Genomics and Applied Biology 2024, Vol.15 http://bioscipublisher.com/index.php/gab © 2024 BioSciPublisher, an online publishing platform of Sophia Publishing Group. All Rights Reserved. Sophia Publishing Group (SPG), founded in British Columbia of Canada, is a multilingual publisher. BioSciPublisher, operated by Sophia Publishing Group (SPG), is an international Open Access publishing platform that publishes scientific journals in the field of life science. Sophia Publishing Group (SPG), founded in British Columbia of Canada, is a multilingual publisher. Publisher Sophia Publishing Group Editedby Editorial Team of Genomics and Applied Biology Email: edit@gab.bioscipublisher.com Website: http://bioscipublisher.com/index.php/gab Address: 11388 Stevenston Hwy, PO Box 96016, Richmond, V7A 5J5, British Columbia Canada Genomics and Applied Biology (ISSN 1925-1602) is an open access, peer reviewed journal published online by BioSciPublisher. The journal is committed to publishing and disseminating all the latest and outstanding research articles, letters and reviews in all areas of genomics and applied biology. The range of topics including genomic structure and function, evolutionary and comparative genomics, genomics and bioinformatics, gene expression and its function identification, nutrigenomics and application technology of applied biology based on genomics and other topical advisory subjects. All the articles published in Genomics and Applied Biology are Open Access, and are distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. BioSciPublisher uses CrossCheck service to identify academic plagiarism through the world’s leading plagiarism prevention tool, iParadigms, and to protect the original authors’ copyrights.
Genomics and Applied Biology (online), 2024, Vol. 15 ISSN 1925-1602 https://bioscipublisher.com/index.php/gab © 2024 BioSciPublisher, an online publishing platform of Sophia Publishing Group. All Rights Reserved. Sophia Publishing Group (SPG), founded in British Columbia of Canada, is a multilingual publisher Latest Content Genetic Basis of Oil Content in Camellia Species YuejunWu Genomics and Applied Biology, 2024, Vol. 15, No. 30 Research Insight into the Genetic Regulation of Photosynthesis in Sweet Potato Hongyun Zhang, Tong Chen, Lin Zhao Genomics and Applied Biology, 2024, Vol. 15, No. 31 Physiological Responses and Variety Screening for Drought Tolerance in Soybeans During Flowering and Podding Lei Wang, Yue Guo, Xingdong Yao, Mengdi Yang, Ruiquan Song, Haiying Wang Genomics and Applied Biology, 2024, Vol. 15, No. 32 Accelerating Yam Breeding Cycles with Genomic Selection Wenhui Yu, Quantong Cheng Genomics and Applied Biology, 2024, Vol. 15, No. 33 Advances in Genomic Research and Genetic Improvement of Cactaceae Plants Tianhui Shi, Jungui Xu, Yuxin He, Zizhong Wang, Zhen Liu Genomics and Applied Biology, 2024, Vol. 15, No. 34
Genomics and Applied Biology 2024, Vol.15, No.6, 276-284 http://bioscipublisher.com/index.php/gab 276 Research Insight Open Access Genetic Basis of Oil Content in Camellia Species YuejunWu Zhejiang Gongxiang Agricultural Development Co., Ltd., Zhuji, 311800, Zhejiang, China Corresponding author: 452707756@qq.com Genomics and Applied Biology, 2024, Vol.15, No.6 doi: 10.5376/gab.2024.15.0030 Received: 19 Sep., 2024 Accepted: 28 Oct., 2024 Published: 12 Nov., 2024 Copyright © 2024 Wu, This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Wu Y.J., 2024, Genetic basis of oil content in camellia species, Genomics and Applied Biology, 15(6): 276-284 (doi: 10.5376/gab.2024.15.0030) Abstract The primary objective of this study was to elucidate the genetic basis of oil content in various Camellia species, with a particular focus on identifying key genes and genetic markers associated with oil biosynthesis and fatty acid composition. The study identified several significant genetic markers and differentially expressed genes (DEGs) associated with oil content and quality in Camellia species. In Camellia oleifera, single nucleotide polymorphisms (SNPs) and insertion-deletion (InDel) markers within key fatty acid desaturase genes were found to be significantly associated with oil content and composition, explaining up to 17.93% of phenotypic variance. Transcriptomic analyses revealed critical genes involved in lipid metabolism and oil accumulation, such as stearoyl-ACP desaturases (SADs) and fatty acid desaturase 2 (FAD2), which were differentially expressed during seed development. Additionally, integrative proteomic and transcriptomic analyses identified key metabolites and co-expressed genes involved in oil quality during seed ripenin4. Comparative studies between high- and low-oil cultivars highlighted the coordinated regulation of upstream and downstream genes essential for high oleic acid accumulation. The findings from this study provide valuable genetic markers and insights into the molecular mechanisms underlying oil biosynthesis in Camellia species. These discoveries have significant implications for the genetic improvement of oil content and quality in Camellia cultivars through marker-assisted selection and genetic engineering. Keywords Camellia oleifera; Oil biosynthesis; Fatty acid composition; Genetic markers; Transcriptomics 1 Introduction Camellia species, particularly Camellia oleifera, Camellia lanceoleosa, and Camellia chekiangoleosa, are renowned for their high-quality seed oils, which are rich in unsaturated fatty acids and beneficial secondary metabolites (Lin et al., 2019; Gong et al., 2022; Shen et al., 2022). These species are widely cultivated in regions such as Southern China and Southeast Asia, where they serve as significant sources of edible oil (Ye et al., 2023). The oil extracted from Camellia seeds is not only used for culinary purposes but also finds applications in cosmetics and as a lubricant, highlighting its versatility and economic importance (Gong et al., 2020). The oil content in Camellia species is of paramount importance due to its