent in the other parent (QL₃); (4) bands observed in both parents but absented in F₁ (QL₄). Correlations were evaluated between the qualitatively differential gene expression and heterosis of twelve agronomic traits.The differential expressed fragments were also confirmed by reverse Northern blotting.