Preliminary Study On The Heterosis Mechanism Of Tachysurus Hybrids Using RNA-seq Technologies

The divergence of gene expression between species was tightly connected with phenotypic diversity.Investigating the molecular mechanisms resulted from regulatory divergence should be crucial to reveal the evolutionary variation of two related species and novel expression patterns of interspecific hybrids produced by the two species.Here,the total and allele-specific gene expression were quantified in two Pelteobagrus species and interspecific hybrids by RNA-seq.A higher proportion of cis regulatory than trans regulatory were found between parental species and the cis-regulatory divergence was closely associated with the genetic divergence between parental species and considered to determine the mediate gene expression level in Pelteobagrus hybrids.Except genetic divergence,the natural selections also made contributions to the reservation of cis-acting variations through a enough long period of independent evolutionary process since the parental species diverged.Moreover,we found that,in Pelteobagrus hybrids,the expression of alleles from both dominant and non-dominant genome changed along with each other,hence the inheritance of expression level dominance would be achieved,in contrast to studies about intraspecific hybridization or interspecific hybridization between less divergent parents and in accordance with the case that there was significant genetic divergence between parental species in this study.However,trans-factors from dominant genome in Pelteobagrus hybrids also made more contributions to overall dominant expression which was in agreement with previous studies.This study explored the role of cis-and trans-regulatory played in the genetic divergence between parenal species and gene expression changes in the interspecific hybrids whose parental species have significant genetic divergence.High degree of cisregulatory divergence observed among parental species resulted from the long period of independent evolution would be related with significant genetic divergence and lead to the high level of genes with additive expression level in Pelteobagrus hybrids.