Genome-wide analysis of the bZIP gene family in Cinnamomum camphora ('Gantong 1') reveals the putative function in anthocyanin biosynthesis.

Basic leucine zipper (bZIP) transcription factors (TFs) regulate plant development, growth, and secondary metabolism. The formation of red bark of new ornamental cultivar 'Gantong 1' is regulated mainly by anthocyanin anabolism. However, it is unclear whether and which bZIP TFs are involved in this process. We identified 89 genes encoding CcbZIP TFs in Cinnamomum camphora genome that could be divided into 14 subfamilies with similar gene structures and conserved motifs. CcbZIP38 and CcbZIP57 were highly conserved compared to HY5 in Arabidopsis thaliana and they were highly expressed in the bark and leaves of 'Gantong 1' at different stages. The target gene enrichment analysis showed that indicating indirect involvement of CcbZIP38 and CcbZIP57 in the regulation of anthocyanin synthesis. Our study contributes to understanding the molecular mechanism of anthocyanin synthesis regulation by CcbZIP TFs and provides a theoretical basis for genetic improvement of ornamental traits in C. camphora.

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.

Genome-Scale Identification, Classification, and Expression Profiling of MYB Transcription Factor Genes in Cinnamomum camphora.

The camphor tree (Cinnamomum camphora (L.) Presl.) is the representative species of subtropical evergreen broadleaved forests in eastern Asia and an important raw material for essential oil production worldwide. Although MYBs have been comprehensively characterized and their functions have been partially resolved in many plants, it has not been explored in C. camphora. In this study, 121 CcMYBs were identified on 12 chromosomes in the whole genome of C. camphora and found that CcMYBs were mainly expanded by segmental duplication. They were divided into 28 subgroups based on phylogenetic analysis and gene structural characteristics. In the promoter regions, numerous cis-acting elements were related to biological processes. Analysis of RNA sequencing data from seven tissues showed that CcMYBs exhibited different expression profiles, suggesting that they have various roles in camphor tree development. In addition, combined with the correlation analysis of structural genes in the flavonoid synthesis pathway, we identified CcMYBs from three subgroups that might be related to the flavonoid biosynthesis pathway. This study systematically analyzed CcMYBs in C. camphora, which will set the stage for subsequent research on the functions of CcMYBs during their lifetime and provide valuable insights for the genetic improvement of camphor trees.

Conductive cellulose nanofibrils-reinforced hydrogels with synergetic strength, toughness, self-adhesion, flexibility and adjustable strain responsiveness.

The development of biomass-based hydrogel conductive devices is a promising but challenging subject. Here, cellulose was used to develop a strong, tough, and self-adhesive conductive hydrogel by constructing a synergistic covalent cross-link network and multiple physical interactions. Tannic acid-coated cellulose nanofibrils (TA@CNFs), poly(acrylamide), and ferric ions (Fe3+) were introduced in a composite network by coordination and hydrogen bonds. The strategy of interpenetrating network endowed this hydrogel with high mechanical strength (storage modulus over 14 K Pa), and strong toughness and tensile strength (fracture stress up to 108 K Pa). Chelated Fe3+ by metal coordination as inorganic conductive phase leads to good electrical conductivity (conductivity up to 3.12 S m-1). The obtained hydrogel also exhibited fine flexibility, extensive self-adhesion, and adjustable strain responsiveness for monitoring human joint movements. This work provided a new approach to design conductive hydrogels, and also can expand the application of cellulose-reinforced materials in the sensor field.

Biomass Fractionation and Lignin Fractionation towards Lignin Valorization.

Lignin, as the most abundant aromatic biopolymer in nature, has attracted great attention due to the complexity and richness of its functional groups for value-added applications. The yield of production of lignin and the reactivity of prepared lignin are very important to guarantee the study and development of lignin-based chemicals and materials. Various fractionation techniques have been developed to obtain high yield and relatively high-purity lignin as well as carbohydrates (hemicelluloses and celluloses) and to reduce the condensed and degraded nature of conventional biorefinery lignin. Herein, novel and efficient biomass fractionation and lignin fractionation towards lignin valorization are summarized and discussed.

New insight into the phylogeographic pattern of Liriodendron chinense (Magnoliaceae) revealed by chloroplast DNA: east-west lineage split and genetic mixture within western subtropical China.

