The analysis of growth performance and expression of growth-related genes in natural gynogenic blunt snout bream muscle derived from the blunt snout bream (Megalobrama amblycephala, ♀) × Chinese perch (Siniperca chuatsi, ♂)

Gynogenesis is an advanced breeding technique that can quickly establish pure lines, increase progenies genetic variation, cultivate strains with higher dominant traits. As a good model for cross order species hybridization, there are few reports on the study of natural gynogenetic blunt snout bream (GBSB), even on the differences in growth between gynogenesis progenies and their parent fish (blunt snout bream♀ and Chinese perch♂). In this research we compared the growth characteristics of the natural GBSB with its parents. It was found that GBSB had a faster growth rate and higher meat content than its female parent, and the diameter and density of muscle fibers were between those of paternal and maternal fish. We performed transcriptome sequencing of muscle tissues from GBSB and BSB, it identified 1353 significant DEGS in the muscle of the GBSB compared to the BSB, with 820 up- and 533 down-regulated genes. And the relative expression of myosins was notable rise in GBSB. In addition, the MRFs of gene structure, motifs, and phylogenetic relations were characterized in BSB and CP. It showed that MRFs and mstn central domain was highly conserved, but the number of conservative motifs in MRFs of CP is generally higher than that of BSB. Further, the relative expression of myosin complex, myogenic regulatory factors (MRFs), growth hormone/insulin-like growth factor (GH/IGF)-axis and most hypothalamic-pituitary-gonadal (HPG)-axis genes in GBSB were higher than that of the female fish and some were closer to that of the paternal fish. Through the distant hybridization between BSB and CP, a gynogenetic progeny with enhanced growth rate compared to the maternal fish was successfully generated. The research has contributed significant insights into the genes and molecular properties associated with muscle development, as well as their potential functional correlations in response to different functional requirements during the growth process of hybrid progeny formed by cross breeding.