RNA-Seq analysis reveals expression regulatory divergence of W-linked genes between two contrasting chicken breeds

Abstract The regulation of gene expression is a complex process involving organism function and phenotypic diversity, and is caused by cis- and trans- regulation. While prior studies identified the regulatory pattern of the autosome rewiring in hybrids, the role of gene regulation in W sex chromosomes is not clear due to their degradation and sex-limit expression. Here, we developed reciprocal crosses of two chicken breeds, White Leghorn and Cornish Game, which exhibited broad differences of gender-related traits, and assessed the expression of the genes on W chromosome to disentangle the contribution of cis- and trans-factors to expression divergence. We found that there was not appear to be an association between female fecundity and W chromosome gene expression, that 44% of expressed genes had divergent expression between breeds in both tissues, with only 17% of them showing greater expression in White Leghorn. We observed that the proportion of trans-acting genes in W chromosome was higher than cis-regulatory divergence. There were most parental divergence expression genes in muscle, also more heterosis compared with other two tissues. A strong dominant impact of Cornish alleles in brain, while obvious crosses-specific regulatory patterns appeared in liver. Taken together, this work describes the regulatory divergence of W-linked genes between two contrasting breeds and indicates sex chromosomes have a unique regulation and expression mechanism.