Search Results (92)

Urban trees play a crucial role in regulating hydrological processes within urban ecosystems by intercepting rainfall to effectively reduce surface runoff and mitigate urban flooding. Current research lacks a systematic quantification of rainfall interception capacity and its community-level impacts at the urban scale. This study adopts a city-scale perspective, integrating field survey data with the i-Tree Eco model to systematically explore the contributions of 20 factors to the average annual rainfall interception of tree species and the average annual rainfall interception efficiency of communities. The study revealed that Deciduous broadleaf trees (1.28 m³ year⁻¹) and Pure coniferous forests (90.7 mm year⁻¹) exhibited substantial rainfall interception capacity. Relative Height, Average Tree Height, Average Crown Width, and Planting Density of trees significantly influence interception capacity. Urban planning can optimize the selection of tree species (e.g., Paulownia, Populus tomentosa, etc.) and community structure (e.g., mixed planting of conifers and deciduous broadleaf trees) to improve rainfall interception capacity, thereby effectively reducing stormwater runoff, mitigating the risk of urban flooding. These findings provide a scientific basis for designing urban vegetation to mitigate flooding, support water management, and advance sponge city development. Full article

MicroRNA319 (miR319) and its targets TEOSINTE-BRANCHED1/CYCLOIDEA/PCF (TCP) transcription factors are well-characterized regulators of leaf and flower development, yet their role in root development remains elusive. Here, we demonstrated that overexpression of miR319a led to a decrease in the number and density of lateral roots in poplar, while repressing miR319a by short tandem target mimics (STTM) promoted lateral root (LR) development. The auxin signaling repressors IAA3.1 and IAA3.2 were upregulated in miR319a-OE plants but downregulated in miR319a-STTM plants. After exogenous applications of naphthaleneacetic acid (NAA), which exhibited the characteristics and physiological functions of the endogenous auxin indole-3-acetic acid, the number and density of LR in WT increased by 30% and 44%, respectively. In miR319a-OE plants, the LR number increased by 23% and 48%, and the LR density increased by 10% and 26%. NAA treatment can partially compensate for the phenotype of inhibited LR development caused by the overexpression of miR319a. After N-1-naphthylphthalamic acid (NPA) treatment, which is a key inhibitor of the directional (polar) transport of the auxin hormone in plants, the LR number in WT decreased by 70%. In the overexpression plants, the number of lateral roots decreased by 85–87%, and in the STTM plants, the number of lateral roots decreased by about 83%. It was proved that NPA treatment could reverse the phenotype of increased LR number in miR319a-STTM plants. Expression analysis revealed that miR319a significantly inhibited the expression of the key auxin-regulated genes IAA3.1 and IAA3.2, suggesting that auxin signaling might mediate its effects on lateral root formation. Additionally, we compared the fluorescence signal in the reporter line with GFP expression driven by the auxin-responsive DR5 promoter within the genetic backgrounds of WT, miR319a-OE, and miR319a-STTM plants, which revealed that auxin signaling was stronger in the epidermal cells and elongation zone cells in the LR of miR319a-OE plants, whereas in LR of WT and miR319a-STTM plants, auxin signaling was more pronounced in the root tip meristematic cells. Furthermore, transactivation assays and expression analysis indicated that IAA3.2 was a downstream target of TCP19. Chromatin immunoprecipitation coupled with quantitative PCR (ChIP-qPCR) confirmed that TCP19 directly bound to the promoter region of IAA3.2. These findings establish that miR319a targeted and cleaved TCP19, and TCP19 further directly and negatively regulates the expression of IAA3.2, thereby controlling LR development in Populus tomentosa (P. tomentosa). The formation of LR can expand the plant root system, which is of great significance for the vegetative propagation of plants and the in-vitro regeneration of explants. Moreover, the formation of LR is an important strategy for plants to cope with environmental stresses. This study provides a theoretical basis for breeding poplars more suitable for vegetative propagation. Full article

