Search Results (74)

Flowering is a key agronomic trait that directly influences the yield of the tea-oil tree (Camellia oleifera). Floral initiation, which precedes flower bud differentiation, represents a critical developmental stage affecting the flowering outcomes. However, the molecular mechanisms underlying floral initiation in C. oleifera remain poorly understood. In this study, buds from five key developmental stages of a 12-year-old C. oleifera cultivar ‘changlin53’ were collected as experimental samples. Scanning electron microscopy was employed to identify the stage of floral initiation. UPLC-MS/MS was used to analyze endogenous gibberellin (GA) concentrations, while transcriptomic analysis was performed to reveal the underlying transcriptional regulatory network. Six GA types were detected during floral initiation and petal development. GA₄ was exclusively detected at the sprouting stage (BII), while GA₃ was present in all samples but was significantly lower in BII and the flower bud primordium formation stage (BIII) than in the other samples. A total of 64 differentially expressed genes were concurrently enriched in flower development, reproductive shoot system development, and shoot system development. Weighted gene co-expression network analysis (WGCNA) identified eight specific modules significantly associated with different developmental stages. The magenta module, containing Unigene0084708 (CoFT) and Unigene0037067 (CoLEAFY), emerged as a key regulatory module driving floral initiation. Additionally, GA20OX1 and GA2OX8 were identified as candidate genes involved in GA-mediated regulation of floral initiation. Based on morphological and transcriptomic analyses, we conclude that floral initiation of C. oleifera is a continuous regulatory process governed by multiple genes, with the FT-LFY module playing a central role in the transition from apical meristem to floral meristem. Full article

Seed germination is a critical phase in the plant lifecycle of Camellia oleifera (oil tea), directly influencing seedling establishment and crop reproduction. In this study, we examined transcriptomic and physiological changes across five defined germination stages (G0–G4), from radicle dormancy to cotyledon emergence. Using RNA sequencing (RNA-seq), we assembled 169,652 unigenes and identified differentially expressed genes (DEGs) at each stage compared to G0, increasing from 1708 in G1 to 10,250 in G4. Functional enrichment analysis revealed upregulation of genes associated with cell wall organization, glucan metabolism, and Photosystem II assembly. Key genes involved in cell wall remodeling, including cellulose synthase (CESA), phenylalanine ammonia-lyase (PAL), 4-coumarate-CoA ligase (4CL), caffeoyl-CoA O-methyltransferase (COMT), and peroxidase (POD) showed progressive activation during germination. A Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed dynamic regulation of phenylpropanoid and flavonoid biosynthesis, photosynthesis, carbohydrate metabolism, and hormone signaling pathways. Transcription factors such as indole-3-acetic acid (IAA), ABA-responsive element binding factor (ABF), and basic helix–loop–helix (bHLH) were upregulated, suggesting hormone-mediated regulation of dormancy release and seedling development. Physiologically, cytokinin (CTK) and IAA levels peaked in G4, antioxidant enzyme activities were highest in G2, and starch content increased toward later stages. These findings provide new insights into the molecular mechanisms underlying seed germination in C. oleifera and identify candidate genes relevant to rootstock breeding and nursery propagation. Full article

Camellia chekiangoleosa Hu. (C. chekiangoleosa) is a typical high-altitude oil-tea Camellia species. Due to altitude being an important factor affecting crop growth and quality, the influence of environmental conditions associated with low (60 m) and high (600 m) altitudes on the economic and quality characteristics of fruit ripening was assessed in this study. Our investigations showed that altitude has no influence on the growth pattern of C. chekiangoleosa fruit shells and seed oils, and the differences in samples between different altitudes gradually decreased with the ripening of C. chekiangoleosa. Nevertheless, mature C. chekiangoleosa fruit shells and seed oils from low and high altitudes showed some differences. Specifically, the fruit shells of C. chekiangoleosa cultivated in low-altitude areas contained more soluble sugar, protein, total polyphenols, total flavonoids, and tea saponin. Meanwhile, low-altitude cultivation elevated the abundance of α-tocopherol, β-sitosterol, β-amyrinol, flavonoids, and polyphenols in mature seed oils but decreased the oil yield. Moreover, few effects of altitude on fatty acid composition were observed in mature seed oils. Cluster and receiver operating characteristic (ROC) analysis indicated that the influence of altitude on the quality of mature seed oils was strongly associated with oil yield and α-tocopherol. Taken together, the present study suggests that when cultivating C. chekiangoleosa in low-altitude regions, more energy should be devoted to improving oil yield. The results of the fruiting process and quality trait variation in C. chekiangoleosa during the low-altitude introduction process can provide an important theoretical basis for the introduction and cultivation of this oil-tea species. Full article

