Predicting the potential global distribution of Ageratina adenophora under current and future climate change scenarios

Distinct effects of phyllosphere and rhizosphere microbes on invader Ageratina adenophora during its early life stages

Microbes strongly affect invasive plant growth. However, how phyllosphere and rhizosphere soil microbes distinctively affect seedling mortality and growth of invaders across ontogeny under varying soil nutrient levels remains unclear. In this study, we used the invader Ageratina adenophora to evaluate these effects. We found that higher proportions of potential pathogens were detected in core microbial taxa in leaf litter than rhizosphere soil and thus leaf inoculation had more adverse effects on seed germination and seedling survival than soil inoculation. Microbial inoculation at different growth stages altered the microbial community and functions of seedlings, and earlier inoculation had a more adverse effect on seedling survival and growth. The soil nutrient level did not affect microbe-mediated seedling growth and the relative abundance of the microbial community and functions involved in seedling growth. The effects of some microbial genera on seedling survival are distinct from those on growth. Moreover, the A. adenophora seedling-killing effects of fungal strains isolated from dead seedlings by non-sterile leaf inoculation exhibited significant phylogenetic signals, by which strains of Allophoma and Alternaria generally caused high seedling mortality. Our study stresses the essential role of A. adenophora litter microbes in population establishment by regulating seedling density and growth.

Current and future distribution of Forsythia suspensa in China under climate change adopting the MaxEnt model

This study evaluated the potential impact of climate change on the distribution of Forsythia suspensa, a valuable traditional Chinese medicinal plant, using the MaxEnt model integrated with Geographic Information System (GIS). By analyzing occurrence data from various databases and environmental variables including climate and soil factors, we forecasted the present and future (2050s and 2070s) habitat suitability of F. suspensa under different greenhouse gas emission scenarios (RCP8.5, RCP4.5, RCP2.6). Results indicated that the suitable habitats for F. suspensa were primarily located in North, East, Central, Northwest, and Southwest China, with a significant potential expansion of suitable habitats anticipated by the 2070s, particularly under the high emission scenario. The study identified precipitation and temperature as the primary environmental drivers impacting the distribution of F. suspensa. Furthermore, a northward shift in the centroid of suitable habitats under future climate scenarios suggested a potential migration response to global warming. This work provides crucial insights into the future conservation and cultivation strategies for F. suspensa amidst changing climatic conditions.

Phytochemically analysed extract of Ageratina adenophora (Sprengel) R.M.King & H. Rob. initiates caspase 3-dependant apoptosis in colorectal cancer cell: A synergistic approach with chemotherapeutic drugs

ETHNOPHARMACOLOGICAL RELEVANCE

Ageratina adenophora (Sprengel) R.M.King & H.Rob. has been used as traditional indigenous medicine all across the globe for its diverse therapeutic applications such as anticancer, analgesic, antipyretic, thermogenic, antiseptic, antimicrobial as well as astringent. The various ethnic groups of India use plant parts to treat cuts and wounds, venomous insect bites, skin lesions, blisters, scabies and other skin irritations, gastritis and indigestion problems, cough, stomach ache and dysentery. The Portuguese traditionally extract the juice from the plant and use it for cancer, diabetes, liver disorder, gallbladder and stomach ailments. Nigerian healers use different parts of the plant to treat diabetes, fever and inflammation.

AIM OF THE STUDY

The aim of this study is to investigate the cytotoxic potential of A. adenophora hydroalcoholic leaves extract (AHL) on Colorectal cancer (CRC) cell lines (HCT-116, HCT-15 and HT-29), synergistic potential with chemotherapeutic drugs 5FU and Cisplatin as well as reactive oxygen species (ROS) generation, based on the sample collected from Mao district of Manipur, India. Identification of bioactive phytocompounds in AHL was also performed by HRLCMS.

