Orchid seeds generally rely on mycorrhizal fungi for successful germination and development, but communication between fungal exudates and orchid seeds before contact is poorly understood. The researchers used G. conopsea and GS2, a strain originally isolated from the orchid’s roots, to investigate whether fungal products alone could initiate host responses. The fungus was grown in liquid culture, and its filtered exudates were freeze-dried, concentrated 60-fold, sterilized and applied to surface-disinfected seeds for 18 days. Sterile water served as the control.

The study combined RNA sequencing with four biological replicates, untargeted metabolomics of the exudates, hormone measurements with five replicates, fatty acid profiling with five replicates and transmission electron microscopy. RNA sequencing identified 5,172 significantly upregulated and 18,051 significantly downregulated genes in treated seeds relative to controls. Upregulated genes were enriched in starch and sucrose metabolism, fatty acid biosynthesis and elongation, plant hormone signal transduction, brassinosteroid biosynthesis and zeatin biosynthesis. Among the induced genes were fatty acid-associated genes including PKp, KASII, KAR, FatB and RAM2, several brassinosteroid-biosynthesis genes, and the cytokinin-related genes IPT and CYP735A.

Targeted hormone analysis found that brassinolide content in treated seeds reached 14 times the control level. Several bioactive cytokinins also increased, including trans-zeatin-riboside, cis-zeatin-riboside, cis-zeatin and N6-(Δ2-isopentenyl)adenosine, with cis-zeatin-riboside measured at 4.7 times the control value. Three bioactive gibberellins—GA3, GA4 and GA7—were detected, with GA7 accounting for more than 99.9% of total gibberellins and increasing significantly after treatment. Gibberellin regulatory genes were induced and abscisic-acid signaling was repressed, patterns the authors associated with possible release of seed dormancy. These measurements show associations with exudate exposure; they do not prove that every altered pathway was required for fungal colonization.

Separate experiments using GS2 during symbiotic germination provided functional evidence for a role for brassinosteroids and cytokinins. Exogenous 24-epibrassinolide at 5 µmol L-1 increased seed germination by 3.0 percentage points, whereas the brassinosteroid-biosynthesis inhibitor brassinazole reduced it by 4.7 points and significantly reduced the number of colonized cells in protocorms. Exogenous 6-benzylaminopurine at 10 µmol L-1 increased germination by 5.7 points, while zeatin at 1 and 5 µmol L-1 increased it by 4.6 and 6.7 points, respectively. Lovastatin did not significantly alter germination rate but reduced protocorm dimensions in a concentration-dependent manner; at 50 µmol L-1, protocorm length and width fell by 29.5% and 28.8%, respectively.

Exudate exposure was also associated with increased lipid accumulation. Transmission electron microscopy showed a greater area ratio of lipid droplets in treated seeds, and quantitative gas chromatography-mass spectrometry confirmed higher fatty acid content than in controls. The induction of RAM2 and FatB occurred alongside this increase. During symbiotic germination, fatty acid accumulation was observed before GS2 colonization, which began at 12 days post-symbiosis, while key components of the common symbiosis signaling pathway—CASTOR, POLLUX/DMI1, CCaMK/DMI3 and CYCLOPS/IPD3—were induced by day 3 and remained highly expressed after colonization. The authors therefore proposed that the pathway may mediate some exudate-induced changes, describing this as a potential mechanism rather than a demonstrated complete signaling chain.

Evolutionary comparisons showed that the orchid retained RAM2 and other components of the common symbiosis signaling pathway, whereas the fully mycoheterotrophic orchids Neottia fugongensis and Gastrodia elata lacked those genes in the analysis. The gene FatM and the arbuscular-mycorrhiza-specific genes RAM1, STR and STR2 were not detected in orchid-mycorrhizal hosts. GcRAM2 expression was approximately 25 times higher in fungus-colonized adult orchid roots than in non-colonized roots, and in situ hybridization localized its expression to GS2-colonized protocorm cells. In a cross-species functional test, expression of GcRAM2 restored substantial colonization by Rhizophagus irregularis in roots of the Medicago truncatula ram2 mutant, supporting conservation of its fatty acid-related function.