high levels of oleic acid, which is beneficial for human health (Lin et al., 2018). The presence of unsaturated fatty acids makes Camellia oil a desirable alternative to other vegetable oils, promoting its use in various industrial applications, including food production and pharmaceuticals (Yao et al., 2016; Lin et al., 2019). Additionally, the genetic diversity and adaptability of Camellia species to different environmental conditions enhance their agricultural value, making them a reliable crop for oil production (Barreiro et al., 2021). Recent genomic studies have provided insights into the genes involved in oil biosynthesis, offering potential for genetic improvement and increased oil yield (Lu et al., 2022; Shen et al., 2022). This study aims to explore the genetic basis of oil content in various Camellia species by examining the allelic diversity of key genes associated with oil production. By leveraging recent advancements in genomic and transcriptomic analyses, this study seeks to identify genetic markers and candidate genes that influence oil content and quality. The findings will contribute to the development of marker-assisted selection strategies to enhance oil yield and quality in Camellia species, thereby supporting their agricultural and industrial applications.
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).
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,
Genomics and Applied Biology 2024, Vol.15, No.6, 276-284 http://bioscipublisher.com/index.php/gab 279 qA07.SOC, being consistently detected across multiple environments (Zhao et al., 2022). Similarly, in Camelina sativa, QTL mapping identified loci associated with oil content and fatty acid composition, aiding in the breeding of high-yielding varieties (Li et al., 2021). These studies suggest that similar QTL mapping efforts in Camellia could reveal critical loci for oil content improvement. 4.3 Identification of genetic markers linked to high oil content traits The identification of genetic markers linked to high oil content traits is crucial for the genetic improvement of Camellia species. In Camellia oleifera, SNP markers within genes coding for fatty acid desaturases have been linked to oil content and quality. Specifically, six SNP markers from the genes Cofad2-A, CoSAD1, and CoSAD2 were validated and found to be significantly associated with oil content traits (Lin et al., 2019). Additionally, transcriptomic analyses have identified differentially expressed genes (DEGs) involved in lipid metabolism and oil biosynthesis, providing further candidate markers for breeding programs (Lin et al., 2018; Gong et al., 2020). These genetic markers and DEGs offer valuable tools for marker-assisted selection and the development of Camellia varieties with enhanced oil content. 5 Candidate Genes for Oil Quality and Quantity 5.1 Identification of specific genes associated with oil composition The identification of specific genes associated with oil composition in Camellia species has been a focal point of recent research. In Camellia oleifera, key genes such as CoSADandCofad2, which code for fatty acid desaturases, have been linked to oil content and fatty acid composition. These genes were found to contain significant single nucleotide polymorphisms (SNPs) and insertion-deletion (InDel) variations that correlate with oil traits, explaining a substantial proportion of phenotypic variance (Lin et al., 2019). Additionally, transcriptomic analyses have identified differentially expressed genes (DEGs) involved in lipid metabolism, such as stearoyl-ACP desaturases (SADs) and fatty acid desaturase 2 (FAD2), which play crucial roles in the biosynthesis of oleic acid (Lin et al., 2018; Wu et al., 2019). 5.2 Functional analysis of candidate genes in oil accumulation Functional analysis of candidate genes has provided insights into their roles in oil accumulation. For instance, the coordinated high expression of upstream genes like HAD, EAR, and KASI has been shown to increase the levels of C16:0-ACP, a precursor for oleic acid biosynthesis. Concurrently, the high expression of SAD genes accelerates oleic acid synthesis, while the low expression of downstream genes such as FAD2, FAD3, FAD7, FAD8, and FAE1 reduces the conversion of oleic acid to other fatty acids, ensuring its accumulation (Wu et al., 2019). Proteomic studies have also highlighted the importance of enzymes like diacylglycerol acyltransferase and glyceraldehyde-3-phosphate dehydrogenase in oil biosynthesis, further validating the roles of these candidate genes (Ye et al., 2021; Gong et al., 2022). 5.3 Comparative analysis of gene expression in high vs. low oil-yielding camellia varieties Comparative transcriptomic analyses between high and low oil-yielding Camellia varieties have revealed significant differences in gene expression profiles. High oil-yielding varieties exhibit a coordinated upregulation of genes involved in fatty acid biosynthesis and oil accumulation, such as SAD and WRI1, while low oil-yielding varieties show higher expression of genes involved in fatty acid degradation (Wu et al., 2019; Ye et al., 2020). These studies have identified critical transcription factors, including ABI3, FUS3, LEC1, and WRI1, which regulate the expression of multiple genes associated with oil biosynthesis and accumulation (Wu et al., 2019). Additionally, the expression patterns of lipid biosynthesis genes have been shown to correlate with the stages of seed development, further emphasizing the dynamic regulation of oil content in Camellia species (Lin et al., 2018; Gong et al., 2020). 6 Advances in Genomic Selection and Breeding for Oil Content 6.1 Applications of genomic selection techniques to improve oil yield Genomic selection techniques have significantly advanced the breeding of Camellia species for enhanced oil yield. The identification of single nucleotide polymorphisms (SNPs) and insertion-deletion (InDel) markers associated
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).
