Genomics and Applied Biology 2024, Vol.15, No.6, 276-284 http://bioscipublisher.com/index.php/gab 277 2 Camellia Species and Oil Composition 2.1 Key camellia species cultivated for oil production Camellia oleifera and Camellia sinensis are two primary species cultivated for oil production. Camellia oleifera, commonly known as the tea oil camellia, is extensively grown in China for its seeds, which are a significant source of edible oil rich in unsaturated fatty acids (Zeng et al., 2014; Lin et al., 2018; Lin et al., 2019). Camellia sinensis, primarily known for tea production, also contributes to oil production, although it is less prominent compared to C. oleifera (Xia et al., 2014). 2.2 Differences in oil composition among species The oil composition varies significantly among different Camellia species. Camellia oleifera oil is renowned for its high oleic acid content, which constitutes a substantial portion of its fatty acid profile (Lin et al., 2018; Wu et al., 2019; Gong et al., 2020). This high oleic acid content is attributed to the coordinated expression of genes involved in fatty acid biosynthesis, such as stearoyl-ACP desaturases (SADs) and fatty acid desaturase 2 (FAD2) (Lin et al., 2018; Wu et al., 2019). In contrast, other species like Camellia sinensis may have different fatty acid profiles, with varying levels of oleic, linoleic, and palmitic acids (Xia et al., 2014). 2.3 Role of genetics in influencing oil content and quality Genetics play a crucial role in determining the oil content and quality in Camellia species. Studies have identified several key genes associated with oil biosynthesis and fatty acid composition. For instance, in Camellia oleifera, genes such as CoSADand CoFAD2 are critical for the synthesis of oleic acid and other fatty acids (Zeng et al., 2014; Lin et al., 2019; Wu et al., 2019). Single nucleotide polymorphisms (SNPs) and insertion-deletion (InDel) variations within these genes have been linked to variations in oil content and quality (Lin et al., 2019). Transcriptomic analyses have further revealed differentially expressed genes (DEGs) during seed development stages, which are associated with lipid metabolism and oil accumulation (Lin et al., 2018; Gong et al., 2020). Moreover, the expression levels of genes like CoFBA and CoSADhave been shown to correlate with oil content, suggesting that enhancing the expression of these genes could improve oil yield and quality in transgenic plants (Zeng et al., 2014). Comparative studies between high- and low-oil cultivars of C. oleifera have also highlighted the coordinated regulation of multiple genes that ensure high oleic acid accumulation (Wu et al., 2019). 3 Genetic Determinants of Oil Biosynthesis in Camellia 3.1 Overview of key genes involved in fatty acid biosynthesis Fatty acid biosynthesis in Camellia species is regulated by a variety of genes that play crucial roles in the metabolic pathways leading to oil production. Key genes identified include stearoyl-ACP desaturases (SADs) and fatty acid desaturase 2 (FAD2), which are critical for the synthesis of oleic acid, a major component of Camellia oil (Yao et al., 2016; Lin et al., 2018; 2019). SADs are responsible for the desaturation of stearic acid to oleic acid, while FAD2 further desaturates oleic acid to linoleic acid. The expression levels of these genes are tightly regulated during seed development, with higher SAD activity and lower FAD2 activity correlating with increased oleic acid content (Yao et al., 2016; Lin et al., 2018; 2019). 3.2 Analysis of metabolic pathways regulating oil content The metabolic pathways regulating oil content in Camellia species involve complex networks of gene interactions and regulatory mechanisms. Transcriptomic and proteomic analyses have revealed that genes involved in lipid metabolism, such as those encoding enzymes for fatty acid synthesis and modification, are differentially expressed during seed development (Figure 1) (Lin et al., 2018; Gong et al., 2020; Ye et al., 2021). Key metabolic pathways include the glycolysis pathway, which provides precursors for fatty acid synthesis, and the triacylglycerol biosynthesis (TAGBS) pathway, which is crucial for the final assembly of storage lipids (Yao et al., 2016; Li et al., 2022). Additionally, the α-linolenic acid metabolism pathway and glutathione metabolism have been identified as important for oil quality and accumulation (Ye et al., 2021).
RkJQdWJsaXNoZXIy MjQ4ODYzMg==