Exudates from GS2, five additional Ceratobasidium strains and a Tulasnella strain induced root-hair branching in M. truncatula. This assay is consistent with the presence of bioactive mycorrhizal factors, potentially lipo-chitooligosaccharides, but the researchers did not identify or structurally characterize those compounds. Untargeted profiling found that GS2 exudates contained 979 lipid or lipid-like metabolites, 673 organoheterocyclic compounds and 591 organic acids and derivatives, with fatty acyls the largest lipid category at 39.63%.

The findings remain limited to one orchid species, selected fungal strains and controlled laboratory seed treatments. Treated seeds entered a pre-germination stage but did not fully germinate, possibly because starch, free sugars or a continuous supply of fungal metabolites was insufficient. The specific fungal molecules that trigger the observed responses, their receptors and their interaction with hormone signaling remain unresolved. The study therefore provides evidence that fungal exudates can alter orchid seed transcription, hormone levels and fatty acid content before physical fungal contact, while presenting hypotheses rather than demonstrated mechanisms for later symbiotic germination and conservation applications.

Subject of Research: Pre-symbiotic responses of Gymnadenia conopsea seeds to Ceratobasidium sp. GS2 exudates

Article Title: Ceratobasidium sp. GS2 exudates elicit downstream transcriptional and physiological responses in seeds of Gymnadenia conopsea ( Orchidaceae )

Article References: Wang, Y., Qian, X., Li, J., Wang, H., Yang, A., Yang, L., Liu, J., & Xing, X. (2026). Ceratobasidium sp. GS2 exudates elicit downstream transcriptional and physiological responses in seeds of Gymnadenia conopsea (Orchidaceae). IMA Fungus, 17, Article e191381. https://doi.org/10.3897/imafungus.17.191381

Image Credits: AI Generated

DOI: 10.3897/imafungus.17.191381

Keywords: Gymnadenia conopsea, Ceratobasidium, orchid seed germination, fungal exudates, mycorrhizal symbiosis, gene expression, phytohormones, fatty acid biosynthesis, common symbiosis signaling pathway, plant–fungus communication, exudates, elicit

Provenance 4 had the lowest mean branch inclination angle, while provenance 2 had the highest proportion of narrow-crowned individuals and the highest measured zeatin levels. Auxin, or indole-3-acetic acid, was lowest in provenance 14. Across the 14 provenances, branch inclination angle was significantly negatively correlated with both zeatin and indole-3-acetic acid. Path analysis indicated a strong negative direct effect of indole-3-acetic acid on branch inclination angle. These findings describe statistical and model-based relationships among the measured variables; the abstract does not report experimental manipulation or direct functional testing of the proposed mechanism.

The transcriptome analysis identified 2,272 differentially expressed genes, including 27 associated with phytohormone signaling pathways. Six members of the SAUR family were up-regulated and three were down-regulated in the narrow-crowned provenance, with distinct expression patterns suggesting that they may participate in auxin-signaling output during branch inclination angle development. Cytokinin regulators A-ARR and B-ARR showed opposite expression patterns. The gibberellin receptor GID1 was down-regulated and the growth-repressor DELLA was up-regulated, which the authors interpreted as consistent with reduced promotion of cell division and elongation.

Additional expression differences were reported in salicylic acid, jasmonic acid, abscisic acid and ethylene signaling. Genes in salicylic acid and jasmonic acid signaling were suppressed, the abscisic acid regulator PP2C decreased and the ethylene-associated component EIN2 increased. The authors interpreted this pattern as evidence of reprogramming in defense-related phytohormone signaling. They concluded that auxin and downstream SAUR genes may be important in regulating branch inclination angle and that provenances 3 and 4 warrant attention as narrow-crowned sources. However, the supplied evidence is an abstract from an early, accepted manuscript subject to further edits; it does not provide detailed sampling methods, effect sizes, uncertainty estimates or functional validation, so the specific molecular mechanisms and breeding implications remain bounded by the reported comparative analysis.

