Integrated metabolomics and transcriptomic analysis reveals metabolic changes of flavor compounds of Camellia assamica host plant after parasitized by Viscumarticulatum.

Tea is one of the most popular beverages, it has many health benefits and flavor properties due to the presence of numerous secondary metabolites. Camellia assamica is also a main source of tea, which is mainly planted in the regions of southwest China. In this study, a non-targeted and targeted metabolomics analysis and sensory evaluation on tea leaves with and without mistletoe (Viscum articulatum) was carried out using liquid chromatography-mass spectrometry. RNA-seq-based transcriptomic analysis was conducted in parallel on the same samples, subsequently gene expression and metabolic differentiation were also investigated. Tea leaves with mistletoe presented much lower contents of (-)-catechin, (-)-epicatechin, (-)-gallocatechin gallate and (-)-epicatechin gallate, but significantly higher levels of free amino acids including Arg, Asp, GABA and Gln than that without mistletoe. Transcriptomic analysis also confirmed the main differentially expressed genes (DEGs) containing phenylpropanoid and flavonoid biosynthesis were down-regulated, but genes of amino acid biosynthesis were up-regulated. qRT-PCR analysis further revealed that the relative expression of CsCHS, CsC4H, CsANS, CsLAR, and CsF3H was hindered, while CsglyA and CsilvE expression was increased.

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.

Integrated Analysis of Transcriptome and Metabolome Provides Insight into Camellia oleifera Oil Alleviating Fat Accumulation in High-Fat Caenorhabditis elegans.

Camellia oil (CO) is a high medicinal and nutritional value edible oil. However, its ability to alleviate fat accumulation in high-fat Caenorhabditis elegans has not been well elucidated. Therefore, this study aimed to investigate the effect of CO on fat accumulation in high-fat C. elegans via transcriptome and metabolome analysis. The results showed that CO significantly reduced fat accumulation in high-fat C. elegans by 10.34% (Oil Red O method) and 11.54% (TG content method), respectively. Furthermore, CO primarily altered the transcription levels of genes involved in longevity regulating pathway. Specifically, CO decreased lipid storage in high-fat C. elegans by inhibiting fat synthesis. In addition, CO supplementation modulated the abundance of metabolic biomarkers related to pyrimidine metabolism and riboflavin metabolism. The integrated transcriptome and metabolome analyses indicated that CO supplementation could alleviate fat accumulation in high-fat C. elegans by regulating retinol metabolism, drug metabolism-cytochrome P450, metabolism of xenobiotics by cytochrome P450, ascorbate and aldarate metabolism, and pentose and glucuronate interconversions. Overall, these findings highlight the potential health benefits of CO that could potentially be used as a functional edible oil.

In-depth potential mechanism of combined demulsification pretreatments (isopropanol ultrasonic pretreatments and Ca2+ flow additions) during aqueous enzymatic extractions of Camellia oils.

Emulsification is the practical limitation of aqueous enzymatic extractions of Camellia oils. This study aimed to investigate the influence and demulsification mechanisms of isopropanol ultrasonic pretreatments and Ca2+ additions on aqueous enzymatic extractions of Camellia oils. Combining isopropanol ultrasonic pretreatments with Ca2+ flow additions obtained the highest free oil recovery (78.03 %) and lowest emulsion content (1.5 %). Results indicated that the superior demulsification performance originated from the decrease in emulsion stabilities and formations. First, demulsification pretreatments reduced the oil (14.69 %) and solid (13.21 %) fractions in emulsions to decrease the stability of as-formed emulsions. Meanwhile, isopropanol ultrasonic pretreatments extracted tea saponins (0.38 mg/mL) and polysaccharides (0.23 mg/mL), while Ca2+ combined with protein isolates (5.82 mg/mL), tea saponins (7.48 mg/mL) and polysaccharides (0.78 mg/mL) to form precipitates and reduce emulsion formation. This work could promote the practical application of aqueous enzymatic extractions of Camellia oils and enlighten the rise of advanced demulsification pretreatments.

