Genome-Wide Identification and Expression Analysis of the YTH Domain-Containing RNA-Binding Protein Family in Cinnamomum camphora.

N6-methyladenosine (m6A) is one of the most abundant chemical modifications on mRNA in eukaryotes. RNA-binding proteins containing the YT521-B (YTH) domain play crucial roles in post-transcriptional regulation of plant growth, development, and stress response by reading the m6A mark. However, the YTH domain-containing RNA-binding protein family has not been studied in a valuable and medicinal tree such as Cinnamomum camphora (C. camphora) yet. In this study, we identified 10 YTH genes in C. camphora, located on eight out of 12 chromosomes. Phylogenetic analysis revealed that these genes can be classified into two major classes, YTHDF (CcDF) and YTHDC (CcDC). Closely related CcYTHs within the same class exhibited a similar distribution of conserved motifs and domain organization, suggesting functional similarities among these closely related CcYTHs. All CcYTH proteins possessed a highly conserved YTH domain, with CcDC1A containing an additional CCCH domain. The liquid-liquid phase separation (LLPS) predictions indicate that CcDC1A, CcDF1A, CcDF1C, CcDF3C, CcDF4C, and CcDF5C may undergo phase transitions. Quantitative expression analysis revealed that tissue-specific expression was observed fo CcYTHs. Notably, there were two genes, CcDF1A and CcDF5C; both exhibited significantly higher expression levels in various tissues than other genes, indicating that the m6A-YTH regulatory network in C. camphora might be quite distinct from that in most plants such as Arabidopsis thaliana (A. thaliana) with only one abundant YTH protein. According to the analysis of the up-stream cis-regulatory elements of these YTH genes, these genes could be closely related to stress, hormones, and development. The following stress response experiments further verified that their expression levels indeed changed under both PEG and NaCl treatments. These findings not only provide a foundation for future functional analysis of CcYTHs in C. camphora, but also provide insights into the functions of epigenetic mark m6A in forest trees.

The potential of Bacillus species isolated from Cinnamomum camphora for biofuel production.

BACKGROUND: Increasing concerns about climate change and global petroleum supply draw attention to the urgent need for the development of alternative methods to produce fuels. Consequently, the scientific community must devise novel ways to obtain fuels that are both sustainable and eco-friendly. Bacterial alkanes have numerous potential applications in the industry sector. One significant application is biofuel production, where bacterial alkanes can serve as a sustainable eco-friendly alternative to fossil fuels. This study represents the first report on the production of alkanes by endophytic bacteria. RESULTS: In this study, three Bacillus species, namely Bacillus atrophaeus Camph.1 (OR343176.1), Bacillus spizizenii Camph.2 (OR343177.1), and Bacillus aerophilus Camph.3 (OR343178.1), were isolated from the leaves of C. camphora. The isolates were then screened to determine their ability to produce alkanes in different culture media including nutrient broth (NB), Luria-Bertani (LB) broth, and tryptic soy broth (TSB). Depending on the bacterial isolate and the culture media used, different profiles of alkanes ranging from C8 to C31 were detected. CONCLUSIONS: The endophytic B. atrophaeus Camph.1 (OR343176.1), B. spizizenii Camph.2 (OR343177.1), and B. aerophilus Camph.3 (OR343178.1), associated with C. camphora leaves, represent new eco-friendly approaches for biofuel production, aiming towards a sustainable future. Further research is needed to optimize the fermentation process and scale up alkane production by these bacterial isolates.

Adjusting function of camphor on primary metabolism in Cinnamomum camphora stressed by high temperature.

