Search Results (166)

Potato late blight, Phytophthora infestans, remains a major global threat to potato production due to the rapid genetic change, long-distance dispersal and fungicide resistance. To clarify the genetic structure and phenotypic characteristics of P. infestans populations in southwestern China during 2019–2025, this study analyzed 241 isolates collected from Sichuan, Chongqing, Guizhou, Yunnan and Hubei. The isolates were characterized using 14 SSR markers, together with mating-type determination, metalaxyl sensitivity assays, mitochondrial haplotype identification and virulence profiling. A total of 70 alleles and 118 multilocus genotypes were detected, with certain genotypes (SW-40, SW-48 and SW-81) broadly distributed across regions, while the simultaneous presence of numerous low-frequency genotypes reflected high overall genetic diversity. Population genetic analyses revealed weak regional differentiation and strong genetic connectivity, with most genetic variation occurring within regional populations, where self-fertile isolates, metalaxyl-resistant phenotypes and mitochondrial haplotype Ia were predominant. Cluster and principal component analyses separated the isolates into three major genetic groups, with the largest group containing most isolates and showing close genetic similarity to the Blue_13 reference genotype. These findings indicate that southwestern China harbors a highly diverse and admixed P. infestans population, likely driven by frequent pathogen movement among potato-growing regions. Full article

Fire occurrence in Southwest China is jointly shaped by meteorological conditions, topography, vegetation status, and human activities. To improve the interpretability and validation rigor of regional fire susceptibility assessment, this study developed a grid-day-based susceptibility assessment framework for Yunnan, Sichuan, Guizhou, and Chongqing using MODIS active-fire detections and multi-source environmental data from 2015 to 2024 at a 5 km grid resolution. A sensitivity analysis was conducted to determine the training sample configuration, and a 1:2 positive-to-negative sampling ratio was adopted. Random Forest (RF), Support Vector Machine (SVM), and Logistic Regression (LR) were compared, and SHapley Additive exPlanations (SHAP), together with partial dependence plots (PDP), were used to interpret key drivers and their interactions. Data from 2015 to 2018 were used for model training, while data from 2019 to 2024 were used to evaluate the model’s cross-year transferability within the same study domain, rather than full spatiotemporal independence. The results show that the 1:2 sampling ratio achieved a favorable balance between fire detection and false-alarm control. In five-fold stratified cross-validation, RF outperformed LR and SVM (AUC = 0.9167; F1-score = 76.70%). In the cross-year transferability test, areas classified as high and very high susceptibility captured 62.04–68.95% of the observed fire points while accounting for less than 32% of the total area. Soil moisture and maximum temperature contributed most strongly to the model output, and their interaction revealed a pronounced dry-hot statistical response pattern associated with elevated susceptibility. Fire susceptibility also exhibited stable positive spatial autocorrelation, with hotspot areas concentrated in the dry-hot valleys near the Sichuan-Yunnan border and in central-southern Yunnan. Because the model was built with under-sampled negatives and same-day environmental matching, the output should be interpreted as a relative fire susceptibility index for spatial assessment and statistical attribution rather than as a calibrated occurrence probability or a forward-looking daily forecast. Full article

Five new species of Orthosinus Motschulsky, 1863 from China are described: O. borisi sp. nov. (♂♀) and O. urceolatus sp. nov. (♂♀) from Xizang Autonomous Region, O. diaoluoshanensis sp. nov. (♂) from Hainan Province, O. sulcatus sp. nov. (♂♀) from Sichuan Province and O. tengchongensis sp. nov. (♂) from Yunnan Province. Detailed morphological descriptions, diagnostic illustrations, and habitus photographs are provided for each species. An identification key and a distribution map for all known Chinese species of Orthosinus are also provided. With these additions, the number of known Chinese species of Orthosinus is increased from two to seven. Molecular phylogenetic and species delimitation analyses of the COI gene were additionally performed for two of the newly described species, O. urceolatus sp. nov. and O. sulcatus sp. nov., along with other congeneric and outgroup specimens. Full article

