Aixin Liang
Yang Zhou
Hasan Riaz
John S. Davis- 1College of Animal Science and Technology, Huazhong Agricultural University, Wuhan, China
- 2VA Nebraska-Western Iowa Health Care System, Department of biosciences, COMSATS University Islamabad, Sahiwal, Pakistan
- 3Department of Obstetrics and Gynecology, University of Nebraska Medical Center, Omaha, NE, United States
Editorial on the Research Topic
Genetic Analysis of Reproductive traits in livestock
Reproduction is one of the most important traits of livestock to maintain the continuity of the species. Improving the reproductive performance of livestock is of importance and tightly related to the selection intensity and production costs (Schmidt et al., 2019). Candidate gene and high throughput studies have been used to better understand the genetic basis of reproductive traits over the last decades (Óvilo and Valdovinos, 2012). However, the identification and analysis of specific functional and positional variants and molecular regulatory pathways influencing reproductive efficiency remain a challenging task. Therefore, the goal of this Research Topic is to present current knowledge about genetic factors affecting reproduction in animals and present state-of-the-art methods for studying genetic influences on reproductive phenotypes. Based on female or male reproductive traits, the thirteen articles published in this Research Topic cover many different species such as pig, cattle, sheep, rabbit, chicken, duck, and turkey. This article collection shows recent advances, recent technologies, and challenges in livestock reproduction.
High-throughput transcriptome sequencing (RNA-Seq) has become the main approach to identify the key genes related to reproductive traits. The work of Mao et al. describe the use of RNA-seq to screen key genes and lncRNAs that affect the fecundity of pigs. The report highlights an important regulatory role that lncRNA MSTRG.3902.1 may play in rpFSH-induced ovulation by affecting the target gene NR5A2 (nuclear receptor subfamily 5, group A, member 2). Likewise, Du et al. use RNA-seq technology to identify differentially expressed genes in ewe adrenal glands under different photoperiod treatments, and identify several novel mRNA, miRNAs, and lncRNAs, which may regulate sheep seasonal estrus. Using RNA-seq technology, Zhang et al. identified several mRNAs (e.g., GAMT, SOHLH1, DMC1, MACROD1, WNT2B, SPIN1, CRH, TTR, and WISP1) that may have direct or indirect functions in the initiation of puberty, which may provide new insight into the mechanisms that initiate puberty in sheep. Moreover, Ross et al. provided a case study that combined information from multiple expression datasets such as RNA-seq, ISO-seq and CAGE-seq, and identified several genes relevant to fertility in Brahman cattle. They demonstrated tissue-specific expression of the selected genes, allele-specific expression, variation in transcription start sites, and untranslated regions. The integration of RNA-seq and other sequencing technologies will be a viable alternative to effectively improve the accuracy of candidate gene selection.
In addition to RNA-seq technology, genome-wide association studies (GWASs) and whole-genome sequencing are also widely used to identify key single nucleotide polymorphisms (SNPs) and candidate genes that correspond to reproductive traits. By using GWASs, Mo et al. identified a total of 29 candidate SNPs for seven litter-size traits and four teat-number traits in Bama Xiang pigs. By using GWASs and haplotype-sharing analysis, Xu et al. observed candidate genes and haplotypes that were significantly associated with egg production traits in laying ducks. In addition, Zhang et al. reported on 10 important candidate genes related to bone traits, and two bone-related pathways such as osteoclast differentiation and MAPK (Mitogen Activated Protein Kinase) signaling pathway in laying chicken populations using whole-genome pooled sequencing. By integrated analysis of GWASs and transcriptome data, the study of Shi et al. identified 7 significant SNPs and proposed 28 candidate genes associated with sow milk production, 10 of which were key candidates. Compared to the traditional the cumulative model, Makanjuola et al. demonstrated that random regression models using pedigree and genomic information can achieve a higher predictive ability for analyzing longitudinal traits such as fertile eggs set in the incubator (FERT), hatch of fertile (HOF), and hatch of set (HOS) in turkeys.
It has been reported that splicing isoforms may exert distinct functions in reproductive physiological processes, such as progesterone receptor isoforms (Rekawiecki et al., 2011) and prolactin receptor isoforms (Binart et al., 2010). The article of Kern et al. describe four isoforms of preferentially expressed antigen in melanoma Y-linked (PRAMEY) in the bovine testis and spermatozoa. The study implicates that the 58 and 30 kDa PRAMEY isoforms are involved in spermatogenesis, whereas the 13 kDa PRAMEY isoform is responsible for sperm maturation and sperm motility.
Microbial communities in the reproductive tract are involved in the maintenance of host fertility and health (Feng and Liu, 2022). Endometrial inflammation is common in postpartum dairy cows, and alterations in the uterine microbiota are associated with perinatal disease. The study of Kudo et al. revealed that Trueperella is present in higher abundance in the uterus and vagina of the endometritis group and is negatively correlated to the abundance of Lactobacillus. As mentioned in their article, their findings are helpful for predicting endometritis and developing prevention or treatment strategies.
Myostatin (MSTN) is regarded as a negative regulator of muscle development and regeneration, and natural mutations of MSTN result in an obvious double muscle phenotypic effect in cattle, dogs, sheep, and pigs. In this Research Topic, Zheng et al. developed a heritable double muscle buttocks in rabbits via MSTN mutation using the CRISPR/Cas9 system. This may improve rabbit meat production efficiency and promote the development of the rabbit industry.
In summary, integration of the available technological approaches provides more powerful tools for the identification of novel functional candidate genes, specific genetic variants, and molecular pathways affecting reproductive traits. The CRISPR/Cas9 system is an efficient genome editing tool for the validation of functional genes in relation to reproduction, which may significantly improve reproductive efficiency in livestock.
Author contributions
All authors have made a substantial, direct and intellectual contribution to the work and approved it for publication.
Acknowledgments
We want to thank all the authors for their novel work and the external reviewers for their valuable comments to improve the quality of the articles. We also appreciate the continuous support of the Frontiers staff.
Conflict of interest
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.
Publisher’s note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
References
Binart, N., Bachelot, A., and Bouilly, J. (2010). Impact of prolactin receptor isoforms on reproduction. Trends Endocrinol. Metab. 21 (6), 362–368. doi:10.1016/j.tem.2010.01.008
Feng, T., and Liu, Y. (2022). Microorganisms in the reproductive system and probiotic’s regulatory effects on reproductive health. Comput. Struct. Biotechnol. J. 20, 1541–1555.
Óvilo, C., and Valdovinos, C. (2012). Animal reproduction in livestock - genetic basis and improvement of reproductive traits. Oxford ,UK: ©Encyclopedia of Life Support Systems.
Rekawiecki, R., Kowalik, M. K., and Kotwica, J. (2011). Nuclear progesterone receptor isoforms and their functions in the female reproductive tract. Pol. J. Vet. Sci. 14 (1), 149–158. doi:10.2478/v10181-011-0024-9
Keywords: reproduction, SNP, GWAS, RNA-seq, molecular pathway
Citation: Liang A, Zhou Y, Riaz H and Davis JS (2023) Editorial: Genetic analysis of reproductive traits in livestock. Front. Genet. 13:1116038. doi: 10.3389/fgene.2022.1116038
Received: 05 December 2022; Accepted: 15 December 2022;
Published: 04 January 2023.
Edited and reviewed by:
Johann Sölkner, University of Natural Resources and Life Sciences Vienna, AustriaCopyright © 2023 Liang, Zhou, Riaz and Davis. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: John S. Davis, jsdavis@unmc.edu