Comparative transcriptome analysis among parental inbred and crosses reveals the role of dominance gene expression in heterosis in Drosophila melanogaster

We observed heteroses for body weight in Drosophila melanogaster after generating hybrids from three inbred lines. To better understand the mechanism for this phenomenon at the mRNA level, we compared the mRNA profiles of the parental and hybrid lines using high-throughput RNA-seq. A total of 5877 differentially expressed genes (DEGs) were found and about 92% of these exhibited parental expression level dominance. Genes in the dominance category were functionally characterized using the Kyoto Encyclopedia of Genes and Genomes (KEGG) and the gene classifications offered by the Gene Ontology (GO) Consortium. The analysis identified genes associated with crucial processes such as development and growth in all three crosses. Functional assignments involving aminoglycan metabolism, starch and sucrose metabolism, and galactose metabolism are significantly overrepresented amongst the 215 common dominance DEGs. We conclude that dominance DEGs are important in heteroses in Drosophila melanogaster and contribute specifically to body weight heterosis.