This study reports a newly recorded araphid diatom, Protoraphis hustedtiana var. nana Takano, from Weizhou Island, China. This variety was found epiphytic on Sargassum spp. Its morphology was examined in detail using light and scanning electron microscopy, and its ecological habitat and geographical distribution were documented.

The carbon sequestration capacity of the water source area of the Middle Route of the South-to-North Water Diversion Project (hereinafter referred to as the water source area) is strongly influenced by climate variability. This study employed FORCCHN2, a second-generation individual-based forest ecosystem carbon cycling model, to estimate forest net ecosystem productivity (NEP) in the water source area from 2002 to 2020 and to assess its spatiotemporal dynamics and key driving factors. Results indicated that from 2002 to 2020, the average pixel-scale forest NEP ranged from 308.88 to 761.22 g C·m⁻²·a⁻¹, with radiation and temperature identified as primary determinants. Over this period, NEP exhibited a significant downward trend, decreasing at an average annual rate of 4.41 g C·m⁻²·a⁻¹, with spatial heterogeneity in this decline. Pixel-based correlation analysis of interannual variations in gross primary productivity (GPP), soil respiration (SR), and vegetation respiration (VR), along with their associations with climate factors, revealed that in the eastern region, rising temperatures led to a higher SR increase relative to GPP. Additionally, reductions in solar radiation in the northwest and southwest regions contributed to GPP decline in these areas.

This study investigated the Rhodoleia championii Hook. f. + Castanopsis fordii Hance community, a representative subtropical forest in Nankun Mountain, Longmen County, Guangdong Province. Quadrat-based surveys, coupled with the variance ratio method (VR) and Fisher’s exact test, were employed to assess species diversity and interspecific associations. Results revealed that: (1) The community exhibited high species diversity, with a relatively even distribution of species in the tree layer, whereas the shrub layer contained a greater number of species but exhibited uneven distribution, leading to a lower diversity index; (2) The overall interspecific associations within the community were significantly positive, suggesting a stable community structure. In the tree layer, one highly significant positive association pair, five significant positive association pairs, and two significant negative association pairs were identified; (3) Based on population clustering, interspecific connectivity, and ecological habits, the 14 dominant populations were classified into four ecological species groups. Species within the same group exhibited similar ecological adaptations and resource requirements, generally displaying positive associations, while species from different groups predominantly exhibited negative associations. These findings provide a theoretical basis for the conservation and management of natural secondary forests in Nankun Mountain.

Ammopiptanthus nanus (M. Pop.) Cheng f. is a rare Tertiary relict species that originated along the Tethys coast and is currently classified as a state Grade Ⅱ protected plant due to demographic scarcity. This study examined the population age structure and demographic dynamics through analyses of static life tables, survival curves, survival function curves, and time series models. Results showed that mature individuals constituted the largest proportion of the population (48.1%), while saplings accounted for the lowest proportion (7.0%), reflecting a declining age structure. The species exhibited a Deevey-Ⅱ survival curve, with a stable overall mortality rate. However, a pronounced decline in the early stages, followed by a stabilization phase in the middle period and a subsequent decline in the later stages, suggests a heightened risk of extinction. Enhancing seedling recruitment and improving the survival rate during the transition from juvenile to adult stages are critical for ensuring population sustainability and long-term viability.

This study examined the chemical properties of soil in six sand-fixing shrub communities in Ulan Buhe Desert, focusing on the 0–150 cm soil layer. Results demonstrated that: (1) Soil organic matter content was significantly higher in all shrub communities than in the control site (BS) (P<0.05). The Nitraria tangutorum Bobrov+Kalidium foliatum (Pall.) Moq. community exhibited the most favorable pH and electrical conductivity. The Ammopiptanthus mongolicus (Maxim. ex Kom.) S. H. Cheng+N. tangutorum community had the highest total nitrogen content, while the highest alkali-hydrolyzed nitrogen content was recorded in the Krascheninnikovia ceratoides (L.) Gueldenst. community. Total potassium levels were highest in the Zygophyllum xanthoxylon (Bunge) Maxim. community. (2) Correlation analysis revealed that pH, conductivity, organic matter, total phosphorus, and available phosphorus were significantly positively correlated with multiple soil quality indicators. (3) The soil quality index (SQI) evaluation identified the N. tangutorum + K. foliatum community as having the highest soil quality, followed by the Haloxylon ammodendron (C. A. Mey.) Bunge+N. tangutorum community and the A. mongolicus + N. tangutorum community, all of which exhibited significantly better soil properties than other communities and the control. These three shrub communities play a critical role in improving soil quality in the Ulan Buhe Desert and have substantial implications for ecological restoration efforts in arid environments.