Oil-tea (Camellia oleifera), a typical oilseed tree, produces high-quality edible vegetable oils that contain rich unsaturated fatty acids and diverse lipid-soluble active compounds such as squalene. Although squalene biosynthesis and its molecular regulation have been studied in several plants, the molecular mechanisms underlying squalene biosynthesis in oil-tea seeds remain uncertain. We investigated and determined squalene accumulation with seed development. We conducted comparative transcriptomic analyses using the RNA-seq technique at the early, fast biosynthesis, and late stages of squalene accumulation with oil-tea seed development and identified 13 squalene biosynthesis key enzyme genes (such as CoHMGR_4, CoAACT_2, CoFPS_1, and CoFPS_2) in developing oil-tea seeds. According to whether the expressions of key enzyme genes were associated with squalene accumulation we found that the precursor IPP of squalene biosynthesis obtained via the MVA pathway was dominant with oil-tea seed development. Based on the gene co-expression analyses, we identified multiple transcription factors potentially involved in regulating squalene biosynthesis such as CoMYC2, CoREM39, CobZIP5, CoERF and CoWRKY. Using yeast one-hybrid and dual-luciferase assay experiments we demonstrated that the transcription factor CoMYC2 could activate the expression of a key enzyme gene CoHMGR_4, suggesting that CoMYC2 might be a critical regulator during squalene biosynthesis in oil-tea seed development. This study gives not only insights into understanding the molecular basis of squalene biosynthesis in oil-tea developing seeds but also provides gene resources for developing genetically improved varieties with higher content of squalene in oil-tea. Full article

To address the low shelling rate and high seed breakage in existing oil tea fruit shelling devices, a novel laser scoring device was designed for fresh Camellia oleifera fruits. Experimental studies were conducted to optimize the key parameters of the custom-built laser scoring machine, aiming to improve scoring qualification rates. Through single-factor tests and response surface methodology, a regression model was developed to characterize the relationship between the scoring qualification rate and the following three variables: conveyor speed (12 mm/s), laser power (97 W), and defocusing distance (10 mm). The study revealed interactive effects among these parameters. After optimization and verification under ideal conditions, the device achieved a peak average qualification rate of 85.6%. Full article

In order to explore the effects of planting two economic crops in Moso plantations on the composition of soil phosphorus-functional microbial community, this study collected soil samples of Persimmon and Tea-oil plantations cultivated on the original bamboo soil for 3 years for comparison. Soil physical and chemical measurements and metagenomic sequencing were used to evaluate the effects of crop cultivation on the diversity of soil phosphorus-functional microorganisms. Results show that (1) Moso forests are converted to different crops after the soil pH values decline, and other physical and chemical properties of soil and microbial biomass phosphorus (MBP) content rise. (2) Soil microbial community structure changed with crop planting. The number of phosphorus-functional bacteria in Persimmon soil was higher than Tea-oil and Moso soils, with the total number of phosphorus-functional bacteria and unique phosphorus-functional bacteria in Persimmon soil being the highest. (3) The relative abundance of phoU, phoR, ugpA, ugpB, gcd and ppaC genes was significantly increased, while the abundance of pstA, pstB and pstC genes was decreased by crop replanting. (4) The dominant phosphorus-functional microorganisms under different crop cultivation were closely related to basic soil properties. Bradyrhizobium and Camellia abundances were significantly positively correlated with soil total phosphorus (TP), while Sphingomonas was significantly negatively correlated with soil TP. Soil electrical conductivity (EC), soil total nitrogen (TN) and soil MBP were positively correlated with the ppx–gppA gene. AP, EC and TN were positively correlated with the phoB gene, while TN and MBP were negatively correlated with the phoP gene. These results suggested that land use patterns could directly change soil environmental conditions, thereby affecting phosphorus-functional microbial communities. In conclusion, the conversion of Moso plantations to commercial crops is beneficial for the optimization of the soil system, promoting the activation and release of soil phosphorus to maintain the dynamic balance of soil microbial community. Full article