Climate change is increasingly reshaping species habitat suitability worldwide. Primula L., the largest genus in Primulaceae, comprises 404 species in China (including 296 endemic species) and is characterized by high endemism and numerous rare and endangered taxa. However, global warming has intensified habitat fragmentation and loss, while its distribution patterns and key environmental drivers remain insufficiently understood. We compiled 7647 occurrence records of 404 wild Primula species in China and integrated 60 environmental variables (climatic, topographic, and soil factors). Using the MaxEnt model combined with ArcGIS spatial analysis, we assessed current and future habitat suitability, identified dominant environmental drivers, and quantified conservation gaps under multiple climate scenarios. Species richness is highly concentrated in Sichuan (186 species), Yunnan (177 species), and Xizang (165 species), with the Hengduan Mountains and eastern Himalayas representing the core distribution area and showing clear peripheral differentiation. The optimized MaxEnt model performed well (AUC = 0.858), identifying temperature seasonality (bio4, 39.8%) and elevation (27.1%) as the main limiting factors. The total suitable habitat area is 268.52 × 10⁴ km², with high-suitability areas mainly distributed in the Hengduan Mountains, southeastern Qinghai–Xizang Plateau, and the Central Mountain Range of Taiwan. Under three shared socioeconomic pathway (SSP) scenarios (SSP126, SSP245, and SSP585), suitable habitat shows a persistent decline, most pronounced under SSP585 in the 2090s (−20.73%), accompanied by a 25.86% reduction in low-suitability areas. Localized expansion of high-suitability habitats suggests that the Hengduan Mountains and southeastern Qinghai–Xizang Plateau may act as potential climatic refugia. Habitat loss consistently exceeds habitat gain, while the distribution centroid shifts westward and northwestward, with migration distances increasing under higher-emission scenarios. Conservation gap analysis indicates that 90.01% of high-suitability habitats lie outside the current protected area network, revealing a strong mismatch between biodiversity hotspots and conservation coverage. These findings highlight the urgent need to expand protected areas and establish micro-reserves in key gap regions (southwestern Sichuan, northwestern Yunnan, southeastern Xizang, and southern Gansu), and to integrate climate-driven migration corridors into conservation planning to support long-term alpine plant persistence under climate change. Full article

Lysimachia foenum-graecum Hance (LFG), renowned for its potent aroma, is widely utilized as a culinary spice in the food industry. This study employed GC-IMS and GC-MS to analyze samples from four distinct regions: Guangxi (GX), Guizhou (GZ), Sichuan (SC), and Yunnan (YN). The profiling effort led to the identification of 51 and 47 volatile compounds, respectively, with alcohols, aldehydes, esters, and ketones constituting the predominant organic compounds (74%). The GX samples exhibited the highest overall compound content, while SC samples were characterized by the highest ester content. Significant variations in compound concentrations were observed across different sources. PLS-DA identified 15 distinctive volatile markers that differentiate the four regions. Odor activity value (OAV) analysis revealed five key volatile compounds linalool, borneol, estragole, undecanal, and β-Ionone. In addition, cellular-level assays demonstrated the pharmacological activity of LFG. These findings provide valuable insights for the application of LFG in the food industry. Full article

An earthquake lethality model was employed to assess the casualty distribution in Yunnan, Guizhou, and Sichuan provinces, taking into account the ground motion acceleration with different 50-year exceedance probabilities. When the probability is 63%, fatalities are predominantly concentrated in central and south-western Yunnan, as well as central, southern, and western Sichuan. At a 10% probability, the peaks of the casualties are observed in southern, eastern, and central Sichuan. In Yunnan (excluding the northwest and southeast regions), the casualty density exhibits unevenness, whereas Guizhou experiences relatively low casualties (except in the eastern and western mountainous areas). Xichang incurs the most substantial losses, followed by Lancang. Xundian, Songming, and Dongchuan demonstrate a high propensity for fatalities, and the risk is relatively high in the vicinity of the Longjiang and Nujiang faults. If a destructive earthquake occurs near these areas within the next 50 years, the probability of a Level-I emergency response exceeds 10%. When the ground motion acceleration doubles (especially when the exceedance probability drops to 2% in 50 year and 0.1% in a year), the predicted number of casualties remains relatively stable. However, the grid of the casualty population exhibits a higher degree of spatial concentration of casualties, and the disaster-affected area expands. There exists no linear correlation between earthquake-induced fatalities and the ground motion level. When the 50-year exceedance probability decreases from 63% to 10%, the casualty rate may increase by several dozen times. Full article