Subject of Research: Provenance-associated phytohormone and gene-expression patterns underlying branch inclination angle variation in Chamaecyparis hodginsii

Article Title: Phytohormone and transcriptome analyses reveal the mechanisms underlying branch inclination angle formation in narrow-crowned Chamaecyparis hodginsii

Article References: Cai, X., Chen, Z., Bai, J., Xiao, J., Liu, J., Lin, Y., Lin, Y., Lu, B., Gao, T., Chen, L., He, T., Chen, L., Rong, J., & Zheng, Y. (2026). Phytohormone and transcriptome analyses reveal the mechanisms underlying branch inclination angle formation in narrow-crowned Chamaecyparis hodginsii. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10049-z

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10049-z

Keywords: Chamaecyparis hodginsii, branch inclination angle, narrow-crowned provenances, auxin, zeatin, SAUR genes, cytokinin signaling, transcriptome analysis, phytohormones, forest tree breeding, Phytohormone, transcriptome

Biostimulants occupy a curious regulatory and scientific niche. Unlike fertilizers, they are not defined primarily by the nutrients they deliver, and unlike pesticides, they do not kill pests directly. Instead, as the review emphasizes, they regulate plant metabolism. The authors stress that plant-derived extracts almost never act through a single active constituent. A typical extract is a dense biochemical cocktail containing phytohormone-like compounds, antioxidants, osmoprotectants, phenolics, oligosaccharides, fatty acids, proteins and peptides. This compositional complexity is not a nuisance to be purified away; it is the point. Multiple molecules converge on multiple signaling pathways simultaneously, producing effects that no isolated compound could replicate.

The mechanistic core of the review centers on hormone signaling. Extracts modulate the major stress hormones of plants, including abscisic acid, salicylic acid, jasmonic acid and ethylene, which together orchestrate everything from stomatal closure during drought to the activation of pathogen defenses. Transcriptomic studies cited in the review show that treatment with extracts such as those from Ascophyllum nodosum, a brown seaweed long used in commercial biostimulant products, upregulates stress-responsive genes in crops ranging from Arabidopsis to soybean and tomato. In effect, the extracts behave like a training signal, priming the plant’s own defense machinery so that when real stress arrives, the response is faster and stronger.

Beyond hormones, the review catalogues a suite of physiological adjustments that extracts induce. Treated plants accumulate more osmolytes, small compatible solutes such as proline and glycinebetaine that help cells retain water and maintain turgor under drought or salt stress. Antioxidant defenses are strengthened, allowing plants to neutralize the reactive oxygen species that spike when photosynthesis is disrupted. Ionic homeostasis is restored, helping roots exclude sodium or compartmentalize it away from sensitive metabolic machinery. Perhaps most intriguingly, the review highlights evidence that extracts regulate water transport through aquaporins, the membrane channels that control the flow of water across plant cells, offering a direct physical route to improved drought tolerance.

The review also draws attention to the rhizosphere, the teeming microbial zone around plant roots. Extracts influence rhizosphere interactions and microbiome dynamics, according to the authors, thereby improving nutrient acquisition and systemic resilience. Studies combining seaweed extracts with plant growth-promoting rhizobacteria in wheat, rice, onion and cucumber report synergistic effects on growth and yield that neither partner achieves alone. This reframes biostimulants not merely as foliar tonics but as ecosystem engineers that reshape the underground communities on which crop nutrition depends, a perspective increasingly central to soil health science.

Case studies across stress types give the review its agronomic weight. Under drought, moringa leaf extract has improved rice yield and grain quality through enhanced antioxidant activity, while seaweed extract has bolstered sugarcane drought resistance by modulating root architecture and soil properties. Under salinity, extracts from Ascophyllum, willow, licorice root and grape seed have each improved photosynthetic stability and ion balance in crops such as tomato, maize, pea and faba bean. Heat stress studies in wheat and maize report that moringa and sorghum water extracts preserve photosynthetic pigments, while cold stress trials in barley and tomato show brown seaweed extracts triggering cold-acclimation gene expression. Biotic stress studies add another layer, with laminarin from brown algae eliciting grapevine defenses against downy mildew and botrytis, and seaweed extracts reducing fungal disease on carrot foliage.

