Applications of Chinese Camellia oleifera and its By-Products: A Review

Isolation and identification of triterpenoid saponins with antiproliferative and hemolytic activities from Camellia oleifera Abel seeds

Seven previously undescribed triterpenoid saponins, oleiferasaponins G1-G7 (1-7), along with two known congeners (8 and 9) were isolated from seeds of Camellia oleifera Abel. Their structures were determined by extensive spectroscopic data. All isolated compounds are decorated with an aglycone and tetrasaccharide moiety. Compounds 1-5 were characterized by an uncommon acylation at C-16 instead of hydroxylation among the identified triterpenoid saponins in Camellia plants. Importantly, compounds 6-9 exhibited excellent antiproliferation effects against HCT-116, HL-60 and HepG2. According to preliminary structure-activity relationship investigations, a free hydroxyl group at the C-16 position of saponins was beneficial for their antiproliferation activity. Interestingly, compounds 1-5 displayed neither antiproliferation nor hemolytic activity, which suggests that the hemolytic and antiproliferation activity of the test saponins exhibit a relatively consistent pattern in their structure-activity relationships.

Enriched Flavonoid Compounds Confer Enhanced Resistance to Fusarium-Induced Root Rot in Oil Tea Plants

Root rot in Camellia oleifera complicates the development of targeted control measures owing to its complex aetiology. Although breeding resistant varieties of C. oleifera presents a promising solution, research into cultivation strategies and potential resistance mechanisms against root rot remains limited. In this study, we investigated six cultivars of C. oleifera that exhibit varying levels of resistance to root rot. We conducted transcriptome analysis, measurements of soil physicochemical properties and an analysis of the fungal microbiome to explore the relationship between Fusarium-induced root rot and flavonoid compounds in the rhizosphere. The resistant cultivar CL18 demonstrated superior performance concerning root rot incidence, root health status and the expression levels of genes associated with flavonoid biosynthesis in this study. Significant differences were observed in the composition and diversity of rhizosphere fungal communities among the various cultivars of C. oleifera. The abundance of Fusarium in the rhizosphere soil of CL18 was low, and a negative correlation was identified between the flavonoid content in the soil and the abundance of Fusarium. Our study uncovers the role of flavonoids in the resistance of C. oleifera to root rot, thereby offering new strategies for disease management and the breeding of resistant cultivars.

The Extract of Camellia Seed Cake Alleviates Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) in Mice by Promoting Coenzyme Q Synthesis

Background: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a prevalent metabolic disorder. Camellia seed cake, a byproduct of oil extraction, contains a variety of bioactive compounds. This study investigated the regulatory effects and underlying mechanisms of camellia seed cake extract (CSCE) using a high-fat diet (HFD)-induced MASLD mouse model. Methods: Mice were divided into four groups: normal control (N, standard diet), HFD model (M), HFD-fed mice treated with low-dose CSCE (L), and HFD-fed mice treated with high-dose CSCE (H). CSCE was administered via oral gavage for eight weeks. Body weight, blood lipid levels, liver weight, hepatic lipid accumulation, oxidative stress markers, ATP levels, and the NADH/NAD+ ratio were measured. Transcriptomic and lipidomic analyses were performed to identify potential regulatory pathways, and qPCR analysis was conducted to confirm the expression levels of essential genes. Results: CSCE significantly reduced HFD-induced increases in body and liver weights, improved blood lipid profiles and hepatic lipid accumulation, alleviated oxidative stress, increased ATP levels, and reduced the NADH/NAD+ ratio. Transcriptomic analysis demonstrated notable enrichment of genes associated with oxidative phosphorylation, mitochondrial function, and lipid metabolism after treatment. The lipidomic analysis demonstrated that the hepatic lipid profile of the H group approached that of the N group, with Coenzyme Q9 (CoQ9) and Coenzyme Q10 (CoQ10) levels significantly increased by 173.32% and 202.73%, respectively, compared to the M group. qPCR validation confirmed that CoQ synthesis-related genes (Coq2-10, Pdss1, Pdss2, and Hmgcr) were significantly upregulated in the treatment groups. Conclusions: CSCE enhances mitochondrial function by promoting CoQ synthesis, alleviates metabolic dysfunction, and could represent a potential natural intervention for MASLD.

Flavonoids from Camellia oleifera flower ameliorate type 2 diabetes mellitus by regulating the p53 pathway

BACKGROUND

Camellia oleifera flower (COF) is rich in flavonoids and polyphenols, strongly preventing postprandial hyperglycemia and improving diabetes. However, research on the effective ingredients in COF extracts that have hypoglycemic effects is limited, and the mechanism by which COF extracts improve liver insulin resistance and glucose and lipid metabolism still needs to be clarified, requiring further investigation.

AIM

To systematically clarify the role of COF extracts in improving insulin resistance in diabetes mice and to explore their key targets and mechanisms in anti-type 2 diabetes (T2DM).

MATERIALS AND METHODS

Ultrafiltration combined with liquid chromatography-mass spectrometry (UPLC-Q-MS) was used to analyze α-glucosidase inhibitors in COF extracts qualitatively. Blood glucose, lipid, oxidative stress, and liver function indicators were detected in the db/db type 2 diabetes mouse model. Then, RNA-seq was used to identify differentially expressed mRNAs (DEGs) in the liver, screen for key genes and metabolic pathways, and validate the results' accuracy through qPCR experiments.