Vegetation is an important component of ecosystems and plays an important role in carbon balance, water balance, and energy conversion. The spatial and temporal changes in the normalized difference vegetation index (NDVI), water resources, and hydrometeorological factors in southwest China between 2003 and 2020 were investigated using multisource remote sensing data. Correlation analyses were performed to assess the correlation among NDVI, water resource changes, and hydrometeorological factors with different time lags. A stepwise regression model with different lag times was constructed to clarify the effects of four topographic factors and eight climatic factors on NDVI, and the following conclusions were obtained: (1) NDVI increased from 2003 to 2020, and the increase became obvious after 2012. (2) NDVI was considerably affected by alterations in the soil water content caused by natural changes. The correlation of NDVI with evapotranspiration and precipitation was high, followed by NDVI’s correlation with surface temperature. The spatial distribution of the positive correlation between NDVI and evapotranspiration and NDVI and precipitation was relatively consistent, and a positive correlation was observed in most parts of Southwest China. (3) The hydrometeorological factors mainly affected NDVI with a lag of 0–1 month, and the correlation was high in western Sichuan and most of Yunnan. In Yunnan, Available Water Capacity (AWC) affected NDVI with a lag of 0–2 months; the lag was 0–1 month in western Yunnan and 1–2 months in eastern Yunnan. (4) In terms of different vertical heights, the NDVI in the regions with altitudes higher than 3000 m was affected by climate change, especially evapotranspiration and precipitation. (5) Digital Elevation Model (DEM), Latitude (Lat), Evapotranspiration (ET), Precipitation (PRCP), Land Surface Temperature (LST), and NDVI were closely related in the construction of stepwise regression models with different lag times. Full article

Critical metals such as gallium and germanium are strategic mineral resources widely used in advanced technology, including semiconductors and solar cells. These metals are recovered as by-products from the processing of Zn–Pb and bauxite ores. In China, the Sichuan–Yunnan–Guizhou (SYG) region is abundant in Zn–Pb and bauxite ore deposits, such as the Huize Zn–Pb–Ge deposit and the Wuchuan–Zheng’an–Daozhen (WZD) area Al–Ga deposit. Although previous studies have proposed models to explain the enrichment mechanisms of critical metals in this area, the metal sources of these deposits remain controversial. In this study, samples were collected from the Paleoproterozoic Kunyang Group to the Permian Emeishan basalts, and the metal sources of these deposits were traced by comparing the Pb isotopic ratios and Zn/Cd ratios of potential source rocks and deposits. The findings indicate: (1) The Pb isotopic compositions of most samples are relatively homogeneous, but certain differences exist among strata from different geological periods. (2) The metal sources of the Yunnan and Guizhou bauxite may both have been controlled by the underlying carbonate rocks, but the specific source horizons differ significantly between the two regions. (3) Based on the Pb isotopic compositions of regional strata and Zn–Pb deposits, it appears that the regional basement and sedimentary cover likely contributed significantly to the ore-forming metals, whereas the Emeishan basalts may have played a relatively minor role. However, due to the complex lithology and substantial thickness of the basement and cover strata in the SYG region, there may be issues of sampling inadequacy. Nonetheless, this study provides important foundational data and insights for tracing the metal sources of deposits in this region using Pb isotopes and Zn/Cd ratios. Full article