Leaves are essential for photosynthesis and transpiration, directly influencing plant growth and development. Leaf morphology, such as length, width, and area, affects photosynthetic efficiency and transpiration rates. In this study, we investigated the role of PtoWOX1 in leaf morphogenesis by generating both overexpression and CRISPR/Cas9 knockout lines in P. tomentosa. The results showed that PtoWOX1A and PtoWOX1B encode nuclear-localized transcription factors highly expressed in young leaves, particularly in palisade and epidermal cells. Knockout of PtoWOX1 resulted in reduced leaf width and area, enlarged upper epidermal cells, and lower stomatal density. Overexpression led to wrinkled leaf surfaces and reduced margin serration. Anatomical analysis revealed altered palisade cell arrangement and increased leaf thickness in knockout lines, accompanied by higher chlorophyll content and enhanced photosynthetic rates. Additionally, PtoWOX1A interacts with PtoYAB3B, suggesting a complex that regulates leaf margin development. These findings clarify the function of PtoWOX1 in regulating mid-lateral axis development and leaf margin morphology and provide new insights for the molecular breeding of poplar. Full article

Calcium-dependent protein kinases (CDPKs) are crucial regulators in calcium-mediated signal transduction pathways, playing a pivotal role in plant response to abiotic stresses. However, there is still limited knowledge regarding the genes of the Populus tomentosa CDPK family and their underlying functions in response to arsenic (As) stress and arbuscular mycorrhizal fungi (AMF) colonization. In our study, 20 PtCDPKs were identified in the P. tomentosa genome. Phylogenetic analysis categorized these PtCDPK genes into four subgroups based on sequence homology. Motif analysis revealed that PtCDPK genes within the same group share a similar exon–intron structure, conserved domains, and composition. The promoters of PtCDPK genes were found to contain a multitude of cis-acting elements, including light-response elements, phytohormone-response elements, and stress-response elements. The analysis of genes provided insights into the evolutionary dynamics and expansion of the PtCDPK gene family within P. tomentosa. The PtCDPK genes exhibited a strong collinear relationship with the CDPK genes of two model plants, namely, Arabidopsis thaliana and Oryza sativa L. Specifically, 10 gene pairs showed collinearity with Arabidopsis; in contrast, 14 gene pairs were collinear with rice. Transcriptome analysis of gene expression levels in P. tomentosa roots under both As stress and arbuscular mycorrhizal fungi (AMF) colonization conditions revealed that 20 PtCDPK genes had differential expression patterns. Under As stress, AMF inoculation led to the upregulation of 11 PtCDPK genes (PtCDPKSK5, X2, 1-3, 20-1, 24, 26-X1-1, 26-X1-2, 29-1, 29-2, 32, and 32-X1) and the downregulation of 8 PtCDPK genes, including PtCDPK1-1, 1-2, 8-X1, 10-X4, 13, 20-2, 26-X2, and 26-X3. The RT-qPCR results for 10 PtCDPK genes were consistent with the transcriptome data, indicating that AMF symbiosis plays a regulatory role in modulating the expression of PtCDPK genes in response to As stress. The principal findings of this study were that PtCDPK genes showed differential expression patterns under As stress and AMF colonization, with AMF regulating PtCDPK gene expression in response to As stress. Our study contributes to developing a deeper understanding of the function of PtCDPKs in the Ca²⁺ signaling pathway of P. tomentosa under As stress and AMF inoculation, which is pivotal for elucidating the molecular mechanisms underlying As tolerance in AMF-inoculated P. tomentosa. Full article

