Cinnamomum camphora is a traditional aromatic plant used to produce linalool and borneol flavors in southern China; however, its leaves also contain many other unutilized essential oils. Herein, we report geographic relationships for the yield and compositional diversity of C. camphora essential oils. The essential oils of 974 individual trees from 35 populations in 13 provinces were extracted by hydrodistillation and analyzed qualitatively and quantitatively by gas chromatography-mass spectrometry and gas chromatography-flame ionization detection, respectively. Oil yields ranged from 0.01% to 3.46%, with a significantly positive correlation with latitude and a significantly negative correlation with longitude. In total, 41 compounds were identified, including 15 monoterpenoids, 24 sesquiterpenoids, and two phenylpropanoids. Essential oil compositions varied significantly among individuals and could be categorized into various chemotypes. The six main chemotypes were eucalyptol, nerolidol, camphor, linalool, selina, and mixed types. The other 17 individual plants were chemotypically rare and exhibited high levels of methyl isoeugenol, methyl eugenol, δ-selinene, or borneol. Eucalyptol-type plants had the highest average oil yield of 1.64%, followed in decreasing order by linalool-, camphor-, mixed-, selina-, and nerolidol-type plants. In addition, the five main compounds exhibited a clear geographic gradient. Eucalyptol and linalool showed a significantly positive correlation with latitude, while selina-6-en-4-ol was significantly and negatively correlated with latitude. trans-Nerolidol and selina-6-en-4-ol showed significantly positive correlations with longitude, whereas camphor was significantly and negatively correlated with longitude. Canonical correspondence analysis indicated that environmental factors could strong effect the oil yield and essential oil profile of C. camphora.

Cinnamomum species attract attentions owing to their scents, medicinal properties, and ambiguous relationship in the phylogenetic tree. Here, we report a high-quality genome assembly of Cinnamomum camphora, based on which two whole-genome duplication (WGD) events were detected in the C. camphora genome: one was shared with Magnoliales, and the other was unique to Lauraceae. Phylogenetic analyses illustrated that Lauraceae species formed a compact sister clade to the eudicots. We then performed whole-genome resequencing on 24 Cinnamomum species native to China, and the results showed that the topology of Cinnamomum species was not entirely consistent with morphological classification. The rise and molecular basis of chemodiversity in Cinnamomum were also fascinating issues. In this study, six chemotypes were classified and six main terpenoids were identified as major contributors of chemodiversity in C. camphora by the principal component analysis. Through in vitro assays and subcellular localization analyses, we identified two key terpene synthase (TPS) genes (CcTPS16 and CcTPS54), the products of which were characterized to catalyze the biosynthesis of two uppermost volatiles (i.e. 1,8-cineole and (iso)nerolidol), respectively, and meditate the generation of two chemotypes by transcriptional regulation and compartmentalization. Additionally, the pathway of medium-chain triglyceride (MCT) biosynthesis in Lauraceae was investigated for the first time. Synteny analysis suggested that the divergent synthesis of MCT and long-chain triglyceride (LCT) in Lauraceae kernels was probably controlled by specific medium-chain fatty acyl-ACP thioesterase (FatB), type-B lysophosphatidic acid acyltransferase (type-B LPAAT), and diacylglycerol acyltransferase 2b (DGAT 2b) isoforms during co-evolution with retentions or deletions in the genome.

Cinnamomum plants are rich in natural essential oils, which are widely used as materials in the fragrance, insecticidal, antibacterial agent, pharmaceutical, and food industries; however, few studies have investigated the essential oil components of Cinnamomum bodinieri. Therefore, this study investigated the diversity of essential oils from the leaves of 885 individual C. bodinieri plants across 32 populations in five provinces. Essential oils were extracted by hydrodistillation, and then qualitative and quantitative analyses of the compounds were performed by GC-MS and GC-FID. A total of 87 chemical constituents were identified in the essential oils, including 33 monoterpenes, 48 sesquiterpenes, and six other compounds. The average oil yield was 0.75%, and individual oil yields ranged from 0.01% to 4.28%. A total of 16 chemotypes were classified according to variations in the essential oil chemical constituents of C. bodinieri, among which the camphor-type, citral-type, and eucalyptol-type were dominant. Moreover, the borneol-type, cymol-type, elemol-type, methylisoeugenol-type, and selina-6-en-4-ol-type were reported in C. bodinieri for the first time. The yield and principal components of the essential oils were mainly affected by altitude, temperature, and sunshine duration, among which altitude had the most significant effect; thus, low-altitude areas are more suitable for the synthesis and accumulation of essential oils. Based on the different characteristics of the essential oils in the leaves of C. bodinieri, several excellent populations and individuals were identified in this study. Moreover, the findings provide a foundation for breeding superior varieties and studying essential oil biosynthesis mechanisms in the future.