Camellia oleifera is an important woody oil plant in southern China, and developing its industry can enhance forest resource uses and increase edible oil supply. This study investigated the floral characteristics of different C. oleifera varieties, analysed the species and diversity of flower-visiting insects in different habitats, identified the main pollinators and their flower-visiting behaviours, and explored the relationship between pollinating insects and their floral characteristics. The floral lifespan of individual C. oleifera flowers was 5–8 d across cultivars, which is essentially the same. However, floral traits and nectar sugar composition exhibited distinct differences. There were 22 species of insect pollinators from 14 genera and 8 families, including Hymenoptera and Diptera, in 3 habitats. High-potential pollinators varied by habitat, with Apis cerana and Phytomia zonata being the most frequent. A comparison showed that A. cerana was the best pollinator, whereas P. zonata had a larger population, was not affected by oil tea nectar poisoning, and could still pollinate. Therefore, the contribution of P. zonata cannot be overlooked. Redundancy analysis revealed the response relationship between the floral traits of C. oleifera and three insect population characteristics. Stamen length was the main floral trait affecting insect populations. Full article

Tea oil is an important high-quality edible oil derived from woody plants. Camellia oleifera is the largest and most widely planted oil-producing plant in the Camellia genus in China, and its seeds are the most important source for obtaining tea oil. In current research, improving the yield and quality of tea oil is the main goal of oil tea genetic breeding. The aim of this study was to investigate the degree of genetic variation in an early crossing population of C. oleifera and identify single nucleotide polymorphisms (SNPs) and genes significantly associated with fruit traits, which can provide a basis for marker-assisted selection and gene editing for achieving trait improvement in the future. In this study, we selected a crossing population of approximately 40-year-old C. oleifera with a total of 330 samples. Then, ddRAD sequencing was used for SNP calling and population genetic analysis, and association analysis was performed on fruit traits measured repeatedly for two consecutive years. The research results indicate that over 8 million high-quality SNPs have been identified, but the vast majority of SNPs occur in intergenic regions. The nucleotide polymorphism of this population is at a low level, and Tajima’s D values are mostly greater than 0, indicating that the change in this population was not suitable for the model of central evolution. The population structure analysis shows that the population has seven theoretical sources of genetic material and can be divided into seven groups, and the clustering analysis results support the population structure analysis results. Association analysis identified significant SNPs associated with genes related to the seed number of a single fruit and seed kernel oil content. Our findings provide a basis for molecular breeding and future genetic improvement of cultivated oil tea. Full article

Advancement of the oil tea industry requires the development of high-yielding and superior-quality varieties of Camellia oleifera, a major oilseed crop. However, traditional breeding methods, hampered by lengthy cycles and low selection accuracy, significantly constrain the breeding process. Identifying single nucleotide polymorphisms (SNPs) associated with target traits, and applying molecular marker-assisted selection (MAS) for these traits, can thereby shorten the breeding cycles and amplify the breeding efficiency. In this study, we utilized the hexaploid C. oleifera as the reference genome to identify high-quality SNPs and constructed a high-density genetic linkage map of C. oleifera that spanned 1566.733 cM, included 3097 SNPs, and was anchored to 15 linkage groups. Using interval mapping, we localized quantitative trait loci (QTLs) for 11 juvenile traits in C. oleifera, identifying 15 QTLs for growth traits and 24 QTLs for leaf traits, including 4 stable QTLs. The logarithm of odds (LOD) scores for individual QTLs ranged from 3.48 to 14.62, explaining 9.86–48.61% of the phenotypic variance. We further identified 2 SNPs associated with growth traits (marker11-951 and marker12-68) and 10 SNPs associated with leaf traits (marker11-276, marker11-410, marker11-560, marker13-16, marker13-39, marker13-110, marker13-731, marker14-701, marker14-910, and marker14-1331). These results provide valuable insights into the genetic mapping of key traits in C. oleifera and will contribute to the development of new varieties with high yield and superior quality in the future. Full article