RESULTS

17 α-glucosidase inhibitors were identified as flavonoids from COF. Through db/db type 2 diabetes mouse model, it was indicated that COF could significantly improve symptoms of hyperglycemia and hyperlipidemia, alleviate oxidative stress, and protect liver and pancreatic tissues by regulating key differential genes expressed, including Nek2, Cdk1, Ccnb1, and Ccnb2 via the p53 signaling pathway and ameliorate the insulin resistance effect.

CONCLUSION

This study demonstrated the anti-diabetic effect of COF, explored its potential hypoglycemic target, and provided data support for future T2DM prevention and drug treatment.

Methyl Jasmonate (MeJA) Promotes the Self-Pollen Tube Growth of Camellia oleifera by Regulating Lignin Biosynthesis

Self-incompatibility (SI) poses a significant reproductive barrier, severely impacting the yield, quality, and economic value of Camellia oleifera. In this study, methyl jasmonate (MeJA) was employed as an exogenous stimulus to alleviate SI in C. oleifera. The research findings revealed that an exogenous dose of 1000 μmol·L-1 MeJA enhanced the germination and tube growth of C. oleifera self-pollen and greatly improved ovule penetration (18.75%) and fertilization (15.81%), ultimately increasing fruit setting (18.67%). It was discovered by transcriptome analysis that the key genes (CAD, C4H) involved in the lignin production process exhibited elevated expression levels in self-pistils treated with MeJA. Further analysis showed that the lignin concentration in the MeJA-treated pistils was 31.70% higher compared with the control group. As verified by pollen germination assays in vitro, lignin in the appropriate concentration range could promote pollen tube growth. Gene expression network analysis indicated that transcription factor bHLH may be pivotal in regulating lignin biosynthesis in response to MeJA, which in turn affects pollen tubes. Further transient knockdown of bHLH (Co_33962) confirmed its important role in C. oleifera pollen tube growth. In summary, the application of MeJA resulted in the stimulation of self-pollen tube elongation and enhanced fruit setting in C. oleifera, which could be associated with the differential change in genes related to lignin synthesis and the increased lignin content.

Enhanced Antifungal Efficacy of Validamycin A Co-Administered with Bacillus velezensis TCS001 against Camellia anthracnose

Anthracnose, a fungal disease harming fruit trees and crops, poses a threat to agriculture. Traditional chemical pesticides face issues like environmental pollution and resistance. A strategy combining low-toxicity chemicals with biopesticides is proposed to enhance disease control while reducing chemical use. Our study found that mixing validamycin A (VMA) and Bacillus velezensis TCS001 effectively controlled anthracnose in Camellia oleifera. The combination increased antifungal efficacy by 65.62% over VMA alone and 18.83% over TCS001 alone. It caused pathogen deformities and loss of pathogenicity. Transcriptomic analysis revealed that the mix affected the pathogen's metabolism and redox processes, particularly impacting cellular membrane functions and inducing apoptosis via glycolysis/gluconeogenesis. In vivo tests showed the treatment activated C. oleifera's disease resistance, with a 161.72% increase in polyphenol oxidase concentration in treated plants. This research offers insights into VMA and TCS001's mechanisms against anthracnose, supporting sustainable forestry and national edible oil security.

Comparative Transcriptomic and Lipidomic Analysis of Fatty Acid Accumulation in Three Camellia oleifera Varieties During Seed Maturing

Camellia oleifera, a major woody oil crop in China, produces tea oil rich in unsaturated fatty acids, earning it names like liquid gold and eastern olive oil. This study provides an integrated investigation of the transcriptome and lipidome within seeds at the maturing process across three C. oleifera varieties, revealing a significant relationship between fatty acid production and genes involved in lipid synthesis. Through transcriptomic analysis, 26,344 genes with varied expression were found. Functional enrichment analysis highlighted that pathways related to starch and sucrose metabolism, plant hormone signal transduction, and lipid accumulation were highly enriched among the differentially expressed genes. Coordinated high expression of key genes (ACCase, KAS I, KAS II, KAS III, KAR, HAD, EAR, SAD, LPAAT, LACS, DGAT, PDAT) during the late maturation stage contributes largely to high oil content. Additionally, expression variations of SAD and FADs among different varieties were explored. The analysis suggests that high expression of genes such as FAD3, FAD7, and FAD8 notably increased linolenic acid content. This research provides new insights into the molecular mechanisms of oil biosynthesis in C. oleifera, offering valuable references for improving yield and quality.

ABA and MeJA Induced Catechin and Epicatechin Biosynthesis and Accumulation in Camellia oleifera Fruit Shells

Camellia oleifera Abel, one of the most valuable woody oil plants, has been widely cultivated for extracting edible oil. The shell of C. oleifera is a by-product generated in the processing of edible oil extraction. However, there is still limited research on the maturity and high-value resource utilization of shell by-products. We found that the C. oleifera 'Huashuo' (HS) fruit shells contained a high content of catechins. Abscisic acid (ABA) and methyl jasmonate (MeJA) enhanced the accumulation of catechins in C. oleifera fruit shells, providing a basis for production and application of the catechins in fruit shells of C. oleifera. We further found that 500 μM ABA and 900 μM MeJA significantly promoted the accumulation of catechin (C) and epicatechin (EC) in fruit shells. Following treatment with 900 μM MeJA, the expressions of CoPAL1, CoC4H1, CoC4H2, CoC4H3, Co4CL1, Co4CL2, CoF3'H1, CoLAR1, CoLAR2, CoLAR3, CoANR2, and CoANRL2 were significantly upregulated, while after 500 μM ABA treatment the expressions of CoPAL3, CoCHS1, CoCHS4, CoF3'H1, CoDFR, CoLAR1, CoLAR2, CoLAR3, CoANS1, CoANR1, and CoANR2 increased dramatically. These results indicate that appropriate concentrations of ABA and MeJA activate C and EC biosynthesis and promote their accumulation in fruit shells. Our results provide new ideas and guidance for promoting the resource utilization of C. oleifera fruit shells.

