Exploring the RNA Editing Events and Their Potential Regulatory Roles in Tea Plant (Camellia sinensis L.).

RNA editing is a post-transcriptional modification process that alters the RNA sequence relative to the genomic blueprint. In plant organelles (namely, mitochondria and chloroplasts), the most common type is C-to-U, and the absence of C-to-U RNA editing results in abnormal plant development, such as etiolation and albino leaves, aborted embryonic development and retarded seedling growth. Here, through PREP, RES-Scanner, PCR and RT-PCR analyses, 38 and 139 RNA editing sites were identified from the chloroplast and mitochondrial genomes of Camellia sinensis, respectively. Analysis of the base preference around the RNA editing sites showed that in the -1 position of the edited C had more frequent occurrences of T whereas rare occurrences of G. Three conserved motifs were identified at 25 bases upstream of the RNA editing site. Structural analyses indicated that the RNA secondary structure of 32 genes, protein secondary structure of 37 genes and the three-dimensional structure of 5 proteins were altered due to RNA editing. The editing level analysis of matK and ndhD in six tea cultivars indicated that matK-701 might be involved in the color change of tea leaves. Furthermore, 218 PLS-CsPPR proteins were predicted to interact with the identified RNA editing sites. In conclusion, this study provides comprehensive insight into RNA editing events, which will facilitate further study of the RNA editing phenomenon of the tea plant.

N-doped carbon fibers in situ prepared by hydrothermal carbonization of Camellia sinensis branches waste for efficient removal of heavy metal ions.

N-doped carbon fibers (NCFs) were in situ prepared by Camellia sinensis branches waste through hydrothermal carbonization with urea/ZnCl2 at 160-280 °C under 0.8-8.9 MPa. The structural characteristics of NCFs were investigated by elemental analysis, SEM, TEM, XRD, XPS, Raman spectra, and BET surface area. The highest N content of NCFs obtained at 280 °C was 8.96%, and the main forms of doped N were pyridinic N, pyrrolic N, and graphitic N. Moreover, NCFs were applied to remove metal ions successfully. The results showed that NCF-240 had the maximum adsorption amounts of 106.52, 125.23, and 153.49 mg/g for Cu2+, Pb2+, and Zn2+, respectively, while NCF-280 had the best removal ability on Cr6+ (145.67 mg/g). Finally, it demonstrated that the adsorption behavior of NCFs was well fitted by the pseudo-second-order kinetic and the Langmuir adsorption isotherm models.

Structural analysis and heavy metal adsorption of N-doped biochar from hydrothermal carbonization of Camellia sinensis waste.

N-doped biochar as adsorption material for heavy metal removal has attracted increasing concern in environmental application due to its unique features. Here, N-doped biochar was prepared by hydrothermal carbonization of Camellia sinensis branch waste using KOH/NH4Cl at 120-280 °C for 2 h under 0.4-6.5 MPa, followed by structural analysis. The results showed that the highest N content determined by elemental analysis could reach up to 6.18% in biochar, and the major N species were involved in graphitic N, pyrrolic N, and pyridinic N. Interestingly, these N-doped biochar exhibited the effective adsorption ability of Cu2+, Pb2+, Zn2+, and Cr6+. The batch adsorption behavior had a better adjustment to the pseudo-second-order kinetic and the Langmuir adsorption isotherm models. In brief, the present results are attributed to develop low-cost adsorbent for removing heavy metal ions.

Urea/ZnCl2 in situ hydrothermal carbonization of Camellia sinensis waste to prepare N-doped biochar for heavy metal removal.

Environmental benefits of biochar require a simple and effective method for preparation of functional N-doped biochar. In this study, urea/ZnCl2 was developed to prepare N-doped biochar via in situ hydrothermal carbonization (HTC) of Camellia sinensis waste at 120-280 °C for 2 h under 1.0-9.8 MPa. Physicochemical and structural properties of the N-doped biochar were investigated by Raman spectra, elemental analysis, BET surface area, SEM, TEM, XRD, and XPS. The results showed that the N content in biochar could reach up to 7.79% at 280 °C. Surface chemistry suggested that pyridinic N, pyrollic N, and graphitic N were the major N species on the biochar. Moreover, the N-doped biochar was successfully employed to remove metal ions Cu2+, Pb2+, Zn2+, and Cr6+. Adsorption data fit closely to the pseudo-second-order kinetic equation and the Langmuir adsorption isotherm model for all metal ions.

[Engineering of a flavonoid 3'-hydroxylase from tea plant (Camellia sinensis) for biosynthesis of B-3',4'-dihydroxylated flavones].

Objective: A flavonoid 3'-hydroxylase from tea plant was engineered to synthesize B-3',4'-dihydroxylated flavones such as eriodictyol, dihydroquercetin and quercetin. Methods: Four articifical P450 constructs harboring both flavonoid 3'-hydroxylase gene from Camellia sinensis (CsF3'H) and P450 reductase gene from Arabidopsis thaliana (ATR1 or ATR2) were introduced into Escherichia coli strains TOP10, DH5α and BL21, resultantly engineering strains S1 to S12. The plasmid pYES-Dest52-CsF3'H harboring CsF3'H gene was introduced into yeast Saccharomyces cerevisiae WAT11 designated as strain S13. The plasmid pES-HIS-CsF3H::AtFLS 9 AA was constructed through fusing flavanone 3-hydroxylase gene from Camellia sinensis (CsF3H) and flavonol synthase gene from Arabidopsis thaliana (AtFLS). Plasmid pES-URA-CsF3'H and pES-HIS-CsF3H::AtFLS 9 AA were then co-introduced into yeast S. cerevisiae WAT11 designated as strain S14. Results: Strain S6 generated highest bioconversion efficiency at 25℃ among all E. coli strains during 24 h fernentation. Supplemented with 1000 µmol/L naringenin, dihydrokaempferol and kaempferol, the maximum amounts of eriodictyol, dihydroquercetin and quercetin produced by strain S13 were 734.32 µmol/L, 446.07 µmol/L and 594.64 µmol/L respectively. Supplemented with 5 mmol/L naringenin, the maximum amounts of eriodictyol, kaempferol, quercetin, dihydroquercetin and dihydrokaempferol produced by strain S14 were 1412.16 µmol/L, 490.25 µmol/L, 445.75 µmol/L, 66.75 µmol/L and 73.50 µmol/L during 36-48 h fermentaion respectively. Conclusion: CsF3'H was engineered for biosynthesis of B-3',4'-dihydroxylated flavone.