METHODS

The AHL was evaluated for its cytotoxic as well as antiproliferative activities by 3-(4, 5-dimethylthiazol-2-yl)-2, 5 diphenyltetrazolium bromide (MTT) assay, clonogenic and cell migration assays. The total phenolic content (TPC) and total flavonoid content (TFC) were quantified by Folin-ciocalteu and Aluminium chloride assays respectively. Caspase 3 activation was evaluated using Caspase-3 Assay Kit. Apoptosis detection by flow cytometry was carried out using annexin V-FITC/PI apoptosis detection kit. The apoptotic cells were also visualized by Giemsa and 4',6-Diamidino-2-phenylindole (DAPI) staining. The intracellular Reactive oxygen species (ROS) generation was also evaluated using fluorescent probe 2',7'-dichlorodihydrofluorescein di-acetate (H2DCFDA) in flow cytometry. The combination effects of AHL with chemotherapeutic drugs 5FU and Cisplatin were also evaluated. The identification of phytochemical constituents of AHL were analysed by HR-LCMS.

RESULTS

The AHL induced cytotoxic activity significantly in HCT-116 with IC50 of 65.65 ± 2.10 μg/mL, but non-cancerous cell HeK-293 was least cytotoxic. Colony formation and cell migration were inhibited in a dose and time dependent manner. The cell morphology upon AHL treatment was significantly altered with apoptotic features. The extract was rich in total phenolic (82.09 ± 0.35mgGAE/g) and total flavonoid (58.31 ± 0.55 mgQAE/g) contents. AHL induced apoptosis as detected by AnnexinV/PI, via activation of caspase 3 and elevated production of Reactive oxygen species (ROS). AHL in combination with 5FU and Cisplatin acts synergistically and potentiates the therapeutic properties of the extract. Sesquiterpenes, phenolic as well as flavonoid derivatives with anticancer properties were detected in AHL by HRLCMS, and these phytoconstituents may be attributed for anticancer property of AHL.

CONCLUSION

The present study evaluates the effectiveness of AHL against Colorectal cancer cell lines. AHL is cytotoxic and induces apoptosis in HCT-116 cells by caspase 3 activation and increased ROS production that can be attributed to sesquiterpenoids. Thus, the plant A. adenophora has therapeutic potential for Colorectal cancer and can be further exploited for developing anticancer drug.

Habitat suitability of Opuntia ficus-indica (L.) MILL. (CACTACEAE): a comparative temporal evaluation using diverse bio-climatic earth system models and ensemble machine learning approach

A comprehensive evaluation of the habitat suitability across the India was conducted for the introduced species Opuntia ficus-indica. This assessment utilized a newly developed model called BioClimInd, takes into account five Earth System Models (ESMs). These ESMs consider two different emission scenarios known as Representative Concentration Pathways (RCP), specifically RCP 4.5 and RCP 8.5. Additionally, the assessment considered two future time frames: 2040-2079 (60) and 2060-2099 (80). Current study provided the threshold limit of different climatic variables in annual, quarter and monthly time slots like temperature annual range (26-30 °C), mean temperature of the driest quarter (25-28 °C); mean temperature of the coldest month (22-25 °C); minimum temperature of coldest month (13-17 °C); precipitation of the wettest month (250-500 mm); potential evapotranspiration Thronthwaite (1740-1800 mm). Predictive climatic habitat suitability posits that the introduction of this exotic species is deemed unsuitable in the Northern as well as the entirety of the cooler eastern areas of the country. The states of Rajasthan and Gujarat exhibit the highest degree of habitat suitability for this particular species. Niche hypervolumes and climatic variables affecting fundamental and realized niches were also assessed. This study proposes using multi-climatic exploration to evaluate habitats for introduced species to reduce modeling uncertainties.