Modulating interfacial structure and lipid digestion of natural Camellia oil body by roasting and boiling processes.

Oil body (OB) is the lipid-storage organelle in oilseed, and its stability is crucial for oilseed processing. Herein, effects of roasting and boiling on the structure, stability, and in vitro lipid digestion of Camellia OB were studied. The interfacial structure and physical stability of the extracted OB were investigated by electrophoresis, confocal-Raman spectroscopy, zeta-potential, and surface hydrophobicity, etc. Boiling caused protein loss on the OB surfaces, forming a stable phospholipid interface, which resulted in coalescence of the droplets (d > 100 µm) and negative ζ-potential (-3 âˆ¼ -8 mV) values at a pH of 2.0. However, roasting partially denatured the proteins in the seeds, which were adsorbed on the OB surfaces. The random coil structure of interfacial protein increased to ∼20 % after thermal treatment. Besides, heating decreased the surface hydrophobicity of OB and improved lipid digestion. After boiling 60 min, the extent of lipolysis increased from 41.7 % (raw) to 57.4 %.

Transcriptome Analysis Reveals Putative Induction of Floral Initiation by Old Leaves in Tea-Oil Tree (Camellia oleifera 'changlin53').

Floral initiation is a major phase change in the spermatophyte, where developmental programs switch from vegetative growth to reproductive growth. It is a key phase of flowering in tea-oil trees that can affect flowering time and yield, but very little is known about the molecular mechanism of floral initiation in tea-oil trees. A 12-year-old Camellia oleifera (cultivar 'changlin53') was the source of experimental materials in the current study. Scanning electron microscopy was used to identify the key stage of floral initiation, and transcriptome analysis was used to reveal the transcriptional regulatory network in old leaves involved in floral initiation. We mined 5 DEGs related to energy and 55 DEGs related to plant hormone signal transduction, and we found floral initiation induction required a high level of energy metabolism, and the phytohormones signals in the old leaves regulate floral initiation, which occurred at stage I and II. Twenty-seven rhythm-related DEGs and 107 genes associated with flowering were also identified, and the circadian rhythm interacted with photoperiod pathways to induce floral initiation. Unigene0017292 (PSEUDO-RESPONSE REGULATOR), Unigene0046809 (LATE ELONGATED HYPOCOTYL), Unigene0009932 (GIGANTEA), Unigene0001842 (CONSTANS), and Unigene0084708 (FLOWER LOCUS T) were the key genes in the circadian rhythm-photoperiod regulatory network. In conjunction with morphological observations and transcriptomic analysis, we concluded that the induction of floral initiation by old leaves in C. oleifera 'changlin53' mainly occurred during stages I and II, floral initiation was completed during stage III, and rhythm-photoperiod interactions may be the source of the main signals in floral initiation induced by old leaves.

Photosynthetic carbon and nitrogen metabolism of Camellia oleifera Abel during acclimation to low light conditions.

Tea-oil tree (Camellia oleifera Abel) is an important woody oil crop with high economic value. However, it has low photosynthetic production considering the low light intensity of its growth environment. To understand the acclimation mechanism of tea-oil trees to low light conditions, three light intensity treatments were conducted: high light (450-500 µmol. m-2. s-1), medium light (180-200 µmol. m-2. s-1), and low light (45-50 µmol. m-2. s-1). The carbon (C) and nitrogen (N) metabolism network were constructed by investigating the leaf anatomy, photosynthetic characteristics, N partitioning, transcriptome and metabolome. Results demonstrated that a larger proportion light energy was used for photochemical reactions in an environment with lower light intensity, which resulted in an increase in photosystem II photochemical efficiency and instantaneous light use efficiency (LUE) at the leaf level. As the light intensity increased, decreased electron transfer and carboxylation efficiencies, photorespiration and dark respiration rates, LUE at plant level, and N use efficiency (PNUE) were observed. Leaves trended to harvest more light using higher expression levels of light-harvesting protein genes, higher chlorophyll content, more granum and more tightly stacked granum lamella under lower light intensity. At transcriptional and metabolic levels, the TCA cycle, and the synthesis of starch and saccharides were weakened as light intensity decreased, while the Calvin cycle did not show the regularity between different treatments. Less N was distributed in Rubisco, respiration, and cell wall proteins as light decreased. Storage N was prominently accumulated in forms of amino acids (especially L-arginine) and amino acid derivatives as under medium and low light environments, to make up for C deficiency. Therefore, tea-oil trees actively improve light-harvesting capacity and enlarges the storage N pool to adapt to a low light environment, at the cost of a decrease of photosynthetic C assimilation and PNUE.