Negative air ions (NAIs) can purify the atmosphere and maintain human health. In this study, we selected six tree species, Pinus tabuliformis, Pinus bungeana, Acer truncatum, Sophora japonica, Koelreuteria paniculata, Quercus variabilis, Robinia pseudoacacia, and Populus tomentosa, and we established for the first time five “capacity indicators” to characterize and judge the capacity of plants to release negative ions: they comprised the release contribution rate L, release coefficient n, release rate s, instantaneous current number v, and total level of release Z. These indicators were used to assess the ability of the plants to release NAIs by themselves. The results showed the following. (1) The daily variations in L and n show “W” and “concave” shapes, respectively, and the contribution capacity at night is significantly higher than that during the day. The diurnal variations in s, v, and Z all showed a “bimodal” pattern. The NAI release rate and release level of each tree species during the day were significantly higher than those at night. (2) The trees released the most NAIs during the day at approximately 10:00, while Robinia pseudoacacia and Populus tomentosa peaked with a 2 h lag (12:00). The NAI release capacity of each tree species was the worst at 13:00. (3) During the growing season, the self-contribution effects L and n of the plants were the strongest in May. The release rates and release levels s, v, and Z were the lowest in August. The coniferous plants released NAIs at the fastest rate in September and broad-leaved plants in July, with the highest release levels. In this study, the plants released the most NAIs from 10:00 a.m. to 11:00 a.m., which is the best time to travel. Quercus variabilis was preferentially recommended in the pairing of species of tree with the quickest NAI release and the highest total number released, followed by Koelreuteria paniculata and Sophora japonica. Full article

From 2016 to 2021, a field experiment was conducted in the North China Plain to study the long-term effects of drip irrigation and nitrogen coupling on the growth, biomass allocation, and irrigation water and fertilizer use efficiency of short-rotation triploid Populus tomentosa plantations. The experiment adopted a completely randomized block design, with one control (CK) and six water–nitrogen coupling treatments (IF, two irrigation levels × three nitrogen application levels). Data analysis was conducted using ANOVA, regression models, Spearman’s correlation analysis, and path analysis. The results showed that the effects of water and nitrogen treatments on the annual increment of diameter at breast height (ΔDBH), annual increment of tree height (ΔH), basal area of the stand (BA_S), stand volume (V_S), and annual forest productivity (AFP) in short-rotation forestry exhibited a significant stand age effect. The coupling of water and nitrogen significantly promoted the DBH growth of 2-year-old trees (p < 0.05), but after 3 years of age, the promoting effect of water and nitrogen coupling gradually diminished. In the 6th year, the above-ground biomass of Populus tomentosa was 5.16 to 6.62 times the under-ground biomass under different treatments. Compared to the I45 treatment (irrigation at soil water potential of −45 kPa), the irrigation water use efficiency of the I20 treatment (−20 kPa) decreased by 88.79%. PFP showed a downward trend with the increase in fertilization amount, dropping by 130.95% and 132.86% under the I20 and I45 irrigation levels. Path analysis indicated that irrigation had a significant effect on the BA_S, V_S, AFP, and TGB of 6-year-old Populus tomentosa (p < 0.05), with the universality of irrigation being higher than that of fertilization. It is recommended to implement phased water and fertilizer management for Populus tomentosa plantations in the North China Plain. During 1–3 years of tree age, adequate irrigation should be ensured and nitrogen fertilizer application increased. Between the ages of 4 and 6, irrigation and fertilization should be ceased to reduce resource wastage. This work provides scientific guidance for water and fertilizer management in short-rotation plantations. Full article

Understanding species-specific mechanisms governing symbiotic fungal responses to plant traits and soil factors is critical for optimizing urban tree “plant-soil-fungus” systems under pollution stress. To address this gap, we combined δ¹³C/δ¹⁵N isotope analysis and ITS sequencing for three common street trees in Beijing: Sophora japonica, Ginkgo biloba, and Populus tomentosa. In S. japonica, symbiotic fungal abundance was positively associated with leaf δ¹⁵N, indicating root exudate-mediated “plant-microbe” interactions during atmospheric NO_x assimilation. G. biloba, with weak NO_x assimilation, exhibited a negative correlation between fungal abundance and soil available N/P, suggesting mycorrhizal nutrient compensation under low fertility. P. tomentosa showed decreased fungal abundance with increasing soil N/P ratios and specific leaf area, reflecting carbon allocation trade-offs that limit mycorrhizal investment. These results demonstrate that symbiotic fungi respond to atmospheric and edaphic drivers in a tree species-dependent manner. Urban greening strategies should prioritize S. japonica for its NO_x mitigation potential and optimize fertilization for G. biloba (nutrient-sensitive fungi) and P. tomentosa (nutrient balance sensitivity). Strategic mixed planting of P. tomentosa with S. japonica could synergistically enhance ecosystem services through complementary resource acquisition patterns. This study provides mechanism-based strategies for optimizing urban tree management under atmospheric pollution stress. Full article