Cinnamomum camphora has great economic value for its wide utilization in traditional medicine and furniture material, and releases lots of monoterpenes to tolerate high temperature. To uncover the adjusting function of monoterpenes on primary metabolism and promoting their utilization as anti-high temperature agents, the photosynthetic capacities, primary metabolite levels, cell ultrastructure and associated gene expression were surveyed in C. camphora when it was blocked monoterpene biosynthesis with fosmidomycin (Fos) and fumigated with camphor (a typical monoterpene in the plant) under high temperature (Fos+38 °C+camphor). Compared with the control (28 °C), high temperature at 38 °C decreased the starch content and starch grain size, and increased the fructose, glucose, sucrose and soluble sugar content. Meanwhile, high temperature also raised the lipid content, with the increase of lipid droplet size and numbers. These variations were further intensified in Fos+ 38 °C treatment. Compared with Fos+ 38 °C treatment, Fos+ 38 °C+camphor treatment improved the starch accumulation by promoting 4 gene expression in starch biosynthesis, and lowered the sugar content by suppressing 3 gene expression in pentose phosphate pathway and promoting 15 gene expression in glycolysis and tricarboxylic acid cycle. Meanwhile, Fos+ 38 °C+camphor treatment also lowered the lipid content, which may be caused by the down-regulation of 2 genes in fatty acid formation and up-regulation of 4 genes in fatty acid decomposition. Although Fos+ 38 °C+camphor treatment improved the photosynthetic capacities in contrast to Fos+ 38 °C treatment, it cannot explain the variations of these primary metabolite levels. Therefore, camphor should adjust related gene expression to maintain the primary metabolism in C. camphora tolerating high temperature.

A systematic genome-wide analysis and screening of the NAC family genes related to wood formation in Cinnamomum camphora.

Many processes, such as growth, aging, and adaptation to abiotic stress, are regulated in plants by NAC transcription factors. In woody plants, NAC transcription factors acts as a primary switch that regulates secondary xylem development by activating various downstream transcription factors and modulating expression levels of genes involved in the synthesis of the secondary cell wall. Our team had previously sequenced the whole genome of the camphor tree (Cinnamomum camphora). Here, we performed a detailed analysis of the NAC gene family of C. camphora and examined its evolutionary history. The genomic sequences of 121 NAC genes of C. camphora were identified and classified into 20 subfamilies in 2 major classes based on the phylogenetic analysis and structural features. Expansion of the CcNAC gene family occurred mainly by fragment replication and was influenced by the purifying selection. By analyzing predicted interactions of the homologous AtNAC proteins, we identified five CcNACs that potentially regulate xylem development in C. camphora. RNA sequencing revealed distinct expression profiles of CcNACs in seven different plant tissues. Subcellular localization prediction revealed that 120, 3, and 2 CcNACs have biological functions in the nucleus, cytoplasm, and chloroplast, respectively. Furthermore, we verified expression patterns of five CcNACs (CcNAC012, CcNAC028, CcNAC055, CcNAC080, and CcNAC119) in various tissue types using qRT-PCR. Our results will facilitate further in-depth studies of the molecular mechanisms by which CcNAC transcription factors regulate wood formation and other processes in C. camphora.

Genome-Wide Characterization and Analysis of bHLH Transcription Factors Related to Anthocyanin Biosynthesis in Cinnamomum camphora ('Gantong 1').

Cinnamomum camphora is one of the most commonly used tree species in landscaping. Improving its ornamental traits, particularly bark and leaf colors, is one of the key breeding goals. The basic helix-loop-helix (bHLH) transcription factors (TFs) are crucial in controlling anthocyanin biosynthesis in many plants. However, their role in C. camphora remains largely unknown. In this study, we identified 150 bHLH TFs (CcbHLHs) using natural mutant C. camphora 'Gantong 1', which has unusual bark and leaf colors. Phylogenetic analysis revealed that 150 CcbHLHs were divided into 26 subfamilies which shared similar gene structures and conserved motifs. According to the protein homology analysis, we identified four candidate CcbHLHs that were highly conserved compared to the TT8 protein in A. thaliana. These TFs are potentially involved in anthocyanin biosynthesis in C. camphora. RNA-seq analysis revealed specific expression patterns of CcbHLHs in different tissue types. Furthermore, we verified expression patterns of seven CcbHLHs (CcbHLH001, CcbHLH015, CcbHLH017, CcbHLH022, CcbHLH101, CcbHLH118, and CcbHLH134) in various tissue types at different growth stages using qRT-PCR. This study opens a new avenue for subsequent research on anthocyanin biosynthesis regulated by CcbHLH TFs in C. camphora.

