In a discovery that could reshape how scientists think about biological invasions, researchers in China have shown that the notorious invasive plant Ageratina adenophora—widely known as crofton weed—does not simply overwhelm native ecosystems through chemical warfare or sheer competitive vigor. Instead, it appears to selectively recruit microbes from the very native plants and soils it invades, and then reprograms its own metabolism in dramatically different ways depending on which microbial partners it acquires. Sometimes this microbial hijacking boosts the invader’s growth; sometimes it suppresses it. The difference, according to a new study published in the journal Plant and Soil, lies in the fine-scale choreography between the microbes the plant picks up and the metabolic pathways it switches on or off in response.
Ageratina adenophora, a perennial herb in the daisy family native to Mexico and Central America, has spread aggressively across Asia, Africa, Oceania and parts of Europe, forming dense monocultures in forest understories and agricultural land. Earlier work by the same research group, based at Yunnan University and the Kunming University of Science and Technology, had established that the invader can enrich rare soil bacteria in its roots and that microbes from local plants can alter its growth. But the underlying molecular logic—why the same native microbiome sometimes acts as fuel and sometimes as a brake—remained obscure. The new study tackles that question by combining microbial community profiling with untargeted metabolomics, effectively tracking both who is living on and inside the plant and what the plant is chemically doing about it.
The experimental setup was elegant in its simplicity. The researchers applied inoculants derived from local plants in two distinct forms: leaf inoculants, which carried microbes from the surface and interior of native plant foliage, and soil inoculants, which carried the rhizosphere and soil-borne community. Seedlings of A. adenophora were exposed to these treatments and then sorted into two strikingly different groups—those whose growth was promoted and those whose growth was inhibited. The team then analyzed the bacterial and fungal communities associated with the leaves and roots of both groups, alongside comprehensive metabolite profiling of the plant tissues.
The results revealed that the route of microbial acquisition matters enormously. When the invader received leaf inoculants, its metabolic machinery pivoted toward glutathione metabolism, isoflavonoid biosynthesis and carbon metabolism. Glutathione, a tripeptide antioxidant, is a central player in how plants manage reactive oxygen species and buffer cellular stress, and its upregulation suggests the plant was actively detoxifying and retooling its redox balance in response to the incoming leaf microbiome. Isoflavonoids, a class of phenolic secondary metabolites more famous in legumes, are versatile compounds involved in both defense signaling and interactions with microbial partners, hinting that the invader’s chemistry was shifting toward managing its new microbial residents. Carbon metabolism, meanwhile, points to a reallocation of photosynthetic resources—precisely what one would expect if growth trajectories were being recalibrated.
Soil inoculation told a chemically different story. Rather than the antioxidant and phenolic programs triggered by leaf microbes, soil exposure activated cutin, suberin and wax biosynthesis, along with the metabolism of linoleic and arachidonic acids. These pathways all converge on the plant’s outer boundaries: cutin and waxes build the cuticle that seals the aerial surfaces, while suberin forms the corky, hydrophobic barrier in roots that controls what crosses into the vascular cylinder. Linoleic and arachidonic acid metabolism connects to lipid-derived defense signaling, a well-characterized branch of plant immunity in which fatty acids act as precursors to jasmonates and other regulatory molecules. In other words, soil microbes pushed the invader to fortify its interfaces—thickening its physical and lipid-based barriers—whereas leaf microbes pushed it to rewire its internal metabolic economy.
The microbial side of the ledger was equally revealing. Among the differential microbes identified across treatments, the genus Paenibacillus stood out: it was highly enriched in both growth-promoted and growth-inhibited seedlings, making it a central hub of the invader’s recruited community regardless of outcome. Paenibacillus species are known in agricultural contexts as plant growth-promoting rhizobacteria, capable of nitrogen fixation, hormone production and induced systemic resistance, so their strong enrichment fits the invader’s talent for turning potentially benign native bacteria into functional allies. Bacillus, another genus with a storied reputation for promoting plant growth and suppressing pathogens, was mostly associated with growth promotion across treatments—with one notable exception: in soil-inoculated roots, Bacillus showed a negative correlation with the invader’s performance, suggesting that even a “friendly” genus can flip its role depending on the tissue and the context.
Perhaps the most conceptually important finding is how the plant’s metabolic state tracked its growth outcome. Seedlings that were inhibited by the inoculants converged on defense-related metabolic programs, including cysteine and methionine metabolism—amino acid pathways with deep links to plant immunity, since cysteine feeds glutathione and sulfur-containing defense compounds and serves as a signaling node in pathogen responses. Growth-promoted seedlings, by contrast, lit up growth-related pathways such as tryptophan and arginine biosynthesis. Tryptophan is the precursor of the auxin indole-3-acetic acid, the master hormone of plant development, and arginine feeds polyamine biosynthesis and nitrogen storage, both intimately tied to cell division and expansion. The pattern suggests a fundamental resource-allocation decision: the invader either invests its carbon and nitrogen budgets in defense chemistry or channels them toward biosynthetic growth, and the microbes it recruits appear to tip that balance.