Comparative transcriptomic analysis unveils the deep phylogeny and secondary metabolite evolution of 116 Camellia plants.

Camellia plants include more than 200 species of great diversity and immense economic, ornamental, and cultural values. We sequenced the transcriptomes of 116 Camellia plants from almost all sections of the genus Camellia. We constructed a pan-transcriptome of Camellia plants with 89 394 gene families and then resolved the phylogeny of genus Camellia based on 405 high-quality low-copy core genes. Most of the inferred relationships are well supported by multiple nuclear gene trees and morphological traits. We provide strong evidence that Camellia plants shared a recent whole genome duplication event, followed by large expansions of transcription factor families associated with stress resistance and secondary metabolism. Secondary metabolites, particularly those associated with tea quality such as catechins and caffeine, were preferentially heavily accumulated in the Camellia plants from section Thea. We thoroughly examined the expression patterns of hundreds of genes associated with tea quality, and found that some of them exhibited significantly high expression and correlations with secondary metabolite accumulations in Thea species. We also released a web-accessible database for efficient retrieval of Camellia transcriptomes. The reported transcriptome sequences and obtained novel findings will facilitate the efficient conservation and utilization of Camellia germplasm towards a breeding program for cultivated tea, camellia, and oil-tea plants.

Hair growth-promoting effects of Camellia seed cake extract in human dermal papilla cells and C57BL/6 mice.

OBJECTIVES: Camellia seed cake is a by-product of Camellia oleifera Abel seed after oil extraction. Washing hair with Camellia seed cake extract is a traditional Chinese custom that has lasted for over one thousand years. However, the hair growth-promoting effects of Camellia seed cake extract were not investigated so far. This work examined the effects of de-saponinated Camellia seed cake extracts (DS-CSE) on hair growth, using in vitro and in vivo models. METHODS: The studies on cell proliferation, cell cycle regulation, and K+ channels activation effects of DS-CSE were performed on human dermal papilla cells (DPCs). Relative expression of insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), and transforming growth factor-ß (TGF-ß1) in DPCs was determined by RT-PCR. Relative expression of ERK and AKT was determined by Western blot analysis. Hair growth-promoting effects were also measured in C57BL/6J mice model. RESULTS: DS-CSE treatment significantly proliferated DPCs, relating to the increased proportion of DPCs in S and G2 /M phases, the activation of potassium channels and the promoted phosphorylation of ERK and AKT in DPCs. DS-CSE treatment also significantly upregulated the mRNA levels of HGF, VEGF and IGF-1, and downregulated the mRNA level of TGF-ß1. Topical application of DS-CSE promoted hair growth on shaven back mice and also upregulated the expression of VEGF in mice. CONCLUSION: Our results demonstrated that DS-CSE exerts a hair growth-promoting effect in vitro and in vivo by proliferating DPCs through the ERK and AKT signaling pathways and regulating the expression of growth factors.

cDNA cloning, prokaryotic expression, and functional analysis of squalene synthase (SQS) in Camellia vietnamensis Huang.