This study investigated the diversity and spatial distribution of vascular plants in Wudi County through a comprehensive field survey. Results indicated that: (1) Wudi County harbored 346 vascular plant species distributed across 72 families and 235 genera, comprising one family, one genus, and one species of ferns; three families, seven genera, and 11 species of gymnosperms; and 68 families, 227 genera, and 334 species of angiosperms. While the region exhibited high plant diversity, herbaceous plants accounted for a large proportion, with relatively few woody plants, resulting in a structurally simple plant community. (2) Species richness increased significantly from north to south, with biodiversity hotspots occurring in distinct clusters, although these clusters remained spatially isolated. (3) The flora was characterized by a high proportion of alien species, with several invasive taxa posing significant ecological threats. Overall, the vascular plant community in Wudi County is relatively simple, and the invasive species present a pressing challenge. To enhance biodiversity conservation, efforts should focus on promoting the introduction and cultivation of native plant species while strengthening the management of invasive alien taxa.

Environmental filtering and dispersal limitation are important drivers of beta-diversity in plant communities. This study investigated the relationships between beta-diversity, geographic distance, and environmental distance in rare and endangered plant communities associated with Davidia involucrata and Euptelea pleiosperma along the eastern margin of the Qinghai-Tibet Plateau, China. The aim was to assess the relative contributions of environmental filtering and dispersal limitation on community assembly in these threatened plant assemblages. A total of 21 rare and endangered plant species were recorded across 26 plant communities. Beta-diversity exhibited significant positive correlations with latitude, elevation, soil pH, and soil NH₄ concentration. Furthermore, beta-diversity was significantly positively correlated with both geographic and environmental distances. Multiple regression analysis of distance matrices (MRM) indicated that geographic and environmental distances collectively explained 19.1% of the variation in species composition, while principal coordinates of neighbor matrices (PCNM) analysis indicated that these factors explained 24.5% of the variation. Overall, these results suggest that beta-diversity in rare and endangered plant communities along the eastern margin of the Qinghai-Tibet Plateau is shaped by both environmental filtering and dispersal limitation, with environmental filtering playing a more dominant role in structuring species composition.

Solanum lycopersicum L. is one of the most widely cultivated cash crops globally, but its susceptibility to gray mold (Botrytis cinerea) causes significant economic losses. ERF transcription factors play a key role in plant stress responses. In this study, SlERF.F4 overexpression lines were generated and compared with wild-type tomato variety ‘AC’ (‘Ailsa Craig’) fruits to investigate the role of SlERF.F4 in mediating resistance to gray mold in tomatoes. Compared with ‘AC’ fruits, SlERF.F4-overexpressed (SlERF.F4-OE) fruits exhibited enhanced resistance to B. cinerea, as indicated by a slower lesion expansion following inoculation. Physiological and biochemical analyses revealed that the production rate of reactive oxygen species (ROS), including O₂^-. and H₂O₂ content, as well as malondialdehyde (MDA) levels, were significantly lower in SlERF.F4-OE fruits than in ‘AC’ fruits. Concurrently, antioxidant enzyme activities, including peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD), were significantly elevated in SlERF.F4-OE fruits. In addition, phenylalanine ammonia-lyase (PAL) activity was higher in SlERF.F4-OE fruits than in ‘AC’ fruits. These results suggest that SlERF.F4 enhances resistance to B. cinerea in S. lycopersicum fruits by regulating reactive oxygen homeostasis and defense enzyme activity. This study provides novel insights into the function of SlERF.F4 in fruit disease resistance.