Phytotoxicity of Chemical Compounds from Cinnamomum camphora Pruning Waste in Germination and Plant Cultivation.

Much previous research has indicated most composts of pruning waste are characterized by potential phytotoxicity, it is highly correlated with the chemical compounds of raw materials. Cinnamomum camphora, a common kind of pruning waste in Southeast Asia and East Asia, is characterized by intense bioactivities due to complex chemical components. This study investigated the potential phytotoxicity of C. camphora pruning waste in light of germination and higher plant growth. C. camphora extracted from leaves completely inhibited seed germination and still showed suppression of root elongation at an extremely low dosage. C. camphora extract also displayed significant inhibition of nutrient absorption in tomato seedlings, including moisture, available nutrients (N, P and K) and key microelements (Fe, Mn, Zn and S). The gene expression of aquaporins and transporters of nitrate and phosphate was significantly up-regulated in roots. This could be regarded as a positive response to C. camphora extract for enhancing nutrient absorption. Moreover, the severe damage to the plasma membrane in roots caused by C. camphora extract might seriously affect nutrient absorption. Camphor is the main component of the C. camphora extract that may induce the phytotoxicity of plasma membrane damage, resulting in the inhibition of nutrient absorption and low biomass accumulation. This study provided a new understanding of the ecotoxicological effects of C. camphora pruning waste, indicating that the harmless disposal of pruning waste requires much attention and exploration in the future.

Effects of Cinnamomum camphora Leaves Extracts-Flocculants Composite Algaecide on Microcystis aeruginosa Growth and Microcystins Release.

In this study, a composite algaecide containing flocculants and Cinnamomum. camphora leaves extracts (CCCLE) were synthesized. The inhibition and flocculation effects on Microcystis aeruginosa (M. aeruginosa) were investigated, and the release of microcystin-LR (MC-LR) was determined. Results showed that the CCLEC composite algaecide was effective for the inhibition and flocculation of M. aeruginosa, and the optimal dose of CCLEC composite algaecide was 1.8%, which resulted in an algae inhibition ratio of 98.00% and a flocculation efficiency of 99.44% within 5 days of M. aeruginosa culturing. Besides, the total amount of MC-LR decreased by 80.04% on day 20 compared with the control group, while the concentration of intracellular MC-LR on day 5 was 36.69 µg L-1, which was related to a portion of cells underwent apoptosis-like cell death under CCLEC composite algaecide stress. The results of this study may improve our understanding of the M. aeruginosa control by CCCLE composite algaecide.

Analysis of endophytic bacterial community diversity and metabolic correlation in Cinnamomum camphora.

The structure and diversity of microbial communities in the leaves of Cinnamomum camphora at different growth stages were studied by high-throughput sequencing. Moreover, the relationships between microbial communities and borneol content were analyzed in this paper. The results indicated that the community structure of endophytic bacteria in C. camphora exhibited temporal variations, with the microbial diversity presented as follows: T1 (low content period) > T3 (peak period) > T2 (small peak period). The population of endophytic bacteria and the ratio of primary metabolism in the leaves of C. camphora were T2 > T1 > T3, while the metabolic intensity of endophytic bacterial terpenoids and polyketides was T3 > T2 > T1, which had the same trend as borneol content in C. camphora. The metabolic ratio of terpenoids and polyketides in T3 was 7.44% higher than that in T1, while that in T2 was 4.10% higher than that in T1. The abundance and diversity of Clostridium_sensu_stricto_1, Ochrobactrum, Escherichia-Shigella, Pseudomonas, and Massilia significantly promoted the content of terpenoids in C. camphora. Together, those results provide the first evidence that borneol content and potential metabolic intensity in leaves of C. camphora greatly depend on microbial communities composition and diversity.

Effects of exogenous 3-indoleacetic acid and cadmium stress on the physiological and biochemical characteristics of Cinnamomum camphora.