Genomics and Applied Biology 2024, Vol.15, No.6, 276-284 http://bioscipublisher.com/index.php/gab 281 7.2 Epigenetic modifications affecting gene expression related to oil content Epigenetic modifications, such as DNA methylation and histone modification, can influence gene expression without altering the DNA sequence, thereby affecting oil content in Camellia species. Transcriptomic analyses have identified differentially expressed genes (DEGs) associated with oil biosynthesis at various developmental stages, indicating that epigenetic regulation plays a crucial role in oil accumulation (Zeng et al., 2014; Lin et al., 2018). For example, the expression of key genes involved in lipid metabolism and fatty acid biosynthesis, such as stearoyl-ACP desaturases (SADs) and fatty acid desaturase 2 (FAD2), is tightly regulated during seed development, suggesting that epigenetic mechanisms may modulate these genes to enhance oil production (Zeng et al., 2014; Lin et al., 2018). Additionally, the identification of alternative splicing events and long noncoding RNAs (lncRNAs) in Camellia oleifera seeds further supports the role of epigenetic modifications in regulating oil biosynthesis (Gong et al., 2020). 7.3 Interaction between genetics and environmental conditions in oil biosynthesis The interaction between genetic factors and environmental conditions is critical in determining the oil biosynthesis pathways in Camellia species. Genetic studies have identified single nucleotide polymorphisms (SNPs) and insertion-deletion (InDel) variations in key genes associated with oil content and fatty acid composition, which are influenced by environmental factors. For instance, the association analysis of four key genes coding for fatty acid desaturases in Camellia oleifera revealed significant marker-trait associations, indicating that both genetic and environmental factors contribute to oil yield (Lin et al., 2019). Moreover, integrative analyses combining transcriptomic and proteomic data have shown that the expression of genes involved in oil biosynthesis is modulated by environmental conditions, such as temperature and nutrient availability, further emphasizing the complex interplay between genetics and the environment (Ye et al., 2021). These findings suggest that optimizing both genetic selection and environmental management could enhance oil production in Camellia species. 8 Future Directions and Research Opportunities 8.1 Emerging technologies in genomics and bioinformatics for oil trait analysis The advent of advanced genomic and bioinformatics technologies has opened new avenues for the analysis of oil traits in Camellia species. Techniques such as single-molecule long-read isoform sequencing (Iso-Seq) and RNA-Seq have been instrumental in uncovering the complexity of the transcriptome and identifying key genes involved in oil biosynthesis and accumulation. The integration of these technologies with gas chromatography has provided a comprehensive understanding of the oil biosynthesis pathways at different developmental stages (Gong et al., 2020). Additionally, the use of association genetics to identify single nucleotide polymorphisms (SNPs) related to kernel oil content and quality has shown promise for marker-assisted selection in breeding programs (Lin et al., 2019). The development of chromosome-level genome assemblies, as seen in Camellia lanceoleosa and Camellia chekiangoleosa, provides valuable resources for understanding genome evolution and the genetic basis of oil traits (Gong et al., 2022; Shen et al., 2022). Future research should focus on leveraging these genomic tools to explore the allelic diversity of key genes and their regulatory networks, which could significantly enhance the efficiency of breeding high oil-yielding Camellia varieties. 8.2 Prospective research on understudied camellia species with oil potential While significant progress has been made in understanding the oil biosynthesis pathways in Camellia oleifera, other Camellia species with potential oil yield remain understudied. For instance, Camellia chekiangoleosa and Camellia reticulata have shown promise due to their high-quality seed oil and unique genetic traits (Yao et al., 2016; Xie and Wang, 2018). Comparative transcriptomic analyses have identified genes responsible for fruit count and oil yield, which could be targeted in breeding programs to enhance oil production (Xie and Wang, 2018). Additionally, the first chromosome-level genome sequence of Camellia chekiangoleosa provides a foundation for exploring the genetic basis of oil biosynthesis and improving oil traits through genetic manipulation (Shen et al., 2022). Future research should aim to conduct comprehensive genomic and transcriptomic studies on these understudied species to identify novel genes and pathways that contribute to oil accumulation. This could lead to the development of new Camellia cultivars with enhanced oil yield and quality.