Analysis and evaluation of Camellia oleifera Abel. Germplasm fruit traits from the high-altitude areas of East Guizhou Province, China

Camellia oleifera, a significant woody edible oil species, was examined using 48 germplasm resources from high-altitude regions in East Guizhou Province, China, to analyze fruit quality. The analysis aimed to identify high-performance germplasm, providing theoretical and research foundations for selecting and cross-breeding superior C. oleifera varieties in these regions. Fifteen primary traits of mature fruits were measured and analyzed, including four phenotypic traits (single fruit weight, transverse diameter, longitudinal diameter, peel thickness) and eleven quality traits (fresh seed yield rate, dry seed yield rate, dry kernel yield rate, seed kernel oil content, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, α-linolenic acid, cis-11-eicosenoic acid). A comprehensive evaluation employing cluster and principal component analyses (PCA) was conducted. The cluster analysis categorized the germplasms into five groups at a squared Euclidean distance of 14, with the first category comprising 17 germplasms, the second 28, and the third, fourth, and fifth each containing one. PCA reduced the 15 traits to five principal components (PCs), with PC1 having the highest eigenvalue of 3.57 and a contribution rate of 23.8%, mainly representing phenotypic traits. PC2, contributing 20.44%, represented linoleic acid, while PC3, PC4, and PC5, with contribution rates of 12.99%, 9.13%, and 7.45% respectively, predominantly represented seed kernel oil content, fresh seed yield, and palmitoleic acid. Employing a weighted sum method, a comprehensive evaluation function was developed to calculate total scores for each superior individual, forming the basis for rankings and selections. Notable variability was detected in single fruit weight, peel thickness, and fresh and dry seed yields, while oleic acid exhibited the lowest coefficient of variation. Dry seed yield showed a robust positive correlation with seed kernel oil content and the concentrations of palmitic and linoleic acids, whereas seed kernel oil content was inversely correlated with cis-11-eicosenoic acid levels. Five PCs with eigenvalues > 1 were identified, highlighting the top ten superior individuals: QD (Qian Dong: the code of eastern Guizhou Province)-33 > QD-34 > QD-48 > QD-38 > QD-27 > QD-15 > QD-35 > QD-5 > QD-14 > QD-36. Thus, the 48 C. oleifera germplasms from East Guizhou's high-altitude areas demonstrate significant potential for enhancing traits such as single fruit weight, peel thickness, and fresh and dry seed yields. Specifically, QD-33, QD-34, and QD-48 exhibited superior comprehensive performance, designating them as prime candidates for variety selection and breeding.

Camellia Oleifera oil-loaded chitosan nanoparticles embedded in hydrogels as cosmeceutical products with improved biological properties and sustained drug release

Hydrogels based on poly(vinyl alcohol), silk sericin, and gelatin containing Camellia oleifera oil (CO)-loaded chitosan nanoparticles (CSNPs) were fabricated. The loading of CO into CSNPs was achieved by a two-step procedure, which included an oil-in-water emulsion and an ionic gelation method. SEM images of CO-loaded CSNPs illustrated the spherical shape with aggregation of the nanoparticles. The particle size and polydispersity index were 541-1089 nm and 0.39-0.65, respectively. The encapsulation efficiency and loading capacity were 3-16 % and 4-6 %, respectively. The gelatin/poly(vinyl alcohol)/sericin hydrogels were fabricated and incorporated with CO or CO-loaded CSNPs with different concentrations of CO-loaded CSNPs. All hydrogels demonstrated a porous structure. Besides, the hydrogels containing CO-loaded CSNPs showed a more controlled and sustained release profile than the hydrogels containing CO. Moreover, the hydrogels showed tyrosinase inhibition (9-13 %) and antioxidant activity (37-60 %). Finally, the hydrogels containing CO-loaded CSNPs were non-toxic to the Normal Human Dermal Fibroblasts and NCTC clone 929 cells, even at a high dosage of 50 mg/mL. As a result, these hydrogels exhibited excellent potential for use in cosmeceutical industries.

Genome-Wide Analyses of MADS-Box Genes Reveal Their Involvement in Seed Development and Oil Accumulation of Tea-Oil Tree (Camellia oleifera)

The seeds of Camellia oleifera produce high amount of oil, which can be broadly used in the fields of food, industry, and medicine. However, the molecular regulation mechanisms of seed development and oil accumulation in C. oleifera are unclear. In this study, evolutionary and expression analyses of the MADS-box gene family were performed across the C. oleifera genome for the first time. A total of 86 MADS-box genes (ColMADS) were identified, including 60 M-type and 26 MIKC members. More gene duplication events occurred in M-type subfamily (6) than that in MIKC subfamily (2), and SEP-like genes were lost from the MIKCC clade. Furthermore, 8, 15, and 17 differentially expressed ColMADS genes (DEGs) were detected between three developmental stages of seed (S1/S2, S2/S3, and S1/S3), respectively. Among these DEGs, the STK-like ColMADS12 and TT16-like ColMADS17 were highly expressed during the seed formation (S1 and S2), agreeing with their predicted functions to positively regulate the seed organogenesis and oil accumulation. While ColMADS57 and ColMADS07 showed increasing expression level with the seed maturation (S2 and S3), conforming to their potential roles in promoting the seed ripening. In all, these results revealed a critical role of MADS-box genes in the C. oleifera seed development and oil accumulation, which will contribute to the future molecular breeding of C. oleifera.