Oil–tea camellia has a long history of cultivation and utilization, with a history of more than 2000 years. In China, it is the main woody oil crop with high economic value and a national resource with unique characteristics. Concurrently, it is also known as one of the four major woody oil crops in the world. However, the genetic background of Camellia drupifera Lour. on Hainan Island in China is still unclear, and there is a great lack of systematic genetic characterization, which seriously hinders the development and utilization of oil–tea camellia germplasm resources and genetic improvement on Hainan Island. To analyze the genetic diversity and kinship between C. drupifera and its related species, this study utilized SSR molecular marker technology to genotype 160 individuals from 23 populations. A total of 137 alleles were amplified from the 14 polymorphic primers, with an average of 9.786. The average number of effective alleles and that of Shannon’s information index for each locus were 1.865 and 0.633, respectively, suggesting that the screened SSR markers presented a moderately high level of polymorphism. Additionally, the mean observed heterozygosity (0.915) was greater than the mean expected heterozygosity (0.450), indicating an excess of heterozygotes in the tested population. The results of the principal component analysis (PCA), molecular variation analysis of variance (AMOVA) and population structure analysis were generally consistent; specifically, there was a high degree of individual heterozygosity within the population, and genetic variation occurred primarily among individuals within the population (90%) but rarely among groups (10%). Additionally, the UPGMA clustering divided the 160 germplasm resources into four major clades, and C. drupifera was principally grouped in two distinct branches; meanwhile, Camellia gauchowensis was also mainly clustered in these two clades. Camellia oleifera individuals were chiefly concentrated in other independent branches. It can be speculated that C. drupifera is genetically close to C. gauchowensis, but genetically distant from C. oleifera. This study can provide the scientific basis for the identification, collection, preservation, evaluation, and innovative utilization of oil–tea camellia. Full article

Camellia oleifera, a widely cultivated woody oil crop, holds economic significance because of its ability to grow without encroaching on cultivated land. The pericarp of C. oleifera is abundant in flavonoids and phenolic acids, which offer significant nutritional benefits. This study used metabolomic technology (UPLC-ESI-MS/MS) to discern metabolite variances in the pericarp of three C. oleifera types (COT, BFOT, and SFOT) during the maturity stage and subsequently analyzed and compared them. A total of 1117 metabolites were detected in the study, including 277 flavonoids, 221 phenolic acids, 108 lipids, 93 amino acids and their derivatives, 83 organic acids, 59 nucleotides and their derivatives, 57 alkaloids, 52 lignans, 44 tannins, 23 terpenoids, and 100 miscellaneous metabolites (such as sugars, alcohols, vitamins, and other unclassified substances). Clustering and PCA analyses revealed distinct separation of COT, BFOT, and SFOT, indicating variances in metabolites within the pericarp peels of these three C. oleifera types. KEGG enrichment analysis demonstrated that 143 shared differential metabolites were primarily associated with amino acid biosynthesis. These findings are expected to significantly enhance the current knowledge of the C. oleifera pericarp and pave the way for future development and use efforts. Full article

Oil tea camellia (Camellia spp.) is an important woody oil crop with a high nutritional and economic value. Whole-genome resequencing (WGR) technology can provide an in-depth understanding of the genetic background of this plant as well as a reference for breeding research, germplasm resource conservation, and genetic modification. In this study, we analyzed SNP and InDel variations in 49 individual oil tea camellia germplasm samples collected from five populations located in three provinces of China: Hainan, Guangdong and Guangxi. The samples were analyzed through WGR after the ploidy of the samples was determined through flow cytometry. A total of 239,441,603 high-quality single nucleotide polymorphisms (SNPs) and 23,510,374 high-quality insertion/deletion variation sites (InDels) were obtained. The distribution of SNPs and InDels in different functional regions differed significantly, with a high density of variations in non-coding regions, such as intergenic regions and introns, and a relatively low density of variations in coding regions. Transition was the main type of SNP variation. A population genetic diversity analysis revealed that the sampled oil tea camellia populations exhibited a high genetic diversity and extensive genetic variation. The genetic diversity of the oil tea camellia populations in the Hainan region was higher than inland regions. This study also determined the genetic diversity of and variations between octoploid and decaploid oil tea camellia in the tropics and between Hainan-based and inland oil tea camellia. Such findings provide a reference for the conservation of germplasm resources and the genetic modification of oil tea camellia. Full article

