Tissue Specific Heterophile Aggregation of Protogenes Promoted Heterosis

Abstract A plethora of studies have described heterosis or hybrid vigor; however, a global understanding of its regulation and the transmission of transcriptional levels between parents and hybrid has yet to be attained. To improve our understanding the molecular mechanisms controlling maize heterosis, we used an incomplete diallel cross design consisting of four elite maize inbred lines and six of their hybrids to measure the degree of variation in gene expression between the parents and their hybrids. We found that differentially expressed genes (DEGs) drove diversity of tissue specific heterosis and that heterophile expression was a generally complementary mechanism of gene expression in hybrids. However, the full expression of heterosis was due to the proportion of super dominant gene expression patterns that aggregate the regulatory network of dominant genes in response to adversity, and thus promotes heterosis in hybrids. Our results provide a new understanding and perspective into the regulatory mechanisms that control heterosis and represent an important step towards a more comprehensive explanation of heterosis in maize.