Genomic Insights into Combating Anthracnose with an Endophytic Bacillus amyloliquefaciens Strain

Anthracnose, caused by Colletotrichum spp., is a common disease of Camellia oleifera. In this study, a Bacillus amyloliquefaciens strain, GZY63, was isolated from fruit of the anthracnose-resistant cultivar of Ca. oleifera "Ganzhouyou7." Plate confrontation assays and field experiments demonstrated the strong inhibitory effect of GZY63 on anthracnose, and this strain exhibited broad-spectrum resistance to nine pathogenic Colletotrichum spp. This strain shows potential as a fungicide alternative, but genetic information on this strain is critical for its optimal use. Combining Illumina and Nanopore sequencing, we assembled a high-quality circular genome of GZY63 that contained no plasmids. The GZY63 complete genome was approximately 3.93 Mb and had an average guanine-cytosine content of 46.5%. The genome comprised 4,024 predicted coding sequences and 12 types of gene clusters involved in secondary metabolite production. This genome information provides insights into the mechanism underlying the antagonistic impact of the GZY63 strain on anthracnose and its symbiotic relationship with Ca. oleifera.

Integrated analysis of miRNAs, transcriptome and phytohormones in the flowering time regulatory network of tea oil camellia

Camellia oleifera is a crucial cash crop in the southern region of China. Timely flowering is a crucial characteristic for maximizing crop productivity. Nevertheless, the cold temperature and wet weather throughout the fall and winter seasons in South China impact the timing of flowering and the yield produced by C. oleifera. This study examined the miRNAs, transcriptomes, and phytohormones that are part of the flowering time regulatory networks in distinct varieties of C. oleifera (Sep, Oct, and Nov). This study provides evidence that phytohormones significantly impact the timing of flowering in C. oleifera leaves. There is a positive correlation between the accumulation variations of zeatin (cZ), brassinolide (BL), salicylic acid (SA), 1-amino cyclopropane carboxylic acid (ACC), and jasmonic acid (JA) and flowering time. This means that blooming occurs earlier when the quantity of these substances in leaves increases. Abscisic acid (ABA), trans-zeatin-riboside (tZR), dihydrozeatin (dh-Z), and IP (N6-Isopentenyladenine) exhibit contrasting effects. Furthermore, both miR156 and miR172 play a crucial function in regulating flowering time in C. oleifera leaves by modulating the expression of SOC1, primarily through the miR156-SPL and miR172-AP2 pathways. These findings establish a strong basis for future research endeavors focused on examining the molecular network associated with the flowering period of C. oleifera and controlling flowering time management through external treatments.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-024-01473-2.

Three undescribed dihydrostilbene glycosides from leaves of Camellia oleifera Abel. And their anti-inflammatory activity

Three previously unidentified dihydrostilbene glycosides, named oleiferaside A (1), oleiferaside B (2), and oleiferaside C (3), were discovered through a phytochemical exploration on Camellia oleifera Abel. leaves. Additionally, nine known secondary metabolites (4-12) were also identified. The undescribed secondary metabolites 1-3 were elucidated as 3,5-dimethoxydihydrostilbene 4'-O-α-l-arabinofuranosyl-(1 → 6)-β-d- glucopyranoside, 3,5-dimethoxydihydrostilbene 4'-O-α-l-arabinopyranosyl-(1 → 6)-β-d- glucopyranoside and 3,5-dimethoxydihydrostilbene 4'-O-β-d-apiofuranosyl-(1 → 6)-β-d- glucopyranoside, respectively. HR-MS and NMR spectroscopy were utilized for determining the structures of the isolates. The natural products were assessed for their anti-inflammatory effect using RAW264.7 macrophage stimulated by LPS. The findings demonstrated that compounds 1-4 exhibited inhibitory activities on NO and PGE2 production without causing cytotoxicity. These observations suggest that these compounds may have potential anti-inflammatory properties.

Advances in Separation, Biological Properties, and Structure-Activity Relationship of Triterpenoids Derived from Camellia oleifera Abel

Extensive research has been conducted on Camellia oleifera Abel., a cultivar predominantly distributed in China, to investigate its phytochemical composition, owning to its potential as an edible oil crop. Pentacyclic triterpene saponins, as essential active constituents, play a significant role in contributing to the pharmacological effects of this cultivar. The saponins derived from C. oleifera (CoS) offer a diverse array of bioactivity benefits, including antineoplastic/bactericidal/inflammatory properties, cardiovascular protection, neuroprotection, as well as hypoglycemic and hypolipidemic effects. This review presents a comprehensive analysis of the isolation and pharmacological properties of CoS. Specially, we attempt to reveal the antitumor structure-activity relationship (SAR) of CoS-derived triterpenoids. The active substitution sites of CoS, namely, C-3, C-15, C-16, C-21, C-22, C-23, and C-28 pentacyclic triterpenoids, make it a unique and highly valuable substance with significant medicinal and culinary applications. As such, CoS can play a critical role in transforming people's lives, providing unique medicinal benefits, and contributing to the advancement of both medicine and cuisine.