Bamboo plantations are increasingly recognized as significant terrestrial carbon sinks, yet accurate estimation of biomass and carbon stocks requires species-specific, regionally validated allometric models. Bambusa emeiensis L.C.Chia & H.L.Fung (ci bamboo) is among the most ecologically and economically important clump-forming bamboo species in southwestern China, but robust multi-regional allometric models are lacking. Using destructive sampling data from 127 culms across two major production areas—Sichuan Province (n = 82) and Guizhou Province (n = 45)—we developed additive biomass and carbon storage model systems enforcing mathematical additivity via nonlinear seemingly unrelated regression (NSUR). Allometric equations used diameter at breast height (D), culm height (H), and compound variables (DH, D²H) as predictors. Regional models achieved R_a² of 0.0879–0.8320 total relative error (TRE): −0.99% to 0.04% for biomass and R_a² of 0.0923–0.8282 (TRE: −1.01% to 0.03%) for carbon storage; culm and total aboveground models attained R_a² ≥ 0.52. Organ-level carbon content (40.79%–44.46%) was significantly lower than the intergovernmental panel on climate change (IPCC) default of 50% (one-sample t-test, p < 0.01 for all organs), with Sichuan values exceeding Guizhou values (independent-samples t-test, p < 0.01), indicating that use of the default would overestimate carbon stocks by 12%–22%. Cross-regional validation revealed prediction biases of up to ±19.24% when applying single-region models outside their training area, whereas the combined model held errors within ±11.36% for biomass and ±8.49% for carbon storage. External validation using 32 independent culms from Hunan, Yunnan, and Chongqing confirmed the robustness of the combined model (TRE: −6.30% to 4.27%). A key limitation is that belowground biomass was not measured. The established models provide scientifically rigorous and practically applicable tools for regional carbon accounting of B. emeiensis plantations under China’s national greenhouse gas inventory framework and for informing sustainable bamboo management planning, and demonstrate that species- and region-specific carbon fractions are essential for accurate carbon stock assessments. Full article

Background/Objectives: Fingered citron (Citrus medica L. var. sarcodactylis (Siebold ex Hoola van Nooten) Swingle) is rich in phenolic constituents, yet systematic comparisons of free and bound phenolics across tissues and origins remain limited. This study compared the peel, pulp, and blend (whole fruit) of fingered citron from five Chinese regions: Zhejiang (ZJ), Yunnan (YN), Sichuan (SC), Guangdong (GD), and Guangxi (GX). Methods: Phenolic compositions were determined by colorimetric assays and HPLC. Antioxidant activity was assessed by ORAC and PSC, and hypoglycemic-related activity by α-glucosidase and α-amylase inhibition and glucose consumption in an insulin-resistant HepG2 (IR-HepG2) cell model. Results: Phenolic distribution followed the order peel > blend > pulp, and free > bound. HPLC identified 11 free and 5 bound phenolics, predominantly hesperidin, quercetin, and 5,7-dimethoxycoumarin. GX peel exhibited the highest free phenolic content (106.34 ± 0.23 mg GAE/100 g FW) and superior ORAC (30.56 ± 0.50 μmol TE/g FW), strongly correlating with total phenolics (r = 0.98, p < 0.01). Free phenolics showed stronger α-glucosidase and α-amylase inhibition, whereas bound phenolics produced higher glucose consumption in the IR-HepG2 cell model. The GX blend bound fraction showed the highest glucose consumption (5.48 ± 0.98 mmol/L). Conclusions: Under fresh-weight-based conditions, phenolic composition and in vitro bioactivities differed by fruit part, region, and phenolic fraction. Peel, especially GX peel, tended to show higher phenolic levels and stronger antioxidant-related performance, whereas the GX blend bound fraction showed the highest glucose-consumption-promoting activity. Full article