Camellia vietnamensis Huang, which belongs to Camellia oleifera, is a traditional Chinese medicinal plant widely planted on Hainan Island. Tea saponin is an important functional component of C. vietnamensis, and squalene is the precursor substance that controls its formation. Squalene synthase (SQS: EC 2.5.1.21) synthesizes squalene from 2 molecules of farnesyl pyrophosphate (FPP). In this study, 1683 bp of the C. vietnamensis SQS gene, designated as CvSQS, was cloned and encoded 414 amino acids. Bioinformatics and phylogenetic tree analysis revealed the high homology of CvSQS with squalene synthases from other plants. For soluble proteins, the carboxy-terminal deleted CvSQS was obtained for expression in Escherichia coli Transetta (DE3), and the recombinant protein with a weight of 42.5 kDa was detected using SDS-PAGE and Western blot. After an enzymatic reaction, the presence of squalene in the product was analyzed using GC-MS detection, which indicated that CvSQS had catalytic activity. The tissue specificity of CvSQS and its presence in seeds at various ripening stages was detected by q-RT PCR. CvSQS had the highest transcriptional level in leaves, followed by seeds, roots, and flowers; the amount of CvSQS in the seeds was highest in September. The identification and functional characterization of CvSQS is essential for further studies on the regulation mechanism of tea saponin in C. vietnamensis.

Chromosome-level genome of Camellia lanceoleosa provides a valuable resource for understanding genome evolution and self-incompatibility.

The section Oleifera (Theaceae) has attracted attention for the high levels of unsaturated fatty acids found in its seeds. Here, we report the chromosome-scale genome of the sect. Oleifera using diploid wild Camellia lanceoleosa with a final size of 3.00 Gb and an N50 scaffold size of 186.43 Mb. Repetitive sequences accounted for 80.63% and were distributed unevenly across the genome. Camellia lanceoleosa underwent a whole-genome duplication event approximately 65 million years ago (65 Mya), prior to the divergence of C. lanceoleosa and Camellia sinensis (approx. 6-7 Mya). Syntenic comparisons of these two species elucidated the genomic rearrangement, appearing to be driven in part by the activity of transposable elements. The expanded and positively selected genes in C. lanceoleosa were significantly enriched in oil biosynthesis, and the expansion of homomeric acetyl-coenzyme A carboxylase (ACCase) genes and the seed-biased expression of genes encoding heteromeric ACCase, diacylglycerol acyltransferase, glyceraldehyde-3-phosphate dehydrogenase and stearoyl-ACP desaturase could be of primary importance for the high oil and oleic acid content found in C. lanceoleosa. Theanine and catechins were present in the leaves of C. lanceoleosa. However, caffeine can not be dectected in the leaves but was abundant in the seeds and roots. The functional and transcriptional divergence of genes encoding SAM-dependent N-methyltransferases may be associated with caffeine accumulation and distribution. Gene expression profiles, structural composition and chromosomal location suggest that the late-acting self-incompatibility of C. lanceoleosa is likely to have favoured a novel mechanism co-occurring with gametophytic self-incompatibility. This study provides valuable resources for quantitative and qualitative improvements and genome assembly of polyploid plants in sect. Oleifera.

Comparative transcriptomic analysis reveals genes related to the rapid accumulation of oleic acid in Camellia chekiangoleosa, an oil tea plant with early maturity and large fruit.

Camellia chekiangoleosa has a higher oleic acid content and a shorter reproductive cycle than typical oil tea plants. It was intensively sampled over six C. chekiangoleosa seed development stages. The content of fatty acids determined by GC showed that the accumulation of fatty acids gradually increased from the S1 to S5 stages, and the maximum concentration was reached in S5. Then, fatty acids declined slightly in S6. The main fatty acid component showed the same accumulation trend as the total fatty acids, except linolenic acid, which remained at a low level throughout seed developmental stages. Changes in the expression of fatty acid accumulation-related genes were monitored using second-generation and SMRT full-length transcriptome sequencing. Finally, 18.92 G accurate and reliable data were obtained. Differential expression analysis and weighted coexpression analysis revealed two "gene modules" significantly associated with oleic acid and linoleic acid contents, and the high expression of ENR, KAS I, and KAS II, which accumulate substrates for oleic acid synthesis, was thought to be responsible for the rapid accumulation of fatty acids in the early stage. The rapid increase in fatty acids in the second stage may be closely related to the synergy between the high expression of SAD and low expression of FAD2. In addition, many transcription factors, such as ERF, GRAS, GRF, MADS, MYB and WRKY, may be involved in the fatty acid synthesis. Our data provide a rich resource for further studies on the regulation of fatty acid synthesis in C. chekiangoleosa.