Application strategy emerges as a critical variable. The review distinguishes between foliar sprays, seed priming and soil drenching, noting that dose, timing and method can determine whether an extract helps or does nothing at all. Seed priming with moringa leaf extract has reduced chilling injury in spring maize and improved rice seedling establishment under water deficit, while foliar application has induced terminal heat tolerance in quinoa. Processing matters too: the review notes that extraction methods, from mechanical disruption to enzyme-assisted techniques, shape which phytochemicals survive into the final product, and that even storage temperature can alter cytokinin and auxin concentrations in seaweed concentrates.

The most forward-looking section concerns nanotechnology. Plant-mediated nanoparticles and nano-formulations, the authors report, improve the stability, delivery efficiency and bioavailability of bioactive phytochemicals. Examples span the emerging literature: Sargassum-synthesized zinc oxide nanoparticles inducing salt tolerance in maize, neem-mediated silver nanoparticles improving drought-stressed soybean growth, Spirulina-derived carbon dots used for seed nanopriming in rice, and nano-encapsulated biostimulants enhancing photosynthetic efficiency in heat-stressed peppers. Nano-encapsulation can also protect volatile or easily degraded compounds, such as essential oils, from rapid environmental loss. The authors caution, implicitly, that nanoparticle-plant interactions, including uptake, transport and potential toxicity, remain active areas of investigation, and that environmental implications must be weighed alongside agronomic gains.

What emerges from the synthesis is a picture of plant-derived biostimulants as systems-level interventions rather than simple inputs. A single seaweed extract may simultaneously adjust hormone signaling, boost antioxidant capacity, alter root growth, feed beneficial microbes and prime defense genes, all without introducing novel genetic material or synthetic chemistry. For farmers facing increasingly erratic rainfall, salinizing soils and heat waves, this profile is attractive precisely because it works with the plant’s existing physiology rather than overriding it. The review’s case studies consistently report improvements in photosynthetic stability, stress tolerance and yield under optimized application strategies, suggesting that the gap between laboratory promise and field performance is narrowing.

The authors close with a research agenda that reads like a roadmap for the next decade of the field. Future progress, they argue, will require integrating multi-omics approaches, combining transcriptomics, metabolomics and proteomics to resolve exactly which molecules in a complex extract drive which responses, alongside microbiome profiling to track how extracts reshape root communities over time, and precision nanotechnology to deliver the right bioactive to the right tissue at the right moment. If that integration succeeds, the humble plant extract, long dismissed as folk agronomy, could become a cornerstone of sustainable agriculture, helping crops weather a climate that is growing less forgiving by the season.

Subject of Research: Mechanisms of plant-derived biostimulants in enhancing crop stress tolerance and sustainable agriculture

Article Title: Mechanistic insights into plant-derived biostimulants for sustainable agriculture and stress tolerance

Article References: Mishra, A., Bhatt, U., & Soni, V. (2026). Mechanistic insights into plant-derived biostimulants for sustainable agriculture and stress tolerance. Plant Biosystems, 160(6), Article 295. https://doi.org/10.1007/s44473-026-00314-2

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00314-2

Keywords: biostimulants, plant extracts, seaweed extracts, abiotic stress, drought tolerance, salinity stress, phytohormones, antioxidants, nanotechnology, soil microbiome, sustainable agriculture, moringa oleifera

The review, which combines decades of published studies with the author’s own doctoral research, focuses on four pillars of charophyte biology: the formation of the sexual organs and fertilisation, the dormancy of oospores, the induction of germination, and the cultivation of these algae under artificial conditions. The stakes are considerable. Characeae are sensitive indicators of clean water, and their decline under eutrophication has been documented across Europe and beyond. At the same time, their evolutionary position as part of the sister group to land plants makes every insight into their reproduction a potential window into how plants first conquered the terrestrial world. Understanding why these algae appear, disappear and return in aquatic systems, the review argues, requires a multidimensional approach that fuses morphology, anatomy, physiology, genetics, geobotany and ecology.