Extraction of cellulose nanocrystalline from Camellia oleifera Abel waste shell: Study of critical processes, properties and enhanced emulsion performance

Cellulose nanocrystals (CNCs) extracted from the waste shell of Camellia oleifera Abel (C. oleifera) are gaining attention as valuable materials. In this study, CNCs were extracted from the agricultural waste shell of C. oleifera through phosphoric acid and sulfuric acid hydrolysis, respectively. Firstly, we optimized the alkaline treatment process for cellulose isolation by using response surface methodology. Furthermore, the properties of CNCs were investigated by neutralizing them with NaOH and NH3·H2O, and by dialysis in water. In addition, the characterization methods including FT-IR, TGA, AFM and TEM were used to analysis the properties of the synthesized CNCs. Finally, CNCs were studied for their application in essential oil-based Pickering emulsions. CNCs obtained from sulfuric acid showed the smallest particle size and good dispersibility. Moreover, the release profiles of essential oils in the emulsions were followed by Peppa's kinetic release model. The antibacterial activity of the emulsions against E. coli and S. aureus showed that CNCs-stabilized emulsions enhanced the antibacterial activity of essential oils. Therefore, neutralization treatments may enhance the properties of CNCs, and CNCs stabilized Pickering emulsions can enhance antibacterial activity of essential oil. This study provides insight into the potential application of CNCs derived from C. oleifera waste shells.

Highly efficient isolation and purification of high-purity tea saponins from industrial camellia oil production by porous polymeric adsorbents

BACKGROUND

Recovery of high-purity tea saponin (TS), a promising non-ionic surfactant with well-documented properties, is one of the major challenges to broadening its industrial applications. In this study, an innovative and sustainable strategy for the highly-efficient purification of TS was developed by using well-designed highly-porous polymeric adsorbents.

RESULTS

The prepared Pp-A with controllable macropores (~96 nm) and appropriate surface hydrophobic properties was found more favorable for achieving high adsorption efficiency towards TS/TS-micelles. Kinetic results showed the adsorption follows the pseudo-second-order model (R2  = 0.9800), and the Langmuir model is more qualified to explicate the adsorption isotherms with Qe-TS  ~ 675 mg g-1 . Thermodynamic studies revealed the monolayer adsorption of TS was an endothermic process that was conducted spontaneously. Interestingly, ethanol-driven desorption (90% v/v ethanol) of TS was rapidly (< 30 min) complete due to the possible ethanol-mediated disassembling of TS-micelles. A possible mechanism that involves the interactions between the adsorbents and TS/TS-micelles, the formation and disassembling of TS-micelles was proposed to account for the highly efficient purification of TS. Afterwards, Pp-A-based adsorption method was developed to purify TS directly from industrial camellia oil production. Through selective adsorption, pre-washing, and ethanol-driven desorption, the applied Pp-A enabled the direct isolation of high-purity TS (~96%) with a recovery ratio > 90%. Notably, Pp-A exhibited excellent operational stability and is of high potential for long-term industrial application.

CONCLUSION

Results ensured the practical feasibility of the prepared porous adsorbents in purifying TS, and the proposed methodology is a promising industrial-scale purification strategy. © 2023 Society of Chemical Industry.

Total Flavonoids from Camellia oleifera Alleviated Mycoplasma pneumoniae-Induced Lung Injury via Inhibition of the TLR2-Mediated NF-κB and MAPK Pathways

Mycoplasma pneumoniae (M. pneumoniae) is an atypical bacterial pathogen responsible for community-acquired pneumonia primarily among school-aged children and young adults. Camellia oleifera (C. oleifera) has been used as a medicinal and edible plant in China for centuries, the constituents from which possessed various bioactivities. Notably, flavonoids existing in residues of C. oleifera defatted seeds exhibited significant anti-inflammatory activities. In the present study, we investigated the impact of total flavonoids from C. oleifera (TFCO) seed extract on M. pneumoniae pneumonia. TFCO was obtained using multiple column chromatography methods and identified as kaempferol glycosides via UPLC-HRESIMS. In a M. pneumoniae pneumonia mouse model, TFCO significantly reduced the lung damage, suppressed IL-1β, IL-6, and TNF-α production, and curbed TLR2 activation triggered by M. pneumoniae. Similarly, in RAW264.7 macrophage cells stimulated by lipid-associated membrane proteins (LAMPs), TFCO suppressed the generation of proinflammatory cytokines and TLR2 expression. Moreover, TFCO diminished the phosphorylation of IκBα, JNK, ERK, p38, and p65 nuclear translocation in vitro. In conclusion, TFCO alleviated M. pneumoniae-induced lung damage via inhibition of TLR2-mediated NF-κB and MAPK pathways, suggesting its potential therapeutic application in M. pneumoniae-triggered lung inflammation.

