Rhizobacteria’s Effects on the Growth and Competitiveness of Solidago canadensis Under Nutrient Limitation

Abstract

The role of rhizosphere bacteria in facilitating plant invasion is increasingly acknowledged, yet the influence of specific microbial functional traits remains insufficiently understood. This study addresses this gap by isolating two bacterial strains, Bacillus sp. ScRB44 and Pseudomonas sp. ScRB22, from the rhizosphere of the invasive weed Solidago canadensis. We assessed their nitrogen utilization capacity and indoleacetic acid (IAA) production capabilities to evaluate their ecological functions. Our three-stage experimental design encompassed strain promotion, nutrient stress, and competition phases. Bacillus sp. ScRB44 demonstrated robust IAA production and significantly improved the nitrogen utilization efficiency, significantly enhancing S. canadensis growth, especially under nutrient-poor conditions, and promoting a shift in biomass allocation toward the roots, thereby conferring a competitive advantage over native species. Conversely, Pseudomonas sp. ScRB22 exhibited limited functional activity and a negligible impact on plant performance. These findings underscore that the ecological impact of rhizosphere bacteria on invasive weeds is closely linked to their specific growth-promoting functions. By enhancing stress adaptation and optimizing resource allocation, certain microorganisms may facilitate the establishment of invasive weeds in adverse environments. This study highlights the significance of microbial functional traits in invasion ecology and suggests novel approaches for microbiome-based invasive weed management, with potential applications in agricultural soil health improvement and ecological restoration.

1. Introduction

Biological invasion is a phenomenon in which alien species successfully establish and spread within new ecosystems due to natural or anthropogenic factors [1]. These invasions not only alter ecological communities but also significantly affect the global distribution of organisms, posing a serious threat to global biodiversity [2]. With the deepening of globalization, invasive alien species, e.g., invasive weeds, have caused substantial ecological and economic damage worldwide [3]. This disruption can severely alter ecosystem structure and function [4], impacting nutrient cycling and energy flow. For example, invasive plants can influence the carbon cycle by increasing community productivity and contributing more biomass to the soil [5].

Invasive weeds adapt well to new environments and frequently form beneficial microbial interactions [6,7] and enhance their competition for resources like nutrients, light, and water [8,9]. Studies emphasize rhizospheric microorganisms’ role in plant performance, as plants selectively recruit them via root exudates, where these microbes influence plant development and stress responses [10].

The rhizosphere harbors diverse microorganisms that promote plant health by enhancing nutrient uptake and pathogen resistance [11], though their efficacy depends on specific environmental conditions [12]. Root-associated microbes can enhance plant performance by modulating the bacterial community for beneficial traits like hormone production and nutrient solubilization [13], while plants employ innate immunity against pathogens [14], a system these microbes can influence to regulate plant growth [15].

Nitrogen-fixing bacteria are among the most extensively studied plant-beneficial microbes due to their ability to convert atmospheric nitrogen into a form usable by plants [16]. Beyond nitrogen fixation, these bacteria possess multiple functional traits that enhance plant growth and soil health, including (1) symbiotic associations with host plants [17], (2) production of growth-promoting hormones (e.g., auxins, cytokinins), (3) phosphate solubilization, (4) soil structure modification, and (5) organic matter decomposition [18,19,20]. Other growth-promoting bacteria, such as species of Herbaspirillum, also contribute to nitrogen acquisition through nitrogen fixation, nitrification, and phytohormone production [21]. These hormones can influence root architecture, increasing the surface area for nutrient absorption [22,23].

Soil microbial interactions influence not only plant growth and nutrient acquisition but also resistance to stress and competition with other plant species [24]. These microbes benefit from root exudates as carbon sources [25], and in turn, plants can shape microbial communities by promoting or suppressing specific populations [26]. Invasive weeds often manipulate rhizosphere microbial structures to enhance their growth and competitive ability, creating soil conditions that support their continued spread [27]. Increased microbial diversity in the rhizosphere reinforces mutual feedback between plants and microbes, driving ecosystem-level changes [28]. Therefore, understanding plant microbe interactions in the rhizosphere is essential for uncovering the mechanisms of plant invasion.