Biomod2 modeling for predicting the potential ecological distribution of three Fritillaria species under climate change

The Fritillaria species ranked as a well-known traditional medicine in China and has become rare due to excessive harvesting. To find reasonable strategy for conservation and cultivation, identification of new ecological distribution of Fritillaria species together with prediction of those responses to climate change are necessary. In terms of current occurrence records and bioclimatic variables, the suitable habitats for Fritillaria delavayi, Fritillaria taipaiensis, and Fritillaria wabuensis were predicted. In comparison with Maxent and GARP, Biomod2 obtained the best AUC, KAPPA and TSS values of larger than 0.926 and was chosen to construct model. Temperature seasonality was indicated to put the greatest influence on Fritillaria taipaiensis and Fritillaria wabuensis, while isothermality was of most importance for Fritillaria delavayi. The current suitable areas for three Fritillaria species were distributed in south-west China, accounting for approximately 17.72%, 23.06% and 20.60% of China's total area, respectively. During 2021-2100 period, the suitable habitats of F. delavayi and F. wabuensis reached the maximum under SSP585 scenario, while that of F. taipaiensis reached the maximum under SSP126 scenario. The high niche overlap among three Fritillaria species showed correlation with the chemical composition (P ≤ 0.05), while no correlation was observed between niche overlap and DNA barcodes, indicating that spatial distribution had a major influence on chemical composition in the Fritillaria species. Finally, the acquisition of species-specific habitats would contribute to decrease in habitat competition, and future conservation and cultivation of Fritillaria species.

Genetic Evidence for Colletotrichum gloeosporioides Transmission Between the Invasive Plant Ageratina adenophora and Co-occurring Neighbor Plants

To understand the disease-mediated invasion of exotic plants and the potential risk of disease transmission in local ecosystems, it is necessary to characterize population genetic structure and spatio-temporal dynamics of fungal community associated with both invasive and co-occurring plants. In this study, multiple genes were used to characterize the genetic diversity of 165 strains of Colletotrichum gloeosporioides species complex (CGSC) isolated from healthy leaves and symptomatic leaves of invasive plant Ageratina adenophora, as well as symptomatic leaves of its neighbor plants from eleven geographic sites in China. The data showed that these CGSC strains had a high genetic diversity in each geographic site (all Hd > 0.67 and Pi > 0.01). Haplotype diversity and nucleotide diversity varied greatly in individual gene locus: gs had the highest haplotype diversity (Hd = 0.8972), gapdh had the highest nucleotide diversity (Pi = 0.0705), and ITS had the lowest nucleotide diversity (Pi = 0.0074). Haplotypes were not clustered by geographic site, invasive age, or isolation source. AMOVA revealed that the genetic variation was mainly from within-populations, regardless of geographic or isolation origin. Both AMOVA and neutrality tests indicated these CGSC strains occurred gene exchange among geographic populations but did not experience population expansion along with A. adenophora invasion progress. Our data indicated that A. adenophora primarily accumulated these CGSC fungi in the introduced range, suggesting a high frequency of CGSC transmission between A. adenophora and co-occurring neighbor plants. This study is valuable for understanding the disease-mediated plant invasion and the potential risk of disease transmission driven by exotic plants in local ecosystems.

Effects of Septoglomus constrictum and Bacillus cereus on the competitive growth of Ageratina adenophora

Beneficial microorganisms play a pivotal role in the invasion process of exotic plants, including arbuscular mycorrhizal fungi (AMF) and Bacillus. However, limited research exists on the synergistic influence of AMF and Bacillus on the competition between both invasive and native plants. In this study, pot cultures of Ageratina adenophora monoculture, Rabdosia amethystoides monoculture, and A. adenophora and R. amethystoides mixture were used to investigate the effects of dominant AMF (Septoglomus constrictum, SC) and Bacillus cereus (BC), and the co-inoculation of BC and SC on the competitive growth of A. adenophora. The results showed that inoculation with BC, SC, and BC + SC significantly increased the biomass of A. adenophora by 14.77, 112.07, and 197.74%, respectively, in the competitive growth between A. adenophora and R. amethystoides. Additionally, inoculation with BC increased the biomass of R. amethystoides by 185.07%, while inoculation with SC or BC + SC decreased R. amethystoides biomass by 37.31 and 59.70% compared to the uninoculated treatment. Inoculation with BC significantly increased the nutrient contents in the rhizosphere soil of both plants and promoted their growth. Inoculation with SC or SC + BC notably increased the nitrogen and phosphorus contents of A. adenophora, therefore enhancing its competitiveness. Compared with single inoculation, dual inoculation with SC and BC increased AMF colonization rate and Bacillus density, indicating that SC and BC can form a synergistic effect to further enhance the growth and competitiveness of A. adenophora. This study reveals the distinct role of S. constrictum and B. cereus during the invasion of A. adenophora, and provide new clues to the underlying mechanisms of interaction between invasive plant, AMF and Bacillus.