Wood, as a natural and renewable resource, plays a crucial role in industrial production and daily life. Lignin, as one of the three major components of the plant cell secondary wall, plays a key role in conferring mechanical strength and enhancing stress resistance. The caffeic acid-O-methyltransferase (COMT) family of oxygen-methyltransferases is a core regulatory node in the downstream pathway of lignin biosynthesis. Here, our report shows that caffeic acid-O-methyltransferase 2 (COMT2) exhibits high conservation across several species. Tissue expression analysis reveals that COMT2 is specifically highly expressed in the secondary xylem of Populus tomentosa stems. We demonstrated that the specific overexpression of COMT2 in fiber cells of Populus tomentosa led to a significant increase in plant height, stem diameter, internode number, and stem dry weight. Furthermore, we found that the specific overexpression of COMT2 in fiber cells promotes xylem differentiation, lignin accumulation, and the thickening of the secondary cell wall (SCW) in fiber cells. Our results indicate that key downstream lignin biosynthesis enzyme genes are upregulated in transgenic plants. Additionally, mechanical properties of stem bending resistance, puncture resistance, and compressive strength in the transgenic lines are significantly improved. Moreover, we further created the DUFpro:COMT2 transgenic lines of Populus deltoides × Populus. euramericana cv ‘Nanlin895’ to verify the functional conservation of COMT2 in closely related poplar species. The DUFpro:COMT2 Populus deltoides × Populus. euramericana cv ‘Nanlin895’ transgenic lines exhibited phenotypes similar to those observed in the P. tomentosa transgenic plants, which showed enhanced growth, increased lignin accumulation, and greater wood strength. Overall, the specific overexpression of the caffeic acid O-methyltransferase gene COMT2 in poplar stem fiber cells has enhanced the wood biomass, wood properties, and mechanical strength of poplar stems. Full article

In perennial trees, wood development is a carbon-demanding process, pivotal for secondary cell wall (SCW) formation and xylem development. Sugars, functioning both as carbon substrates and signaling molecules, orchestrate cambial proliferation and xylem differentiation. However, few molecular candidates involved in the sugar-mediated regulation of wood development have been characterized. Cell wall invertases (CWINs), a subclass of the invertase enzyme family localized in the apoplastic space, catalyze the irreversible hydrolysis of sucrose into glucose and fructose, thereby governing carbon allocation in sink tissues. Here, PtoCWIN4 shows preferential expression in the stem of Populus tomentosa and has a high efficiency in sucrose cleavage activity. We demonstrated that the knockout of PtoCWIN4 results in stunted growth, aberrant branching patterns, and compromised secondary xylem formation. In contrast, mutant lines displayed enhanced SCW thickness accompanied by elevated cellulose and hemicellulose accumulation. Following this, the knockout of PtoCWIN4 led to impaired carbon partitioning from sucrose to hexose metabolites during wood development, corroborating the enzyme’s role in sustaining sucrose hydrolysis. Collectively, these findings establish PtoCWIN4 as a master regulator of sucrose-to-hexose conversion, a metabolic gateway critical for balancing structural biomass production and developmental growth during wood formation. Full article

