Maternal effects shape the alternative splicing of parental alleles in reciprocal cross hybrids of Megalobrama amblycephala x Culter alburnus
Background Maternal effects contribute to adaptive significance for shaping various phenotypes of many traits. Potential implications of maternal effects are the cause of expression diversity, but these effects on mRNA expression and alternative splicing (AS) have not been fully elucidated in hybrid animals. Results Two reciprocal cross hybrids following hybridization of Megalobrama amblycephala (blunt snout bream, BSB) and Culter alburnus (topmouth culter, TC) were used as a model to
... model to investigate maternal effects. In a comparison of BSB- and TC- homoeolog expression from the two reciprocal cross hybrids, we identified 49–348 differentially expressed BSB-homoeologous genes and 54–354 differentially expressed TC-homoeologous genes. 2402, 2959, and 3418 AS events between the two reciprocal cross hybrids were detected in Illumina data of muscle, liver, and gonads, respectively. Moreover, 21,577 (TC-homoeologs) and 30,007 (BSB-homoeologs) AS events were found in the 20,131 homoeologous gene pairs of TBF 3 based on PacBio data, while 30,561 (TC-homoeologs) and 30,305 (BSB-homoeologs) AS events were found in BTF 3 . These results further improve AS prediction at the homoeolog level. The various AS patterns in bmpr2a belonged to the bone morphogenetic protein family were selected as an AS model to investigate expression diversity and their potential effects to body shape traits. Conclusions The distribution of differentially expressed genes and AS in BSB- and TC-subgenomes exhibited various changes between the two reciprocal cross hybrids, suggesting that maternal effects were the cause of expression diversity. These findings provide a novel insight into mRNA expression changes and AS under maternal effects in lower vertebrates.