Indoleacetic acid (IAA) is a plant growth regulator that plays an important role in plant growth and development, and participates in the regulation of abiotic stress. To explore the effect of IAA on cadmium toxicity in Cinnamomum camphora, an indoor potted experiment was conducted with one-year-old C. camphora seedlings. The influence of IAA on cadmium accumulation, net photosynthetic rates, respiration, photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll and carotenoids), osmoregulatory substances (proline, soluble sugar and soluble protein) and the malondialdehyde content in C. camphora leaves treated with 30 mg kg-1 cadmium was analysed with or without the addition of 10 mg kg-1 IAA. Cadmium accumulation in the leaves of C. camphora with the addition of exogenous IAA was significantly higher than accumulation during cadmium stress without additional IAA (ca 69.10% after 60 days' incubation). During the culture period, the net photosynthetic rate in C. camphora leaves subjected to cadmium stress without the addition of IAA was up to 24.31% lower than that of control plants. The net photosynthetic rate in C. camphora leaves subjected to cadmium stress and addition of IAA was up to 30.31% higher than that of leaves subjected to cadmium stress without the addition of IAA. Chlorophyll a, total chlorophyll and carotenoid contents in the cadmium-stressed leaves without the addition of IAA were lower than those in the control treatment. The presence of IAA increased the chlorophyll a, total chlorophyll and carotenoid contents relative to the cadmium stress without the addition of IAA. The respiration rate and concentrations of proline, soluble sugar, soluble protein and malondialdehyde in C. camphora leaves subjected to cadmium stress without the addition of IAA were higher than those in the control. The addition of IAA reduced the respiration rate, and the concentrations of proline, soluble sugar, soluble protein and malondialdehyde in C. camphora leaves when compared with the cadmium stress without the addition of IAA. These results indicate that exogenous IAA improves photosynthetic performance and the growth environment of C. camphora by enhancing the net photosynthetic rate, increasing concentrations of osmoregulatory substances, removing reactive oxygen radicals and eliminating potential damage, thereby reducing the toxic effects of cadmium on C. camphora.

Nitrogen transfer from one plant to another depends on plant biomass production between conspecific and heterospecific species via a common arbuscular mycorrhizal network.

The formation of a common mycorrhizal network (CMN) between roots of different plant species enables nutrient transfers from one plant to another and their coexistence. However, almost all studies on nutrient transfers between CMN-connected plants have separately, but not simultaneously, been demonstrated under the same experimentation. Both conspecific and heterospecific seedlings of Cinnamomum camphora, Bidens pilosa, and Broussonetia papyrifera native to a karst habitat in southwest China were concurrently grown in a growth microcosm that had seven hollowed compartments (six around one in the center) being covered by 35.0-µm and/or 0.45-µm nylon mesh. The Ci. camphora in the central compartment was supplied with or without Glomus etunicatum and 15N to track N transfers between CMN-connected conspecific and heterospecific seedlings. The results showed as follows: significant greater nitrogen accumulations, biomass productions, 15N content, % Ntransfer, and the Ntransfer amount between receiver plant species ranked as Br. papyrifera≈Bi. pilosa > Ci. camphora under both M+ and M-, and as under M+ than under M- for Ci. camphora but not for both Bi. Pilosa and Br. papyrifera; the CMN transferred more nitrogen (15N content, % Ntransfer, and Ntransfer amount) from the donor Ci. camphora to the heterospecific Br. papyrifera and Bi. pilosa, with a lower percentage of nitrogen derived from transfer (%NDFT). These findings suggest that the CMN may potentially regulate the nitrogen transfer from a donor plant to individual heterospecific receiver plants, where the ratio of nitrogen derived from transfer depends on the biomass strength of the individual plants.

Transcriptome analysis and identification of genes related to terpenoid biosynthesis in Cinnamomum camphora.