Camellia luteoflora is a rare and endangered plant endemic to China. It has high ornamental and potential economic and medicinal value, and is an important germplasm resource of Camellia. To understand the distributions and differences in metabolites from different parts of C. luteoflora, in this study, we used liquid chromatography–tandem mass spectrometry (LC–MS/MS) to examine the types and contents of chemical constituents in five organs of C. luteoflora: roots, stems, leaves, flowers, and fruits. The results showed that a total of 815 metabolites were identified in the five organs and were classified into 18 main categories, including terpenoids (17.1%), amino acids (10.4%), flavonoids (10.3%), sugars and alcohols (9.8%), organic acids (9.0%), lipids (7.1%), polyphenols (4.8%), alkaloids (4.8%), etc. A total of 684 differentially expressed metabolites (DEMs) in five organs were obtained and annotated into 217 KEGG metabolic pathways, among which metabolic pathways, ABC transporters, the biosynthesis of cofactors, and the biosynthesis of amino acids were significantly enriched. In DEMs, flowers are rich in flavonoids, polyphenols, organic acids, and steroids; fruits are rich in amino acids, alkaloids, vitamins, and xanthones; stems are rich in lignans; and leaves have the highest relative content of phenylpropanoids, ketoaldehydic acids, quinones, sugars and alcohols, terpenoids, coumarins, lipids, and others; meanwhile, the metabolite content is lower in roots. Among the dominant DEMs, 58 were in roots, including arachidonic acid, lucidone, isoliquiritigenin, etc.; 75 were in flowers, including mannose, shikimic acid, d-gluconic acid, kaempferol, etc.; 45 were in the fruit, including pterostilbene, l-ascorbic acid, riboflavin, etc.; 27 were in the stems, including salicylic acid, d-(-)-quinic acid, mannitol, (-)-catechin gallate, etc.; there was a maximum number of 119 dominant metabolites in the leaves, including oleanolic acid, l-glucose, d-arabitol, eugenol, etc. In sum, the rich chemical composition of C. luteoflora and the significant differences in the relative contents of metabolites in different organs will provide theoretical references for the study of tea, flower tea, edible oil, nutraceuticals, and the medicinal components of C. luteoflora. Full article

Between 2023 and 2024, a type of green alga was observed for the first time settling on Oil-tea Camellia leaves and branches in the eastern Oil-tea Camellia planting area of Hainan Island, forming a layer of gray-green moss with a rough surface that seriously interfered with the leaves’ normal photosynthesis. To further research the issue, this study used the plant photosynthesis measurement system and the paraffin sectioning technique to compare and analyze the changes in photosynthetic characteristics and anatomical structure of healthy and green algal-covered Oil-tea Camellia leaves. At the same time, the algal strain was effectively separated and purified using the plate delineation method, and its species classification was determined by combining morphological observation and molecular identification based on SSU-ITS sequences. The results of the study demonstrated that the coating of green alga facilitated the lignification of the leaf’s epidermal cell walls. After being covered by the green alga, the intercellular CO₂ concentration (Ci) increased significantly by 21.5%, while the net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) all significantly decreased by 72.8%, 30.4%, and 24.9%, respectively. More specifically, the green alga that covers the leaves of Oil-tea Camellia was identified as Desmodesmus armatus of Chlorophyta. Notably, the green alga had a long growth cycle, did not undergo a decline phase within one month, had an optimal growth pH of 11.0, and could flourish in excessively alkaline conditions. In conclusion, this study not only reported for the first time the phenomena of D. armatus infesting Oil-tea Camellia leave, but also showed its unique physiological and ecological properties, providing a foundation for future research on relevant prevention and control approaches. Full article

Drought stress is a critical environmental factor that significantly impacts plant growth and productivity. However, the transcriptome analysis of differentially expressed genes in response to drought stress in Camellia oleifera Abel. is still unclear. This study analyzed the transcriptome sequencing data of C. oleifera under drought treatments. A total of 20,674 differentially expressed genes (DEGs) were identified under drought stress, with the number of DEGs increasing with the duration of drought. Specifically, 11,793 and 18,046 DEGs were detected after 8 and 15 days of drought treatment, respectively, including numerous upregulated and downregulated genes. Gene Ontology (GO) enrichment analysis showed that the DEGs were primarily involved in various biological processes. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that carbon metabolism, glyoxylate and dicarboxylate metabolism, proteasome, glycine, serine, and threonine metabolism were the main affected pathways. Among the DEGs, 376 protein kinases, 42 proteases, 168 transcription factor (TF) genes, and 152 other potential functional genes were identified, which may play significant roles in the drought response of C. oleifera. The expression of relevant functional genes was further validated using quantitative real-time PCR (qRT-PCR). These findings contribute to the comprehension of drought tolerance mechanisms in C. oleifera and bolster the identification of drought-resistant genes for molecular breeding purposes. Full article