Hainan Island possesses unique ecological conditions that nurture abundant wild tea resources. This study systematically investigated the distribution patterns and growth models of wild tea trees in Hainan through literature review and field surveys. Curvilinear regression analysis was employed to establish growth relationships among tree height (H), crown width (P), diameter at breast height (DBH, D), and basal diameter (d). Wild tea populations are distributed in Wuzhishan City, Baoting County, Qiongzhong County, Baisha County, Ledong County, and Lingshui County, spanning longitudes 108.85°E–109.91°E, latitudes 18.21°N–19.19°N, and elevations 357.0–1410.6 m. The population primarily occur in secondary forests and cultivated tea gardens, with significant canopy density fluctuations. The wild tea tree resources in the study area were mainly distributed in sheets, and 6915 wild tea trees were preliminarily investigated in 6 cities and counties, and the area with the largest number of wild tea trees was Wuzhishan, with a total of 4461 trees, accounting for 64.51% of the total. Wild tea tree diameter structure showed a normal distribution characteristic with grade II seedlings accounting for the main body (40.68%), followed by grade I seedlings (25.29%), and only 2.22% of the V–VI. large-diameter wild tea trees remaining, showing an obvious juvenile structure. Maximum crown width (11.5 m) and tree height (26.0 m) were recorded in Wuzhishan City, alongside the highest coefficients of variation for crown width (56.53%) and height (53.87%), with a crown-to-height ratio of 0.62. Optimal cubic regression models for growth relationships were: H=0.614+0.014C-0.258C²+2.13C³ (R²=0.488, h<700 m); H=1.949-0.001D+0.020D²+0.248D³ (R²=0.340, 700 m≤h<1300 m); D=-0.726+0.001d-0.024d²+1.026d³‌ (R²=0.887, h≥1300 m). The research would provide critical data for ecological monitoring in Hainan Tropical Rainforest National Park, tea germplasm conservation, and green certification of tea industries. It also would advance carbon sink management under China’s carbon neutrality goals and highlights the urgency for scientific conservation and sustainable utilization of wild tea resources to enhance biodiversity and regional socioecological resilience.

Coffee, one of the most important economic crops worldwide, is widely cultivated in tropical and subtropical regions and serves as a major source of income for many countries and regions. Caffeine (1,3,7-trimethylxanthine) is the main metabolite in coffee beans and related products, which not only imparts the characteristic bitter taste and stimulates effect of coffee but also exerts multiple biological functions. The N-methyltransferase (NMT) gene family plays a key role in the caffeine biosynthetic pathway. Therefore, systematic identification of coffee NMT family members and analysis of the expression patterns at different developmental stages are of great importance for investigating caffeine metabolism, improving coffee quality, and breeding stress-resistant varieties. In this study, a total of 27 NMT genes were identified in allotetraploid Coffea arabica, including 14 genes from the C subgenome and 13 from the E subgenome, distributed across 10 chromosomes. Gene structure analysis revealed that family members shared similar motif compositions but differed in intron arrangement and number. Cis-acting element analysis showed that the promoters of C. arabica NMT genes were enriched with various regulatory elements related to light response, stress response and hormone signaling, and contained transcription factor binding sites such as MYB, MYC and W-box. Transcriptome analysis further demonstrated that NMT genes exhibited dynamic expression during fruit development, with the ripening stage showing the highest number of differentially expressed genes (14 703), while the expansion stage showed the lowest (4419). Moreover, C. arabica NMT genes displayed clear temporal and tissue-specific expression patterns. Weighted gene co-expression network analysis (WGCNA) identified 12 co-expression modules, among which the ivory, coral1 and darkolivegreen modules were enriched in pathways related to environmental stress and protein folding, energy metabolism and nucleic acid metabolism, respectively. Core gene network analysis revealed the critical roles of NMT genes in caffeine metabolism, stress response, and developmental regulation. Taken together, this study systematically identified the NMT gene family in allotetraploid C. arabica, characterized the expression patterns during different stages of fruit development, and elucidated the potential functional differentiation, thereby providing a theoretical basis for coffee breeding.