BACKGROUND: Cinnamomum camphora has been cultivated as an economically important tree for its medicinal and aromatic properties. Selective breeding has produced Cinnamomum plants for special uses, including spice strains with characteristic flavors and aromas and high-potency medicinal cultivars. The molecular biology underlying terpenoid biosynthesis is still unexplored. RESULTS: Gas chromatography-mass spectrometry was used to analyze the differences in contents and compositions of essential oil terpenoids in linalool- and borneol-type chemotypes of C. camphora. The data revealed that the essential oils consist primarily of monoterpenes with only very minor quantities of sesquiterpenes and diterpenes and that the essential oil differs in different chemotypes of C. camphora, with higher yields of (-)-borneol from the borneol-type than from the linalool-type. To study the terpenoid biosynthesis of signature compounds of the major monoterpenes, we performed RNA sequencing to profile the leaf transcriptomes of the two chemotypes of C. camphora. A total of 23.76 Gb clean data was generated from two chemotypes and assembled into 156,184 unigenes. The total length, average length, N50 and GC content of unigenes were 155,645,929 bp, 997 bp, 1430 bp, and 46.5%, respectively. Among them, 76,421 unigenes were annotated by publicly available databases, of which 67 candidate unigenes were identified to be involved in terpenoid biosynthesis in C. camphora. A total of 2863 unigenes were identified to be differentially expression between borneol-type and linalool-type, including 1714 up-regulated and 1149 down-regulated unigenes. Most genes encoding proteins involved in terpenoid precursor MVA and MEP pathways were expressed in similar levels in both chemotypes of C. camphora. In addition, 10 and 17 DEGs were significantly enriched in the terpene synthase activity and oxidoreductase activity terms of their directed acyclic graphs (DAG), respectively. Three monoterpene synthase genes, TPS14-like1, TPS14-like2 and TPS14-like3 were up-regulated in the borneol-type compared to the linalool-type, and their expression levels were further verified using quantitative real-time PCR. CONCLUSIONS: This study provides a global overview of gene expression patterns related to terpenoid biosynthesis in C. camphora, and could contribute to a better understanding of the differential accumulation of terpenoids in different C. camphora chemotypes.

Investigation of Lipid Metabolism by a New Structured Lipid with Medium- and Long-Chain Triacylglycerols from Cinnamomum camphora Seed Oil in Healthy C57BL/6J Mice.

In the present study, a new structured lipid with medium- and long-chain triacylglycerols (MLCTs) was synthesized from camellia oil (CO) and Cinnamomum camphora seed oil (CCSO) by enzymatic interesterification. Meanwhile, the antiobesity effects of structured lipid were investigated through observing the changes of enzymes related to lipid mobilization in healthy C57BL/6J mice. Results showed that after synthesis, the major triacylgeride (TAG) species of intesterificated product changed to LaCC/CLaC (12.6 ± 0.46%), LaCO/LCL (21.7 ± 0.76%), CCO/LaCL (14.2 ± 0.55%), COO/OCO (10.8 ± 0.43%), and OOO (18.6 ± 0.64%). Through second-stage molecular distillation, the purity of interesterified product (MLCT) achieved 95.6%. Later, male C57BL/6J mice were applied to study whether the new structured lipid with MLCT has the efficacy of preventing the formation of obesity or not. After feeding with different diets for 6 weeks, MLCTs could reduce body weight and fat deposition in adipose tissue, lower plasma triacylglycerols (TG) (0.89 ± 0.16 mmol/L), plasma total cholesterol (TC) (4.03 ± 0.08 mmol/L), and hepatic lipids (382 ± 34.2 mg/mice) by 28.8%, 16.0%, and 30.5%, respectively, when compared to the control 2 group. This was also accompanied by increasing fecal lipids (113%) and the level of enzymes including cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), hormone-sensitive lipase (HSL), and adipose triglyceride lipase (ATGL) related to lipid mobilization in MLCT group. From the results, it can be concluded that MLCT reduced body fat deposition probably by modulating enzymes related to lipid mobilization in C57BL/6J mice.

Response of basal metabolic rate to complete submergence of riparian species Salix variegata in the Three Gorges reservoir region.