Genome-Wide Detection of SPX Family and Profiling of CoSPX-MFS3 in Regulating Low-Phosphate Stress in Tea-Oil Camellia

Camellia oleifera a member of the family Theaceae, is a phosphorus (P) tolerator native to southern China. The SPX gene family critically regulates plant growth and development and maintains phosphate (Pi) homeostasis. However, the involvement of SPX genes in Pi signaling in Tea-Oil Camellia remains unknown. In this work, 20 SPX genes were identified and categorized into four subgroups. Conserved domains, motifs, gene structure, chromosomal location and gene duplication events were also investigated in the SPX gene family. Defense and stress responsiveness cis-elements were identified in the SPX gene promoters, which participated in low-Pi stress responses. Based on transcriptome data and qRT-PCR results, nine CoSPX genes had similar expression patterns and eight genes (except CoPHO1H3) were up-regulated at 30 days after exposure to low-Pi stress. CoSPX-MFS3 was selected as a key candidate gene by WGCNA analysis. CoSPX-MFS3 was a tonoplast protein. Overexpression of CoSPX-MFS3 in Arabidopsis promoted the accumulation of total P content and decreased the anthocyanin content. Overexpression of CoSPX-MFS3 could enhance low-Pi tolerance by increased biomass and organic acid contents in transgenic Arabidopsis lines. Furthermore, the expression patterns of seven phosphate starvation genes were higher in transgenic Arabidopsis than those in the wild type. These results highlight novel physiological roles of the SPX family genes in C. oleifera under low-Pi stress, and lays the foundation for a deeper knowledge of the response mechanism of C. oleifera to low-Pi stress.

Unilateral cross-incompatibility between Camellia oleifera and C. yuhsienensis provides new insights for hybridization in Camellia spp

Camellia yuhsienensis was used to cross with Camellia oleifera to improve the resistance of oil camellia anthracnose. However, unilateral cross-incompatibility (UCI) between C. oleifera and C. yuhsienensis was found during the breeding process. Five C.oleifera cultivars and four C. uhsienensis materials were tested to confirm the UCI between C. oleifera and C. yuhsienensis. 'Huashuo' (HS) and 'Youza 2' (YZ2) were used to represent these two species to characterize the UCI, including pollen tube growth, fertilization and fruit development. The results demonstrated that UCI was prevalent between C. oleifera and C. yuhsienensis. The asynchronous flowering period was a pre-pollination barrier that limited mating between these two species under natural conditions. Interspecific pollen tubes were observed through the styles of these two plants, though the growth rates differed considerably. At 96 hours after pollination, the pollen tube of YZ2 barely entered the ovule, but remained at the base of the style and became swollen. However, the HS pollen tube entered the ovule 48 hours after pollination, double fertilization was observed, and the fruit and seeds developed commonly. Relative to compatible combinations, most unfertilized ovules in incompatible combinations failed to grow, turned brown 150 days after pollination, and the fruits were smaller than expected with uneven enlargement. Investigations on both semi-in vivo and in vitro pollen tubes gave us new idea for thought: the HS style has a stronger inhibitory effect on the interspecific pollen tubes, while calcium alleviates the inhibitory of styles but failed to prevent the appearance of abnormal pollen tube morphology. This study provides useful information on interspecific hybridization between C. oleifera and C. yuhsienensis for understanding reproductive isolation mechanisms and breeding programs in genus Camellia.

Co-regulatory effects of hormone and mRNA-miRNA module on flower bud formation of Camellia oleifera

Few flower buds in a high-yield year are the main factors restricting the yield of Camellia oleifera in the next year. However, there are no relevant reports on the regulation mechanism of flower bud formation. In this study, hormones, mRNAs, and miRNAs were tested during flower bud formation in MY3 ("Min Yu 3," with stable yield in different years) and QY2 ("Qian Yu 2," with less flower bud formation in a high-yield year) cultivars. The results showed that except for IAA, the hormone contents of GA₃, ABA, tZ, JA, and SA in the buds were higher than those in the fruit, and the contents of all hormones in the buds were higher than those in the adjacent tissues. This excluded the effect of hormones produced from the fruit on flower bud formation. The difference in hormones showed that 21-30 April was the critical period for flower bud formation in C. oleifera; the JA content in MY3 was higher than that in QY2, but a lower concentration of GA₃ contributed to the formation of the C. oleifera flower bud. JA and GA₃ might have different effects on flower bud formation. Comprehensive analysis of the RNA-seq data showed that differentially expressed genes were notably enriched in hormone signal transduction and the circadian system. Flower bud formation in MY3 was induced through the plant hormone receptor TIR1 (transport inhibitor response 1) of the IAA signaling pathway, the miR535-GID1c module of the GA signaling pathway, and the miR395-JAZ module of the JA signaling pathway. In addition, the expression of core clock components GI (GIGANTEA) and CO (CONSTANS) in MY3 increased 2.3-fold and 1.8-fold over that in QY2, respectively, indicating that the circadian system also played a role in promoting flower bud formation in MY3. Finally, the hormone signaling pathway and circadian system transmitted flowering signals to the floral meristem characteristic genes LFY (LEAFY) and AP1 (APETALA 1) via FT (FLOWERING LOCUS T) and SOC1 (SUPPRESSOR OF OVEREXPRESSION OF CO 1) to regulate flower bud formation. These data will provide the basis for understanding the mechanism of flower bud alternate formation and formulating high yield regulation measures for C. oleifera.

