The creation of mutant germplasm of nonmuscular stickleback is a hot spot in fish genetics and breeding research in recent years. Heterogeneous silver crucian carp is favored by consumers for its tender and delicious meat, but the more than 80 tiny intermuscular spines in its body have brought a lot of trouble to eaters.
Micro-CT scan of a non-intermuscular spiny silver crucian mutant. Photo courtesy of interviewee
In recent years, the team of Academician Gui Jianfang of the Institute of Hydrobiology of the Chinese Academy of Sciences revealed through whole genome analysis that silver crucian carp is a triploid, that is, it contains two sets of triploid genomes, and thus pioneered and perfected the method of rapidly creating key gene mutants through gene editing in double triploid silver crucian and diploid goldfish. Based on these breakthroughs, Academician Gui Jianfang’s team created a precision breeding technology for polyploid fish, and cooperated with Professor Gao Zexia of Huazhong Agricultural University to create a new germplasm without intermuscular spiny mutants in triploid silver crucian after more than a year of efforts. The relevant research results were recently published online in the international journal Aquaculture.
The researchers first found that the double triploid silver crucian runx2b has two partial homology genes (Cgrunx2b-A and Cgrunx2b-B), and each partial homologous gene has 3 alleles with highly consistent sequences. Then the ossification process of the intermuscular spines was traced, and it was found that the intermuscular spines began to ossify from the tail of the fish towards the head about 14 days after hatching, and it was found that knocking out CgRunx2b-A or CgRunx2b-B alone did not affect the development of intermuscular spines, but knocking out all alleles of CgRunx2b-A and CgRunx2b-B at the same time would result in a complete loss of intermuscular spines. As a result of the above studies, 291 silver crucian mutants with complete loss of intermuscular spines have been obtained.
The study revealed that CgRunx2b-A and CgRunx2b-B synergistically regulate the development of intermuscular spines in silver crucians. More importantly, the silver crucian non-intermuscular spiny mutant and the oligomyomyotic intermuscular spiny mutant created this time have laid the foundation for the cultivation of a new strain of silver crucian carp without intermuscular spines. In the next step, the researchers will establish a cloning line without intermuscular spines through female nuclear reproduction, and evaluate economic traits such as growth traits with the main breed of heterogeneous silver crucian under the same feeding conditions. (Source: China Science News, Li Sihui, Sun Hui)
Related paper information:https://doi.org/10.1016/j.aquaculture.2023.739300