Utilizing high-throughput Illumina sequencing, we examined how small RNA (sRNA) profiles vary in Chinese white poplar (Populus tomentosa) across two pivotal infection stages by the rust fungus Melampsora larici-populina: the biotrophic growth phase (T02; 48 h post infection) and the urediniospore development and dispersal phase (T03; 168 h), both essential for plant colonization and prolonged biotrophic engagement. Far exceeding random expectations, siRNA clusters predominantly arose from transposon regions, with pseudogenes also contributing significantly, and infection-stage-specific variations were notably tied to these transposon-derived siRNAs. As the infection advanced, clusters of 24 nt siRNAs in transposon and intergenic regions exhibited pronounced abundance shifts. An analysis of targets indicated that Populus sRNAs potentially regulate 95% of Melampsora larici-populina genes, with pathogen effector genes showing heightened targeting by sRNAs during the biotrophic and urediniospore phases compared to controls, pointing to selective sRNA-target interactions. In contrast to conserved miRNAs across plant species, Populus-specific miRNAs displayed a markedly greater tendency to target NB-LRR genes. These observations collectively highlight the innovative roles of sRNAs in plant defense, their evolutionary roots, and their dynamic interplay with pathogen coevolution. Full article

The accurate point cloud completion of individual tree crowns is critical for quantifying crown complexity and advancing precision forestry, yet it remains challenging in dense plantations due to canopy occlusion and LiDAR limitations. In this study, we extended the scope of conventional point cloud completion techniques to artificial planted forests by introducing a novel approach called Multi−feature Fusion Completion of Populus (MFCPopulus). Specifically designed for Populus Tomentosa plantations with uniform spacing, this method utilized a dataset of 1050 manually segmented trees with expert−validated trunk−canopy separation. Key innovations include the following: (1) a hierarchical adversarial framework that integrates multi−scale feature extraction (via Farthest Point Sampling at varying rates) and biologically informed normalization to address trunk−canopy density disparities; (2) a structural characteristics split−collocation (SCS−SCC) strategy that prioritizes crown reconstruction through adaptive sampling ratios, achieving a 94.5% canopy coverage in outputs; (3) a cross−layer feature integration enabling the simultaneous recovery of global contours and a fine−grained branch topology. Compared to state−of−the−art methods, MFCPopulus reduced the Chamfer distance variance by 23% and structural complexity discrepancies (ΔD_b) by 33% (mean, 0.12), while preserving species−specific morphological patterns. Octree analysis demonstrated an 89−94% spatial alignment with ground truth across height ratios (HR = 1.25−5.0). Although initially developed for artificial planted forests, the framework generalizes well to diverse species, accurately reconstructing 3D crown structures for both broadleaf (Fagus sylvatica, Acer campestre) and coniferous species (Pinus sylvestris) across public datasets, providing a precise and generalizable solution for cross−species trees’ phenotypic studies. Full article

As global climate change and urban issues worsen, increasing carbon offsets is crucial, with urban plants playing a key role. However, research on assessing plant carbon sequestration (CSE) capacity at the regional scale, selecting urban plants, and optimizing CSE capacity-based scenarios is still limited. A total of 272 plant species were surveyed in the nine cities of the Zhengzhou Metropolitan Area (ZMA). The i-Tree and biomass models estimated the average carbon storage (CS) density at 9.32 kg C m⁻² and the CSE density at 0.55 kg C y⁻² m⁻² in the ZMA. The highest CS density (13.58 kg C m⁻²) was observed in Pingdingshan, while the lowest CSE density (0.36 kg C y⁻¹ m⁻²) was observed in Xuchang. Hierarchical and cluster analyses identified plant species with balanced CSE capacity, adaptability, and ornamental value, such as Populus tomentosa Carr. and Salix babylonica L., as well as shrubs like Abelia biflora Turcz and Kerria japonica (L.) DC. Vegetation regeneration modeling indicated that CS could increase by 37%–41% along roads, 28%–43% in amenity areas, and 17%–30% near waterfronts over the next 50 years. These findings serve as a reference for urban regeneration and planning aimed at enhancing the carbon reduction potential of urban green spaces (UGS). Full article