Sexual reproduction in charophytes is a spectacle in miniature. Male and female organs, the antheridia and oogonia, arise from short shoots formed at the nodes of branchlets. The male antheridium matures through a striking colour transformation, from green through pale yellowish-green to vivid orange, before releasing thousands of flagellated spermatozoids into the water. As long ago as 1967, researchers linked that orange hue to the accumulation of carotenoid-rich plastoglobuli. The female oogonium is an ovoid structure encircled by spiral cells, and its fertilisation was described in exquisite detail as far back as 1871 by Anton de Bary, who observed spermatozoids massing at five tube-like channels and threading through a narrowed funnel at the apex of the oocyte. What follows is the formation of a thickened cellulose layer around the zygote, a layer whose absence is thought to signal infertility.

Yet even this well-trodden path conceals one of the great mysteries of the field: nobody knows exactly when meiosis occurs in charophytes. Over more than a century, researchers have proposed at least four conflicting hypotheses, placing meiosis just before oospore germination, in the early stages of gametangia, during protonema development, or immediately after fertilisation. The problem is technical as much as conceptual. Oogonia and oospores are loaded with starch, which makes ultrathin sectioning for microscopy notoriously difficult. The review identifies establishing reliable sectioning methods for every developmental stage as one of the most important prerequisites for finally solving this puzzle, a reminder that even foundational cell biology can stall on the limitations of laboratory technique.

Genetics is beginning to fill gaps that morphology alone cannot. Studies of Chara globularis have revealed the presence of MIKC-type MADS box genes in both oogonia and antheridia, suggesting these key regulators of sex-specific cell differentiation existed before the major diversification of plant lineages. Immunofluorescence work has shown PIN2-like auxin transporters in antheridial filaments, along with polar auxin transport in internodal cells, features long thought to be hallmarks of land plants that evidently evolved far earlier. Cell wall chemistry tells a similar story: charophytes contain the same cellulose, pectin, hemicellulose, lignin and proteins as land plants, differing mainly in proportions, although recent work has found that some species lack hydroxyproline and arabinogalactan proteins that are ubiquitous in terrestrial flora.

Asexual reproduction adds a second, quieter strategy. Many charophytes propagate vegetatively through modified rhizoid or nodal cells, forming starch-filled bulbils that act as overwintering reserves, star-shaped in Nitellopsis obtusa, strawberry-shaped in Chara baltica, cardioid-shaped in Chara fragifera. These structures can regenerate new shoots after drought, fragmentation or the death of apical cells, ensuring population persistence when conditions are unfavourable for oospores. One species stands apart: Chara canescens has never been observed reproducing vegetatively and depends entirely on oospores, reproducing either sexually in dioecious populations or parthenogenetically, with genetically and chromosomally distinct female lines. Notably, the review reports that severing the rhizoid filaments connecting bulbils prevents new shoot development, hinting at unknown signalling pathways that modern molecular tools have yet to touch.

The oospore is the charophyte’s long-term insurance policy, a resting stage embedded in aquatic sediments that resists drought and mechanical stress far better than any vegetative fragment. Whether it germinates depends on a cascade of cues. The review maps these onto the biogeographic concept of zonobiomes, showing that the climate zone from which material originates predicts which dormancy-breaking treatment works: species of the warm-temperate zonobiome V generally respond to pre-treatment at 15 degrees Celsius, whereas species of zonobiome VI require cold storage. Cold treatment followed by irradiation with long-wave light emerges as the most broadly effective method, though species-specific exceptions abound, such as a New Zealand Nitella that prefers room-temperature storage. Freshly extracted oospores, it turns out, are more deeply dormant than those recovered from sediments, likely because abscisic acid is gradually degraded during storage.