One-year old seedlings of Salix variegata (submergence-tolerant) and Cinnamomum camphora (submergence-intolerant) were selected and subjected to complete submergence (2 m) for 1, 5, 10, and 20 days, to elucidate the submergence- tolerance mechanism of S. variegata in the Three Gorges reservoir region. The basal CO2 emission ratios (BCERs) and O2 consumption rates (OCRs) of leaf, stem, and root were determined. The basal O2 consumption rates (BOCRs) were calculated from the OCRs of different parts and their biomass allocations and used for evaluating the basal metabolic rate (BMR) of species with BCERs. The results showed that: (1) The BCERs of both species responded to flooding similarly, and no significant differences occurred between the submerged S. variegata (SS) and the submerged C. camphora (SC) seedlings, and between the control S. variegata (CS) and the control C. camphora (CC) seedlings. (2) The BOCRs of SS were significantly lower than those of SC on days 1 and 20, while no significant differences occurred between CS and CC for every duration. Therefore, the BMRs, evaluated from BOCRs rather than from BCERs, were related to submergence-tolerance of species, and the response of BMR to submergence would contribute to the survival of S. variegata seedlings under flooding.

PAHs uptake and translocation in Cinnamomum camphora leaves from Shanghai, China.

Foliage uptake and inner-leaf translocation of polycyclic aromatic hydrocarbons (PAHs) by Cinnamomum camphora from different urbanized areas were comparatively investigated in this study. Spatial and seasonal variations of ∑16PAHs in leaves were observed, likely due to the diversity of leaf wax contents sampled in different seasons and locations. A negative correlation between the wax contents and ∑16PAHs concentrations in the cuticular wax was observed. The low values of TFf-m (translocation factor from foliar dust to mesophyll) indicated a poor translocation ability of PAHs from the foliar dust to the mesophyll. However, the transportation of PAHs from the foliar dust to the cuticular wax was the primary pathway of leaf accumulation, and TFf-w (translocation factor from foliar dust to cuticular wax) values showed an increasing tendency of low molecular weight (LMW) PAHs and a decreasing tendency of high molecular weight (HMW) PAHs. This result indicated a rapid diffusion of gas-phase PAHs with LMW and a slow desorption of the particle-bound PAHs with HMW in the foliar dust. The concentrations of PAHs pollutants followed an obvious order of Rural area>Suburb area>Urban area in winter, and the higher contaminated locations were associated with some pollution sources nearby. Furthermore, the results of principal component analysis with multiple linear regression analysis analysis indicated that PAHs in leaves derived mainly from vehicle emissions. Overall, the accumulation and transformation of PAHs in leaves suggests the extensive amount of atmospheric pollutant release in high urbanization area.

De novo comparative transcriptome analysis provides new insights into sucrose induced somatic embryogenesis in camphor tree (Cinnamomum camphora L.).

BACKGROUND: Somatic embryogenesis is a notable illustration of cell totipotency, by which somatic cells undergo dedifferentiation and then differentiate into somatic embryos. Our previous work demonstrated that pretreatment of immature zygotic embryos with 0.5 M sucrose solution for 72 h efficiently induced somatic embryo initiation in camphor tree. To better understand the molecular basis of somatic embryogenesis induced by osmotic stress, de novo transcriptome sequencing of three tissues of camphor tree (immature zygotic embryos, sucrose-pretreated immature zygotic embryos, and somatic embryos induced from sucrose-pretreated zygotic embryos) were conducted using Illumina Hiseq 2000 platform. RESULTS: A total of 30.70 G high quality clean reads were obtained from cDNA libraries of the three samples. The overall de novo assembly of cDNA sequence data generated 205592 transcripts, with an average length of 998 bp. 114229 unigenes (55.56 % of all transcripts) with an average length of 680 bp were annotated with gene descriptions, gene ontology terms or metabolic pathways based on Blastx search against Nr, Nt, Swissprot, GO, COG/KOG, and KEGG databases. CEGMA software identified 237 out of 248 ultra-conserved core proteins as 'complete' in the transcriptome assembly, showing a completeness of 95.6 %. A total of 897 genes previously annotated to be potentially involved in somatic embryogenesis were identified. Comparative transcriptome analysis showed that a total of 3335 genes were differentially expressed in the three samples. The differentially expressed genes were divided into six groups based on K-means clustering. Expression level analysis of 52 somatic embryogenesis-related genes indicated a high correlation between RNA-seq and qRT-PCR data. Gene enrichment analysis showed significantly differential expression of genes responding to stress and stimulus. CONCLUSIONS: The present work reported a de novo transcriptome assembly and global analysis focused on gene expression changes during initiation and formation of somatic embryos in camphor tree. Differential expression of somatic embryogenesis-related genes indicates that sucrose induced somatic embryogenesis may share or partly share the mechanisms of somatic embryogenesis induced by plant hormones. This study provides comprehensive transcript information and gene expression data for camphor tree. It could also serve as an important platform resource for further functional studies in plant embryogenesis.