The genome of oil-Camellia and population genomics analysis provide insights into seed oil domestication.

BACKGROUND: As a perennial crop, oil-Camellia possesses a long domestication history and produces high-quality seed oil that is beneficial to human health. Camellia oleifera Abel. is a sister species to the tea plant, which is extensively cultivated for edible oil production. However, the molecular mechanism of the domestication of oil-Camellia is still limited due to the lack of sufficient genomic information. RESULTS: To elucidate the genetic and genomic basis of evolution and domestication, here we report a chromosome-scale reference genome of wild oil-Camellia (2.95 Gb), together with transcriptome sequencing data of 221 cultivars. The oil-Camellia genome, assembled by an integrative approach of multiple sequencing technologies, consists of a large proportion of repetitive elements (76.1%) and high heterozygosity (2.52%). We construct a genetic map of high-density corrected markers by sequencing the controlled-pollination hybrids. Genome-wide association studies reveal a subset of artificially selected genes that are involved in the oil biosynthesis and phytohormone pathways. Particularly, we identify the elite alleles of genes encoding sugar-dependent triacylglycerol lipase 1, ß-ketoacyl-acyl carrier protein synthase III, and stearoyl-acyl carrier protein desaturases; these alleles play important roles in enhancing the yield and quality of seed oil during oil-Camellia domestication. CONCLUSIONS: We generate a chromosome-scale reference genome for oil-Camellia plants and demonstrate that the artificial selection of elite alleles of genes involved in oil biosynthesis contributes to oil-Camellia domestication.

Comparative study on fruit development and oil synthesis in two cultivars of Camellia oleifera.

BACKGROUND: The oil-tea tree (Camellia oleifera Abel.) is a woody tree species that produces edible oil in the seed. C. oleifera oil has high nutritional value and is also an important raw material for medicine and cosmetics. In China, due to the uncertainty on maturity period and oil synthesis mechanism of many C. oleifera cultivars, growers may harvest fruits prematurely, which could not maximize fruit and oil yields. In this study, our objective was to explore the mechanism and differences of oil synthesis between two Camellia oleifera cultivars for a precise definition of the fruit ripening period and the selection of appropriate cultivars. RESULTS: The results showed that 'Huashuo' had smaller fruits and seeds, lower dry seed weight and lower expression levels of fatty acid biosynthesis genes in July. We could not detect the presence of oil and oil bodies in 'Huashuo' seeds until August, and oil and oil bodies were detected in 'Huajin' seeds in July. Moreover, 'Huashuo' seeds were not completely blackened in October with up to 60.38% of water and approximately 37.98% of oil in seed kernels whose oil content was much lower than normal mature seed kernels. The oil bodies in seed endosperm cells of 'Huajin' were always higher than those of 'Huashuo' from July to October. CONCLUSION: Our results confirmed that C. oleifera 'Huashuo' fruits matured at a lower rate compared to 'Huajin' fruits and that 'Huajin' seeds entered the oil synthesis period earlier than 'Huashuo' seeds. Moreover, 'Huashuo' fruits did not mature during the Frost's Descent period (October 23-24 each year).

Oral administration of camellia oil ameliorates obesity and modifies the gut microbiota composition in mice fed a high-fat diet.

Obesity, which is often caused by adipocyte metabolism dysfunction, is rapidly becoming a serious global health issue. Studies in the literature have shown that camellia oil (Camellia oleifera Abel) exerted potential lipid regulation and other multiple biological activities. Here, we aimed to investigate the effects of camellia oil on obese mice induced by a high-fat diet and to explore gut microbiota alterations after camellia oil intervention. The results showed that oral administration of camellia oil dramatically attenuated the fat deposits, serum levels of the total cholesterol, triacylglycerol, low-density lipoprotein cholesterol, fasting plasma glucose, the atherosclerosis index, the hepatic steatosis and inflammation in high-fat diet-induced obese mice. Meanwhile, the high-density lipoprotein cholesterol level in obese mice was enhanced after the camellia oil treatment. Furthermore, 16S rRNA analysis showed that certain aspects of the gut microbiota, especially the gut microbiota diversity and the relative abundance of Actinobacteria, Coriobacteriaceae, Lactobacillus and Anoxybacillus, were significantly increased by camellia oil treatment while the ratio of Firmicutes to Bacteroidetes was decreased. Taken together, our finding suggested that camellia oil was a potential dietary supplement and functional food for ameliorating fat deposits, hyperglycemia and fatty liver, probably by modifying the gut microbiota composition.

