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Livestock farming provides a major source of animal protein and occupation opportunities for a large proportion of the world’s population, and its profitability could be effectively increased by improvement of either feed efficiency (
This Research Topic aimed to collect new research in the field of “Genetics of reproduction in livestock species”. After announcing the Research Topic, a total of 20 original articles were received. However, after intensive review processes, only five articles were accepted and published in this Research Topic. A summary of the results of the articles in this Research Topic is as follows.
1. Identification of genes related to sexual differentiation and sterility in embryonic gonads of mule ducks by transcriptome analysis (
Gonad development is a factor involved in the reproduction process in different livestock species. This study was conducted to investigate the genes associated with early-stage gonad development in ducks. Embryonic gonadal tissues of three duck types, comprising mule, Jinding, and Muscovy, were collected and subjected to RNA sequencing analysis. In this study, among a total of 9,471 detected genes, 12 genes related to testicular development, 11 genes highly expressed in female gonads, seven genes responsible for female sterility and eight genes for male sterility, and five genes for both female and male sterility were identified. This study provides new information about the differential development of male and female gonads and sterility mechanisms in mule ducks and a theoretical basis for future research on sex determination and differentiation in ducks, and possibly sterility in birds. 2. Genetic parameters estimation and genome molecular marker identification for gestation length in pigs (
Pig is a major component of meat production in many countries. Regarding the important role of gestation length in piglet maturation and body development, the aim of this study was the estimation of genetic parameters and identification of genomic molecular markers for gestation length in pigs. In this study estimates of heritability and repeatability for gestation length were 0.16 and 0.24, respectively. Genotyping of animals using the Porcine 50 K Chip and genome-wide association analysis resulted in identification of 1,002 single nucleotide polymorphisms, associated with gestation length. This study proposed 4,588 candidate genes; however, a total of 20 genes were most suggestive of candidate genes. This article provides new genetic parameters and molecular information for gestation length in pigs. 3. Genome-wide analysis for the melatonin trait associated genes and SNPs in dairy goat (
Melatonin is one of the factors regulating reproduction in vertebrates with a strong influence on biological rhythms in many organisms ( 4. Comparative gonad transcriptome analysis in cobia (
Cobia is known as a fast-growing fish with a high commercial value, and many fish producers favor a monosex culture because of the higher body size of female fish. However, the effects of genetic factors associated with the sexual development and sexual phenotype in cobia are largely unknown. This study is possibly the first attempt to detect sex-biased differentially expressed genes (DEGs) in cobia fish gonads, using comparative gonad transcriptome sequencing analysis. A total of 76 candidate genes, including 42 known testis-biased and 34 known ovary-biased DEGs were identified as the genes involved in sex determination cascades or sex differentiation pathways. A total of 11 pathways, including Wnt signaling, oocyte meiosis, TGF-β signaling, and MAPK signaling pathways, were identified as functionally related to sex determination and differentiation. The results of this study provide a molecular basis for further studies on cobia’s sex determination mechanism and facilitation of monosex culturing. 5. The alternative transcription and expression characterization of
The different fertilities and meiosis stabilities of established and neo-autotetraploids are known (
In addition to the subjects published in this Research Topic, there are several other interesting areas, including high-throughput methods, that should be subjected to future studies on the genetics of reproduction.
Genome-wide association studies (GWAS) are widely used for detection of genomic regions associated with productive and reproductive traits. Previous GWASs resulted in detection of many quantitative trait loci and candidate genes associated with reproductive traits in different livestock species, such as cattle (
The recent discovery of the CRISPR/Cas9 system has made on-target genetic engineering achievable in any organism. Specific mutations in major genes associated with the performance of farm animals have been a hot Research Topic for more than two decades. This has provided an important phenotypic and genotypic database to search for the most important major genes and mutations. However, instead of successive generations of selection and planned mating, use of a reverse engineering approach can create desired mutation(s) in a single generation by using the CRISPR/Cas9 approach. This technology has been used for the identification of three well-known major fecundity genes in farm animals, including the Booroola mutation in ovine
Gene drive comprises the introduction of synthetic fragments involving a driving element, the CRISPR/Cas9 system, into the target genome, which can increase the spreading chance of specific alleles through the population compared to the standard Mendelian inheritance (
Understanding major genes/mutations associated with the reproductive performance of farm animals could have a great impact on the economic efficiency of animal production enterprises. The articles published in this Research Topic improved our understanding of the genetics of reproduction in livestock species. However, there are huge numbers of questions about genetic factors associated with reproduction performance in farm animals, which should be considered in future studies.
PZ, SE, and RA wrote the paper and MF revised the paper. All authors listed have made a substantial, direct, and intellectual contribution to the work and approved it for publication.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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