Influence of the emulsifier on nanostructure and clinical application of liquid crystalline emulsions

Liquid crystals are appealing in pharmaceutical and cosmetic fields due to their unique structures that combine the properties of both liquid and solid states. Forming an emulsion into liquid crystals can be affected by a number of factors, including the emulsion composition and temperature. Changing the types and concentrations of surfactants could be another factor that affects liquid crystals. Currently, most liquid crystal research focuses on the nanostructure of liquid crystal systems without evaluating the efficacy of liquid crystals clinically. In this study, liquid crystalline emulsions made from camellia seed oil with four different surfactants (Olivem 1000, Polyaquol-2W, Nikkomulese LC, and Lecinol S-10 with Tween 80) were created. The liquid crystal emulsions were formulated in the form of oil-in-water (o/w) emulsions with Camellia oleifera seed oil serving as the main ingredient in the oil phase (10% w/w). All formulations exhibited liquid crystal characteristics with lamellar structures as determined by the polarized light microscopy and small-angle X-ray scattering with supporting data of the nanostructure from wide-angle X-ray scattering and differential scanning calorimetry (DSC). They all showed good stability under normal (room temperature) and accelerated conditions (4 °C and 40 °C) in long-term storage (6 months). Using the reconstructed human epidermis as a skin model, all formulations did not cause skin irritation. In the clinical trial, all formulations were able to reduce transepidermal water loss (TEWL) and increase skin hydration immediately after application. This lasted at least 10 h. All formulations showed distinct Maltese crosses under the polarized light microscope with a positive result for liquid crystals in wide angle X-ray scattering (WAXS) and small angle X-ray scattering (SAXS) methods. Moreover, among all formulations tested, Formulation D, which contained Lecinol S-10 and Tween 80 as emulsifiers, showed the most robust interaction between the surfactant and water molecules in the lamellar structure under DSC. The formulation was stable in long-term normal and accelerated conditions. Above all, Formulation D, which was formulated with Lecinol S-10 with Tween 80, had the best clinical result, was nonirritating to the skin, and can be used as a cream base in the pharmaceutical and cosmeceutical sectors.

Transcriptomic and metabolomic insights on the molecular mechanisms of flower buds in responses to cold stress in two Camellia oleifera cultivars

INTRODUCTION

The Camellia oleifera (C. oleifera) cultivars 'Huashuo' (HS) and 'Huaxin' (HX) are new high-yielding and economically valuable cultivars that frequently encounter prolonged cold weather during the flowering period, resulting in decreased yields and quality. The flower buds of HS sometimes fail to open or open incompletely under cold stress, whereas the flower buds of HX exhibit delayed opening but the flowers and fruits rarely drop.

METHODS

In this study, flower buds at the same development stage of two C. oleifera cultivars were used as test materials for a combination of physiological, transcriptomic and metabolomic analyses, to unravel the different cold regulatory mechanisms between two cultivars of C. oleifera.

RESULTS AND DISCUSSION

Key differentially expressed genes (DEGs) and differentially expressed metabolites (DEMs) involved in sugar metabolism, phenylpropanoid biosynthesis, and hormone signal transduction were significantly higher in HX than in HS, which is consistent with phenotypic observations from a previous study. The results indicate that the flower buds of HX are less affected by long-term cold stress than those of HS, and that cold resistance in C. oleifera cultivars varies among tissues or organs.This study will provide a basis for molecular markers and molecular breeding of C. oleifera.

Gene coexpression analysis reveals key pathways and hub genes related to late-acting self-incompatibility in Camellia oleifera

INTRODUCTION

Self-incompatibility (SI) is an important strategy for plants to maintain abundant variation to enhance their adaptability to the environment. Camellia oleifera is one of the most important woody oil plants and is widely cultivated in China. Late acting self-incompatibility (LSI) in C. oleifera results in a relatively poor fruit yield in the natural state, and understanding of the LSI mechanism remains limited.

METHODS

To better understand the molecular expression and gene coexpression network in the LSI reaction in C. oleifera, we conducted self- and cross-pollination experiments at two different flower bud developmental stages (3-4 d before flowering and 1 d before flowering), and cytological observation, fruit setting rate (FSR) investigation and RNA-Seq analysis were performed to investigate the mechanism of the male -female interaction and identify hub genes responsible for the LSI in C. oleifera.

RESULTS

Based on the 21 ovary transcriptomes, a total of 7669 DEGs were identified after filtering out low-expression genes. Weighted gene coexpression network analysis (WGCNA) divided the DEGs into 15 modules. Genes in the blue module (1163 genes) were positively correlated with FSR, and genes in the pink module (339 genes) were negatively correlated with FSR. KEGG analysis indicated that flavonoid biosynthesis, plant MAPK signaling pathways, ubiquitin-mediated proteolysis, and plant-pathogen interaction were the crucial pathways for the LSI reaction. Fifty four transcription factors (TFs) were obtained in the two key modules, and WRKY and MYB were potentially involved in the LSI reaction in C. oleifera. Network establishment indicated that genes encoding G-type lectin S-receptor-like serine (lecRLK), isoflavone 3'-hydroxylase-like (CYP81Q32), cytochrome P450 87A3-like (CYP87A3), and probable calcium-binding protein (CML41) were the hub genes that positively responded to the LSI reaction. The other DEGs inside the two modules, including protein RALF-like 10 (RALF), F-box and pectin acetylesterase (MTERF5), might also play vital roles in the LSI reaction in C. oleifera.