Gibberellins (GAs) regulate diverse growth processes throughout the plant life cycle. DELLA proteins function as key repressors in the GA signaling pathway, inhibiting plant growth and development. The high expression of DELLA family genes in Dendrobium officinale Kimura et Migo seeds may be related to their poor natural germination. To identify interacting proteins of DoDELLA and elucidate its role in seed germination, a cDNA library was constructed from D. officinale seeds using Gateway recombination technology. A recombinant bait vector for DoDELLA4 was generated using homologous recombination and used to screen interacting proteins from the cDNA library. The constructed library exhibited a capacity of 1.20×10⁷ CFU, with an average insert size exceeding 1 000 bp and a recombination efficiency of 100%. The recombinant bait vector pGBKT7-DoDELLA4 effectively suppressed self-activation in SD/-Trp/-Leu/-His/-Ade medium supplemented with 20 mmol/L 3-AT. Screening identified 70 potential interacting proteins, and yeast two-hybrid assays confirmed interactions between DoDELLA4 and DoELIP1, 5807, DoTZF, DoUBQ, and DoGRPA3. These findings establish a foundation for further investigation into the molecular mechanisms by which DoDELLA regulates seed germination in D. officinale.

The effects of methyl jasmonate (MeJA) on the synthesis of antioxidant compounds in Lavandula angustifolia Mill. leaf suspension cells were investigated by introducing varying concentrations of MeJA into the culture medium. The optimal conditions for enhancing antioxidant synthesis were determined, and non-targeted metabolomics was employed to analyze the impact of MeJA on metabolite production. Results demonstrated that 8 mg/L MeJA inhibited both cell growth and antioxidant activity, whereas 2 mg/L MeJA significantly promoted the biosynthesis of antioxidant compounds. Compared with the untreated group, cells treated with 2 mg/L MeJA exhibited a 1.30-fold increase in ABTS radical scavenging activity and a 2.56-fold increase in ferric reducing antioxidant power (FRAP). Additionally, total phenol, flavonoid, and triterpene contents were elevated by 1.45-fold, 1.59-fold, and 1.24-fold, respectively. Metabolomic profiling using UHPLC-Q-TOF-MS identified 1 403 metabolites, with 151 showing significant differences between untreated and MeJA-treated cells. These differential metabolites were associated with 177 metabolic pathways, predominantly enriched in metabolic pathways and ABC transporter pathways. These findings suggest that MeJA modulates antioxidant biosynthesis in L. angustifolia suspension cells primarily by influencing metabolic signal transduction and regulating ABC transporter activity.

This study explored the effects of silver nanoparticles (AgNPs) on root growth, cellular integrity, and negative gravitropism in Arabidopsis thaliana (L.) Heynh.. Results revealed that: (1) Treatment with 30 mg/L AgNPs led to a significant accumulation of Ag in roots, surpassing the levels observed in roots treated with 0.12 mg/L Ag⁺ (equivalent to the Ag⁺ released from 30 mg/L AgNPs). (2) Exposure to 30 mg/L AgNPs markedly inhibited the number and length of root hairs. Transcriptome sequencing and RT-qPCR analyses indicated that 30 mg/L AgNPs suppressed the expression of key genes associated with root hair cell development, including AtRHS12, AtRHS14, AtCOW1, and AtMRH12. (3) Both 30 mg/L AgNPs and 30 mg/L Ag⁺ induced root callus formation and caused significant root cell damage in A. thaliana. However, no significant root damage was observed in plants treated with 0.12 mg/L Ag⁺, suggesting that the Ag⁺ released from AgNPs was insufficient to cause cellular damage. (4) Exposure to 30 mg/L AgNPs induced a spiral growth pattern in the main root, contrasting with the leftward growth induced by 30 mg/L and 0.12 mg/L Ag⁺. Transcriptome sequencing and RT-qPCR analyses revealed that both 30 mg/L AgNPs and 30 mg/L Ag⁺ significantly down-regulated ethylene-regulated genes such as AtERS1, AtETR2, AtERF1, AtERF11, and AtEBP, while up-regulating the key ethylene synthesis gene AtACS7. These findings suggest that AgNPs and Ag⁺ may influence negative gravitropism in A. thaliana roots by modulating ethylene signaling pathways and ethylene biosynthesis. In conclusion, 30 mg/L AgNPs inhibit root hair growth, induce root cell damage, and influence gravitropic bending in A. thaliana roots through the ethylene signaling pathway. The observed toxic effects are likely attributable to the intrinsic properties of the nanoparticles.

