Genomics and Applied Biology 2024, Vol.15, No.6, 276-284 http://bioscipublisher.com/index.php/gab 278 Figure 1 Development of C. oleifera seeds. A Phenotypic characterization of C. oleifera seeds in four growth periods. S1, nutrition synthesis stage; S2, fat accumulation stage; S3, mature stage; and S4, late mature stage. B Changes in morphological indexes of developing fruits and seeds. Data represent the mean values from three biological replicates, and error bars indicate standard deviations (Adopted from Ye et al., 2021) 3.3 Importance of regulatory genes (e.g., transcription factors) in oil synthesis Regulatory genes, particularly transcription factors, play a significant role in the regulation of oil biosynthesis in Camellia species. MYB transcription factors, for instance, have been identified as key regulators of lipid metabolism and seed maturation (Li et al., 2022). These transcription factors can activate or repress the expression of target genes involved in fatty acid biosynthesis and accumulation. Other important transcription factors include WRI1, which interacts with multiple genes encoding enzymes critical for oil synthesis, and ABI3, FUS3, and LEC1, which are associated with seed development and oil accumulation (Wu et al., 2019; Gong et al., 2020). The coordinated expression of these transcription factors ensures the efficient regulation of oil biosynthesis pathways, leading to high oil content in Camellia seeds. 4 Genomic Studies on Oil Content Variation 4.1 Summary of genome-wide association studies (GWAS) on oil content in camellia Genome-wide association studies (GWAS) have been instrumental in identifying genetic variations associated with oil content in various plant species, including Camellia. In Camellia oleifera, a significant GWAS identified 362 single-nucleotide polymorphisms (SNPs) within four key genes coding for fatty acid desaturases, which are crucial for oil production. This study found 90 significant marker-trait associations, with six SNP markers validated in a hybrid population, explaining up to 17.93% of the phenotypic variance in oil content (Lin et al., 2019). These findings highlight the potential of GWAS in uncovering genetic markers that can be used for marker-assisted selection to improve oil content in Camellia species (Ghidoli et al., 2023). 4.2 Insights from QTL mapping in camellia species Quantitative trait loci (QTL) mapping has provided valuable insights into the genetic control of oil content in Camellia species. Although specific QTL mapping studies in Camellia are limited, analogous research in related species like Brassica napus and Camelina sativa has demonstrated the effectiveness of this approach. For instance, in Brassica napus, stable QTLs for seed oil content were identified on chromosome A07, with one major QTL,
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