Genomics and Applied Biology 2024, Vol.15, No.6, 276-284 http://bioscipublisher.com/index.php/gab 282 8.3 Challenges and opportunities in breeding high oil-yielding camellia varieties Breeding high oil-yielding Camellia varieties presents several challenges and opportunities. One of the main challenges is the complex polyploidization and large genome size of Camellia species, which complicates genetic analysis and breeding efforts (Gong et al., 2020). However, recent advances in genomic technologies, such as the assembly of reference genomes and multi-omic studies, have provided new insights into the genetic basis of oil traits (Ye et al., 2023). The identification of differentially expressed genes (DEGs) and transcription factors involved in oil biosynthesis and fatty acid accumulation has revealed coordinated mechanisms that regulate these processes (Lin et al., 2018; Wu et al., 2019). Additionally, the use of quantitative proteomics and transcriptomics has highlighted the impact of environmental factors, such as harvesting time, on oil content and quality (Wang et al., 2022). Future breeding programs should focus on integrating these genomic and proteomic data to develop molecular markers for marker-assisted selection and to identify key genes for genetic engineering. By addressing these challenges and leveraging the opportunities presented by emerging technologies, it is possible to accelerate the breeding of high oil-yielding Camellia varieties and improve the economic viability of Camellia oil production. 9 Conclusioning Remarks The genetic basis of oil content in Camellia species, particularly Camellia oleifera, has been extensively studied, revealing several key genetic factors. Transcriptomic and proteomic analyses have identified differentially expressed genes (DEGs) and proteins associated with lipid metabolism and oil biosynthesis. Key genes such as stearoyl-ACP desaturases (SADs) and fatty acid desaturase 2 (FAD2) have been implicated in the regulation of oleic acid levels during seed development. Additionally, MYB transcription factors have been identified as crucial regulators of seed oil biosynthesis, with specific MYB genes showing significant expression during seed maturation. Single nucleotide polymorphisms (SNPs) within genes like CoSAD and CoFAD2 have also been linked to variations in oil content and quality, providing markers for genetic selection. Furthermore, the expression of genes involved in metabolic pathways such as fatty acid metabolism and flavonoid biosynthesis has been shown to correlate with oil accumulation and quality. The genetic insights gained from these studies have significant implications for Camellia breeding programs. The identification of SNP markers associated with high oil content and quality can facilitate marker-assisted selection, enabling the development of superior Camellia cultivars with enhanced oil yield and composition. The understanding of key regulatory genes such as MYB transcription factors and their role in lipid metabolism can be leveraged to manipulate gene expression through genetic engineering, potentially increasing oil production. Additionally, the comprehensive transcriptomic and proteomic data provide a valuable resource for identifying candidate genes for targeted breeding and biotechnological interventions aimed at improving oil biosynthesis pathways. The integration of these genetic findings into breeding programs can accelerate the development of high-yielding, high-quality oil-producing Camellia varieties, thereby enhancing the economic and nutritional value of Camellia oil. In conclusion, the genetic insights into oil content in Camellia species have provided a deeper understanding of the molecular mechanisms underlying oil biosynthesis and accumulation. These findings not only elucidate the complex genetic regulation of oil production but also offer practical applications for improving Camellia oil yield and quality through advanced breeding techniques and genetic engineering. The continued exploration of genetic factors and their interactions will be crucial for further advancements in Camellia oil production, ultimately contributing to the sustainable development of this valuable oil crop. Acknowledgments Thank you to the reviewers for their rigorous academic approach in reviewing this study's manuscript and offering many constructive suggestions. Conflict of Interest Disclosure The author affirms that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.