Monitoring the distribution pattern and invasion status of Ageratina adenophora across elevational gradients in Sikkim Himalaya, India

Understanding the spread intensity and population dynamics of invasive plant species is a prerequisite for developing management strategies in the Himalayan Forest ecosystems that are experiencing an accelerated rate of climate change. Although there are studies on the occurrence of few invasive species in the Himalayan ecosystems, systematic information on their intensity of spread and species association is still missing. Considering existing data gaps, we aimed to assess the intensity of spread and distribution pattern of A. adenophora, one of the high-concern invasive species (HiCIS) of India that is causing havoc in the Himalayas, across an elevational gradient. Field data were collected in 2018 and 2021 in the Indian federal state of Sikkim, located in the Eastern Himalayas. We analyzed the population status and species association of A. adenophora along an elevational gradient ranging from > 600 m to 2700 m above sea level, which was divided into seven gradients of 300 m width, and each gradient was further randomly sampled. Overall, 81 species were present in association with A. adenophora, including 58 herbs, 19 shrubs, and 4 climbers, belonging to 30 families and 67 genera in the region. No other species continuously co-occurred along with A. adenophora throughout the elevation ranging from > 600 m to 2700 m. The species observed increased frequency (100%), density (40.51 ind./100 m²), and basal cover (11.25 cm²/m²) in the elevational gradient 1500-1800 m in 2018. In 2021, A. adenophora dominated the highest elevational gradient (< 2400-2700 m) with increased frequency (99.96%), density (58.41 ind./100m²), and basal cover (42.54 cm²/100m²), which demonstrated rapid invasion and improved plant health and reproductive vigor in comparison to the lower elevational gradient in Sikkim Himalaya. Despite being completely absent at the highest elevation (< 2400-2700 m), in 2018, it observed gregarious spread at the highest elevation in 2021, which is of serious concern to ecologists. The presence of the targeted species in all seven studied altitudinal gradients reflects stage III of the species invasion. An enormous shift in the distribution pattern along elevational gradients within a short time span is alarming for the Himalayan ecosystem since it is becoming a thriving habitat for invasive species owing to anthropogenic activity. We mapped the potential geographical extent using the species distribution model (SDM) and predicted the suitable habitat of distribution in Sikkim Himalaya. In order to curtail the spread and counteract the negative impact of this species on native vegetation in Sikkim Himalaya and ultimately reverse the process, local and regional initiatives for its biological control and management must be taken.

Predicting Climate Change Effects on the Potential Distribution of Two Invasive Cryptic Species of the Bemisia tabaci Species Complex in China

Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) are two invasive cryptic species of the Bemisia tabaci species complex (Hemiptera: Aleyrodidae) that cause serious damage to agricultural and horticultural crops worldwide. To explore the possible impact of climate change on their distribution, the maximum entropy (MaxEnt) model was used to predict the potential distribution ranges of MEAM1 and MED in China under current and four future climate scenarios, using shared socioeconomic pathways (SSPs), namely SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5, over four time periods (2021-2040, 2041-2060, 2061-2080, and 2081-2100). The distribution ranges of MEAM1 and MED were extensive and similar in China under current climatic conditions, while their moderately and highly suitable habitat ranges differed. Under future climate scenarios, the areas of suitable habitat of different levels for MEAM1 and MED were predicted to increase to different degrees. However, the predicted expansion of suitable habitats varied between them, suggesting that these invasive cryptic species respond differently to climate change. Our results illustrate the difference in the effects of climate change on the geographical distribution of different cryptic species of B. tabaci and provide insightful information for further forecasting and managing the two invasive cryptic species in China.

