Tree Genetics and Molecular Breeding 2025, Vol.15, No.3, 128-137 http://genbreedpublisher.com/index.php/tgmb 134 8.3 Epigenetic signatures linked to superior oil accumulation in highland trees The Camellia oleifera population in high-altitude areas also exhibits epigenetic characteristics associated with high oil content accumulation. Joint multi-omics analysis revealed that transcription factors such as WRI1, MYB, and ZIP could regulate the expression of key lipid synthesis genes, and these expression activities were also closely related to certain specific DNA methylation modifications and transcriptional variations (Gong et al., 2020; Ye et al., 2021). Furthermore, through QTL mapping and association analysis, researchers also found that some specific SNP loci on genes such as SAD and FAD2 were significantly associated with the high oil trait, and these loci could be used as markers in molecular breeding (Lin et al., 2019; Lin et al., 2024). That is to say, these epigenetic and gene-level changes work together to create the excellent oil accumulation capacity of high-altitude Camellia oleifera. 9 Applications and Breeding Implications 9.1 Epigenetic markers for oil yield trait selection In recent years, genomic and transcriptomic studies have identified many key genes related to lipid accumulation, such as SAD, FAD2 and WRI1, etc. (Wu et al., 2019; Gong et al., 2020; Yang et al., 2024). Through genome-wide association study (GWAS) and QTL mapping, researchers identified some SNP and InDel variations closely related to oil content and fatty acid composition. These variations can be used as molecular markers for screening Camellia oleifera materials with high oil content and high-quality fatty acids (Lin et al., 2019; Lin et al., 2024). Furthermore, transcriptional variations and alternative splicing also provide new epigenetic marker resources (Gong et al., 2020). The application of these markers can improve the efficiency of molecular marker-assisted selection (MAS) and cultivate Camellia oleifera varieties with high oil yield more precisely. 9.2 Integration of epigenetics into molecular breeding programs Multiomics studies such as transcriptomics, proteomics and metabolomics have shown that the process of lipid accumulation involves the joint regulation of multiple genes (Wu et al., 2019; Ye et al., 2021; Yang et al., 2024). If epigenetic information such as DNA methylation, histone modification, and non-coding RNA is also incorporated, a more comprehensive understanding of the genetic mechanism of lipid accumulation can be achieved (Gong et al., 2020). By integrating the QTL mapping results, candidate genes and epigenetic regulatory networks, truly important regulatory factors can be screened out. This is very helpful for promoting gene editing and precision breeding in Camellia oleifera, and can also accelerate the breeding speed of superior varieties (Ye et al., 2023; Lin et al., 2024). 9.3 Potential for environment-specific oil crop improvement Different ecological environments such as high altitude and low altitude have significant effects on lipid accumulation and the expression of related genes (Wu et al., 2019; Ye et al., 2021; Yang et al., 2024). Epigenetic variation is an important way for plants to adapt to the environment, and it can provide theoretical support for breeding Camellia oleifera varieties adapted to specific environments (Liu et al., 2023; Ye et al., 2023). If the epigenetic markers and regulatory genes related to environmental response can be identified, there is hope to breed new types of Camellia oleifera that are adapted to different ecological regions and have stronger oil accumulation capacity, and achieve targeted improvement and regionalized efficient cultivation of Camellia oleifera. 10 Concluding Remarks Epigenetic variations such as DNA methylation and histone modification can regulate gene expression, thereby influencing the external traits of plants and their ability to adapt to the environment. In Camellia oleifera, the expression of genes related to oil accumulation and lipid metabolism is closely related, and the expression of these genes is affected by environmental factors, such as altitude and climate. Epigenetic mechanisms provide a possible molecular basis for Camellia oleifera to regulate lipid synthesis in different altitude environments, and also help explain the reasons for the differences in lipid content and fatty acid composition. Although epigenetic regulation has great potential in crop improvement, its practical application in woody crops such as Camellia oleifera still faces many difficulties. For instance, it remains uncertain whether epigenetic
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