The intricate interplay between photosynthetic efficiency and terpenoid biosynthesis in plants remains a pivotal yet underexplored area in secondary metabolism research. This study elucidates the physiological and molecular mechanisms underlying this synergy in Cinnamomum burmanni, a chemically diverse Lauraceae species, through a multi-omics approach. A high-quality chromosome-level genome of C. burmanni (1.14 Gb, scaffold N50: 94.90 Mb) was assembled, and evolutionary analyses revealed species-specific gene family expansions, particularly in mono-, sesqui-, and diterpenoid biosynthesis pathways. Comparative analyses of photosynthetic traits across chemotypes demonstrated that the borneol-type exhibits superior photosynthetic capacity, characterized by elevated net photosynthetic rate, transpiration rate, stomatal conductance, intercellular CO₂, carboxylation efficiency and non-photochemical quenching. The phenotype is linked to upregulated chlorophyll metabolism, carotenoid biosynthesis regulators, and enhanced light-harvesting complex and photosystem components, optimizing light energy conversion. Mechanistically, photosynthetic activity modulates precursor flux into terpenoid pathways by regulating rate-limiting enzymes. Additionally, lineage-specific expansions of terpene synthase and isopentenyl diphosphate synthase gene families underpin specialized terpenoid production. A post-transcriptional regulatory network involving 14 miRNAs (e.g., miR396, miR2950) was identified, coordinately targeting 11 key genes in both photosynthesis and terpenoid synthesis, suggesting a dual role in metabolic fine-tuning. This work advances understanding of the evolutionary and physiological integration of photosynthesis and secondary metabolism in aromatic plants, offering a genomic foundation for biotechnological applications in metabolite synthesis and chemotype breeding.

The essential oil of Cinnamomum burmannii (Nees and T. Nees) Blume is rich in monoterpenes and sesquiterpenes. The post-transcriptional regulatory mechanisms controlling the expression of terpenoid-related genes have not yet been clarified in C. burmannii. Here, we conducted a metabolomic analysis of the leaves of C. burmannii across four developmental stages using gas chromatography–mass spectrometry. We also identified miRNAs and their target genes involved in terpenoid biosynthesis using small RNA sequencing. A total of 135 differentially expressed metabolites were detected, including 65 terpenoids, 15 aldehydes, and 13 benzenes. A total of 876 miRNAs from 148 families were detected, among which 434 miRNAs were differentially expressed, including three known miRNAs and 431 novel miRNAs. Four miRNAs (gma-miR5368, novel_miR_377, novel_miR_111, and novel_miR_251) were predicted to regulate the expression of four differential expressed genes involved in the monoterpenoid and sesquiterpenoid synthesis. miRNAs families miR396, miR5185, and miR9408 were predicted to play diverse regulatory roles in monoterpenoid and sesquiterpenoid synthesis during the leaf development of C. burmannii. The results of our study shed new light on the roles of regulatory genes in terpenoid biosynthesis. Our findings also have implications for the further promotion of essential oil production using the leaves of C. burmannii.

The genus Cinnamomum encompasses diverse species with various applications, particularly in traditional medicine and spice production. This study focuses on Cinnamomum burmanni, specifically on a high-D-borneol-content chemotype, known as the Meipian Tree, in Guangdong Province, South China. This research explores essential oil diversity, chemotypes, and chloroplast genomic diversity among 28 C. burmanni samples collected from botanical gardens. Essential oils were analyzed, and chemotypes classified using GC-MS and statistical methods. Plastome assembly and phylogenetic analysis were conducted to reveal genetic relationships. Results showed distinct chemotypes, including eucalyptol and borneol types, with notable variations in essential oil composition. The chloroplast genome exhibited conserved features, with phylogenetic analysis revealing three major clades. Borneol-rich individuals in clade II suggested a potential maternal inheritance pattern. However, phylogenetic signals revealed that the composition of essential oils is weakly correlated with plastome phylogeny. The study underscores the importance of botanical gardens in preserving genetic and chemical diversity, offering insights for sustainable resource utilization and selective breeding of high-yield mother plants of C. burmanni.