Hainan oil-tea Camellia (locally termed Shanyou in Hainan) is a regionally endemic decaploid species thriving under monsoonal tropical climatic conditions, which confers its distinctive flavor profile and quality attributes. This paper summarized recent research on Shanyou, examining its evolutionary distribution, growth traits, the exceptional quality characteristics of the oil, and methodologies for germplasm identification. Furthermore, strategic recommendations were proposed to advance the development of the Hainan Shanyou industry, in order to provide a critical foundation for subsequent research, product development, and the establishment of a premium Shanyou oil brand, thereby facilitating the distinctive development of the regional industry.

This study was aimed to explore the impact mechanism of long-term different land use patterns on the physical and chemical properties and aggregate stability of tropical soils, thereby providing a scientific foundation for enhancing soil fertility and improving soil structure in tropical regions. For this purpose, three land use types with a history of nearly 30 years were selected as the research objects, namely artificially managed rubber plantation (MR), naturally managed rubber plantations (NR), and low human-disturbed longan orchards (NL). The basic physical and chemical properties of soil, the distribution of water-stable aggregates, and the characteristics of aggregate stability in the 0-20 cm, 20-40 cm, and 40-60 cm soil layers were specifically analyzed. With the increase of soil depth, the soil pH in both MR and NL patterns showed a decreasing trend. In different profile layers, the pH of MR was lower than that of NL and NR. Under each soil layer, the contents of large soil aggregates (>2 mm, 1-2 mm) in the NR pattern were significantly higher than those in MR and NL. Conversely, the contents of small soil aggregates (<0.25 mm, 0.25-0.5 mm) were significantly lower than those in MR and NL patterns. Both the Mean Weight Diameter (MWD) and Geometric Mean Diameter (GMD) of soil water-stable aggregates in the NR pattern were significantly higher than those in MR and NL, and the fractal dimension (D) value was significantly lower than that in MR and NL. This indicates that the soil aggregates under the natural management pattern are more stable. Analysis of variance showed that land use patterns had an extremely significant impact on soil particle size distribution and aggregate stability. Soil depth significantly influenced the distribution of aggregates in the <0.25 mm, 0.25-0.5 mm, 0.5-1 mm, and 1-2 mm particle size fractions, with the intensity of the impact increasing as aggregate size decreased. The interaction effect between land use pattern and soil depth significantly affected soil aggregates (>2 mm, 1-2 mm) and the fractal dimension (D) value. Correlation analysis revealed that the soil aggregate stability indices (content of aggregates >2 mm, MWD, GMD) were negatively correlated with soil available phosphorus and positively correlated with soil organic matter (SOM); the fractal dimension (D) was negatively correlated with the content of soil aggregates (>2 mm) and significantly positively correlated with the content of soil aggregates (<0.25 mm). In conclusion, land use pattern is the most critical factor affecting soil aggregate stability. The naturally managed rubber plantation pattern can significantly increase the content of soil aggregates, enhance soil aggregate stability, and thereby improve soil structure.

Cassava (Manihot esculenta Crantz), a vital tropical food crop, exhibits significant sensitivity to low temperature, which severely restricts its cultivation range. Lignin is a key stress-resistant component in cell walls, playing a crucial role in plant adaptation to low temperature stress. However, the function of cinnamyl alcohol dehydrogenase (CAD), a pivotal enzyme in lignin biosynthesis, during low-temperature stress responses remains unclear. This study analyzed physiological phenotypes, CAD enzyme activity and lignin accumulation in cassava under low temperature stress. CAD enzyme activity was significantly increased by 66.7% and lignin content was also increased by 14.8% at the low temperature of 10 ℃. Transcriptome profiling identified MeCAD2 as the key gene responsive to low temperature stress. Heterologous expression of MeCAD2 confirmed that its encoded MeCAD2 protein possessed CAD enzymatic activity. Virus-induced gene silencing (VIGS) of MeCAD2 in cassava resulted in a 18.9% reduction in CAD enzyme activity and a 12.3%–22.4% decrease in lignin content. Furthermore, under low temperature stress, MeCAD2-silenced plants exhibited exacerbated leaf damage, a 172.5% increase in malondialdehyde (MDA) accumulation, and intensified reactive oxygen species (ROS) staining. The results indicate that MeCAD2 enhances cassava low-temperature tolerance by regulating lignin deposition. This study elucidated the critical role of MeCAD2 in cassava’s response to low-temperature stress, providing a novel candidate gene for molecular breeding.