Genomics and Applied Biology 2024, Vol.15, No.6, 276-284 http://bioscipublisher.com/index.php/gab 283 References Aznar-Moreno J., and Durrett T., 2017, Simultaneous Targeting of multiple gene homeologs to alter seed oil production in Camelina sativa, Plant and Cell Physiology, 58: 1260-1267. https://doi.org/10.1093/pcp/pcx058 Barreiro R., Rodríguez-Solana R., Alonso L., Salinero C., Sánchez J., and Pérez-Santín E., 2021, Fast 1H-NMR species differentiation method for camellia seed oils applied to Spanish ornamentals plants, Comparison with Traditional Gas Chromatography. Plants, 10(10): 1984. https://doi.org/10.3390/plants10101984 Brock J., Scott T., Lee A., Mosyakin S., and Olsen K., 2020, Interactions between genetics and environment shape Camelina seed oil composition, BMC Plant Biology, 20: 1-15. https://doi.org/10.1186/s12870-020-02641-8 Ghidoli M., Ponzoni, E., Araniti, F., Miglio, D., and Pilu, R., 2023, Genetic improvement of Camelina sativa (L.) crantz: opportunities and challenges, Plants, 12(3): 570. https://doi.org/10.3390/plants12030570 Gong W., Song Q., Ji K., Gong S., Wang, L., Chen, L., Zhang, J., and Yuan, D., 2020, Full-length transcriptome fromCamellia oleifera seed provides insight into the transcript variants involved in oil biosynthesis, Journal of Agricultural and Food Chemistry, 68(49): 14670-14683. https://doi.org/10.1021/acs.jafc.0c05381 Gong W., Xiao S., Wang L., Liao Z., Chang Y., Mo W., Hu G., Li W., Zhao G., Zhu H., Xiaoming H., Ji K., Xiang X., Song Q., Yuan D., Jin S., and Zhang L., 2022, Chromosome-level genome of Camellia lanceoleosa provides a valuable resource for understanding genome evolution and self-incompatibility, The Plant Journal : for Cell and Molecular Biology, 110(3): 881-898. https://doi.org/10.1111/tpj.15739 Jiang W., Henry I., Lynagh P., Comai L., Cahoon E., and Weeks D., 2017, Significant enhancement of fatty acid composition in seeds of the allohexaploid, Camelina sativa, using CRISPR/Cas9 gene editing, Plant Biotechnology Journal, 15: 648-657. https://doi.org/10.1111/pbi.12663 Lee K., Jeon I., Yu H., Kim S., Kim H., Ahn S., Lee J., Lee S., and Kim H., 2021, Increasing monounsaturated fatty acid contents in hexaploid Camelina sativa seed oil by FAD2 gene knockout using CRISPR-Cas9, Frontiers in Plant Science, 12: 702930. https://doi.org/10.3389/fpls.2021.702930 Li H., Hu X., Lovell J., Grabowski P., Mamidi S., Chen C., Amirebrahimi M., Kahanda I., Mumey B., Barry K., Kudrna D., Schmutz J., Lachowiec J., and Lu C., 2021, Genetic dissection of natural variation in oilseed traits of camelina by whole‐genome resequencing and QTL mapping, The Plant Genome, 14(2): e20110. https://doi.org/10.1002/tpg2.20110 Li H., Song K., Li B., Zhang X., Wang D., Dong S., and Yang L., 2023, CRISPR/Cas9 editing sites identification and multi-elements association analysis in Camellia sinensis, International Journal of Molecular Sciences, 24(20): 15317. https://doi.org/10.3390/ijms242015317 Li S., Huang H., Ma X., Hu Z., Li J., and Yin H., 2022, Characterizations of MYB transcription factors in Camellia oleifera reveal the key regulators involved in oil biosynthesis, Horticulturae, 8(8): 742. https://doi.org/10.3390/horticulturae8080742 Lin P., Wang K., Zhou C., Xie Y., Yao X., and Yin H., 2018, Seed Transcriptomics analysis in Camellia oleifera uncovers genes associated with oil content and fatty acid composition, International Journal of Molecular Sciences, 19(1): 118. https://doi.org/10.3390/ijms19010118 Lin P., Yin H., Yan C., Yao X., and Wang K., 2019, Association genetics identifies single nucleotide polymorphisms related to kernel oil content and quality in Camellia oleifera, Journal of Agricultural And Food Chemistry, 67(9): 2547-2562. https://doi.org/10.1021/acs.jafc.8b03399 Lu C., Gao L., and Zhang Q., 2022, A high-quality genome assembly of the mitochondrial genome of the oil-tea tree Camellia gigantocarpa (Theaceae), Diversity, 14(10): 850. https://doi.org/10.3390/d14100850 Morineau C., Bellec Y., Tellier F., Gissot L., Kelemen Z., Nogué F., and Faure J., 2017, Selective gene dosage by CRISPR-Cas9 genome editing in hexaploid Camelina sativa, Plant Biotechnology Journal, 15: 729-739. https://doi.org/10.1111/pbi.12671 Peng S., Lu J., Zhang Z., Ma L., Liu C., and Chen Y., 2020, Global transcriptome and correlation analysis reveal cultivar-specific molecular signatures associated with fruit development and fatty acid determination in Camellia oleifera abel, International Journal of Genomics, 2020(1): 6162802. https://doi.org/10.1155/2020/6162802 Shen T., Huang B., Xu M., Zhou P., Ni Z., Gong C., Wen Q., Cao F., and Xu L., 2022, The reference genome of Camellia chekiangoleosa provides insights into Camellia evolution and tea oil biosynthesis, Horticulture Research, 9: uhab083. https://doi.org/10.1093/hr/uhab083 Wang J., Gao X., Liu M., Li J., Yang H., Wang Z., and Yang L., 2022, Camellia oil trait and DIA quantitative proteomics analyses reveal the impact of harvesting time on the oil content and quality of the late-maturing cultivar C. oleifera ‘Huaxin’, Food Quality and Safety, 6: fyac055. https://doi.org/10.1093/fqsafe/fyac055