Camphora officinarum Nees is a significant economic tree because of its aromatic, medicinal, and ornamental attributes. The diverse flavonoids present within the leaves of C. officinarum have been neglected for an extended period, hindering a comprehensive understanding of the molecular mechanisms responsible for color transformation and resistance to adverse environmental conditions. In this study, multi-omics analyses were conducted to systematically compare the relative contents of flavonoid metabolites and the expression profiles of flavonoid-related genes across three developmental stages of C. officinarum leaves. A total of 175 flavonoid compounds were detected via metabolomics, with flavonols being the most abundant. Through weighted gene co-expression network analysis, 25 key DEGs encoding CHS, DFR, FLS, ANS, F3′H, and LAR genes are predicted to be involved in anthocyanin biosynthesis for color change during leaf development. Notably, ten MYB, seven bHLH, and three ERF factors are potentially implicated in the regulation of key genes, underscoring their significant contributions to the color mechanisms underlying flavonoid biosynthesis. Other flavonoids, e.g., apigenin, isorhamnetin glycosides, sakuranetin, and sakuranin, may facilitate the adaptation of C. officinarum for protective purposes against adverse environmental conditions. These findings lay a theoretical foundation for resource exploration and the ornamentation improvement of C. officinarum.

Camphora officinarum Nees constitutes a pivotal tree species within the evergreen broad-leaved forests of East Asia, endowed with significant economic, ornamental, and ecological importance. Nevertheless, previous research has markedly underestimated the genetic diversity of this species, thereby hindering our efforts in conserving resources and enhancing genetic breeding. The current study generated 155 chloroplast genomes from specimens of C. officinarum obtained from six provinces/regions in China. The results reveal the identification of seven distinct clades (I–VII), with Clades II, III, V, and VII exhibiting genome expansions, primarily influenced by lineage-specific elongation of inverted repeats (IRs), whereas Clades I, IV, and VI maintained conserved IR lengths. Despite the structural plasticity, the GC content remained highly conserved. Geographic patterns indicated gene flow between adjacent regions (e.g., Hunan and Hubei with identical IR lengths), but genetic isolation in Fujian. High-polymorphism regions (psba-matK, ycf1, ycf2, and ndhF) were identified as superior phylogenetic markers, enhancing intraspecies-level resolution. Simple sequence repeats (SSRs) varied significantly among clades, dominated by A/T-rich mononucleotide repeats. These repeats, along with divergent repeat types (e.g., absence of reverse repeats in Clades V/VI), serve as robust tools for resource identification and evolutionary trajectory inference. Phylogenetically, samples from Fujian formed a distinct lineage, while samples from other regions, especially Guangdong, were mixed, with this finding probably being a reflection of historical cultivation and anthropogenic translocation. This study offers a framework for the genetic breeding and investigation of the evolutionary history of C. officinarum.

Schima superba, belonging to the genus Schima of Theaceae, is a common large tree in evergreen broad-leaved forests in subtropical regions of China. As one of the largest transcription factor families in plants, MYB transcription factors play an important role in plant stress response by specifically binding to cis-acting elements in different gene promoter regions to accurately regulate gene expression. However, there are few studies on MYB transcription factors in S. superba. The MYB transcription factor family of S. superba was found and examined in this study using the genomic and transcriptome data of the S. superba. A set of 220 MYB transcription factors was identified from S. superba and classified into four subfamilies. These transcription factors were unevenly distributed on 18 chromosomes of S. superba. The conserved domains of the same subfamily members are highly similar to the conserved motifs. The collinearity analysis between species showed that there were few orthologous genes located on chromosome 18 of S. superba. Numerous elements linked to phytohormone response, stress adaptation, and growth control can be found in the promoter regions of the S. superba MYB transcription factor family, according to an analysis of the promoter cis-acting elements. Verification via qRT-PCR showed that among 15 SsMYBs genes tested, SsMYB24 expression peaked at 96 h of drought stress, followed by a rapid downregulation upon rewatering to initial levels. This expression pattern aligned with the transcriptome data. This study is helpful to further identify the function of SsMYB transcription factors and provide a new molecular mechanism for improving drought tolerance of S. superba.