International Journal of Aquaculture, 2025, Vol.15, No.2, 76-87 http://www.aquapublisher.com/index.php/ija 78 on 1 120 wrinkled disc abalones, the survival rate of selected high-heat-resistant families has been significantly improved (Yu et al., 2021). Secondly, disease-resistant breeding is becoming increasingly the focus. Under the conditions of tight breeding of abalone, bacterial sepsis, red meat diseases and other diseases are prone to outbreaks, posing a serious threat to yield. Traditional methods have achieved certain results through hybrid selection and breeding. For example, the new Haliotis diversicolor variety "Dongyou No.1" exhibits approximately 30% higher disease resistance compared to ordinary populations. However, disease resistance is usually controlled by polygenics and phenotype determination requires disease exposure, making breeding difficult (Zhou et al., 2023). GS provides a new idea for disease-resistant breeding: through genome-wide association analysis, disease-resistant SNP markers and candidate genes can be identified, so as to perform early genome-level seed selection. Broad-spectrum adaptability is also a new breeding direction, that is, improving the tolerance of abalone to multiple environmental stresses, including resistance to hypoxia and typhoons and waves. Low dissolved oxygen or even red tides often occur in nearshore aquaculture water bodies in summer and autumn, so the cultivation of hypoxic-resistant strains is increasingly attracting attention. An invention patent proposes a method to quickly determine the ability of abalone to resist hypoxia, which can be used to early screening of tolerant individuals. This phenotyping technique provides tool support for stress-resistant breeding. With accurate hypoxia-resistant phenotype data, combined with GS analysis, it is expected to cultivate new abalone products that are more adaptable to hypoxia environments. 3 Development of Abalone Genetic Resources and Accumulation of Omics Data 3.1 Progress in abalone genome sequencing and construction of reference genomes The construction of high-quality reference genomes provides a fundamental information platform for genetic breeding in abalone. With the application of third-generation sequencing and advanced assembly technologies, the quality of abalone genome assemblies has improved significantly. In 2024, researchers assembled the genome of the tropical abalone (Haliotis asinina) to the chromosome level using PacBio HiFi long-read sequencing combined with Omni-C technology. This effort resulted in 16 pseudo-chromosomes covering 1.12 Gb-more than 98% of the total genome length-with a contig N50 of 67.09 Mb and genome completeness of 97.6%. A total of 25 422 protein-coding genes were annotated, providing a valuable resource for comparative genomic studies on heat tolerance mechanisms in abalone (Nguyen et al., 2022). In addition to H. asinina, reference genomes of several other abalone species have been published. A U.S. research team constructed a reference genome for the red abalone (H. rufescens) as part of the California Conservation Genomics Project (CCGP); this genomic map aids in assessing the genetic diversity and adaptive potential of wild red abalone populations. Meanwhile, a high-quality reference genome for the endangered black abalone (H. cracherodii) was assembled using PacBio and Hi-C technologies, providing essential genetic data for species restoration efforts (Franchini et al., 2011). In Australia, researchers also reported a draft reference genome of the South African abalone (H. midae), with a total length of approximately 1.5 Gb and a contig N50 of 0.24 Mb. In practical breeding applications, reference genomes can be used to design capture chips or SNP arrays, enabling genome-wide scanning of breeding populations. 3.2 Acquisition and utilization of omics resources such as transcriptome and metabolomic group In addition to genome sequencing, the accumulation of functionalomics data also provides important information for abalone breeding. In terms of transcriptomics, the abalone gene expression profiles under different developmental stages, tissues and treatment conditions have been widely analyzed. In the anti-pathogenic study, the researchers conducted transcriptome sequencing of the gill tissue after the pathogenic bacteria of wrinkle disc abalone infection, and identified 7 656 up-regulated and 2 789 down-regulated differentially expressed genes, which were enriched in redox processes, immune responses and other pathways. Among them, upregulated genes include pattern recognition receptors (such as C1q-like proteins, NOD-like receptors) and effector molecules (such as IL-17, lysozyme, superoxide dismutase, etc.), showing that abalone has initiated defense responses such as innate immunity and apoptosis regulation under the challenge of bacteria (Fang et al., 2022). Such transcriptomic data helps to lock in disease-related candidate genes (such as immune receptors, antimicrobial
RkJQdWJsaXNoZXIy MjQ4ODYzNA==