International Journal of Molecular Zoology, 2025, Vol.15, No.1, 38-47 http://animalscipublisher.com/index.php/ijmz 38 Review and Progress Open Access Genetic Regulation of Fast Growth Traits and Genomic Selection for Breeding in Groupers Chengmin Sun1, RudiMai 2 1 Center for Tropical Marine Fisheries Research, Hainan Institute of Tropical Agricultural Resources, Sanya, 572025, Hainan, China 2 Hainan Tropical Agricultural Resources Research Institute, Tropical Bioresources Research Center, Sanya, 572025, Hainan, China Corresponding author: rudi.mai@hitar.org International Journal of Molecular Zoology, 2025, Vol.15, No.1 doi: 10.5376/ijmz.2025.15.0005 Received: 01 Jan., 2025 Accepted: 10 Feb., 2025 Published: 25 Feb., 2025 Copyright © 2025 Sun and Mai, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Sun C.M., and Mai R.D., 2025, Genetic regulation of fast growth traits and genomic selection for breeding in groupers, International Journal of Molecular Zoology, 15(1): 38-47 (doi: 10.5376/ijmz.2025.15.0005) Abstract Grouper has become a key aquaculture species in recent years due to its fast growth and high efficiency. However, traditional breeding methods are inefficient and have long cycles, making it difficult to meet the demand for high-yield and high-resistance new strains. To explore the genetic mechanism of its rapid growth, the study was carried out from two levels: genetic basis and molecular regulation, and the current more mature genome breeding strategies were sorted out. There are still difficulties in actual operation, such as high typing costs, imperfect reference genomes, and limited breeding efficiency. It is worth noting that hybrid groupers show obvious growth advantages, which may be driven by the "middle parent effect". In other words, although the two parents have their own shortcomings, they have a stronger growth ability after combination. From this perspective, scientifically designing parent combinations may be a more realistic breakthrough at present. The study emphasizes that, only by truly establishing high-quality and renewable genome resources and using a new generation of molecular tools can grouper breeding be accelerated and improved, and the entire industry can embark on the road of sustainable development. Keywords Grouper; Growth traits; Genetic regulation; Genomic selection; Molecular breeding 1 Introduction The rapid development of grouper aquaculture is due to consumer preference for high-quality, fast-growing fish that can improve production efficiency and economic benefits (Liu et al., 2022; Ai et al., 2023; Wu et al., 2024). Therefore, breeding high-performance grouper varieties that meet market demand is an important driving force to support the development of sustainable aquaculture (Ai et al., 2023; Hsu et al., 2024). Growth rate is one of the most core traits in grouper breeding, which directly affects yield, production cycle and economic returns (Liu et al., 2022; Wu et al., 2023). In the study of giant grouper (Epinephelus lanceolatus), Wu et al. (2023) constructed a high-density genetic map containing 2 988 SNPs and found 6 growth-related QTLs, which can explain 4.65% to 12.56% of the phenotypic variation. Through RNA-Seq analysis, 27 differentially expressed genes overlapping with these QTLs were screened out, mainly involving key functions such as PPAR signaling pathways, carbon metabolism, and RNA transport. Judging from these results, breeding faster-growing varieties has become the highlight of grouper farming. Genetic improvement projects are also increasingly inclined to be carried out around these growth-related genetic markers, and precision breeding is gradually replacing traditional empirical methods. But, improving growth traits in grouper is not easy. One problem is that, groupers have long generation times. They also need large numbers of fish for breeding, and it’s hard to measure their traits accurately when they’re still young. These challenges slow down genetic progress and make traditional breeding methods less effective (Wu et al., 2023; Hsu et al., 2024). Also, growth traits in grouper are controlled by many different genes and are influenced by the environment. So, it is difficult to analyze its genetic mechanism and apply effective selection strategies (Yang et al., 2020; Zhang et al., 2022; Wu et al., 2023). In addition, due to the polygenic nature of growth traits and the need for
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