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Many studies have shown that individuals from invasive populations of many different plant species grow larger than individuals from native populations and that this difference has a genetic basis. This increased vigor in invasive populations is thought to be due to life history tradeoffs, in which selection favors the loss of costly defense traits, thereby freeing resources that can be devoted to increased growth or fecundity. Despite the theoretical importance of such allocation shifts for invasions, there have been no efforts to understand apparent evolutionary shifts in defensegrowth allocation mechanistically. Real location of nitrogen (N) to photosynthesis is likely to play a crucial role in any growth increase; however, no study has been conducted to explore potential evolutionary changes in N allocation of introduced plants. Here, we show that introduced Ageratina adenophora. a noxious invasive plant throughout the subtropics, appears to have evolved increased N allocation to photosynthesis (growth) and reduced allocation to cell walls, resulting in poorer structural defenses. Our results provide a potential mechanism behind the commonly observed and genetically based increase in plant growth and vigor when they are introduced to new ranges.

Background The formation of symbiotic relationships between invasive plants and soil microorganisms in invaded regions, which enhances their adaptive capacity has been extensively studied. Bacillus , as a representative soil beneficial microorganism, can be recruited by invasive plants to their rhizosphere to promote growth. However, it remains unclear how dominant Bacillus species in the rhizosphere changes, and what feedback effects these changes may have, when invasive plants encounter biotic resistance in the invaded region, particularly from plant competition and insect herbivory. Results This study investigated the contents of Bacillus idriensis , B. mycoides , B. thuringiensis in the rhizosphere soil of Ageratina adenophora under different biotic resistance. It showed that B. idriensis exhibited the highest increase in the rhizosphere during plant competition, whereas B. thuringiensis showed the most significant increase under Aphis gossypii infestation. The effect of these Bacillus species on the competitive interactions between A. adenophora and native plant Rabdosia amethystoides were assessed. Inoculation with B. idriensis led to an 185.66% increase in biomass for monocultured A. adenophora and a 175.83% increase in mixed culture, thereby enhancing the positive effect of interspecific competition on the growth of A. adenophora . Additionally, the responses of A. adenophora to infestation by the generalist herbivorous A . gossypii following Bacillus inoculation were examined. B. thuringiensis inoculated significantly increased the levels of jasmonic acid, total phenols, flavonoids in A. adenophora infested by A. gossypii by 49.38%, 20.78%, 18.59%, while significantly reducing the survival rate and nymph density of A. gossypii , indicating enhanced resistance to the herbivore. B. idriensi s improved the tolerance of A. adenophora to A. gossypii through growth promotion. Conclusion Our findings demonstrate that the abundance of distinct Bacillus species in the rhizosphere of A. adenophora varies in response to diverse biotic resistance encountered in the invaded region. These rhizobacterial interactions generate specific feedback effects that collectively enhance the invasiveness of the species.

Background The invasive weed Ageratina adenophora poses significant ecological threats, necessitating novel control strategies. This study investigated the phytotoxic potential of methyl indole-3-acetate (MEIAA) through foliar application. As a methylated derivative of IAA, MEIAA exists in plants at extremely low concentrations and exhibits herbicidal properties distinct from conventional auxin mimics such as 2,4-D. Additionally, we integrated histochemical staining, transmission electron microscopy (TEM), and multi-omics analyses to reveal MEIAA mediated structural changes in A. adenophora . Results At 20 mM (optimized concentration), MEIAA induced dose-dependent stem curvature (1d post-treatment) and apical meristem necrosis (3d). Mechanistic analyses revealed three combined effects: (1) Structural compromise: MEIAA reduced lignin (20–73%), cellulose (9–29%), hemicellulose (4–11%), and pectin (6–36%) in stems, impairing mechanical integrity. Transmission electron microscopy (TEM) further demonstrated severe ultra-structural aberrations, including plasmolysis, organelle disintegration, and cell wall fragmentation. (2) Vascular collapse: Histological staining revealed disorganized vascular bundles and lignin-depleted xylem vessels, disrupting water/nutrient transport. (3) Metabolic-transcriptional dysregulation: Multi-omics integration identified MEIAA-induced perturbations in carbohydrate metabolism (e.g., elevated D-mannose, D-galactose; altered starch/sucrose pathways) and phenylpropanoid biosynthesis (suppressed lignin precursors: coniferaldehyde, sinapaldehyde). Concurrently, MEIAA bi-directionally regulated 26 phytohormone signaling genes (e.g., AUX/IAA, ARF, PYR/PYL), diverting metabolic flux from growth to stress responses. Crucially, qRT-PCR validated RNA-seq reliability, highlighting MEIAA’s unique regulatory divergence from both natural auxin (IAA) and synthetic analogs like 2,4-D. Conclusion These findings position MEIAA as a potent and distinctive auxin-mimic herbicide, disrupting physiological homeostasis via multi-target inhibition. Our results provide a mechanistic foundation for developing MEIAA as an eco-friendly herbicide specifically for controlling invasive A. adenophora .