Genomics and Applied Biology 2024, Vol.15, No.6, 276-284 http://bioscipublisher.com/index.php/gab 284 Wu B., Ruan C., Han P., Ruan D., Xiong C., Ding J., and Liu S., 2019, Comparative transcriptomic analysis of high- and low-oil Camellia oleifera reveals a coordinated mechanism for the regulation of upstream and downstream multigenes for high oleic acid accumulation, 3 Biotech, 9: 1-19. https://doi.org/10.1007/s13205-019-1792-7 Xia E., Jiang J., Huang H., Zhang L., Zhang H., and Gao L., 2014, Transcriptome analysis of the oil-rich tea plant, Camellia oleifera, reveals candidate genes related to lipid metabolism, PLoS ONE, 9(8): e104150. https://doi.org/10.1371/journal.pone.0104150 Xie Y., and Wang X., 2018, Comparative transcriptomic analysis identifies genes responsible for fruit count and oil yield in the oil tea plant Camellia chekiangoleosa, Scientific Reports, 8: 6637. https://doi.org/10.1038/s41598-018-24073-z Yao Q., Huang H., Tong Y., Xia E., and Gao L., 2016, Transcriptome analysis identifies candidate genes related to triacylglycerol and pigment biosynthesis and photoperiodic flowering in the ornamental and oil-producing plant, Camellia reticulata (Theaceae), Frontiers in Plant Science, 7: 163. https://doi.org/10.3389/fpls.2016.00163 Ye C., He Z., Peng J., Wang R., Wang X., Fu M., Zhang Y., Wang A., Liu Z., Jia G., Chen Y., and Tian B., 2023, Genomic and genetic advances of oiltea-camellia (Camellia oleifera), Front. Plant Sci., 14: 1101766. https://doi.org/10.3389/fpls.2023.1101766 Ye Z., Wu Y., Muhammad Z., Yan W., Yu J., Zhang J., Yao G., and Hu X., 2020, Complementary transcriptome and proteome profiling in the mature seeds of Camellia oleifera from Hainan Island, PLoS ONE, 15(2): e0226888. https://doi.org/10.1371/journal.pone.0226888 Ye Z., Yu J., Yan W., Zhang J., Yang D., Yao G., Liu Z., Wu Y., and Hou X., 2021, Integrative iTRAQ-based proteomic and transcriptomic analysis reveals the accumulation patterns of key metabolites associated with oil quality during seed ripening of Camellia oleifera, Horticulture Research, 8: 157. https://doi.org/10.1038/s41438-021-00591-2 Zeng Y., Tan X., Zhang L., Jiang N., and Cao H., 2014, Identification and expression of Fructose-1,6-Bisphosphate aldolase genes and their relations to oil content in developing seeds of tea oil tree (Camellia oleifera), PLoS ONE, 9(9): e107422. https://doi.org/10.1371/journal.pone.0107422 Zhao C., Xie M., Liang L., Yang L., Han H., Qin X., Zhao J., Hou Y., Dai W., Du C., Xiang Y., Liu S., and Huang X., 2022, Genome-wide association analysis combined with quantitative trait loci mapping and dynamic transcriptome unveil the genetic control of seed oil content in Brassica napus L., Frontiers in Plant Science, 13: 929197. https://doi.org/10.3389/fpls.2022.929197
Genomics and Applied Biology 2024, Vol.15, No.6, 285-295 http://bioscipublisher.com/index.php/gab 285 Research Insight Open Access Research Insight into the Genetic Regulation of Photosynthesis in Sweet Potato Hongyun Zhang1, TongChen1, LinZhao2 1 Zhejiang Wuwangnong Seeds Shareholding Co., Ltd, Hangzhou, 310000, Zhejiang, China 2 Crop (Ecology) Research Institute of Hangzhou Academy of Agricultural Sciences, Hangzhou, 310000, Zhejiang, China Corresponding author: zhaolin0227@163.com Genomics and Applied Biology, 2024, Vol.15, No.6 doi: 10.5376/gab.2024.15.0031 Received: 29 Oct., 2024 Accepted: 07 Nov., 2024 Published: 22 Nov., 2024 Copyright © 2024 Zhang et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Zhang H.Y., Chen T., and Zhao L., 2024, Research insight into the genetic regulation of photosynthesis in sweet potato, Genomics and Applied Biology, 15(6): 285-295 (doi: 10.5376/gab.2024.15.0031) Abstract In sweet potato (Ipomoea batatas), improvements in photosynthetic capacity have significant implications for increasing yield, starch production, and resilience under environmental stress. This study explores the genetic regulation of photosynthesis in sweet potato, focusing on key genes, transcription factors, and pathways that enhance photosynthetic efficiency and carbohydrate metabolism. Genes such as IbVP1 and IbMIPS1 play pivotal roles in optimizing photosynthesis, while transcription factors like IbBBX29 and IbC3H18 are critical for stress tolerance and efficient light utilization. Recent advancements in genetic engineering, including CRISPR/Cas9 applications, provide new avenues for precisely modifying photosynthetic traits to boost productivity. Additionally, insights