Non-stomatal limitation to photosynthesis in Cinnamomum camphora seedings exposed to elevated O3.

Ozone (O3) is the most phytotoxic air pollutant for global forests, with decreased photosynthesis widely regarded as one of its most common effects. However, controversy exists concerning the mechanism that underlies the depressing effects of O3 on CO2 assimilation. In the present study, seedlings of Cinnamomum camphora, a subtropical evergreen tree species that has rarely been studied, were exposed to ambient air (AA), ambient air plus 60 [ppb] O3 (AA+60), or ambient air plus 120 [ppb] O3 (AA+120) in open-top chambers (OTCs) for 2 years. Photosynthetic CO2 exchange and chlorophyll a fluorescence were investigated in the second growing season (2010). We aim to determine whether stomatal or non-stomatal limitation is responsible for the photosynthesis reduction and to explore the potential implications for forest ecosystem functions. Results indicate that elevated O3 (E-O3) reduced the net photosynthetic rates (PN) by 6.0-32.2%, with significant differences between AA+60 and AA+120 and across the four measurement campaigns (MCs). The actual photochemical efficiency of photosystem II (PSII) in saturated light (Fv'/Fm') was also significantly decreased by E-O3, as was the effective quantum yield of PSII photochemistry (ΦPSII). Moreover, E-O3 significantly and negatively impacted the maximum rates of carboxylation (Vcmax) and electron transport (Jmax). Although neither the stomatal conductance (gs) nor the intercellular CO2 concentration (Ci) was decreased by E-O3, PN/gs was significantly reduced. Therefore, the observed reduction in PN in the present study should not be attributed to the unavailability of CO2 due to stomatal limitation, but rather to the O3-induced damage to Ribulose-1,5-bisphosphate carboxylase/oxygenase and the photochemical apparatus. This suggests that the down-regulation of stomatal conductance could fail to occur, and the biochemical processes in protoplasts would become more susceptible to injuries under long-term O3 exposure, which may have important consequences for forest carbon and water budget.

[Transcriptome analysis for leaves of five chemical types in Cinnamomum camphora].

Camphor tree (Cinnamomum camphora) is a representative species in Lauraceae family, and can be subdivided into five types: linalool, camphor, cineol, iso-nerolidol and borneol. In this paper, the leaves transcriptomes of Cinnamomum camphora were sequenced with the platform of Illumina HiSeq™ 2000. Based on the GO (Gene Ontology), COG (Clusters of Orthologous Groups), and KEGG (Kyoto Encyclopedia of Genes and Genomes) database, the function classification, pathway annotation, and the coding sequence prediction of all-Unigenes were carried out. 156 278 Unigenes with an average length of 584 bp and N50 (N50 value is defined as the Unigene length where half the assembly is represented by Unigenes of this size or longer) of 1 023 bp were generated by de novo assembly. A total of 5 5955 Unigenes (35.80%) were annotated through similarity comparison, in which 24 717 and 21 806 Unigenes were assigned into GO and COG, respectively. By searching KEGG database, 3 350 Unigenes were involved in biosynthesis of secondary metabolites, in which 424 Unigenes were involved in monoterpenoids, diterpenoids, sesquiterpenoids, and terpenoid backbone biosynthesis. The analysis of monoterpenoids biosynthesis pathway showed that 9 Unigenes likely encode (+)-linalool synthase, and their expression levels were higher in linalool type but lower in cineole type. This study provides a foundation for further characterizing the functional genes in C. camphora.

Spatial distribution and source apportionment of polycyclic aromatic hydrocarbons (PAHs) in Camphor (Cinnamomum camphora) tree bark from Southern Jiangsu, China.