Among rhizospheric microbes, plant growth-promoting rhizobacteria (PGPR) play a particularly important role. While nitrogen-fixing bacteria (e.g., Herbaspirillum) are a subset of PGPR, other PGPR strains enhance plant growth through distinct mechanisms such as indole-3-acetic acid (IAA) production, which stimulates root branching and nutrient uptake [29]. These changes in root structure expand the surface area for water and nutrient absorption, enabling plants to more effectively access critical soil nutrients like phosphorus and potassium. Furthermore, certain PGPR strains possess nitrogen-fixing capabilities, converting atmospheric nitrogen (N₂) into ammonia (NH₃), a form of nitrogen that plants can readily absorb [21]. By boosting both hormone production and nutrient uptake, these microbes significantly enhance plant growth, development, and overall productivity. They give plants a competitive advantage in resource-limited environments, supporting their establishment and survival under various nutrient-deficient conditions [30]. Beyond agriculture, their role in shaping plant microbe dynamics during biological invasions is gaining interest [31].

Microorganisms, particularly PGPRs, play a key role in the invasion process by enhancing the growth and competitiveness of invasive weeds [32]. PGPR can interact with root exudates and chemosensory signals released by invasive weeds, thereby altering the composition and structure of the soil microbial community. These beneficial microbes not only enhance the growth potential of invasive weeds by improving nutrient uptake and stimulating hormone production but also suppress certain soil pathogens and native plant species, ultimately reshaping belowground biodiversity. Through these mechanisms, PGPRs provide invasive weeds with substantial growth and a competitive advantage, enabling them to better adapt to and spread in new environments [33,34,35].

Solidago canadensis L. originates from North America [36], and it has successfully invaded Asia, Europe, Oceania, etc. In particular, S. canadensis has become a notorious weed in diverse habitats in East China, including on roadsides, in abandoned and agricultural fields, and even in open barren areas [37]. This is a highly invasive species due to its rapid reproduction, fast spread, strong growth advantages, and ability to adapt to various environments [38]. It aggressively displaces native plants, causing severe damage to local vegetation and crops, threatening natural and agricultural ecosystems, and reducing biodiversity. Notably, its remarkable adaptability has made it a focal species in plant invasion research [39]. While numerous studies have examined S. canadensis’ growth and invasive characteristics [40,41,42], the specific role of rhizospheric bacteria in facilitating its invasion success remains poorly understood. Recent work has begun to explore microbial contributions to invasion success [43], but the mechanistic understanding remains limited.

Therefore, this study aims to explore the ecological effects and underlying mechanisms of rhizobacteria on the growth and competitive advantage of S. canadensis, addressing two key questions: (1) Do rhizobacteria contribute to the positive growth responses of S. canadensis under nutrient-limited conditions? (2) Do rhizobacteria enhance the competitiveness of S. canadensis? The results will contribute to generating a comprehensive understanding of the role of rhizospheric bacteria in alien plant/weed invasions and further enrich the field of invasion ecology.

2. Materials and Methods

To explore the ecological effects of rhizospheric bacteria on invasive weed Solidago canadensis, three experiments were conducted: (1) isolation and identification of rhizobacteria (Figure 1A), (2) plant growth-promoting experiment under low nutrient stress (Figure 1B), and (3) competition with a native plant (Figure 1C).

2.1. Isolation and Identification of Rhizospheric Bacteria of S. canadensis

Rhizosphere soil samples of S. canadensis were collected from Zhenjiang, Jiangsu Province (32°10′45.92″ N, 119°30′34.04″ E), during the maturation stage (late November). After the bulk soil was shaken off the plant root, the remaining rhizosphere soil, which was intimately attached to the fine roots, was collected using a paintbrush, placed in envelopes, and temporarily stored in 4 °C iceboxes. The samples were immediately transported to the laboratory where they were homogenized and passed through a 2 mm sieve. Soil bacterial suspensions were prepared using sterile distilled water. Then, the isolation [44], purification, and identification of rhizospheric bacteria were conducted according to standard microbiological methods [45], including 16S rRNA sequencing. The experimental procedure was conducted as follows: Root samples of S. canadensis were sequentially washed and oscillated in sterile water to obtain bacterial suspensions, which were then gradient-diluted and spread on LB agar plates for bacterial isolation. Pure cultures were acquired through single-colony picking and streak plating methods, followed by expansion in LB liquid medium and long-term preservation in 50% glycerol under dual conditions of −80 °C and −20 °C. All operations were performed under strictly aseptic conditions in a laminar flow cabinet to ensure the reliability of the strain isolation and purification.