from high-photosynthetic sweet potato varieties and their genetic profiles offer valuable guidance for future breeding programs aimed at achieving higher yield and better adaptability. Understanding the molecular mechanisms behind these genetic factors can facilitate the development of resilient, high-yield sweet potato cultivars, contributing to food security and sustainable agriculture. Keywords Sweet potato (Ipomoea batatas); Photosynthesis; Genetic regulation; CRISPR/Cas9; Crop improvement 1 Introduction Photosynthesis is the fundamental process driving plant growth and productivity, converting light energy into chemical energy stored in carbohydrates. This process is crucial for the biosphere, fixing over 100 billion tons of CO2 annually, which forms the basis of crop production and, consequently, animal and human food supply (Baslam et al., 2020). Enhancing photosynthetic efficiency has been identified as a key strategy to increase crop yields, especially under varying environmental conditions. Genetic modifications and breeding strategies targeting photosynthetic traits have shown promise in improving crop productivity by optimizing the capture and utilization of solar energy (Theeuwen et al., 2022; Keller et al., 2023). Sweet potato (Ipomoea batatas) is a vital crop for food security and nutrition, particularly in developing countries. The efficiency of photosynthesis in sweet potato directly influences its yield and starch production, which are critical for its role as a staple food. Recent studies have highlighted the potential of genetic interventions to enhance photosynthetic efficiency and, consequently, crop yield. For instance, overexpression of the H+-pyrophosphatase gene (IbVP1) in sweet potato has been shown to improve photosynthesis and sucrose content in source leaves, leading to increased starch content and total yield in storage roots (Fan et al., 2021). This underscores the importance of photosynthetic efficiency in maximizing the productivity of sweet potato (Long et al., 2022; Vijayakumar et al., 2023; Tao and Han, 2024). This study investigates the genetic regulation of photosynthesis in sweet potato, identifying key gene targets for manipulation, elucidating the role of specific genes (such as IbVP1) in regulating photosynthesis and carbohydrate metabolism, and exploring the genetic variation of photosynthetic traits and their impact on yield under different environmental conditions. By developing genetic engineering and breeding strategies to improve photosynthetic performance and stress resistance in sweet potato varieties, this study aims to contribute to the development of high-yield, stress-resistant cultivars, thereby enhancing food security and agricultural sustainability.
Genomics and Applied Biology 2024, Vol.15, No.6, 285-295 http://bioscipublisher.com/index.php/gab 286 2 Overview of Photosynthesis in Sweet Potato Sweet potato (Ipomoea batatas) is a significant crop known for its high starch content and adaptability to various environmental conditions. Photosynthesis in sweet potato, like in other plants, involves the conversion of light energy into chemical energy, which is then used to produce carbohydrates. This process is crucial for the growth and yield of sweet potato, particularly in its storage roots, which are the primary sink organs for photoassimilates and energy (Fan et al., 2021). 2.1 Photosynthetic pathways and efficiency in sweet potato Photosynthesis in sweet potato involves both the light-dependent reactions and the Calvin cycle. The efficiency of these pathways can be influenced by various genetic and environmental factors. For instance, the overexpression of the H+-pyrophosphatase gene (IbVP1) in sweet potato has been shown to enhance photosynthetic ability and sucrose content in source leaves, leading to increased starch content and yield in storage roots (Fan et al., 2021). Additionally, transcription factors such as BBX21 have been found to improve photosynthetic rates and water use efficiency under both optimal and drought conditions, further highlighting the genetic regulation of photosynthetic efficiency (Crocco et al., 2018; Ocampo et al., 2021). 2.2 Key components and enzymes involved in photosynthesis Several key components and enzymes are involved in the photosynthetic process in sweet potato. These include chlorophyll-binding proteins, photosystem I and II, and enzymes involved in the Calvin cycle. The expression of genes encoding these components can be regulated by various transcription factors. For example, the transcription factor StABI5 has been shown to negatively regulate chloroplast development and photosynthesis by downregulating genes involved in photosynthesis and carbon fixation (Zhu et al., 2020). Similarly, the overexpression of IbBBX29 has been linked to increased flavonoid accumulation and improved leaf development, which can indirectly affect photosynthetic efficiency (Gao et al., 2022). 