The Sapindus saponaria (soapberry) kernel is rich in oil that has antibacterial, anti-inflammatory, and antioxidant properties, promotes cell proliferation, cell migration, and stimulates skin wound-healing effects. S. saponaria oil has excellent lubricating properties and is a high-quality raw material for biodiesel and premium lubricants, showing great potential in industrial and medical applications. Metabolite and transcriptome analysis revealed patterns of oil accumulation and composition and differentially expressed genes (DEGs) during seed development. Morphological observations of soapberry fruits at different developmental stages were conducted, and the oil content and fatty acid composition of the kernels were determined. Transcriptome sequencing was performed on kernels at 70, 100, and 130 days after flowering (DAF). The oil content of soapberry kernels was lowest at 60 DAF (5%) and peaked at 130 DAF (31%). Following soapberry fruit-ripening, the primary fatty acids in the kernels were C18:1 (oleic acid) and C18:3 (linolenic acid), accounting for an average proportion of 62% and 18%, respectively. The average contents of unsaturated fatty acids and saturated fatty acids in the kernel were 86% and 14%, respectively. Through the dynamic changes in fatty acid composition and DEGs analysis of soapberry kernels, FATA, KCR1, ECR, FAD2 and FAD3 were identified as candidate genes contributing to a high proportion of C18:1 and C18:3, while DGAT3 emerged as a key candidate gene for TAG biosynthesis. The combined analysis of transcriptome and metabolism unveiled the molecular mechanism of oil accumulation, leading to the creation of a metabolic pathway pattern diagram for oil biosynthesis in S. saponaria kernels. The study of soapberry fruit development, kernel oil accumulation, and the molecular mechanism of oil biosynthesis holds great significance in increasing oil yield and improving oil quality.

Phosphorus deficiency poses a significant challenge to plant growth and development, particularly in red soil. To alleviate this limitation, phosphorus-solubilizing bacteria (PSB) play a crucial role by converting insoluble phosphates present in the soil into soluble forms that are accessible to plants. Cornus wilsoniana Wangerin is a representative oil crop cultivated in red soil, holding a prominent position within China’s forestry economic system. Consequently, it is essential to develop highly stable microbial phosphorus enhancement strategies to manage agricultural phosphorus in red soil regions, thereby maintaining the available phosphorus content necessary for the production of C. wilsoniana. In this study, the application of Streptomyces misionensis SwB1 bacterial suspension to the rhizosphere of C. wilsoniana significantly increased the content of various phosphorus fractions (H₂O-P, NaHCO₃-P, NaOH-P, HCl-P) in red soil, with NaHCO₃-P content increasing by 4.97 times and NaOH-P content by 3.87 times. Additionally, the genome of S. misionensis SwB1 contains 25 phosphorus-solubilizing genes, 13 nitrogen-fixing genes, 17 siderophore production genes, and 11 indole-3-acetic acid (IAA) production genes, indicating its potential for enhancing nutrient availability. Comparative genomic analysis of 15 strains belonging to five species of Streptomyces revealed that S. misionensis SwB1 possesses an extensive genetic repertoire and complete gene clusters associated with phosphorus solubilization. Furthermore, five phosphorus solubilization pathways of S. misionensis SwB1 were summarized: the Pst system, Pit system, siderophore transport, phosphatase synthesis, and organic acid synthesis. Ultimately, the inoculation of S. misionensis SwB1 significantly enhanced the growth and biomass accumulation of C. wilsoniana at the seedling stage, evidenced by an increase in fresh weight by 81.44%, a rise in net photosynthetic rate by 18.51%, and a surge in the number of root tips by 36.24%. Taken together, our findings support a sophisticated multi-pathway bacteria phosphorus solubilization approach and identified a highly efficient phosphorus-solubilizing strain, S. misionensis SwB1, which has the potential to become a microbial fertilizer.

We examined the fruit morphology, oil content, and fatty acids (FAs) of 11 populations of Swida wilsoniana in four provinces in southern China. The fruit oil was extracted by the Soxhlet method, and the FA composition was determined by gas chromatography (GC). The variation in oil content ranged from 16.10 ± 4.94% to 33.08 ± 5.52%, and the major FAs were linoleic acid (44.85 ± 6.70%), oleic acid (29.45 ± 7.63%), palmitic acid (19.59 ± 3.98%), stearic acid (1.95 ± 0.39%), and linolenic acid (0.21 ± 0.07%). The unsaturated FAs accounted for 78.38 ± 3.74%. There was high genetic variation in the oil content and FA composition among the populations. We assessed the relationships between the ecological factors and the FA composition among the populations. The oil content was positively correlated with temperature (r = 0.645, p < 0.05) and negatively correlated with latitude (r = −0.653, p < 0.05). Interestingly, both latitude and temperature were strongly correlated with the unsaturated FAs of the fruits. Principal component analysis (PCA) showed that the populations in different areas could be separated based on oil quality and plant growth. In conclusion, the oil content and FA composition were influenced by geographical area. The findings could help to improve fruit oil quality in future S. wilsoniana breeding programs.

Camelliasaponins, bioactive constituents abundant in the by-products of Camellia oleifera oil production, exhibit diverse biological activities. However, their potential in regulating neuroprotective mitophagy remains largely unexplored. This study identifies camelliasaponin B1 (CSB1) as an abundant component in C. oleifera seeds and investigates its cytoprotective mechanisms against oxidative stress. Using an in vitro model of H₂O₂-induced oxidative damage in PC12 cells, we found that CSB1 pretreatment significantly alleviated oxidative stress, as evidenced by reduced reactive oxygen species (ROS) accumulation and enhanced antioxidant enzyme activities (SOD, CAT, GSH-Px). CSB1 also preserved mitochondrial function, restoring membrane potential (ΔΨm), ultrastructure, and respiratory capacity. Mechanistically, CSB1 reduces the expression of BNIP3/NIX-LC3B pathway-related proteins, suggesting a modulatory effect on mitophagy, as supported by transcriptomic analysis, Western blotting, and immunofluorescence. Molecular docking computationally predicted potential interactions between CSB1 and BNIP3/NIX proteins, which require experimental validation. Collectively, these findings suggest that CSB1 acts as a cytoprotective agent that enhances antioxidant defenses, safeguards mitochondrial integrity, and is associated with reduced BNIP3/NIX-LC3B expression and co-localization, offering a potential molecular basis for its development as a neuroprotective agent targeting oxidative stress-related mitochondrial dysfunction.

Swida wilsoniana is an important oil-producing tree species whose fruits are rich in unsaturated fatty acids with high nutritional and medicinal value. Lipases are involved not only in lipid mobilization but also potentially in the regulation of fatty acid composition and oil accumulation in plants. In this study, the fatty acid composition of S. wilsoniana fruits was analyzed using gas chromatography–flame ionization detection (GC-FID), and the three most abundant fatty acids were selected as molecular docking ligands. Based on overall multi-ligand docking performance (including mean affinity across the three ligands), three key lipases—SwL5, SwL8, and SwL12—were identified as having the strongest interactions with these fatty acids. Phylogenetic analysis revealed that SwL5 and SwL12 belong to lipase family II, while SwL8 is classified into family VI. Molecular dynamics simulations were further performed to evaluate the binding stability and to characterize the structural basis of substrate recognition, including key interacting residues. This study provides theoretical insights into the molecular regulation of fatty acid composition in S. wilsoniana, and offers potential gene targets for the genetic improvement of oil quality traits.