Effects of Funneliformis mosseae on the utilization of organic phosphorus in Camellia oleifera Abel.

Arbuscular mycorrhizal (AM) fungi play an important role in the acquisition of phosphorus (P) by plants. The external hyphae of AM fungi function as an extension of plant roots and may downregulate related functions in the roots. It is not clear whether the ability of AM fungi to mineralize organic P affects root phosphatase activities. A pot experiment was conducted to investigate the effect of Funneliformis mosseae on soil organic P mineralization under phytate application and to explore root phosphatase activities, P uptake, and growth in Camellia oleifera Abel. The plants and their growth substrates were harvested 4 and 8 months after planting. The results showed that organic P application had no effect on the total dry mass of nonmycorrhizal plants, but differences in dry mass under P application were observed in mycorrhizal plants in both harvests. Inoculation with F. mosseae increased soil acid phosphatase, phytase, and alkaline phosphatase activities and reduced the soil organic P content. Mycorrhizal plants had higher root activity, shoot and root P contents and root acid phosphatase and phytase activities than nonmycorrhizal plants irrespective of organic P application. In conclusion, AM fungi enhanced the mineralization of soil organic P and positively affect root phosphatase activities.

Identification of miRNA-mRNA Regulatory Modules Involved in Lipid Metabolism and Seed Development in a Woody Oil Tree (Camellia oleifera).

Tea oil camellia (Camellia oleifera), an important woody oil tree, is a source of seed oil of high nutritional and medicinal value that is widely planted in southern China. However, there is no report on the identification of the miRNAs involved in lipid metabolism and seed development in the high- and low-oil cultivars of tea oil camellia. Thus, we explored the roles of miRNAs in the key periods of oil formation and accumulation in the seeds of tea oil camellia and identified miRNA-mRNA regulatory modules involved in lipid metabolism and seed development. Sixteen small RNA libraries for four development stages of seed oil biosynthesis in high- and low-oil cultivars were constructed. A total of 196 miRNAs, including 156 known miRNAs from 35 families, and 40 novel miRNAs were identified, and 55 significantly differentially expressed miRNAs were found, which included 34 upregulated miRNAs, and 21 downregulated miRNAs. An integrated analysis of the miRNA and mRNA transcriptome sequence data revealed that 10 miRNA-mRNA regulatory modules were related to lipid metabolism; for example, the regulatory modules of ath-miR858b-MYB82/MYB3/MYB44 repressed seed oil biosynthesis, and a regulation module of csi-miR166e-5p-S-ACP-DES6 was involved in the formation and accumulation of oleic acid. A total of 23 miRNA-mRNA regulatory modules were involved in the regulation of the seed size, such as the regulatory module of hpe-miR162a_L-2-ARF19, involved in early seed development. A total of 12 miRNA-mRNA regulatory modules regulating growth and development were identified, such as the regulatory modules of han-miR156a_L+1-SPL4/SBP2, promoting early seed development. The expression changes of six miRNAs and their target genes were validated using quantitative real-time PCR, and the targeting relationship of the cpa-miR393_R-1-AFB2 regulatory module was verified by luciferase assays. These data provide important theoretical values and a scientific basis for the genetic improvement of new cultivars of tea oil camellia in the future.

Full-Length Transcriptome from Camellia oleifera Seed Provides Insight into the Transcript Variants Involved in Oil Biosynthesis.