Lolium perenne (Poaceae), a perennial forage, has high economic and nutritional value. It is often used as a replacement control for some invasive plants, as it has achieved good ecological and economic effects. However, its control effects, allelochemicals, allelopathic effects, release pathways, and contents are still unclear in the process of L. perenne replacement control of an invasive plant, Ageratina adenophora (Asteraceae). Therefore, it is necessary to reveal the mechanism of L. perenne replacement control of A. adenophora from the perspective of allelopathy. In this study, L. perenne could effectively inhibit the growth of A. adenophora in the competition assay. In addition, seven norsesquiterpenes (1–7) were isolated and identified from the whole plant of L. perenne, and most of the compounds exhibited potent allelopathic effects on the growth of A. adenophora and one model plant (Lactuca sativa, Asteraceae). Moreover, some active compounds were released into the environment through root secretion and rainwater leaching, and their contents were determined by UPLC-MS/MS (Ultra Performance Liquid Chromatography Tandem Mass Spectrometry). Our results elucidated the allelopathic mechanism of L. perenne’s replacement control, A. adenophora, and provided a theoretical basis for the development of norsesquiterpenes from L. perenne.

The present study was designed to assess the allelopathic potential of invasive weed Ageratina adenophora leaf extracts on seed germination and seedling development efficiency of native tree [viz. Quercus leucotrichophora A. Camus (Oak) and Pinus roxburghii Sarg. (Pine)] and crop [( Triticum aestivum L. (Wheat) and Lens culinaris Medik. (Lentil)] species of Kumaun Himalaya. Pot experiments were conducted in the glasshouse of the Botany Department, D.S.B. Campus, Kumaun University Nainital, following a Completely Randomized Block Design (CRBD) with three treatments (C 1 -25%, C 2 -50%, and C 3 -100% of aqueous leaf extract) and one control, each with five replicates. The experiment lasted one year for tree species and continued until the seed maturation phase for crop species. Parameters such as seed germination proportion, root and shoot measurements, biomass, and crop productivity traits were recorded accordingly. Our bioassay results indicated that the inhibitory effect of leaf extracts on the measured traits of the selected native species was proportional to the applied extract concentrations of A. adenophora . Overall, lentil among crops and oak among tree species exhibited more inhibition compared to wheat and pine, respectively. At the highest concentration, reductions of 44%, 34%, 36%, and 24% in biomass production capacity were recorded for wheat, lentil, pine, and oak, respectively, while wheat and lentil productivity decreased by up to 33% and 45%, respectively. These results suggest that water-soluble allelochemicals produced by A. adenophora may impede the establishment of selected crop and tree species in agroecosystems and forest ecosystems invaded by this weed species. However, further studies on the characterization of phytochemicals and their specific role in seed germination and growth are warranted. Furthermore, the allelopathic potential of A. adenophora can be explored for the preparation of biopesticides and nature-friendly option to improve soil health, crop productivity, and reduce environmental pollution and management of this invasive weed.

A novel bacteria strain, designated YIM B02787 , was isolated from rhizosphere soil of Ageratina adenophora, in Yunnan, southwest China. The strain was aerobic, Gram-stain-negative, rod-shaped and motile with one polar flagellum. Growth occurred at 4-45 °C (optimum, 20-30 °C) and pH 6.0-10.0 (optimum, 7.0-8.0), and in presence of 0-1% (w/v) NaCl. Phylogenetic analyses based on both 16S rRNA gene and genome sequences data revealed that strain YIM B02787 belongs to the genus Massilia, being closely related to Massilia phosphatilytica KCTC 52513 (98.93% similarity), M. putida KCTC 42761 (98.86%), and M. kyonggiensis JCM 19189 (98.78%). The DNA G+C content was 65.9%. The digital DNA-DNA hybridization and average nucleotide identity values between the isolate strain and aforementioned closely neighbors were low, at 35.8-48.9 and 88.5-92.5%, respectively. Strain YIM B02787 contained Q-8 as the ubiquinone and major fatty acids were summed feature 3 (C ω7c and/or C ω6c, 45.5%) and C (27.5%). The polar lipid profile consisted of phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, two unidentified phospholipids, two unidentified aminophospholipids, and one unidentified polar lipid. On the basis of its phylogenetic, phenotypic and chemotaxonomic characteristics, strain YIM B02787 represents a novel species of the genus Massilia, for which the name Massilia orientalis sp. nov. is proposed. The type strain is YIM B02787 (= NBRC 116628  = CGMCC 1.61539 ).