The correlation analyses deepened this picture. In growth-inhibited seedlings, the enriched microbes correlated positively with defense-related lipid metabolites—essentially, the more of these defensive lipids the plant accumulated, the more certain microbes thrived, painting a scenario in which a stressed, defense-oriented host provides a chemical environment that favors a particular microbial set, and that set in turn locks the plant into its defensive posture. In growth-promoted seedlings, the relationship inverted: defense metabolites such as coumarins and flavonoids correlated negatively with microbes, implying that when growth-supporting microbes dominate, the plant dials down its antimicrobial chemistry—perhaps because a flourishing mutualist community signals that costly defense is unnecessary. This negative coupling between antimicrobial metabolites and microbial abundance in healthy, fast-growing plants is consistent with the idea that the invader actively manages its microbiome chemically, suppressing microbes when it tolerates them but retaining the capacity to unleash phenolic defenses when the community composition turns unfavorable.
Taken together, the findings reframe invasion biology’s central question. Classic hypotheses such as the “novel weapons” theory posit that invasive plants succeed by releasing allelochemicals that natives cannot tolerate. This study suggests a complementary and arguably more dynamic mechanism: invasion success may hinge on the invader’s capacity to sense, selectively enrich and metabolically negotiate with local microbes, drawing from both the phyllosphere of neighboring native plants and the soil beneath them. A native community is not merely an obstacle for A. adenophora—it is a microbial menu. The invader’s selective enrichment acts as a regulator of host resource allocation, steering the plant toward either growth or defense, and thereby producing the differential growth responses observed in the field.
The practical implications cut both ways. If native plants or soils can be managed so that their microbial communities push invading seedlings toward the defense-dominated, growth-inhibited state, this could open a biological route to invasion resistance—one that works not by killing the invader but by triggering an internally costly metabolic lock-in. Conversely, the identification of growth-promoting taxa such as Paenibacillus and Bacillus as keystone enrichments highlights how an invader assembles its own support network, and why some invaded landscapes seem to become progressively more invadable over time as microbial legacies accumulate. The researchers also point to climate and context dependence: previous work from the group showed that native plants change the invader’s endophyte assembly in response to climatic factors, implying that the growth-versus-defense switch documented here may itself vary across environmental gradients.
The team has made its data publicly available to accelerate this line of inquiry. Bacterial and fungal sequence datasets from both soil and leaf inoculation experiments are deposited in the NCBI GenBank database under BioProject accession numbers PRJNA1212804, PRJNA1212822, PRJNA1212857 and PRJNA1212867, while the associated metabolite data are archived in the OMIX database at the National Genomics Data Center under accession OMIX013725. The study was funded by the Major Science and Technology Project of Yunnan Province, a region where A. adenophora has caused severe ecological and economic damage and where the line between a native community that resists invasion and one that inadvertently fuels it may be drawn, quite literally, in the chemistry of a seedling’s leaves and roots.
Subject of Research: Microbial recruitment and metabolic reprogramming in the invasive plant Ageratina adenophora, and how leaf- and soil-derived microbes from local plants drive contrasting growth responses through differential metabolic pathways.
Subject of Research: Agriculture
Article Title: Metabolic response and microbial assembly in the invader Ageratina adenophora with contrasting growth under local plant leaf and soil inoculants
Article References: Zhao, C., Liu, Z.-Q., Jin, X.-H., Li, Y.-X., Wang, Y.-L., Zeng, Z.-Y., & Zhang, H.-B. (2026). Metabolic response and microbial assembly in the invader Ageratina adenophora with contrasting growth under local plant leaf and soil inoculants. Plant and Soil. https://doi.org/10.1007/s11104-026-09027-z
Image Credits: AI Generated
DOI: 10.1007/s11104-026-09027-z
Keywords: Ageratina adenophora, invasive plant, plant–microbe interactions, local microbe enrichment, metabolic pathways, glutathione metabolism, isoflavonoid biosynthesis, Paenibacillus, Bacillus, growth responses, plant defense metabolites, Plant and Soil
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Morgan Morrow. (September 4, 2026). Invasive plant growth shaped by soil microbes and local leaf inputs. Scienmag. https://scienmag.com/invasive-plant-growth-shaped-by-soil-microbes-and-local-leaf-inputs/
Morgan Morrow. “Invasive plant growth shaped by soil microbes and local leaf inputs.” Scienmag, 4 September 2026, https://scienmag.com/invasive-plant-growth-shaped-by-soil-microbes-and-local-leaf-inputs/. Accessed 4 September 2026.
Morgan Morrow. “Invasive plant growth shaped by soil microbes and local leaf inputs.” Scienmag. September 4, 2026. https://scienmag.com/invasive-plant-growth-shaped-by-soil-microbes-and-local-leaf-inputs/
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