DISCUSSION

Overall, our study provides a meaningful resource for gene network studies of the LSI reaction process and subsequent analyses of pollen-pistil interactions and TF roles in the LSI reaction, and it also provides new insights for exploring the mechanisms of the LSI response.

Discovery of New Triterpenoids Extracted from Camellia oleifera Seed Cake and the Molecular Mechanism Underlying Their Antitumor Activity

Theasaponin derivatives, which are reported to exert antitumor activity, have been widely reported to exist in edible plants, including in the seed cake of Camellia oleifera (C.), which is extensively grown in south of China. The purpose of this study was to isolate new theasaponin derivatives from C. seed cake and explore their potential antitumor activity and their underlying molecular mechanism. In the present study, we first isolated and identified four theasaponin derivatives (compounds 1, 2, 3, and 4) from the total aglycone extract of the seed cake of Camellia oleifera by utilizing a combination of pre-acid-hydrolysis treatment and activity-guided isolation. Among them, compound 1 (C1) and compound 4 (C4) are newly discovered theasaponins that have not been reported before. The structures of these two new compounds were characterized based on comprehensive 1D and 2D NMR spectroscopy and high-resolution mass spectrometry, as well as data reported in the literature. Secondly, the cytotoxicity and antitumor property of the above four purified compounds were evaluated in selected typical tumor cell lines, Huh-7, HepG2, Hela, A549, and SGC7901, and the results showed that the ED₅₀ value of C4 ranges from 1.5 to 11.3 µM, which is comparable to that of cisplatinum (CDDP) in these five cell lines, indicating that C4 has the most powerful antitumor activity among them. Finally, a preliminary mechanistic investigation was performed to uncover the molecular mechanism underlying the antitumor property of C4, and the results suggested that C4 may trigger apoptosis through the Bcl-2/Caspase-3 and JAK2/STAT3 pathways, and stimulate cell proliferation via the NF-κB/iNOS/COX-2 pathway. Moreover, it was surprising to find that C4 can inhibit the Nrf2/HO-1 pathway, which indicates that C4 has the potency to overcome the resistance to cancer drugs. Therefore, C1 and C4 are two newly identified theasaponin derivatives with antitumor activity from the seed cake of Camellia oleifera, and C4 is a promising antitumor candidate not only for its powerful antitumor activity, but also for its ability to function as an Nrf2 inhibitor to enhance the anticancer drug sensitivity.

Maturity Grading and Identification of Camellia oleifera Fruit Based on Unsupervised Image Clustering

Maturity grading and identification of Camellia oleifera are prerequisites to determining proper harvest maturity windows and safeguarding the yield and quality of Camellia oil. One problem in Camellia oleifera production and research is the worldwide confusion regarding the grading and identification of Camellia oleifera fruit maturity. To solve this problem, a Camellia oleifera fruit maturity grading and identification model based on the unsupervised image clustering model DeepCluster has been developed in the current study. The proposed model includes the following two branches: a maturity grading branch and a maturity identification branch. The proposed model jointly learns the parameters of the maturity grading branch and maturity identification branch and used the maturity clustering assigned from the maturity grading branch as pseudo-labels to update the parameters of the maturity identification branch. The maturity grading experiment was conducted using a training set consisting of 160 Camellia oleifera fruit samples and 2628 Camellia oleifera fruit digital images collected using a smartphone. The proposed model for grading Camellia oleifera fruit samples and images in training set into the following three maturity levels: unripe (47 samples and 883 images), ripe (62 samples and 1005 images), and overripe (51 samples and 740 images). Results suggest that there was a significant difference among the maturity stages graded by the proposed method with respect to seed oil content, seed soluble protein content, seed soluble sugar content, seed starch content, dry seed weight, and moisture content. The maturity identification experiment was conducted using a testing set consisting of 160 Camellia oleifera fruit digital images (50 unripe, 60 ripe, and 50 overripe) collected using a smartphone. According to the results, the overall accuracy of maturity identification for Camellia oleifera fruit was 91.25%. Moreover, a Gradient-weighted Class Activation Mapping (Grad-CAM) visualization analysis reveals that the peel regions, crack regions, and seed regions were the critical regions for Camellia oleifera fruit maturity identification. Our results corroborate a maturity grading and identification application of unsupervised image clustering techniques and are supported by additional physical and quality properties of maturity. The current findings may facilitate the harvesting process of Camellia oleifera fruits, which is especially critical for the improvement of Camellia oil production and quality.

Extraction of Oils and Phytochemicals from Camellia oleifera Seeds: Trends, Challenges, and Innovations

Camellia seed oil, extracted from the seeds of Camellia oleifera Abel., is popular in South China because of its high nutritive value and unique flavor. Nowadays, the traditional extraction methods of hot pressing extraction (HPE) and solvent extraction (SE) are contentious due to low product quality and high environmental impact. Innovative methods such as supercritical fluid extraction (SCFE) and aqueous extraction (AE) are proposed to overcome the pitfalls of the traditional methods. However, they are often limited to the laboratory or pilot scale due to economic or technical bottlenecks. Optimization of extraction processes indicates the challenges in finding the optimal balance between the yield and quality of oils and phytochemicals, as well as the environmental and economic impacts. This article aims to explore recent advances and innovations related to the extraction of oils and phytochemicals from camellia seeds, and it focuses on the pretreatment and extraction processes, as well as their complex effects on nutritional and sensory qualities. We hope this review will help readers to better understand the trends, challenges, and innovations associated with the camellia industry.