Allelopathy has been hypothesized to play a role in exotic plant invasions, and study of this process can improve our understanding of how direct and indirect plant interactions influence plant community organization and ecosystem functioning. However, allelopathic effects can be highly conditional. For example allelopathic effects demonstrated in vivo can be difficult to demonstrate in field soils. Here we tested phytotoxicity of Eupatorium adenophorum (croftonweed), one of the most destructive exotic species in China, to a native plant species Brassica rapa both in sand and in native soil. Our results suggested that natural soils from different invaded habitats alleviated or eliminated the efficacy of potential allelochemicals relative to sand cultures. When that soil is sterilized, the allelopathic effects returned; suggesting that soil biota were responsible for the reduced phytotoxicity in natural soils. Neither of the two allelopathic compounds (9-Oxo-10,11-dehydroageraphorone and 9b-Hydroxyageraphorone) of E. adenophorum could be found in natural soils infested by the invader, and when those compounds were added to the soils as leachates, they showed substantial degradation after 24 hours in natural soils but not in sand. Our findings emphasize that soil biota can reduce the allelopathic effects of invaders on other plants, and therefore can reduce community invasibility. These results also suggest that soil biota may have stronger or weaker effects on allelopathic interactions depending on how allelochemicals are delivered.

Ageratina adenophora is one of the major invasive weeds that causes instability of the ecosystem. Research has reported that A. adenophora produces allelochemicals that inhibit the growth and development of food crops, and also contain some toxic compounds that cause toxicity to animals that consume it. Over the past decades, studies on the identification of major toxic compounds of A. adenophora and their toxic molecular mechanisms have been reported. In addition, weed control interventions, such as herbicides application, was employed to reduce the spread of A. adenophora. However, the development of therapeutic and prophylactic measures to treat the various A. adenophora—induced toxicities, such as hepatotoxicity, splenotoxicity and other related disorders, have not been established to date. The main toxic pathogenesis of A. adenophora is oxidative stress and inflammation. However, numerous studies have verified that some extracts and secondary metabolites isolated from A. adenophora possess anti-oxidation and anti-inflammation activities, which implies that these extracts can relieve toxicity and aid in the development of drug or feed supplements to treat poisoning-related disorders caused by A. adenophora. Furthermore, beneficial bacteria isolated from rumen microbes and A. adenophora can degrade major toxic compounds in A. adenophora so as to be developed into microbial feed additives to help ameliorate toxicity mediated by A. adenophora. This review presents an overview of the toxic mechanisms of A. adenophora, provides possible therapeutic strategies that are available to mitigate the toxicity of A. adenophora and introduces relevant information on identifying novel prophylactic and therapeutic measures against A. adenophora—induced toxicity.

• Eupatorium adenophorum is a malignant invasive plant possessing extraordinary defense potency, but its chemical weaponry and formation mechanism have not yet been extensively investigated. • We identified six cadinene sesquiterpenes, including two volatiles (amorpha-4,7(11)-diene and (–)-amorph-4-en-7-ol) and four nonvolatiles (9-oxo-10,11-dehydroageraphorone, muurol-4-en-3,8-dione, 9-oxo-ageraphorone and 9β-hydroxy-ageraphorone), as the major constitutive and inducible chemicals of E. adenophorum. All cadinenes showed potent antifeedant activity against a generalist insect Spodoptera exigua, indicating that they have significant defensive roles. • We cloned and functionally characterized a sesquiterpene synthase from E. adenophorum (EaTPS1), catalyzing the conversion of farnesyl diphosphate to amorpha-4,7(11)-diene and (–)-amorph-4-en-7-ol, which were purified from engineered Escherichia coli and identified by extensive nuclear magnetic resonance (NMR) spectroscopy. EaTPS1 was highly expressed in the aboveground organs, which was congruent with the dominant distribution of cadinenes, suggesting that EaTPS1 is likely involved in cadinene biosynthesis. Mechanical wounding and methyl jasmonate negatively regulated EaTPS1 expression but caused the release of amorpha-4,7(11)-diene and (–)-amorph-4-en-7-ol. Nicotiana benthamiana transiently expressing EaTPS1 also produced amorpha-4,7(11)-diene and (–)-amorph-4-en-7-ol, and showed enhanced defense function. • The findings presented here uncover the role and formation of the chemical defense mechanism of E. adenophorum – which probably contributes to the invasive success of this plant – and provide a tool for manipulating the biosynthesis of biologically active cadinene natural products.

Local pathogens can accumulate as asymptomatic endophytes, making it difficult to detect the impacts of invasive species as propagators of disease in the invaded range. We used the invasive plant Ageratina adenophora to assess such accumulation. We intensively collected foliar fungal endophytes and leaf spot pathogens of A. adenophora and co-occurring neighbours and performed an inoculation experiment to evaluate their pathogenicity and host range. Ageratina adenophora harboured diverse necrotrophic pathogens; its communities of endophytes and leaf spot pathogens were different in composition and shared only a small number of fungal species. In the pathogen communities of local plant hosts, 21% of the operational taxonomic units (OTUs), representing 50% of strains, also occurred as leaf spot pathogens and/or endophytes of A. adenophora. The local pathogen community was more similar to the endophytes than to the pathogens of A. adenophora. The inoculation experiment showed that local pathogens could infect A. adenophora leaves asymptomatically and that local plant hosts were susceptible to both A. adenophora endophytes and pathogens. Ageratina adenophora is a highly competent host for local pathogens, and its asymptomatic latent pathogens are fungi primarily shared with local neighbours. This poses challenges for understanding the long-term ecological consequences of plant invasion.