International Journal of Marine Science, 2025, Vol.15, No.3, 167-178 http://www.aquapublisher.com/index.php/ijms 175 models or cellular models of abalone may be one of the ways to improve validation efficiency. In addition, using close-range biological substitution is also one of the strategies. For example, bivalve shellfish such as scallops are more mature to edit genes, and some conservative gene functions can be verified and then deduced to abalone. The third challenge is the issue of gene manipulation efficiency and specificity. There is a situation where RNAi is away from the target and is not completely silent, and multiple sets of siRNAs need to be designed and combined with expression analysis to confirm the knockdown effect. CRISPR/Cas9 may be at risk of off-targeting, and highly efficient and specific gRNAs need to be screened and sequenced and verified (Li et al., 2024). At present, the large genome of abalone increases the possibility of off-target, and improving gene editing specificity is an important topic. In addition, polygenic traits often require multiple genes to change in synergistically in order to see significant changes in the phenotype, which poses a challenge to traditional single gene operation. 7 Actual Case Analysis 7.1 Research on disease-resistant breeding of Haliotis discussion hannai Japanese abalone (i.e., Ezo abalone abalone, Haliotis discuss hannai) is an important breed of abalone in cold waters in East Asia. At the end of the 20th century, large-scale artificial breeding of wrinkled abalone was carried out in northern China and South Korea. However, bacterial and viral diseases that break out under intensive breeding conditions pose a serious threat to the industry. For example, Ezo abalone abalone furuncle disease and WS recovery syndrome have caused up to 30%~50% of farming losses. The representative of these is the cultivation of the disease-resistant abalone varieties of "Dongyou No. 1" in Fujian, China. This breed showed high resistance to major bacterial diseases in pathogen-challenged tests in laboratories and production ponds, with survival rates of 20~30% higher than that of ordinary strains under the same infection conditions. "Dongyou No. 1" passed the national variety approval in 2009, becoming the first national-level new aquatic product variety in Fujian Province. After its promotion, it significantly reduced the breeding mortality rate. In South Korea, researchers used family breeding to bind molecular markers to cultivate Ezo abalone abalone strains that are Abalone herpesvirus. By establishing multiple family lines of all siblings, they selected surviving individuals as their parents after artificially infected with the virus, and obtained disease-resistant strains with significantly improved survival rates through 2 generations. Their seedlings increased by about 15% compared with unselected seedlings in field trials (Figure 3) (Yasa et al., 2020). The case shows that through hybrid recombination and family selection, combined with artificial challenge screening, the disease resistance of abalone can be effectively improved. Figure 3 Histological section of abalone H. squamata foot (100× magnification). Control treatmen (A), infected with V. alginolyticus at concentrations of 1 × 105 cfu (B) 1 × 106 cfu (C) and 1 × 107cfu (D). Vacuolations, enlargement of hemolymph sinuses and abscesses werefound in infection treatments (Adopted from Yasa et al., 2020)
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