Camellia oleifera Abel., belonging to the genus Camellia of Theaceae, has been widely used as a cooking oil, lubricant, and in cosmetics. Because of complicated polyploidization and large genomes, reference genome information is still lacking. Systematic characterization of gene models based on transcriptome data is a fast and economical approach for C. oleifera. Pacific Biosciences single-molecule long-read isoform sequencing (Iso-Seq) and Illumina RNA-Seq combined with gas chromatography were performed for exploration of oil biosynthesis, accumulation, and comprehensive transcriptome analysis in C. oleifera seeds at five different developmental stages. We report the first full-length transcriptome data set of C. oleifera seeds comprising 40,143 deredundant high-quality isoforms. Among these isoforms, 37,982 were functionally annotated, and 271 (2.43%) belonged to fatty acid metabolism. A total of 8,344 full-length unique transcript models were obtained, and 8,151 (97.69%) of them produced more than two isoforms, suggesting a high degree of transcriptome complexity in C. oleifera seeds. A total of 783 alternative splicing (AS) events were identified, among which the retained intron was the most abundant. We also obtained 1,910 long noncoding RNAs (lncRNAs) and found that AS events occurred in these lncRNAs. Potential transcript variants of genes involved in oil biosynthesis were also investigated. After performing weighted correlation network analysis, we found seven "gene modules" and hub genes for each module showing a significant association with oil content. The series test of clusters classified these modules into four significant profiles based on gene expression patterns. Protein-protein interaction network analysis showed that upregulated WRI1 interacted with 17 genes encoding the enzymes playing key roles in oil synthesis. MYB and ZIP transcriptional factors also showed significant interactions with key genes involved in oil synthesis. Collectively, our data advance the knowledge of RNA isoform diversity in seeds at different developmental stages and provide a rich resource for functional studies on oil synthesis in C. oleifera.

Soil C-N-P pools and stoichiometry as affected by intensive management of camellia oleifera plantations.

Intensive management of C. oleifera has produced many pure C. oleifera plantations. The transmission of C. oleifera plantation will potentially affect soil C, N, and P pools as well as their stoichiometric characteristics both in top soil layer and vertical soil profile due to the intensive management. To understand changes in vertical pools and stoichiometric characteristics of soil C, N, and P as affected by intensive management of C. oleifera plantations, both mixed and pure C. oleifera plantations were studied. We conducted studies in five locations in Jiangxi, China with both pure and mixed C. oleifera plantations, to compare changes in vertical pools and stoichiometry of C, N, and P. Both C and N pools were significantly different between mixed and pure plantation types of C. oleifera. However, the ratio of C:N, C:P, and N:P was consistently higher in mixed plantations with C:P and N:P altered but C:N ratio did not change with soil depth. The intensive management significantly impact both C and N pools and the stoichiometry of C, N, and P. Intensive management of C. oleifera plantations decreased both C and N pools, especially at the depth of 30-50 cm soil layer. C. oleifera plantation alteration from mixed to pure should be considered in future forest management practice considering the substantial effects on soil element cycling and distribution along vertical soil profile.

Baiyacha, a wild tea plant naturally occurring high contents of theacrine and 3″-methyl-epigallocatechin gallate from Fujian, China.

Baiyacha (BYC) is a kind of wild tea plant growing and utilizing in the remote mountain area of Fujian province, Southeastern China. However, scientific studies on this plant remain limited. Our results showed that BYC exhibits the typical morphological characteristics of Camellia gymnogyna Chang, a closely related species of C. sinensis (L.) O. Kuntze, which was not found in Fujian before. Chemical profiling revealed that parts of BYC plants are rich in purine alkaloids and catechins, especially featuring high levels of theacrine and 3″-methyl-epigallocatechin gallate (EGCG3″Me), chemical compounds with multiple biological activities that are rarely observed in regular tea plants. The contents of EGCG3″Me and theacrine in BYC both increased with the leaf maturity of tea shoots, whereas the caffeine content decreased significantly. The obtained results provide abundant information about the morphology and chemical compounds of BYC and may be used for tea production, breeding, and scientific research in the future.