Experimental Center of Subtropical Forestry

Camellia chekiangoleosa is a significant oil-bearing tree species, known for its high oleic acid content and shorter reproductive cycle compared to traditional oil-tea plants. However, there are few studies on the molecular mechanism and compatibility of the interaction between oil-Camellia scion and rootstock, which poses certain challenges to the cultivation and promotion of oil-Camellia. This study systematically evaluates the effects of hetero-grafting Camellia chekiangoleosa scions onto divergent rootstocks (Camellia chekiangoleosa, Camellia oleifera, and Camellia yuhsienensis). Then the research investigates how rootstock selection alters scion growth and development through phenotypic, biochemical, and transcriptomic analyses. Our findings reveal that the combination of C. oleifera scion grafted onto C. yuhsienensis suppresses auxin (IAA) and cytokinin (ZR) levels while elevating abscisic acid (ABA). Transcriptomic analysis identified that the PYL1, AMY, and INV1 screened by transcriptome data were mainly enriched in starch and sucrose metabolic pathways and plant hormone signal transduction, which collectively prioritize carbon allocation toward growth over storage. Meanwhile, hetero-grafting improved photosynthetic capacity by upregulating light-harvesting complex (LHC) genes and carotenoid biosynthesis enzymes (ZEP), optimizing light energy conversion and photoprotection. These findings provide novel insights into the molecular mechanisms underlying rootstock-scion interactions in oil-Camellia, bridging a critical knowledge gap in this economically important genus.

Camellia oleifera, a woody oilseed species endemic to China, often experiences growth constraints due to seasonal drought. This study investigates the coordinated regulation of photosynthetic traits, stomatal behavior, and hormone responses during drought-rehydration cycles in two cultivars with contrasting drought resistance: 'CL53' (tolerant) and 'CL40' (sensitive). Photosynthetic inhibition resulted from both stomatal and non-stomatal limitations, with cultivar-specific differences. After 28 days of drought, the net photosynthetic rate (Pn) declined by 26.6% in CL53 and 32.6% in CL40. A stable intercellular CO2 concentration (Ci) in CL53 indicated superior mesophyll integrity and antioxidant capacity. CL53 showed rapid Pn recovery and photosynthetic compensation post-rehydration, in contrast to CL40. Drought triggered extensive stomatal closure; >98% reopened upon rehydration, though the total stomatal pore area remained reduced. Abscisic acid (ABA) accumulation was greater in CL40, contributing to stomatal closure and Pn suppression. CL53 exhibited faster ABA degradation and gibberellin (GA3) recovery, promoting photosynthetic restoration. ABA negatively correlated with Pn, transpiration rate (Tr), stomatal conductance (Gs), and Ci, but positively with stomatal limitation (Ls). Water use efficiency (WUE) displayed a parabolic response to ABA, differing by cultivar. This integrative analysis highlights a coordinated photosynthesis-stomata-hormone network underlying drought adaptation and informs selection strategies for drought-resilient cultivars and precision irrigation.

Understanding the interplay between plant leaf functional traits and plant and soil factors under different soil thicknesses is significant for quantifying the interaction between plant growth and the environment. However, in the context of ecological restoration of vegetation in mining areas, there has been a lot of research on trees, shrubs, and grasses, but the characteristics and correlations of leaf functional traits of vines have not been fully studied to a large extent. Here, we report the differences in leaf functional traits of six vine plants (Parthenocissus quinquefolia, Pueraria lobata, Hedera nepalensis, Campsis grandiflora, Mucuna sempervirens, and Parthenocissus tricuspidata) with distinct growth forms in different soil cover thicknesses (20 cm, 40 cm, and 60 cm). In addition, soil factor indicators under different soil cover thicknesses were measured to elucidate the linkages between leaf functional traits of vine plants and soil factors. We found that P. lobata showed a resource acquisition strategy, while H. nepalensis demonstrated a resource conservation strategy. C. grandiflora and P. tricuspidata shifted toward more conservative resource allocation strategies as the soil cover thickness increased, whereas M. sempervirens showed the opposite trend. In the plant trait–trait relationships, there were synergistic associations between specific leaf area (SLA) and leaf nitrogen content (LNC); leaf moisture content (LMC) and leaf nitrogen-to-phosphorus ratio (LN/P); and leaf specific dry weight (LSW), leaf succulence degree (LSD), and leaf dry matter content (LDMC). Trade-offs were observed between SLA and LSW, LSD, and LDMC; between leaf phosphorus content (LPC) and LN/P; and between LMC, LSW, and LDMC. In the plant trait–environment relationships, soil nutrients (pH, soil total phosphorus content (STP), and soil ammonium nitrogen content (SAN)) and soil enzyme activities (cellulase (CB), leucine aminopeptidase (LAP), enzyme C/N activity ratio, and enzyme N/P activity ratio) were identified as the primary drivers of variation in leaf functional traits. Interestingly, nitrogen deficiency constrained the growth of vine plants in the mining area. Our study revealed that the responses of leaf functional traits of different vines under different soil thicknesses have significant species specificity, and each vine shows different resource acquisition and conservation strategies. Furthermore, soil cover thickness primarily influences plant functional traits by directly affecting soil enzyme activities and nutrients. However, the pathways through which soil thickness impacts these traits differ among various functional traits. Our findings provide a theoretical basis and practical reference for selecting vine plants and optimizing soil cover techniques for ecological restoration in mining areas.

