Genomics and Applied Biology 2024, Vol.15, No.6, 276-284 http://bioscipublisher.com/index.php/gab 280 with oil content and fatty acid composition in Camellia oleifera has been a pivotal development. These markers have been validated in various populations, demonstrating their potential for marker-assisted selection to improve oil content and quality (Lin et al., 2019). Additionally, the sequencing and assembly of genomes from multiple oiltea-camellia species have provided a comprehensive understanding of the genetic basis of oil yield, facilitating the identification of key genes related to oil production (Table 1) (Peng et al., 2020; Ye et al., 2023). Table 1 Comparison of assembled genomes of oiltea-camellia (Adopted from Ye et al., 2023) Assembly quelity C. Chekiangoleosa C. Oleifera var. Nanyongensis C. Lanceoleosa Genome size (Gb) 2.73 2.89 2.75 N50 of contigs (Mb) 1.92 1.00 1.20 N50 of scaffolds (Mb) 185.30 185.36 186.43 GC content (%) 39.23 37.51 40.55 Sequences anchored to chromosomes (%) 97.4 91.33 91.85 BUSCO(%) 93.6 90.10 95.42 LAI (%) 11.53 - 12.45 Heterozygosity rate (%) - 2.52 2.20 Number of predicted genes 64608 42426 54172 Note: BUSCO, benchmarking universal single-copy orthologs; LAI, long-terminal-repeat assembly index (Adopted from Ye et al., 2023) 6.2 Recent breeding strategies incorporating genetic insights Recent breeding strategies have increasingly incorporated genetic insights to enhance oil content in Camellia species. For instance, the association analysis of key genes coding for fatty acid desaturases in Camellia oleifera has revealed significant marker-trait associations, which can be utilized in breeding programs to select for desirable oil traits (Lin et al., 2019). Moreover, transcriptomic analyses have identified differentially expressed genes (DEGs) involved in fatty acid biosynthesis and metabolism, providing targets for genetic manipulation to improve oil yield (Xia et al., 2014; Xie and Wang, 2018). The integration of multi-omic approaches, including genomics, transcriptomics, and metabolomics, has further accelerated the breeding process by enabling a more precise evaluation of genetic resources and the mining of key genes associated with important traits (Ye et al., 2023). 6.3 Role of CRISPR/Cas9 and other gene-editing tools in optimizing oil traits CRISPR/Cas9 and other gene-editing tools have revolutionized the optimization of oil traits in Camellia species. The CRISPR/Cas9 system has been successfully employed to target and mutate specific genes involved in fatty acid biosynthesis, such as the FAD2 gene in Camelina sativa, resulting in a significant increase in oleic acid content and a decrease in less desirable polyunsaturated fatty acids (Jiang et al., 2017; Morineau et al., 2017; Lee et al., 2021). This gene-editing approach has also been used to create combinatorial mutants in hexaploid Camelina sativa, providing a large diversity of lipid profiles and enhancing the genetic variability available for breeding (Aznar-Moreno and Durrett, 2017; Morineau et al., 2017). Furthermore, the identification of potential CRISPR/Cas9 editing sites in the Camellia sinensis genome has laid the groundwork for future functional studies and molecular breeding efforts aimed at improving oil traits (Li et al., 2023). 7 Environmental and Epigenetic Influences on Oil Content 7.1 Impact of environmental factors on oil yield in camellia species Environmental conditions play a significant role in determining the oil yield and composition in Camellia species. Studies have shown that factors such as temperature, soil type, and water availability can dramatically influence both the quantity and quality of oil produced. For instance, research on Camelina sativa, a close relative of Camellia, demonstrated that growing conditions significantly affect oil quantity and fatty acid composition, highlighting the importance of environmental factors in oil biosynthesis (Brock et al., 2020). Similarly, the environmental niche assessment of various Camelina species revealed that different environmental conditions lead to significant variations in seed oil content and composition, suggesting that careful management of growing conditions could optimize oil yield in Camellia species (Brock et al., 2020).
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