Gene Expression Variation Explains Maize Seed Germination Heterosis

Abstract

BackgroundHeterosis has been extensively utilization in plant breeding, however, the underlying molecular mechanism remain largely elusive. Maize (Zea mays), which exhibits strong heterosis, is an ideal material for studying heterosis.ResultsIn this study, there is a faster imbibition and development in reciprocal crossing Zhengdan958 hybrids than in their parent lines during seed germination. To investigate the mechanism of heterosis of maize germination, comparative transcriptomic analyses was conducted between reciprocal crossing hybrids and their parental lines. The gene expression patterns showed that 1324 (47.27%) and 1592 (66.44%) of the different expression genes between hybrids and either parental line display parental dominance up or higher levels in Zhengdan958 and Zhengdan958 reciprocal-cross, respectively. Notably, these genes were mainly enriched in metabolic pathways, including carbon metabolism, glycolysis/gluconeogenesis, protein processing in endoplasmic reticulum, etc.ConclusionOur results provide evidence for the higher expression level genes in hybrid involved in metabolic pathways acting as main contributors to maize seed germinating heterosis. These findings provide new insights into the gene expression variation of maize embryo and improve the understanding of maize seed germination heterosis.