A comprehensive annotated checklist of the members of the phytophagous ladybird beetle tribe Epilachnini (Coccinellinae) in China is compiled based on existing published sources and incorporates the latest taxonomic and nomenclatural updates. The checklist documents 176 extant species across 10 genera and provides analyses of regional species richness, distribution, and host plant associations. Regarding regional species richness, Yunnan Province is home to the highest number of species (76), followed by Taiwan (50), Sichuan (48), Guizhou (48), Guangxi (43), Tibet (43), Guangdong (25), Hainan (17), Hubei (17), Hunan (13), Shaanxi (13), Fujian (12), Henan (10), Jiangsu (10), Anhui (7), Shandong (7), Zhejiang (7), Jiangxi (5), Hong Kong (5), Gansu (5), Beijing (4), Hebei (4), Liaoning (3), Shanxi (2), and Chongqing, Jilin, Heilongjiang, Ningxia, and Xinjiang (each with one species). Among the recognized genera, Epilachna Chevrolat, 1837, is currently the most species-rich genera, with 59 species, followed by Afissa Dieke, 1947 (34), Uniparodentata Wang & Cao, 1993 (28), Henosepilachna Li, 1961 (29), Afidentula Kapur, 1958 (10), Diekeana Tomaszewska & Szawaryn, 2015 (9), and Epiverta Dieke, 1947 (4). Additionally, Afidenta Dieke, 1947, Cynegetis Chevrolat, 1837, and Subcoccinella Agassiz & Erichson, 1845 are each represented by a single species. Host plant data are currently available for only 72 species (approximately 41% of the species recorded in China), which are associated with 177 plant species across 34 families. The most frequently recorded host plant families are Solanaceae (43 species), Cucurbitaceae (32), Urticaceae (15), Fabaceae (14), Asteraceae (14), and Poaceae (10), whereas each of the remaining 28 families comprises fewer than 10 host species. For 104 species (59% of the Chinese members of the tribe), host plant associations remain unknown, highlighting a substantial gap in our understanding of their feeding habits. Full article

Environmental loading is a major driver of nonlinear GNSS vertical displacements, yet its spatiotemporal heterogeneity remains insufficiently understood in regions with complex topography. In this study, we investigate the environmental loading effects on GNSS vertical motions across Southwest China using observations from a network of 66 stations. Singular Spectrum Analysis (SSA) and Empirical Orthogonal Function (EOF) analysis were applied to extract annual signals, while component-wise RMS reduction quantified hydrological and atmospheric loading contributions. Spatial statistical analysis, cross-wavelet transform, and k-means clustering examined correlation patterns and phase hysteresis between GNSS observations and modeled loads. Results show that hydrological loading dominates seasonal vertical oscillations, but crustal responses exhibit pronounced spatial heterogeneity controlled by regional topography and hydro-climatic gradients. EOF analysis reveals a dipole pattern induced by the Hengduan Mountains’moisture-blocking effect. Atmospheric loading anomalously dominates the eastern Sichuan Basin, whereas Yunnan displays strong amplitudes with high heterogeneity due to karst hydrogeology. Phase analysis identifies three distinct regimes: a rapid elastic response on the Tibetan Plateau, (with the lag of ~20 ± 5 days, correlation coefficient R ≈ 0.65), intermediate delays in Yunnan (~60 ± 5 days, R ≈ 0.58), and pronounced hysteresis in the Sichuan Basin (~105 ± 5 days, R ≈ 0.38) linked to slow groundwater diffusion and poroelastic processes. These findings highlight the critical role of local hydrogeological dynamics in modulating GNSS vertical deformation and provide new insights for improving environmental loading corrections in complex mountainous regions. Full article

