Yellow-green leaf mutants are common in higher plants, and these non-lethal chlorophyll-deficient mutants are ideal materials for research on photosynthesis and plant development. A novel xantha mutant of Ginkgo biloba displaying yellow-colour leaves (YL) and green-colour leaves (GL) was identified in this study. The chlorophyll content of YL was remarkably lower than that in GL. The chloroplast ultrastructure revealed that YL had less dense thylakoid lamellae, a looser structure and fewer starch grains than GL. Analysis of the photosynthetic characteristics revealed that YL had decreased photosynthetic activity with significantly high nonphotochemical quenching. To explain these phenomena, we analysed the proteomic differences in leaves and chloroplasts between YL and GL of ginkgo using two-dimensional gel electrophoresis (2-DE) coupled with MALDI-TOF/TOF MS. In total, 89 differential proteins were successfully identified, 82 of which were assigned functions in nine metabolic pathways and cellular processes. Among them, proteins involved in photosynthesis, carbon fixation in photosynthetic organisms, carbohydrate/energy metabolism, amino acid metabolism, and protein metabolism were greatly enriched, indicating a good correlation between differentially accumulated proteins and physiological changes in leaves. The identifications of these differentially accumulated proteins indicates the presence of a specific different metabolic network in YL and suggests that YL possess slower chloroplast development, weaker photosynthesis, and a less abundant energy supply than GL. These studies provide insights into the mechanism of molecular regulation of leaf colour variation in YL mutants.

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.

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 camphora is an ecologically and economically significant species, highly valued for its essential oil production and environmental benefits. Although a tissue culture system has been established for C. camphora, large-scale propagation remains limited due to the inconsistent formation of adventitious roots (ARs). This study investigated AR formation from callus tissue, focusing on associated physiological changes and gene expression dynamics. During AR induction, contents of soluble sugars and proteins decreased, alongside reduced activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), and polyphenol oxidase (PPO). Levels of indole-3-acetic acid (IAA) and abscisic acid (ABA) decreased significantly throughout AR formation. Zeatin riboside (ZR) levels initially declined and then rose, whereas gibberellic acid (GA) levels displayed the opposite trend. Comparative transcriptomic and temporal expression analyses identified differentially expressed genes (DEGs), which were grouped into four distinct expression patterns. KEGG pathway enrichment indicated that 67 DEGs are involved in plant hormone signaling pathways and that 38 DEGs are involved in the starch and sucrose metabolism pathway. Additionally, protein–protein interaction network (PPI) analysis revealed ten key regulatory genes, which are mainly involved in auxin, cytokinin, GA, ABA, and ethylene signaling pathways. The reliability of the transcriptome data was further validated by quantitative real-time PCR. Overall, this study provides new insights into the physiological and molecular mechanisms underlying AR formation in C. camphora and offers valuable guidance for optimizing tissue culture systems.

Cinnamomum parthenoxylon (Jack) Meisner is an important spice tree species in southern China. In in vitro cultures of C. parthenoxylon, the young stem explants can differentiate into adventitious buds and roots under different exogenous growth regulator conditions. However, the underlying regulatory mechanisms governing this differentiation process remain unclear. In this study, physiological and biochemical characteristics were measured, and transcriptomic sequencing was performed in different differentiation processes. Significant changes in physiological and biochemical parameters were observed during the differentiation of the young stems. Soluble sugars, soluble proteins, malondialdehyde (MDA), zeatin riboside (ZR), abscisic acid (ABA), gibberellin (GA) content, the (IAA + GA + ZR)/ABA ratio, and polyphenol oxidase (PPO) activity displayed contrasting expression patterns during the formation of adventitious buds and roots. The RNA-seq result revealed that the differentiation direction of young stems is regulated by the synthesis of endogenous hormones and associated signaling pathways. At the same time, phenylpropanoid metabolism and glucose metabolism pathways acted as auxiliary pathways, facilitating the formation of adventitious buds and roots. Furthermore, quantitative real-time PCR (qRT-PCR) results were highly consistent with transcriptome sequencing results. This study lays the foundation for exploring the directional differentiation of young stems in C. parthenoxylon.