This work investigated the effects of harvest season and post harvest storage time on the oil yield and the linalool and camphor proportions of the linalool chemotype of Cinnamomum camphora. Hydrodistilled essential oils were analyzed by GC/FID and GC/MS to determine their chemical constituents. The essential oil yield and linalool proportion showed the same trend a cross leaf life cycles (March to the next January), while the camphor proportion showed the opposite trend. The essential oil yield (1.15-1.19 %) and linalool proportion (90.53-91.24 %) were highest in the rainy season (May and July), and the camphor proportion was low (0.09-0.11 %). After storage at room temperature for thirty days, the oil yield and profile (linalool and camphor proportions) revealed no significant change, although the weight of the leaves decreased significantly every day. These results suggested that the optimal harvesting time was from May to July for a high essential oil yield and linalool content, and low camphor content. Moreover, essential oil extraction is feasible within one month after harvest.

Cinnamomum bodinieri is a tree species highly valued for its superior-quality timber and ecological benefits. However, its large-scale propagation is hindered by the low efficiency of adventitious root (AR) formation. This study investigated the physiological and molecular mechanisms underlying AR formation in C. bodinieri. The results revealed that ARs originate from callus tissue, with the root primordium classified as a latent type. During AR formation, concentrations of soluble protein and soluble sugar decreased, while the activities of superoxide dismutase (SOD), peroxidase (POD), and indole-3-acetic acid oxidase (IAAO) peaked 20 days after cutting (CB2), with polyphenol oxidase (PPO) activity exhibiting an “N”-shaped trend. These findings indicate that substantial nutrient consumption is required for AR formation, with SOD, POD, PPO, and IAAO positively regulating the process. Indole-3-acetic acid (IAA) levels significantly decreased during the early stages of cutting but increased thereafter, whereas the concentration of abscisic acid (ABA) continuously rose. Similar trends were observed for zeatin riboside (ZR) and gibberellic acid (GA). Transcriptome analysis identified 28 key genes involved in plant hormone signal transduction pathways. Furthermore, weighted gene co-expression network analysis (WGCNA) pinpointed 14 hub genes, including CYP94B3 and NAC82, linked to hormone-associated traits. Furthermore, quantitative real-time PCR (qRT-PCR) confirmed the accuracy of the transcriptome sequencing results. This analysis uncovered critical interactions between hormonal signaling pathways and pivotal gene networks. Overall, the findings highlight the central regulatory role of endogenous hormones in AR formation, with IAA serving as the predominant regulator.

Cinnamomum parthenoxylon is a significant essential oil plant in southern China, however, the challenge of rooting cuttings poses a hindrance to its development and widespread cultivation. Adventitious root (AR) formation is a vital mechanism for plants to acclimate to environmental changes, yet the precise regulatory mechanisms governing this process remain largely unknown. This study investigated the morphological, physiological, and transcriptomic alterations during AR formation in C. parthenoxylon. Our findings revealed that the AR in C. parthenoxylon originated from callus tissue. Nutrients, enzymes, and plant hormones exerted crucial functions in cutting propagation, with some gradually shifting roles in the rooting process until the pivotal stage of root primordium initiation. Analysis of differentially expressed genes (DEGs) highlighted the significance of auxin, ethylene, and plant wound signaling pathways in regulating AR. Furthermore, 14 hub genes were identified through protein-protein interaction (PPI) networks, shedding light on key molecular players. Understanding the dynamics involved in AR formation enhances our comprehension of the regulatory mechanisms, offering insights for optimizing cutting treatment methods.