Rubber tree (Hevea brasiliensis), an economically significant species, produces natural rubber, a strategic resource for China. Since rubber tree introduced from South America to Southeast Asia in the 19th century, rubber tree productivity has been substantially improved through sustained genetic improvement. This article comprehensively reviewed the botanical characteristics of the rubber tree, traced its history of introduction and domestication, and analyzed the current applications, achievements, challenges, and future research directions of both conventional breeding techniques (including hybrid breeding, polyploid breeding, mutagenesis breeding, etc.) and modern biotechnological breeding techniques (including molecular marker-assisted selection, genomic selection, genetic modification, gene editing, etc.) in rubber tree improvement. The review aims to provide a reference for researchers in rubber tree genetics and breeding, facilitate progress in this field, and promote the sustainable development of the natural rubber industry.

Aquilaria sinensis, a plant belonging to the genus Aquilaria of the Thymelaeaceae family, can produce agarwood when exposed to natural factors (such as lightning strikes, fire, and insect bite) or artificial factors (such as cuts, holes, and inoculation of fungi). MADS is a transcription factor that plays a significant role in plant growth and development and stress response. However, its function in A. sinensis remains unclear. To elucidate the stress response of MADS-box genes in A. sinensis after injury, this study utilized transcriptomic data derived from A. sinensis to expression heatmaps and screen for differentially expressed genes, leading to the identification and cloning of a MADS-box encoding gene, designated AsMADS12, which exhibited significant differential expression. Comprehensive analyses were subsequently conducted on the domain architecture, physicochemical properties, phylogenetic relationships, and predicted secondary and tertiary structures of AsMADS12. The expression dynamics of the AsMADS12 at various time points after methyl jasmonate (MeJA) treatment were assessed via real-time quantitative PCR (RT-qPCR). Furthermore, subcellular localization of the AsMADS12 was determined by transiently expressing in onion epidermal cells (Agrobacterium-mediated infiltration) and observing fluorescence under a confocal laser scanning microscope. Sequence and evolutionary analyses revealed that AsMADS12 possessed a complete open reading frame (ORF) of 678 bp, encoding a protein of 255 amino acids. The predicted molecular weight of the encoded protein was 25.28 kDa. AsMADS12 contained a typical MEF2-like MADS domain and was classified as a MIKC-type transcription factor. The secondary structure of the protein was mainly composed of 52.00% α-helix, 11.56% extended chain, and 36.44% random coil. Phylogenetic cluster analysis revealed that AsMADS12 was clustered in the same branch as the MADS of Citrus sinensis and Citrus trifoliata. The subcellular localization experiment showed that the AsMADS12 protein was located in the nucleus. The real-time fluorescence quantitative results indicated that methyl jasmonate treatment could induce the expression of AsMADS12, and the expression level was the highest at 24 hours after treatment. It was speculated that AsMADS12 might play a potential role in the formation of agarwood in A. sinensis. This study completed the cloning of the gene for the first time and conducted preliminary exploration, laying the foundation for further research on whether it participates in the formation of agarwood and its role in biotic or abiotic stress responses, thereby providing a theoretical basis for understanding the molecular regulatory mechanism of agarwood formation in A sinensis.

