Comparative Analysis and Structural Modeling of Elaeis oleifera FAD2, a Fatty Acid Desaturase Involved in Unsaturated Fatty Acid Composition of American Oil Palm

Transcriptional and metabolic analysis of oleic acid synthesis in seedless and tenera oil palm species

The oil palm (Elaeis guineensis Jacq.) is a perennial oilseed crop whose mesocarp produces palm oil rich in the unsaturated fatty acid oleic acid, known for its oxidative stability and cardiovascular health benefits. However, the regulatory mechanisms and pathways responsible for variations in oleic acid biosynthesis during fruit development remain inadequately elucidated. The study examined the mesocarp of oil palm fruits from three developmental stages in seedless and Tenera varieties to evaluate oleic acid content. Fruits from Seedless (MS) and Tenera (MT) oil palms, pollinated for 95 days (MS1 and MT1), 125 days (MS2 and MT2), and 185 days (MS3 and MT3), were analyzed using metabolomics via liquid chromatography-tandem mass spectrometry (LC-MS/MS). RNA sequencing was conducted to profile gene expression associated to oleic acid biosynthesis and accumulation. Differential genes and metabolites were mapped and functionally enriched through KEGG pathway analysis. The result revealed that SAD, FabD, LACS6, BC, FabB, and FabI were positively associated with oleic acid content, whereas LACS9 exhibited either a negative or strongly negative correlation. By integrating metabolomic and transcriptomic techniques, this study elucidates the distinct mechanisms of oleic acid biosynthesis in seedless and thin-shelled oil palm varieties. These findings provide a scientific foundation for enhancing oleic acid content and improving the quality of oil palm-derived products.

Research on the Mechanism of Growth of Codonopsis pilosula (Franch.) Nannf. Root Responding to Phenolic Stress Induced by Benzoic Acid

Soil autotoxic chemosensory substances have emerged as the predominant environmental factors constraining the growth, quality, and yield of Codonopsis pilosula in recent years. Among a vast array of chemosensory substances, benzoic acid constitutes the principal chemosensory substance in the successive cultivation of C. pilosula. However, the exploration regarding the stress exerted by benzoic acid on the growth and development of C. pilosula remains indistinct, and there is a scarcity of research on the mechanism of lobetyolin synthesis in C. pilosula. In the current research, it was discovered that exposure to benzoic acid at a concentration of 200 mmol/L conspicuously attenuated the plant height, root length, total length, fresh weight, root weight, root thickness, chlorophyll content, electrolyte osmolality, leaf intercellular CO2 concentration (Ci), net photosynthesis rate (Pn), transpiration rate (Tr), and leaf stomatal conductance (Gs) of C. pilosula. Benzoic acid (200 mmol/L) significantly enhanced the activity of root enzymes, including superoxide dismutase (SOD), malondialdehyde (MDA), and peroxidase (POD), as well as the accumulation of polysaccharides and lobetyolins (polyacetylene glycosides) in the roots of C. pilosula. In this study, 58,563 genes were assembled, and 7946 differentially expressed genes were discovered, including 4068 upregulated genes and 3878 downregulated genes. The outcomes of the histological examination demonstrated that benzoic acid stress augmented the upregulation of genes encoding key enzymes implicated in the citric acid cycle, fatty acid metabolism, as well as starch and sucrose metabolic pathways. The results of this investigation indicated that a moderate amount of benzoic acid could enhance the content of lobetyolin in C. pilosula and upregulate the expression of key coding genes within the signaling cascade to improve the resilience of C. pilosula lobetyolin against benzoic acid stress; this furnished a novel perspective for the study of C. pilosula lobetyolin as a potential substance for alleviating benzoic acid-induced stress.

Integration analysis of ATAC-seq and RNA-seq provides insight into fatty acid biosynthesis in Schizochytrium limacinum under nitrogen limitation stress

BACKGROUND

Schizochytrium limacinum holds significant value utilized in the industrial-scale synthesis of natural DHA. Nitrogen-limited treatment can effectively increase the content of fatty acids and DHA, but there is currently no research on chromatin accessibility during the process of transcript regulation. The objective of this research was to delve into the workings of fatty acid production in S. limacinum by examining the accessibility of promoters and profiling gene expressions.

RESULTS

Results showed that differentially accessible chromatin regions (DARs)-associated genes were enriched in fatty acid metabolism, signal transduction mechanisms, and energy production. By identifying and annotating DARs-associated motifs, the study obtained 54 target transcription factor classes, including BPC, RAMOSA1, SPI1, MYC, and MYB families. Transcriptomics results revealed that several differentially expressed genes (DEGs), including SlFAD2, SlALDH, SlCAS1, SlNSDHL, and SlDGKI, are directly related to the biosynthesis of fatty acids, meanwhile, SlRPS6KA, SlCAMK1, SlMYB3R1, and SlMYB3R5 serve as transcription factors that could potentially influence the regulation of fatty acid production. In the integration analysis of DARs and ATAC-seq, 13 genes were identified, which were shared by both DEGs and DARs-associated genes, including SlCAKM, SlRP2, SlSHOC2, SlTN, SlSGK2, SlHMP, SlOGT, SlclpB, and SlDNAAF3.

CONCLUSIONS

SlCAKM may act as a negative regulator of fatty acid and DHA synthesis, while SlSGK2 may act as a positive regulator, which requires further study in the future. These insights enhance our comprehension of the processes underlying fatty acid and DHA production in S. limacinum. They also supply a foundational theoretical framework and practical assistance for the development of strains rich in fatty acids and DHA.