From the numerous isolated strains, two bacterial strains were selected for further experimentation: Bacillus sp. ScRB44 and Pseudomonas sp. ScRB22. Single colonies of these two strains were selected and picked out into tubes containing LB (Luria–Bertani) culture solution and further incubated and activated in a shaker (200 rpm, 30 °C) for further use.

2.2. Bacterial IAA Production Capacity Assay

The IAA production ability of the bacterial strains was measured using a microplate reader. The specific steps are as follows: To prepare a 50 mg/L IAA standard solution, begin by pouring 500 mL of ultrapure water into a 1000 mL beaker. Then, measure 50 mg of solid IAA using an analytical balance and gently add it to the water. Place the beaker on a magnetic stirrer and stir continuously until the IAA powder is mostly dissolved. Then, slowly add an aqueous sodium hydroxide solution to ensure complete dissolution. Once fully dissolved, transfer the solution to a 1000 mL volumetric flask and carefully adjust the volume to the calibration mark. This stock solution is reserved for later use. Similarly, IAA solutions with concentrations of 40 mg/L, 30 mg/L, 20 mg/L, and 10 mg/L were prepared. The absorbance of each concentration was measured using the microplate reader to generate a standard curve. For the quantification of IAA produced by rhizosphere bacteria, bacteria isolated from the root surface of S. canadensis (stored at −20 °C) were activated and then cultured on R₂A medium using a single colony isolation method. The cultures were incubated in a shaker at 200 rpm and 30 °C for three days. After incubation, the bacterial suspensions were centrifuged at 8000 rpm for 15 min, and the supernatant was carefully collected using a pipette. To determine the IAA concentration, Salkowski’s chromogenic solution was prepared by mixing 1 mL of 0.5 M FeCl₃ and 50 mL of 35% HClO₄ (maintaining a supernatant-to-reagent ratio of 2:3). The reaction was allowed to proceed for 1 h in the dark. Finally, the absorbance of each sample was measured at a wavelength of 530 nm using a spectrophotometer, enabling the quantification of IAA production capacity in bacteria strains.

2.3. Determination of Bacterial Nitrogen Utilization Capacity

The activated bacterial strains were individually inoculated into nitrogen-free Ashby solid nitrogen fixation medium, following the method described by reference [46]. The cultures were incubated at 28 °C for 10 to 15 days to assess their nitrogen utilization ability. During this period, bacterial growth was closely monitored, and each experiment was performed in triplicate to ensure reliability.

2.4. Plant Growth-Promoting Experiments

2.4.1. Propagation of Sterile Seedlings

The experiment was conducted at Jiangsu University, Zhenjiang, Jiangsu Province, starting in April 2023. The seedlings of invasive S. canadensis and native Wedelia chinensis used in the experiments were aseptic seedlings in a sterile cultivation system to avoid potential confounding factors caused by the presence of non-focal microorganisms. These aseptic seedlings were prepared and propagated in sterilized Murashige and Skoog (MS) solid medium according to the method by Dai [47] and Qi [38]. The similar-sized aseptic seedlings with two nodes were placed into flower pots containing 180 g of sterilized solution and 50 g of nutrient solution. They were then placed in a light culture rack until new shoots emerged [48]. After a designated cultivation period, the OD₆₀₀ was adjusted to 1.0 in a sterile environment. At this point, bacteria enumeration was conducted using the dilution-plating method, ensuring the consistency of the initial colony-forming units (CFU) count. Additionally, 1 mL of the bacterial suspension was inoculated into the plants’ root zone, which was then maintained in a controlled greenhouse environment at 25 °C–28 °C and light for 16 h a day at 450 μmoL·m⁻²·s⁻¹ [38].

2.4.2. Nutrient Stress Experiment

This experiment aimed to evaluate the growth responses of S. canadensis under nutrient-limited conditions to address Question 1. Two nutrient concentrations were used (Figure 1B): a normal nutrient concentration (0.5 × Hoagland solution) and a low nutrient concentration (0.02 × Hoagland solution). The control group (CK) was kept bacteria-free, while the treatment group received supplementation with Bacillus sp. ScRB44 and Pseudomonas sp. ScRB22. A total of six treatment groups with five replicates per group were established.