Ammonia preservation and acid solidification are key steps in natural rubber (NR) processing, but there is still a lack of systematic research on the influence on the structure and properties of NR. In this paper, the same batch of fresh latex was treated with 0%, 0.05%, 0.20% ammonia and two solidification methods (acid solidification, biological solidification) to prepare samples. The effects of ammonia preservation and acid solidification on the structure and properties of NR were comprehensively evaluated from the aspects of molecular structure, composition, intrinsic properties, and the mechanical performance of both unfilled and carbon-black-filled vulcanizates. It was found that ammonia preservation led to a decrease in weight-average molecular weigh, the initial plastic value and Mooney viscosity of the acid-solidified samples, whereas the properties remained largely unaffected in biologically solidified counterparts. The addition of ammonia exerted minimal influence on the mechanical properties of unfilled vulcanizates, but significant effects emerged in carbon-black-filled systems. Acid-solidified samples demonstrated higher fatigue temperature rise, while biologically solidified samples showed decreased tensile stress and tear strength. The solidification mode profoundly impacted the molecular structure, chemical composition, intrinsic properties, and mechanical performance of NR. Compared to biological solidification, acid-solidified rubber exhibits higher nitrogen, free fatty acid content and weight-average molecular weight. Furthermore, acid-solidified samples displayed lower initial plasticity and Mooney viscosity. The solidification method significantly affected the properties of both unfilled and carbon-black-filled vulcanizates. Compared to biological solidification, acid-solidified samples exhibited slower cure rates and higher fatigue temperature rise. The results showed that ammonia preservation of fresh latex and subsequent solidification with acid could affect the important components and intrinsic properties of NR, and had a significant impact on the dynamic properties such as fatigue temperature rise and permanent deformation, especially in carbon-black-filled vulcanizates. However, by comparing with the imported RSS, the preservation of fresh latex with ammonia and the subsequent solidification with acid were not the only reasons causing the performance of domestic NR to be worse than that of imported NR and differences in processing maybe the other causes. This work not only reveals the reason of the performance difference between domestic and imported NR products, but also would provide technical support for optimizing the production management of special rubber park.

Phytophthora capsici is a damaging pathogen with a wide host range, causing devastating diseases such as root rot, stem rot, leaf and fruit rot in plants from diverse families like Solanaceae, Cucurbitaceae, and Legumes. The diseases pose a significant threat to the sustainability of related agricultural industries. In this study, we identified a key RXLR effector, Pc13306, from the RXLR effector repertoire of P. capsici. The coding region of Pc13306 comprised 888 nucleotides, encoding 295 amino acids, with a conserved RXLR motif residing at positions 34-37 in the N-terminal region. Utilizing a yeast secretion system, we confirmed that the signal peptide of Pc13306 exhibited robust secretory activity. Quantitative real-time PCR (qRT-PCR) analysis revealed that Pc13306 was specifically upregulated during the late stages of P. capsici infection. Through agrobacterium-mediated transient transformation of Nicotiana benthamiana Pc13306 was demonstrated to significantly enhance lesion expansion and pathogen biomass accumulation, thereby improving infection efficiency. Moreover, Pc13306 induced reactive oxygen species (ROS) bursts and hypersensitive response (HR). Further exploration into the regulatory mechanism of Pc13306 in plant immunity revealed that it activated the salicylic acid (SA) signaling pathway and autophagy processes. Notably, Pc13306 markedly upregulated the expression of core genes involved in pattern-triggered immunity (PTI), indicating its role in modulating plant immune responses. The findings would provide insights into the interaction mechanisms between P. capsici and its host, and facilitate the development of targeted disease control strategies focusing on effectors.

Reasonable fertilization is of great significance for increasing the yield of oil-tea Camellia, and the application of bio-organic fertilizers is superior to the current practice of using farm manure as the main fertilizer for oil-tea Camellia in many aspects. In order to develop and value the specialized bio-organic fertilizers suitable for the soil conditions of oil-tea Camellia plantations in tropical regions, the nutrient contents of oil-tea Camellia leaves, the physical and chemical properties, and enzyme activities of oil-tea Camellia forest soil were determined. The results showed that the application of bio-organic fertilizers and conventional compound fertilizer could significantly increase the water content, relative chlorophyll content (SPAD value), and nutrient elements of oil-tea Camellia leaves. The soil moisture contents and field capacities of different fertilization treatments were higher than those without fertilization, but there were no significant differences in soil bulk density and porosity between the treatments and the control group. All four types of bio-organic fertilizers could increase the contents of soil organic matter, alkaline nitrogen, available phosphorus, available potassium, and soil enzyme activity in different soil layers. T₁ and T₄ bio-organic fertilizer improved the chemical properties of oil-tea Camellia soil more, which is of great significance for the targeted improvement of the fertility and available potassium content of Hainan oil-tea Camellia forest land. The results would provide data for screening specialized bio-organic fertilizers suitable for tropical oil-tea Camellia, laying a scientific foundation for the subsequent large-scale application of bio-organic fertilizers for tropical oil-tea Camellia.