Abstract Oil camellia (Camellia oleifera) is an oil-bearing crop. Jiangxi Province is the second-largest oil-camellia producing region in China. The performance of varieties across different regions of Jiangxi Province was evaluated. Ten areas were selected, and the fruit morphology, weight, moisture content, and primary economic traits of five ‘Changlin’ oil camellia varieties were analysed. Differences in varieties and fruit characteristics in different regions were observed. CL53 had the greatest fruit size, fruit weight, moisture content in the pericarp and fresh seeds, and 100-fresh seed and -dry seed weight. The seed kernel-to-fruit weight, ranked from highest to lowest, was: CL53 (35.10%), CL3 (33.28%), CL18 (30.95%), CL4 (30.17%), and CL40 (28.38%). The weight of dried kernel to fresh fruit (DK/FF) was: CL18 (16.32%), CL53 (13.37%), CL3 (13.18%), CL40 (12.23%), and CL4 (10.25%). Principal component analysis indicated that all five varieties ranked within the top 10 for overall performance. In certain regions, CL18 and CL3 can be prioritized as replacement varieties. The regional adaptability and performance of ‘Changlin’ oil-camellia varieties can be used to optimize variety selection and configuration to enhance oil-camellia production in Jiangxi Province.

Objective: This study aimed to clarify the variation law of phenotypic traits such as the stem, leaf, flower, main branch ear and seed of Prunella vulgaris Linnaeus. (P. vulgaris), providing provide basic data support for protecting its wild germplasm resources. The phenotypic traits of stems, leaves, flowers, main branch ears and seeds of different wild populations of P. vulgaris were measured to reveal the phenotypic variation among and within populations of P. vulgaris, and to provide a scientific basis for the protection, utilization and collection of wild P. vulgaris germplasm resources. Methods: Variance analysis, coefficient of variation analysis, multiple comparison analysis, cluster analysis and principal component analysis were used to study the phenotypic traits of nine wild P. vulgaris populations in different regions of China. Results: The average phenotypic differentiation coefficient of nine traits was 52.04%. Inter-population variation was the main source of phenotypic variation of P. vulgaris. The average variation coefficient of each trait in the population was 21.25%, and the variation range was 15.02–28.94%. Pearson correlation analysis showed that there was a strong autocorrelation between phenotypic traits of wild P. vulgaris, and spikes and stems were greatly affected by environmental factors. According to the diameter of the stem and ear, nine wild P. vulgaris from different geographical populations could be divided into three groups. Group III (AHHS, JXFY) had the best phenotypic traits, and the traits of stem height, stem diameter, leaf length, leaf width and main branch ear length were the largest. The contribution rate of the three principal components screened by principal component analysis was 85.78%. Conclusions: We believe that the phenotypic differentiation among wild populations of P. vulgaris is at a medium level, and the variation within the population is smaller than that between populations, which may be an important reason for the sharp decline in the wild resources of P. vulgaris.

Flavonoids are secondary metabolites that have economic value and are essential for health. Poplar is a model perennial woody tree that is often used to study the regulatory mechanisms of flavonoid synthesis. We used a poplar bud mutant, the red leaf poplar variety 2025 (Populus × euramericana 'Zhonghuahongye'), and green leaves as study materials and selected three stages of leaf color changes for evaluation. Phenotypic and biochemical analyses showed that the total flavonoid, polyphenol, and anthocyanin contents of red leaves were higher than those of green leaves in the first stage, and the young and tender leaves of the red leaf variety had higher antioxidant activity. The analyses of widely targeted metabolites identified a total of 273 flavonoid metabolites (114 flavones, 41 flavonols, 34 flavonoids, 25 flavanones, 21 anthocyanins, 18 polyphenols, 15 isoflavones, and 5 proanthocyanidins). The greatest difference among the metabolites was found in the first stage. Most flavonoids accumulated in red leaves, and eight anthocyanin compounds contributed to red leaf coloration. A comprehensive metabolomic analysis based on RNA-seq showed that most genes in the flavonoid and anthocyanin biosynthetic pathways were differentially expressed in the two types of leaves. The flavonoid synthesis genes CHS (chalcone synthase gene), FLS (flavonol synthase gene), ANS (anthocyanidin synthase gene), and proanthocyanidin synthesis gene LAR (leucoanthocyanidin reductase gene) might play key roles in the differences in flavonoid metabolism. A correlation analysis of core metabolites and genes revealed several candidate regulators of flavonoid and anthocyanin biosynthesis, including five MYB (MYB domain), three bHLH (basic helix-loop-helix), and HY5 (elongated hypocotyl 5) transcription factors. This study provides a reference for the identification and utilization of flavonoid bioactive components in red-leaf poplar and improves the understanding of the differences in metabolism and gene expression between red and green leaves at different developmental stages.

Kadsura coccinea (Lem.) A. C. Smith is a significant tree species of non-timber forest. However, the low germination percentage and lengthy germination time of its seeds pose obstacles to industry development. Aiming at the problem of seed dormancy, this study first determined the seed dormancy period through seed germination test, and then comprehensively evaluated the dormancy characteristics by observing the seed coat structure, measuring endogenous inhibitors, and in vitro embryo culture. The results indicated the dormancy of K. coccinea seeds, and that the germination period was up to 80 days. Its seed coat is composed of exotesta and endotesta. The dense seed coat structure causes water absorption and air permeability obstacles to the seeds and causes mechanical restraint to the development of the embryo. Meanwhile, its seeds have substances that inhibit seed germination, and there are germination inhibitors in distilled water, methanol, petroleum ether, and ethyl acetate extracts of kernels and seed coats. The inhibitory activity of kernel petroleum ether extract was the highest, and the inhibitory activity of seed coat methanol extract was the highest. In addition, the embryo of K. coccinea developed completely and could germinate normally under in vitro conditions. This study has basically proved that the dormancy of K. coccinea seeds is caused by the seed coat (physical dormancy) and endogenous inhibitors (physiological dormancy), which provides a scientific theoretical basis to further explore the method of seed dormancy release of K. coccinea.