Potential distribution of three types of ephemeral plants under climate changes

BACKGROUND

Arid and semi-arid regions account for about 40% of the world's land surface area, and are the most sensitive areas to climate change, leading to a dramatic expansion of arid regions in recent decades. Ephemeral plants are crucial herbs in this area and are very sensitive to climate change, but it is still unclear which factors can determine the distribution of ephemeral plants and how the distribution of ephemeral plants responds to future climate change across the globe.

AIMS

Understanding the impact of climate change on ephemeral plant distribution is crucial for sustainable biodiversity conservation.

METHODS

This study explored the potential distribution of three types of ephemeral plants in arid and semi-arid regions (cold desert, hot desert, and deciduous forest) on a global scale using the MaxEnt software. We used species global occurrence data and 30 environmental factors in scientific collections.

RESULTS

Our results showed that (1) the average value of the area under the receiver operating curve (AUC) of each species was higher than 0.95, indicating that the MaxEnt model's simulation accuracy for each species was good; (2) distributions of cold desert and deciduous forest species were mainly determined by soil pH and annual mean temperature; the key factor that determines the distribution of hot desert species was precipitation of the driest month; and (3) the potential distribution of ephemeral plants in the cold desert was increased under one-third of climate scenarios; in the hot desert, the potential suitable distribution for Anastatica hierochuntica was decreased in more than half of the climate scenarios, but Trigonella arabica was increased in more than half of the climate scenarios. In deciduous forests, the ephemeral plant Crocus alatavicus decreased in nearly nine-tenths of climate scenarios, and Gagea filiformis was increased in 75% of climate scenarios.

CONCLUSIONS

The potential suitable distributions of ephemeral plants in the different ecosystems were closely related to their specific adaptation strategies. These results contribute to a comprehensive understanding of the potential distribution pattern of some ephemeral plants in arid and semi-arid ecosystems.

Mapping the Distribution and Dispersal Risks of the Alien Invasive Plant Ageratina adenophora in China

Identifying the distribution dynamics of invasive alien species can help in the early detection of and rapid response to these invasive species in newly invaded sites. Ageratina adenophora, a worldwide invasive plant, has spread rapidly since its invasion in China in the 1940s, causing serious damage to the local socioeconomic and ecological environment. To better control the spread of this invasive plant, we used the MaxEnt model and ArcGIS based on field survey data and online databases to simulate and predict the spatial and temporal distribution patterns and risk areas for the spread of this species in China, and thus examined the key factors responsible for this weed’s spread. The results showed that the risk areas for the invasion of A. adenophora in the current period were 18.394° N–33.653° N and 91.099° E–121.756° E, mainly in the tropical and subtropical regions of China, and densely distributed along rivers and well-developed roads. The high-risk areas are mainly located in the basins of the Lancang, Jinsha, Yalong, and Anning Rivers. With global climate change, the trend of continued invasion of A. adenophora is more evident, with further expansion of the dispersal zone towards the northeast and coastal areas in all climatic scenarios, and a slight contraction in the Yunnan–Guizhou plateau. Temperature, precipitation, altitude, and human activity are key factors in shaping the distribution pattern of A. adenophora. This weed prefers to grow in warm and precipitation-rich environments such as plains, hills, and mountains; in addition, increasing human activities provide more opportunities for its invasion, and well-developed water systems and roads can facilitate its spread. Measures should be taken to prevent its spread into these risk areas.