2.4.3. Competition Experiment

This experiment aimed to evaluate the impact of different bacterial solutions on the competitive growth of the invasive S. canadensis and the native W. chinensis to address Question 2. The experimental setup used a normal nutrient concentration of 0.5× Hoagland solution. The control group (CK) remained bacteria-free, while the treatment group received supplementation with Bacillus sp. ScRB44 and Pseudomonas sp. ScRB22. Three planting methods were used (Figure 1C): (1) sole planting of invasive S. canadensis, (2) sole planting of native W. chinensis, and (3) mixed planting of S. canadensis and W. chinensis at a 1:1 ratio. A total of nine treatment groups with five replicates per group were established.

2.5. Data Collection, Processing, and Calculation

Evaluation of Primary and Lateral Root Systems and Plant Stature: The plants were carefully uprooted, cleaned, and dried. The seedlings were placed flat on a surface, and plant length was measured using calipers. The primary and lateral root systems were straightened with a clamp, and their dimensions were recorded. The growth status was then assessed based on these measurements.

Quantification of Biomass: The surface soil was removed from the plants, which were then cleaned, and any residual moisture was absorbed using filter paper. The fresh weight biomass was recorded. The plants were then placed in an envelope and baked at 80 °C for 48 h until a constant weight was achieved. The dry weight biomass was measured using an electronic balance, the root-to-shoot ratio was calculated [49,50], and the results were recorded [48].

The Relative Competition Intensity Index (RCI) was used to quantify the impact of Bacillus sp. on the competitive ability of the two plant species. The RCI is calculated using the following formula:

$$RCI\left(\%\right)={\displaystyle \frac{\left(X-Y\right)}{Y}}$$

(1)

where in Equation (1), the RCI reflects the relative competition intensity of Solidago canadensis or native plant species under mixed cultivation compared to their mass under single cultivation. A higher RCI value indicates a greater relative competition intensity of the respective species.

The data were analyzed and graphed using IBM SPSS Statistics 24 (IBM Corp., Armonk, NY, USA) and Origin 2021 (Originlab Co., Northampton, MA, USA). Statistical differences were determined using a one-way ANOVA followed by Tukey’s HSD post hoc test for multiple comparisons, with p < 0.05 considered statistically significant.

3. Results

3.1. Bacterial IAA Production and Nitrogen Fixation Capacity

The IAA production of Bacillus sp. ScRB44 was approximately 20 mg/L, while Pseudomonas sp. ScRB22 produced around 1.7 mg/L (as shown in Figure 2A). ScRB44 showed growth in nitrogen-free Ashby medium (Figure 2B), and ScRB22 showed no growth (Figure 2C).

3.2. Growth-Promoting Effects on S. canadensis

Under normal nutritional conditions, the aboveground and underground fresh weight of S. canadensis significantly increased after the addition of ScRB44 compared to the CK (Figure 3A). Specifically, when compared to ScRB22 and the CK, the aboveground fresh weight increased by 40%, while the underground fresh weight increased by 1.42 times and 0.5 times, respectively, with the addition of ScRB44 and ScRB22 strains (Figure 3B). The root-to-shoot ratio of the plants also significantly increased following inoculation. The average plant height of S. canadensis was 5.42 cm, a 34% increase compared to the CK plants. The average root length of the plants inoculated with ScRB44 was 12.14 cm, approximately 1.5 times greater than the average root length of 4.66 cm for the CK group (Figure 3E). No significant difference in root length was observed in the plants inoculated with ScRB22 compared to the CK group. There was no significant difference in the number of leaves among the three groups.

Under nutrient-limited conditions, a comparison of the growth of S. canadensis across three treatments, ScRB44, ScRB22, and the CK group, revealed notable differences. The plants inoculated with ScRB44 and ScRB22 exhibited significantly greater underground fresh weights compared to the control group. The root-to-shoot ratio also increased significantly in these groups. However, only ScRB44-inoculated plants showed significant increases in aboveground and root length. While plant height and leaf number slightly increased with the addition of ScRB44, these differences were not statistically significant. In contrast, plants inoculated with ScRB22 displayed significant decreases in aboveground fresh weight, plant height, and root length compared to the control group.