2.3 Genetic factors influencing photosynthetic performance Genetic factors play a crucial role in determining the photosynthetic performance of sweet potato. Variations in transcription factors and photosynthesis-related genes can significantly impact photosynthetic traits. For instance, genetic variation in transcription factors and light-reaction genes has been shown to regulate photosynthetic traits by affecting the expression of multiple genes involved in the photosynthetic pathway (Wang et al., 2018). Additionally, the overexpression of genes such as IbMIPS1 and IbNAC43 has been found to influence photosynthetic performance by modulating stress responses and leaf development, respectively (Zhai et al., 2016; Sun et al., 2023). Furthermore, the identification of genetic variations in starch biosynthesis and sucrose metabolism genes provides insights into the molecular mechanisms regulating photosynthesis and carbohydrate metabolism in sweet potato (Zhang et al., 2020). In summary, the genetic regulation of photosynthesis in sweet potato involves a complex interplay of various transcription factors, enzymes, and genetic variations. Understanding these regulatory mechanisms can provide valuable insights into improving photosynthetic efficiency and crop yield in sweet potato. Further research in this area can lead to the development of genetically engineered sweet potato cultivars with enhanced photosynthetic performance and stress tolerance. 3 Genetic Regulation of Photosynthesis 3.1 Regulatory genes and transcription factors The genetic regulation of photosynthesis in sweet potato involves several key genes that influence various aspects of the photosynthetic process. For instance, the H+-pyrophosphatase gene (IbVP1) has been shown to enhance photosynthesis and sucrose content in source leaves, thereby increasing starch content and yield in storage tissues (Fan et al., 2021). Additionally, the IbMIPS1 gene, which is involved in myo-inositol biosynthesis, has been found to upregulate genes related to photosynthesis and stress responses, thereby improving photosynthetic efficiency under stress conditions (Zhai et al., 2016).
Genomics and Applied Biology 2024, Vol.15, No.6, 285-295 http://bioscipublisher.com/index.php/gab 287 Transcription factors (TFs) play a crucial role in regulating the expression of photosynthetic genes. The NAC transcription factor IbNAC43, for example, negatively impacts photosynthetic efficiency by causing leaf curling and reducing chlorophyll content (Figure 1) (Sun et al., 2023). Conversely, the B-box transcription factor IbBBX29 enhances leaf biomass and flavonoid accumulation, which are associated with improved photosynthetic performance (Gao et al., 2022). Another important TF, IbC3H18, has been shown to enhance abiotic stress tolerance and regulate genes involved in photosynthesis and reactive oxygen species (ROS) scavenging (Zhang et al., 2019). Figure 1 Phenotypes of transgenic and wild-type (WT) sweet potato plants in the greenhouse (Adopted from Sun et al., 2023) Image caption: (A) Plant stature and leaf phenotypes of both WT and transgenic plants. Scale bar, 1 cm. ad, adaxial side; ab, abaxial side. (B) Leaf rolling index (LRI). Data are presented as the mean ± SE (n = 6). (C) Relative chlorophyll content. (D) Photosynthetic rate. Data are presented as the mean ± SE (n = 3). Asterisks denote significant differences based on a Student’s t-test. **p < 0.01 (Adopted from Sun et al., 2023) 3.2 Signal transduction pathways affecting photosynthesis Signal transduction pathways are integral to the regulation of photosynthesis, particularly under stress conditions. The overexpression of IbMIPS1, for instance, activates phosphatidylinositol (PI) and abscisic acid (ABA) signaling pathways, which are crucial for maintaining photosynthetic efficiency under salt and drought stress (Zhai et al., 2016). Additionally, the non-tandem CCCH-type zinc-finger protein IbC3H18 regulates abiotic stress-responsive genes through ABA signaling, thereby enhancing photosynthetic performance under adverse conditions (Zhang et al., 2019). Photoreceptors and hormones significantly influence photosynthetic regulation. The transcription factor IbBBX29, which is induced by the hormone auxin (IAA), modulates the expression of genes involved in auxin signaling and flavonoid biosynthesis, thereby enhancing photosynthetic efficiency (Gao et al., 2022). Furthermore, the symbiotic relationship with Piriformospora indica has been shown to increase photosynthetic pigments and efficiency, partly through the regulation of jasmonic acid (JA)-mediated defense mechanisms (Li et al., 2020).
RkJQdWJsaXNoZXIy MjQ4ODYzMg==