BACKGROUND: Subtropical China is a global center of biodiversity and one of the most important refugia worldwide. Mountains play an important role in conserving the genetic resources of species. Liriodendron chinense is a Tertiary relict tree largely endemic to subtropical China. In this study, we aimed to achieve a better understanding of the phylogeographical pattern of L. chinense and to explore the role of mountains in the conservation of L. chinense genetic resources. METHODS: Three chloroplast regions (psbJ-petA, rpl32-ndhF, and trnK5'-matK) were sequenced in 40 populations of L. chinense for phylogeographical analyses. Relationships among chloroplast DNA (cpDNA) haplotypes were determined using median-joining networks, and genetic structure was examined by spatial analysis of molecular variance (SAMOVA). The ancestral area of the species was reconstructed using the Bayesian binary Markov Chain Monte Carlo (BBM) method according to its geographic distribution and a maximum parsimony (MP) tree based on Bayesian methods. RESULTS: Obvious phylogeographic structure was found in L. chinense. SAMOVA revealed seven groups matching the major landscape features of the L. chinense distribution area. The haplotype network showed three clades distributed in the eastern, southwestern, and northwestern regions. Separate northern and southern refugia were found in the Wu Mountains and Yungui Plateau, with genetic admixture in the Dalou Mountains and Wuling Mountains. BBM revealed a more ancient origin of L. chinense in the eastern region, with a west-east split most likely having occurred during the Mindel glacial stage. DISCUSSION: The clear geographical distributions of haplotypes suggested multiple mountainous refugia of L. chinense. The east-west lineage split was most likely a process of gradual genetic isolation and allopatric lineage divergence when the Nanling corridor was frequently occupied by evergreen or coniferous forest during Late Quaternary oscillations. Hotspots of haplotype diversity in the Dalou Mountains and Wuling Mountains likely benefited from gene flow from the Wu Mountains and Yungui Plateau. Collectively, these results indicate that mountain regions should be the main units for conserving and collecting genetic resources of L. chinense and other similar species in subtropical China.

The complete chloroplast genome sequence of Actinidia styracifolia C. F. Liang.

The complete chloroplast (cp) genome sequence of Actinidia styracifolia C. F. Liang was assembled using Illumina pair-end sequencing data in this study. The assembled plastome was 156,845 bp in length, including a large single copy (LSC) region of 88,624 bp and a small single copy (SSC) region of 20,535bp, which were separated by two inverted repeat (IR) regions of 23,843 bp. The plastome contains 113 different genes, consisting of 79 unique protein-coding genes, 30 tRNA genes, and 4 rRNA genes. Phylogenetic analysis based on chloroplast genomes revealed that A. styracifolia has a close genetic relationship with A. eriantha.

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.

The complete chloroplast genome of Cinnamomum camphora and its comparison with related Lauraceae species.

Cinnamomum camphora, a member of the Lauraceae family, is a valuable aromatic and timber tree that is indigenous to the south of China and Japan. All parts of Cinnamomum camphora have secretory cells containing different volatile chemical compounds that are utilized as herbal medicines and essential oils. Here, we reported the complete sequencing of the chloroplast genome of Cinnamomum camphora using illumina technology. The chloroplast genome of Cinnamomum camphora is 152,570 bp in length and characterized by a relatively conserved quadripartite structure containing a large single copy region of 93,705 bp, a small single copy region of 19,093 bp and two inverted repeat (IR) regions of 19,886 bp. Overall, the genome contained 123 coding regions, of which 15 were repeated in the IR regions. An analysis of chloroplast sequence divergence revealed that the small single copy region was highly variable among the different genera in the Lauraceae family. A total of 40 repeat structures and 83 simple sequence repeats were detected in both the coding and non-coding regions. A phylogenetic analysis indicated that Calycanthus is most closely related to Lauraceae, both being members of Laurales, which forms a sister group to Magnoliids. The complete sequence of the chloroplast of Cinnamomum camphora will aid in in-depth taxonomical studies of the Lauraceae family in the future. The genetic sequence information will also have valuable applications for chloroplast genetic engineering.

TraeALDH7B1-5A, encoding aldehyde dehydrogenase 7 in wheat, confers improved drought tolerance in Arabidopsis.

MAIN CONCLUSION: TraeALDH7B1 - 5A , encoding aldehyde dehydrogenase 7 in wheat, conferred significant drought tolerance to Arabidopsis , supported by molecular biological and physiological experiments. Drought stress significantly affects wheat yields. Aldehyde dehydrogenase (ALDH) is a family of enzymes catalyzing the irreversible conversion of aldehydes into acids to decrease the damage caused by abiotic stresses. However, no wheat ALDH member has been functionally characterized to date. Here, we obtained a differentially expressed EST encoding ALDH7 from a cDNA-AFLP library of wheat that was treated with polyethylene glycol 6000. The three full-length homologs of TraeALDH7B1 were isolated by searching the NCBI database and by homolog-based cloning method. Using nulli-tetrasomic lines we located them on wheat chromosomes 5A, 5B and 5D, and named them as TraeALDH7B1-5A, -5B and -5D, respectively. Gene expression profiles indicated that the expressions of all three genes were induced in roots, leaves, culms and spikelets under drought and salt stresses. Enzymatic activity analysis showed that TraeALDH7B1-5A had acetaldehyde dehydrogenase activity. For further functional analysis, we developed transgenic Arabidopsis lines overexpressing TraeALDH7B1-5A driven by the cauliflower mosaic virus 35S promoter. Compared with wild type Arabidopsis, 35S::TraeALDH7B1-5A plants significantly enhanced the tolerance to drought stress, which was demonstrated by up-regulation of stress responsive genes and physiological evidence of primary root length, maintenance of water retention and contents of chlorophyll and MDA. The combined results indicated that TraeALDH7B1-5A is an important drought responsive gene for genetic transformation to improve drought tolerance in crops.