The concentrations and sources of polycyclic aromatic hydrocarbons (PAHs) were investigated in Camphor tree bark from Southern Jiangsu, China. Tree bark samples were collected in August 2012. The Σ15PAHs concentrations were ranged from 6.18 to 1560 ng g(-1)dry weight (dw), with an average value of 407 ng g(-1)dw. Generally, the concentrations of PAHs in the suburban areas were the highest, followed by urban and rural areas. Principal component analysis and diagnostic ratios results showed that vehicle emission, biomass and coal combustion and industrial emission were the major sources of PAHs in tree bark from Southern Jiangsu. Good correlation was found between tree bark and polyurethane foam (PUF) samplers, indicating that both of them respond well to the gas-phase PAHs monitoring.

[Leaf micro-morphology and features in adsorbing air suspended particulate matter and accumulating heavy metals in seven trees species].

The purpose of this study was to assess the relationship between tree leaf micro-morphology and features in adsorbing air suspended particulate matter and accumulating heavy metals. Seven tree species, including Ginkgo biloba, at heavy traffic density site in Huainan were selected to analyze the frequency of air particulate matter retained by leaves, the particle amount of different sizes per unit leaf area retained by leaves and its related micro-morphology structure, and the relationship between particle amount of different sizes per unit leaf area retained by leaves and its related accumulation of heavy metals. We found that the species characterized by small leaf area, special epidemis with abundant fax, and highly uneven cell wall, as well as big and dense stomata and without trichomes mainly absorbed fine particulate matter; while those species with many trichomes mainly retained coarse particulate matter. Accumulation of heavy metals in leaves of the seven species was significantly different except for Ph. Tree species with high capacities in heavy metal accumulation were Ginkgo biloba, Ligustrum lucidum, and Cinnamomum camphora. Accumulation of Cd, Cr, Ni, Zn, Cu and total heavy metal concentration for seven tree species was positively related to the amount of particulate matter absorbed. Correlation coefficients of d10 vs d2.5, d10 vs d1.0, d2.5 vs d1.0 were 0.987, 0.971, 0.996, respective, and the correlate level was significant. The ratios of d2.5/d10, d1.0/d10, d1.0/d2.5 were 0.844, 0.763, 0.822, indicating that the particulate matter from traffic was mainly fine particulates.

Sulfur speciation and bioaccumulation in camphor tree leaves as atmospheric sulfur indicator analyzed by synchrotron radiation XRF and XANES.

Analyzing and understanding the effects of ambient pollution on plants is getting more and more attention as a topic of environmental biology. A method based on synchrotron radiation X-ray fluorescence and X-ray absorption near edge structure spectroscopy was established to analyze the sulfur concentration and speciation in mature camphor tree leaves (CTLs), which were sampled from 5 local fields in Shanghai, China. Annual SO2 concentration, SO4(2-) concentration in atmospheric particulate, SO4(2-) and sulfur concentration in soil were also analyzed to explore the relationship between ambient sulfur sources and the sulfur nutrient cycling in CTLs. Total sulfur concentration in mature camphor tree leaves was 766-1704 mg/kg. The mainly detected sulfur states and their corresponding compounds were +6 (sulfate, include inorganic sulfate and organic sulfate), +5.2 (sulfonate), +2.2 (suloxides), +0.6 (thiols and thiothers), +0.2 (organic sulfides). Total sulfur concentration was strongly correlated with sulfate proportion with a linear correlation coefficient up to 0.977, which suggested that sulfur accumulated in CTLs as sulfate form. Reduced sulfur compounds (organic sulfides, thiols, thioethers, sulfoxide and sulfonate) assimilation was sufficed to meet the nutrient requirement for growth at a balanced level around 526 mg/kg. The sulfate accumulation mainly caused by atmospheric sulfur pollution such as SO2 and airborne sulfate particulate instead of soil contamination. From urban to suburb place, sulfate in mature CTLs decreased as the atmospheric sulfur pollution reduced, but a dramatic increase presented near the seashore, where the marine sulfate emission and maritime activity pollution were significant. The sulfur concentration and speciation in mature CTLs effectively represented the long-term biological accumulation of atmospheric sulfur pollution in local environment.