Bioscience Methods 2025, Vol.16, No.3, 162-172 http://bioscipublisher.com/index.php/bm 163 Gene editing, represented by CRISPR/Cas9, the third-generation genome-directed modification technology, has brought revolutionary tools to aquatic animal breeding (Hallerman et al., 2021). Compared with traditional breeding, which requires multiple generations of hybridization and selection, gene editing can achieve precise genetic improvement in one generation of individuals, significantly shortening the breeding cycle (Zhu et al., 2024). The CRISPR/Cas9 system uses RNA-guided nucleases to produce mutations or knockouts at specific sites in target genes, thereby conferring or enhancing traits such as disease resistance. Unlike transgenic technology, CRISPR technology does not require the insertion of exogenous fragments into the genome, and can produce improved varieties that are "free of exogenous genes" (Roy et al., 2022). Gene editing tools such as CRISPR are rapidly being integrated into the field of aquaculture breeding with their advantages of high efficiency, precision and flexibility, providing unprecedented opportunities for breeding new disease-resistant varieties (Ferdous et al., 2022). This study will introduce common diseases and their hazards in snakehead aquaculture, analyze the mechanistic basis of snakehead immune response, summarize the research status of snakehead disease-resistant genes in recent years, and focus on the application strategy of gene editing technology in snakehead disease-resistant breeding. By drawing on the successful cases of gene editing disease-resistant breeding of other fish (such as salmon and catfish), the inspiration for snakehead is analyzed. At the same time, the ecological safety, food safety and ethical supervision issues that need to be considered in the actual production of gene-edited snakehead are discussed, and the recommended paths for establishing a disease-resistant gene resource library, optimizing the editing platform and promoting industrialization are proposed. This study hopes to provide a comprehensive literature basis and forward-looking perspective for the molecular breeding of disease-resistant snakehead, and accelerate the breeding and application of new disease-resistant snakehead varieties. 2 Research Status of Common Diseases and Disease Resistance Genes of Snakehead Fish 2.1 Analysis of common diseases and hazards of snakehead fish In the intensive farming environment of snakehead fish, high density and stress often lead to the rapid spread of pathogens, causing outbreaks of various diseases. Among bacterial diseases, nocardiosis and Aeromonas hydrophila are the most common. Nocardiosis is caused by infection with N. seriolae, which can invade the skin, muscles and internal organs of snakehead fish, forming a large number of white nodules (granulomas). Diseased fish often show emaciation and lethargy. Dissection shows that organs such as the liver and spleen are covered with granulomas (Figure 1) (Zhang et al., 2022; Teng et al., 2024). Figure 1 Clinical symptoms of snakehead infected with Nocardia (Adopted from Zhang et al., 2022) Image Caption: (A) Clinical signs of diseased hybrid snakehead body surface. Appearance of abdominal cavity (B), liver (C), spleen (D) and kidney (E); The white arrows indicate superficial lesions, black arrows indicate granules of N. seriolae, and yellow arrows indicate the necrosis and granuloma (Adopted from Zhang et al., 2022)
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