Polygonatum cyrtonema Hua is typically cultivated under forest conditions that mimic its natural habitat. The understory environment of Actinidia chinensis Planch. orchards shares similar ecological characteristics with forests, suggesting the potential feasibility of intercropping P. cyrtonema within A. chinensis orchards. However, optimizing an appropriate planting model and creating a suitable growth environment for P. cyrtonema requires experimental validation. This study assessed the growth and physiological adaptability of P. cyrtonema under different intercropping conditions by varying A. chinensis cultivars (‘Hongyang’ and ‘Jinyan’), canopy densities (60%, 30%, and full sunlight), and planting densities (row spacing of 25 cm×25 cm, 25 cm×40 cm, and 35 cm×40 cm). Results demonstrated that P. cyrtonema exhibited greater plant height and basal diameter in orchards planted with A. chinensis cv. Jinyan. Under 60% canopy density, chlorophyll content was elevated, while malondialdehyde (MDA) content and ascorbate peroxidase (APX) activity were lower. A 30% canopy density promoted greater plant height. In full sunlight, leaves had reduced relative water content but exhibited increased soluble protein, proline, MDA, total phenol, and flavonoid concentrations, along with higher catalase (CAT) and APX activity. Lower planting densities resulted in reduced MDA and total phenol concentrations in leaves, whereas higher planting densities were associated with increased MDA content. These findings indicate that intercropping P. cyrtonema within A. chinensis orchards is feasible. Optimal planting conditions were a canopy density of 30%–60% and a row spacing of (25–35) cm×40 cm.

This study investigated the relationship between phenotypic differences in leaf color and physiological factors influencing color expression in different leaf positions of Syzygium album Q. F. Zheng. To achieve this, S. album specimens at the same growth and developmental stage were selected for analysis. The study assessed leaf color using the Royal Horticultural Society Colour Chart (RHSCC), recorded color difference parameters, and measured pH and electrical conductivity (EC) values. In addition, pigment composition and soluble sugar content were quantified to examine their contributions to leaf coloration. Results revealed that: (1) Leaf color varied significantly across different positions, transitioning from red to yellow-green to green, with a gradual decrease in redness (+a*) and a gradual increase in green (-a*) and yellow (+b*). Leaf brightness (L*) exhibited a highly significant positive correlation with both the Chla/b and Fla/Chl ratios (P<0.01) and a negative correlation with soluble sugar content (P<0.05). (2) Leaf red-green coloration (a*) was significantly positively correlated with leaf fluid EC, anthocyanin content, and the OPC/Fla ratio, but significantly negatively correlated with leaf fluid pH, chlorophyll, carotenoid, and flavonoid content. Leaf coloration (C*) was significantly negatively correlated with soluble sugar content. (3) Leaf color differences were not determined by a single plastid pigment but rather by the relative composition and ratio of multiple pigments. The combined analysis of color difference parameters and pigment ratio coefficients facilitated the reduction of perceptual errors in assessing leaf color phenotypes through data mining approaches. These findings provide a theoretical foundation for evaluating color difference parameters and elucidating the physiological mechanisms underlying color expression in colored-leaf tree species.

This study investigated the effects of prolonged subculture on Atractylodes lancea tissue culture seedlings by examining morphological, physiological, biochemical, and transcriptomic changes across the third, tenth, and seventeenth subculture generations. Results indicated that: (1) With increasing subculture generations, growth rates declined, and seedlings exhibited reduced biomass, height, and leaf length-to-width ratios, indicative of phenotypic degradation. (2) Telomerase reverse transcriptase activity and chlorophyll fluorescence parameters (F_o and F_m) decreased, while soluble sugar, hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) increased. (3) Levels of endogenous hormones, including indole-3-acetic acid (IAA), cytokinin (CTK), and gibberellin (GA₃), also increased significantly with successive subcultures, indicating a progressive degree of hormonal dysregulation and degradation. (4) Transcriptome analysis revealed inhibition of fatty acid degradation, down-regulation of genes associated with the mevalonate (MVA) pathway, and blockade of acetyl coenzyme A synthesis. Genes associated with the gibberellin and ethylene pathways were down-regulated, while those related to the abscisic acid and auxin pathways were up-regulated. These disruptions in hormone metabolism and associated physiological processes contributed to metabolic imbalances and molecular-level degradation. Overall, prolonged subculture led to morphological atrophy, metabolic disturbances, accumulation of stress substances, inhibition of primary metabolic processes such as fatty acid degradation and secondary metabolite biosynthesis, and dysregulation of genes related to hormone signal transduction pathways. These combined effects culminated in the progressive degradation of A. lancea tissue culture seedlings.