Intercellular communication mediated by CLAVATA3/EMBRYO SURROUNDING REGION-RELATED (CLE) peptides and their receptors is crucial for plant development and environmental adaptation. In this study, 45 and 89 CLEs were identified in Populus tomentosa and Populus alba × Populus glandulosa, respectively, and, together with the 52 CLEs in Populus trichocarpa, the chromosome localization, gene and protein characteristics, collinearity and gene duplication events, cis-acting regulatory elements in promoters and evolutionary relationships of CLEs in these three poplar species were analyzed. The CLEs of three poplar species were divided into four subfamilies. Among them, the CLEs in subfamilies I, II and IV were A-type CLEs, while those in subfamily III were B-type CLEs. During the evolutionary process of poplar, the selection pressure faced by whole-genome duplication or segmental duplication was purifying selection, and the duplication events led to the expansion of the CLE family in poplar. The exogenous addition of a certain concentration of poplar CLE13 peptides inhibits the root growth of Arabidopsis thaliana and poplar and simultaneously reduces the expression levels of ARFs and LBDs in the roots. In addition, drought stress induces the expression of PtrCLE13A. The overexpression of preCLE13A significantly enhances the osmotic and drought tolerance in Populus tomentosa. These results have provided valuable information for further research on the molecular mechanisms of CLE peptide signaling pathways in the woody model plant poplar regarding plant growth and stress resistance. Full article

Desalinating seawater is a crucial method for addressing the shortage of freshwater resources. High-efficiency, low-cost, and environmentally friendly desalination technologies are key issues that urgently need to be addressed. This work used Populus tomentosa Carr. as a matrix material and prepared Populus tomentosa Carr.@Fe-GA through a complexation reaction to enhance the water evaporation rate and photothermal conversion efficiency of seawater desalination. The concentration of the impregnation solution was further refined, and the bonding mechanism along with the thermal stability of the composite photothermal material was investigated, including an assessment of their photothermal conversion efficiency. The research results indicate that the evaporation rate of water in a 3.5% NaCl solution for Populus tomentosa Carr.@Fe-GA under light intensity conditions of one sun reached 1.72 kg·m⁻²·h⁻¹, which was an increase of 44.5% compared to untreated Populus tomentosa Carr. It achieved a photothermal conversion efficiency of 95.1%, an improvement of 53.6% over untreated Populus tomentosa Carr., and maintained stability and high evaporation performance (95.4%) even after prolonged rinsing. This work realizes the functional utilization of seawater desalination with Populus tomentosa Carr. and offers a novel approach for the development and use of wood-derived photothermal material. Full article

Enhancing the decay resistance of Populus tomentosa wood through environmentally friendly methods is crucial for improving its durability and market competitiveness. Lignified twigs (LT), typically unsuitable as timber due to their small diameter, are rich in lignin, which degrades during thermal induction to produce antifungal organic compounds. In this context, the objective of this study was to develop a lignified twig preservative (LTP) by thermal induction from the LT of Actinidia chinensis var. Jinyang. The antifungal activity of LTP under varying thermal conditions was analyzed, along with its chemical composition. Enzyme activity, cell membrane integrity, and respiratory metabolism in fungi treated with LTP were examined to elucidate antifungal mechanisms. Additionally, the decay resistance of LTP-treated wood was evaluated. Results revealed that LTP produced under N₂ at 220 °C exhibited robust antifungal activity against Trametes versicolor and Gloeophyllum trabeum, attributed to phenolic compounds such as syringaldehyde, syringone, vanillin, and vanillone. LTP inhibited fungal cellulases, hemicellulases, and ligninases by 30%–60%, disrupted cell membrane functionality, and suppressed respiratory metabolism. Poplar wood treated with LTP demonstrated significantly enhanced decay resistance (mass loss < 10%). This thermal-induced feedback pattern shows great potential for LT in wood preservation. Full article