Rhizospheric Bacillus-Facilitated Effects on the Growth and Competitive Ability of the Invasive Plant Ageratina adenophora

The rhizospheric microbial community affects the population establishment of invasive plants in introduced areas, among which Bacillus has numerous functions in promoting plant growth. This study isolated and enriched the Bacillus community in the rhizospheric soil of the invasive plant Ageratina adenophora and the native accompanying plant Rabdosia amethystoides. The effects of these rhizospheric Bacillus communities on the growth and competition of A. adenophora and R. amethystoides were evaluated in pot experiments. The results showed that the number and diversity of Bacillus in the rhizospheric soil of A. adenophora were higher than those of R. amethystoides (A. adenophora: 122 strains in soil, 16 Bacillus taxa; R. amethystoides: 88 strains in soil, 9 Bacillus taxa). After Bacillus inoculation of A. adenophora in a pot experiment, Bacillus idriensis, Bacillus toyonensis and Bacillus cereus were accumulated in the rhizospheric of A. adenophora, which significantly increased the nitrate nitrogen (NO₃ ^--N) content in the soil and the total carbon and nitrogen concentrations in A. adenophora in the mixed treatment. The selective accumulation of Bacillus enhanced the competitive advantage of A. adenophora over the native accompanying plant; the corrected index of relative competition intensity of A. adenophora-inoculated Bacillus reached double that of the uninoculated treatment, and the growth of native plants was greatly suppressed under mixed planting. Our study confirmed that invasion of A. adenophora can lead to the accumulation of specific Bacillus taxa in the rhizospheric soil, which in turn can increase the competitive advantage of A. adenophora.

New Evidence on the Linkage of Population Trends and Species Traits to Long-Term Niche Changes

Despite the assessment of long-term niche dynamics could provide crucial information for investigating species responses to environmental changes, it is a poorly investigated topic in ecology. Here, we present a case study of multi-species niche analysis for 71 common breeding birds in Northern Italy, exploring long-term niche changes from 1992 to 2017 and their relationship with both population trends and species traits. We (i) quantified the realized Grinnellian niche in the environmental space, (ii) compared variations in niche breadth and centroid, (iii) tested niche divergence and conservatism through equivalency and similarity tests, (iv) calculated niche temporal overlap, expansion and unfilling indices, and (v) investigated their association with both population changes and species traits. Results supported niche divergence (equivalency test) for 32% of species, although two-thirds were not supported by the similarity test. We detected a general tendency to adjust the niche centroids towards warmer thermal conditions. Increasing populations were positively correlated with niche expansion, while negatively correlated with niche overlap, albeit at the limit of the significance threshold. We found moderate evidence for a non-random association between niche changes and species traits, especially for body size, clutch size, number of broods per year, inhabited landscape type, and migration strategy. We encourage studies correlating long-term population trends and niche changes with species traits’ information and a specific focus on cause-effect relationship at both the single and multiple-species level.

Current and future distribution of the deciduous shrub Hydrangea macrophylla in China estimated by MaxEnt

Climate change has a significant impact on the growth and distribution of vegetation worldwide. Hydrangea macrophylla is widely distributed and considered a model species for studying the distribution and responses of shrub plants under climate change. These results can inform decision-making regarding shrub plant protection, management, and introduction of germplasm resources, and are of great importance for formulating ecological countermeasures to climate change in the future. We used the maximum entropy model to predict the change, scope expansion/reduction, centroid movement, and dominant climate factors that restrict the growth and distribution of H. macrophylla in China under current and future climate change scenarios. It was found that both precipitation and temperature affect the distribution of suitable habitat for H. macrophylla. Akaike information criterion (AICc) was used to select the feature combination (FC) and the regularization multiplier (RM). After the establishment of the optimal model (FC = QP, RM = 0.5), the complexity and over-fitting degree of the model were low (delta AICc = 0, omission rate = 0.026, difference between training and testing area under the curve values = 0.0009), indicating that it had high accuracy in predicting the potential geographical distribution of H. macrophylla (area under the curve = 0.979). Overall, from the current period to future, the potential suitable habitat of this species in China expanded to the north. The greenhouse effect caused by an increase in CO2 emissions would not only increase the area of high-suitability habitat in Central China, but also expand the area of total suitable habitat in the north. Under the maximum greenhouse gas emission scenario (RCP8.5), the migration distance of the centroid was the longest (e.g., By 2070s, the centroids of total and highly suitable areas have shifted 186.15 km and 89.84 km, respectively).