3.3. Effects of Rhizospheric Bacteria on the Competitiveness of S. canadensis

After inoculation with ScRB44, both S. canadensis and native plants showed increased biomass under monoculture conditions. This increase in biomass was more pronounced in S. canadensis compared to the native plant, with significant differences observed in both the aboveground and underground portions (Figure 4A,B). Furthermore, the root-to-shoot ratios also increased for both plant types under monoculture conditions, with ScRB44 having a more significant effect on S. canadensis. In contrast, inoculation with ScRB22 promoted underground biomass in S. canadensis under monoculture conditions but significantly inhibited both aboveground and underground biomass in native plants. Under mixed planting conditions, the aboveground biomass of S. canadensis increased significantly after inoculation with ScRB44, while no effect was observed on the aboveground biomass of native plants. However, both S. canadensis and native plant showed significant increases in underground biomass after inoculation, with a more significant promotion effect observed for native plants (Figure 4C,D). Comparing their root-to-shoot ratios under mixed planting conditions, both S. canadensis and the native plant showed significant increases, with a more pronounced promotion effect observed for native plants (Figure 4G,H). In contrast, ScRB22 inoculation inhibited both plant types, significantly reducing the underground biomass of S. canadensis and the aboveground biomass of native plants.

From the graph, it can be seen that under monoculture conditions, inoculation with ScRB44 significantly increased plant height and root length in both S. canadensis and native plants. Specifically, the promotion of root length was more pronounced in S. canadensis compared to native plants. In contrast, ScRB22 inoculation exhibited no significant effect on S. canadensis but significantly reduced both plant height and root length in native plants. Under mixed planting conditions, inoculation with ScRB44 did not have a significant effect on plant height for either S. canadensis or native plants (Figure 5A,B). However, there was a significant increase in root length for both species, with a more pronounced effect observed in S. canadensis (Figure 5C,D). Notably, ScRB22 inoculation had no change on either plant height or root length in both plant types under mixed planting conditions.

After inoculating ScRB44, the aboveground biomass RCI and total biomass RCI of S. canadensis were significantly higher than those of the native plants (Figure 6A,C), while the underground biomass RCI showed a more pronounced promotion in native plants(Figure 6B). This indicates that after inoculation with ScRB44, S. canadensis exhibits a higher relative competitive strength compared to native plants. In contrast, ScRB22 inoculation increased the aboveground biomass RCI of S. canadensis but had no significant effect on its underground biomass RCI. Moreover, both plant types showed significantly reduced underground biomass RCI compared to the CK.

4. Discussion

4.1. Biofunctional Differentiation of Rhizobacteria Endows Their Distinct Growth-Promoting Ability on Invasive Weed S. canadensis

This study illustrates that the invasive potential of S. canadensis is strongly influenced by the functional characteristics of its association with rhizobacteria. Specifically, Bacillus sp. ScRB44 significantly enhanced root development and biomass accumulation by producing elevated levels of indole-3-acetic acid (IAA), thereby boosting plant growth under both nutrient-rich and nutrient-poor conditions. These findings align with previous research, such as the ability of Bacillus megaterium to promote soybean growth through phytohormone regulation and increased root surface area [51]. Furthermore, Bacillus species are well-known for their ability to stimulate plant growth by synthesizing IAA, a key plant hormone involved in growth regulation [52]. These findings have important implications for agriculture, particularly in nutrient-deficient soils, as Bacillus sp. ScRB44 has the potential to enhance soil fertility and improve crop resilience, especially under low-input agricultural practices [53]. For example, studies have shown that similar plant growth-promoting rhizobacteria (PGPR) can enhance maize growth in saline soils [54]. Furthermore, a recent analysis confirmed that Bacillus spp. plays a crucial role in improving crop yield and plant health [55].

In contrast, Pseudomonas sp. ScRB22 produced only minimal levels of IAA (1.7 mg/L) and displayed negligible nitrogen utilization activity, leading to a substantially weaker growth-promoting effect. This stark contrast between the two strains underscores the ecological advantage that multifunctional bacteria like Bacillus sp. ScRB44 have, a pattern consistent with studies showing that invasive plants often associate with microbes exhibiting complementary growth-promoting traits [56,57]. While our data focus on IAA and nitrogen utilization efficiency, these results align with broader evidence that microbial synergies contribute to plant invasiveness (e.g., enhanced nutrient acquisition and stress tolerance) [58,59]. These results suggest that S. canadensis may actively recruit rhizobacteria with complementary and synergistic growth-enhancing traits, enabling it to overcome environmental challenges and establish dominance in new habitats.