The Dongchuan District in Kunming City is located in the transition zone between the Yunnan–Guizhou Plateau and the Sichuan Basin. As a region with a copper mining history of over 2000 years, the district has experienced frequent landslides that pose serious threats to human lives, property, and ecological sustainability. Therefore, it is essential to compile a comprehensive landslide inventory and analyze the relationships between landslide spatial distribution and influencing factors for geological hazard prevention. High-resolution remote sensing imagery was interpreted to establish a landslide inventory, based on which the spatial distribution and geometric characteristics of landslides were systematically analyzed. The results show that a total of 1623 landslides were identified, with a total area of 10.36 km². Landslides predominantly occur at elevations of 1000–2000 m, on slopes of 20–45°, with aspects of 255–285°, and relief between 150 and 400 m, in areas with annual rainfall below 825 mm, within 1000 m of rivers and 3000 m of fault lines, and 1000–5000 m of mines. Four landslide clusters were delineated along the Xiao River Fault, highlighting the significant influence of the fault on the spatial distribution of landslides. Most landslides are longitudinal in planform, with travel distances (L) of 50–450 m and heights (H) from 25 to 350 m, both exhibiting allometric scaling with volume. The mean H/L ratio is 0.56 (corresponding to a mean reach angle of 29°), significantly higher than that in Baoshan City (21°). The results provide insights into landslide initiation mechanisms and spatial distribution patterns on the northern margin of the Yunnan–Guizhou Plateau, offering valuable data for landslide hazard assessment and sustainable regional development. Full article

Background: Pine wilt disease (PWD), caused by the pine wood nematode (PWN, Bursaphelenchus xylophilus), is a devastating forest disease. It has been reported in five provincial-level regions in Southwest China (Chongqing, Guizhou, Sichuan, Yunnan, and Tibet), threatening local pine forest ecosystems. Methods: To unravel the population genetic variation and population differentiation of PWN isolates in this region, we purified eighty-one isolates for whole-genome resequencing and bioinformatics analysis, identifying candidate genes associated with runs of homozygosity (ROH). Results: Population structure analysis clustered the 81 isolates into three distinct genetic groups (Groups 1, 2, and 3). Notably, Group 1 exhibited fewer and shorter ROH segments compared to Groups 2 and 3, indicating higher genetic diversity and a different inbreeding history. Functional annotation of genes overlapping ROH regions revealed that Group 1 contained a subset of the genes identified in Groups 2 and 3, primarily enriched in specific molecular function categories. Conclusions: The PWN populations in Southwest China exhibit genetic differentiation, forming three distinct groups. Group 1 shows a reduced ROH burden and lower inbreeding levels, whereas Groups 2 and 3 display more extensive ROH patterns that may reflect historical demographic processes or potential adaptive selection. The differential distribution of ROH-associated genes across groups suggests possible variation in historical demographic processes and could suggest possible directional selection. These findings contribute to understanding the population history and genomic characteristics of PWN in Southwest China, providing insights that could support disease management strategies. Full article

Aconitum carmichaelii Debeaux has been a traditional medicinal resource in China for over two millennia. However, sustainable utilization and preservation strategies for A. carmichaelii require a thorough understanding of environmental factors influencing its distribution. An optimized MaxEnt model was constructed using the ENMeval package based on 185 quality-controlled occurrence records and 10 selected environmental variables (bioclimatic, edaphic, topographic, and anthropogenic). The optimized model demonstrated reliable predictive accuracy, with an area under curve (AUC) value of 0.896. Soil moisture (37.7% contribution), human footprint (HFP) (23.9%), and July solar radiation (11.1%) were the primary variables determining A. carmichaelii distribution. The suitable thresholds were defined as soil moisture > 87.34 mm, HFP > 10.69, and July solar radiation < 19,125.72 kJ m⁻² day⁻¹. At present, highly suitable habitat covers approximately 8.243 × 10⁵ km², predominantly located in the Sichuan Basin and surrounding regions, including Sichuan, Chongqing, Guizhou, and northeastern Yunnan. Future predictions under all Shared Socioeconomic Pathway (SSP) scenarios indicate a significant reduction in highly suitable habitat, with losses of 63.01% (2041–2060, SSP126), 62.62% (2041–2060, SSP245), 61.35% (2041–2060, SSP370), and 61.99% (2061–2080, SSP585). Habitat contraction mainly occurs toward higher altitudes and southwestern areas, with a maximum displacement distance of 50.56 km under the SSP585 scenario. This study enhances our understanding of environmental factors affecting the distribution of A. carmichaelii and offers guidance for its sustainable management and cultivation amid global climate change. Full article