The enrichment of Bacillus sp. ScRB44 in the rhizosphere of S. canadensis likely contributes to its enhanced resource acquisition and competitive performance, thereby facilitating its rapid establishment and ecological dominance. This microbial association provides a biological explanation for the adaptive success of S. canadensis as it spreads invasively across diverse environments. For instance, Bacillus-like strains can enhance the growth of invasive plants by improving nutrient utilization efficiency and strengthening stress tolerance [60], thereby outcompeting native microorganisms. Furthermore, such rhizobacteria have been demonstrated to modulate soil microbial communities to benefit host plants, which aligns with our observations of ScRB44′s growth-promoting effects on S. canadensis [61,62].

4.2. Rhizospheric Bacteria Can Effectively Resist Nutrient Stress for S. canadensis

Under nutrient-limited conditions, Bacillus sp. ScRB44 provided dual adaptive benefits to S. canadensis: enhanced nutrient uptake through IAA-induced root proliferation and improved nitrogen availability via biological nitrogen fixation. These findings are closely related to agricultural practices, suggesting that employing PGPR can potentially reduce dependence on chemical fertilizers, thus promoting sustainable agriculture [63]. By increasing nutrient use efficiency, Bacillus sp. ScRB44 emerges as a promising candidate for enhancing crop productivity, particularly in nutrient-deficient agricultural soils. Previous studies have demonstrated that plant hormones such as IAA play a crucial role in modulating plant responses to environmental stress [64]. PGPRs are also known to help plants acquire phosphorus under limiting conditions by excreting organic acids or solubilizing inorganic phosphorus. For example, certain Pseudomonas and Bacillus strains can release phosphorus from phytate through phytase activity, thereby increasing phosphorus bioavailability [65]. In contrast, Pseudomonas sp. ScRB22, lacking both IAA synthesis and nitrogen-fixing ability, showed limited capacity to support plant growth under nitrogen-deficient conditions and may even exert suppressive effects. Thus, the dual growth-promoting mechanism root growth stimulation via IAA and improved nitrogen availability contribute to reshaping the competitive landscape in favor of the invader. The capacity of S. canadensis to selectively recruit functionally beneficial microbes highlights a key microbial-mediated pathway by which invasive species strengthen their ecological dominance.

Ecologically, the recruitment of ScRB44 equips S. canadensis with a robust microbial strategy to resist nutrient stress and outcompete neighboring native species. This microbial facilitation reshapes the competitive landscape by providing the invader with physiological advantages that are not equally available to its competitors, thereby contributing to its invasive success.

4.3. Rhizobacteria Restructure Resource Competition Dynamics in S. canadensis

The contrasting functional traits of the two rhizobacterial strains led to differing competitive outcomes in both monoculture and coculture systems. In monoculture, treatment with ScRB44 resulted in a 65% increase in belowground biomass allocation in S. canadensis, compared to a 51% increase in W. chinensis. The root-to-shoot ratio also shifted more significantly in S. canadensis, reflecting a more efficient resource allocation strategy. In coculture systems, ScRB44-treated S. canadensis displayed enhanced competitiveness, driven by the synergistic effects of IAA-induced root growth and improved nitrogen utilization efficiency. In contrast, ScRB22 failed to provide similar benefits due to its limited functional capabilities, offering no significant advantage to S. canadensis.

Overall, our findings suggest that a critical factor in the invasive success of S. canadensis is its ability to shape the rhizosphere microbial community in its favor. By selectively recruiting multifunctional rhizobacteria, S. canadensis not only enhances soil fertility but also restructures microbial community composition, creating an environment conducive to its dominance. This study underscores the pivotal role of microbial partners in facilitating plant invasion and provides new insights for agricultural soil management, particularly in improving crop productivity through the manipulation of microbial communities.

5. Conclusions

Our research elucidates the critical role of plant–microbe symbiosis in the invasive success of S. canadensis. Specifically, the association with plant growth-promoting rhizobacteria, such as Bacillus sp. ScRB44, enhances the plant’s nutrient acquisition, stress resilience, and competitive capacity against W. chinensis. This mutualistic interaction not only supports the establishment and spread of S. canadensis in invaded ecosystems where W. chinensis is present but also underscores the significance of rhizosphere microbiota in shaping specific plant community dynamics. Given the reciprocal effects between S. canadensis, W. chinensis, and their associated soil microbial communities, targeting these microbial associations presents a promising avenue for developing sustainable and ecologically sound invasive species management strategies in terms of both invasive species control and agricultural soil improvement. Future research should focus on manipulating these specific plant microbe interactions to mitigate the impacts of invasive weeds, enhance sustainable agricultural productivity, and promote the restoration of native biodiversity and ecosystem health.