Light, nutrients and chemistry complicate the picture further. Some studies find that light intensity and quality trigger germination; others find no effect at all, contradictions the review attributes to differences in geography, species and sample type. Purely inorganic culture media actually inhibit germination, while the addition of organic material, though critical for success, invites contamination by microbes and epiphytes. Desiccation matters too: drying oospores increased germination in some species but not others, and dried oospores of several Chara species germinated after freezing, chilling or warming across storage periods of up to four years. Sediment depth plays a role as well, with heavier Chara oospores germinating from deeper layers than lighter Nitella ones, a finding that underpins the emerging restoration science of so-called ghost ponds, where long-buried viable oospores can resurrect lost aquatic floras.

Perhaps the most practically significant contribution of the review is a new cultivation approach the author calls Eco-in-vitro-cultivation. Traditional laboratory media have long failed to induce the formation and maturation of gametangia in monoecious, diplostichous Chara species such as Chara hispida, with cultures instead succumbing to biofilm overgrowth and reproductive senescence. By combining environmental logger data from outdoor mesocosms at Rostock University, records of temperature, light intensity and light-dark cycles under which germination and gametangia development naturally occurred, with refined in-vitro techniques and a nutrient medium, the researchers achieved successful gametangia initiation and oospore maturation under fully artificial conditions. Because such cultures carry a drastically reduced microbiome, they should also make it easier to distinguish contaminant-specific and bacterial-specific gene sequences in future molecular work.

The broader significance is hard to overstate. Long-term, controlled cultures that complete the full life cycle would open the door to identifying the gene networks governing different modes of reproduction, resolving the timing of meiosis, and testing whether land-plant-like hormone responses in charophytes depend on uniport transporters capable of shuttling both nutrients and phytohormone conjugates. The review also highlights striking gaps, from the complete absence of studies on soil microbes in Chara meadows to the unknown function of mucilage on rhizoids and oospores. What emerges is a portrait of a scientifically glamorous group, central to one of evolution’s greatest transitions, whose everyday biology has been quietly understudied. With standardised, species-specific protocols now within reach, the humble stoneworts may finally give up their secrets, from the sleeping spores in the mud to the genes that first taught green cells to live on land.

Subject of Research: Reproduction, oospore dormancy, germination and cultivation of charophyte algae (Characeae)

Article Title: What we really know about the dormancy, reproduction, germination and cultivation of charophytes ( Characeae )

Article References: Holzhausen, A. (2024). What we really know about the dormancy, reproduction, germination and cultivation of charophytes (Characeae). One Ecosystem, 9, Article e117655. https://doi.org/10.3897/oneeco.9.e117655

Image Credits: AI Generated

DOI: 10.3897/oneeco.9.e117655

Keywords: charophytes, Characeae, stoneworts, oospore dormancy, germination, sexual reproduction, asexual reproduction, gametangia, phytohormones, in-vitro cultivation, aquatic ecology, land plant evolution

The research team, led by Liting Deng and corresponding author Junxing Li, employed a comprehensive foodomics approach, combining untargeted metabolomics with transcriptome sequencing to capture a full portrait of what makes fragrant pumpkin leaves taste and smell the way they do. Across untreated leaves, the researchers identified a staggering 1003 metabolites, of which 40 were volatile aroma compounds. The chemical inventory was dominated by six classes: phenolic acids with 150 representatives, amino acids and their derivatives with 93, organic acids with 83, free fatty acids and saccharides with 77 each, and flavonols with 70. Together these six categories accounted for more than 54 percent of everything the team detected.

That catalogue alone carries significant nutritional implications. Phenolic acids and flavonols are among the most intensively studied classes of plant secondary metabolites, widely associated with antioxidant and anti-inflammatory activity in the human diet. Their abundance in pumpkin leaves, the authors argue, supports the vegetable’s positioning as a health-functional food rather than a mere culinary curiosity. But the study’s central question was not simply what the leaves contain—it was how their flavour chemistry responds to intervention, and whether growers could deliberately steer that chemistry toward a more desirable eating experience.

The intervention in question was a combined foliar formulation, a nutrient spray applied directly to the leaf surface. Foliar feeding is an established agronomic technique that bypasses the soil-root system entirely, delivering dissolved nutrients through the cuticle and stomata where they can be absorbed rapidly into metabolic pathways. Because amino acids and aromatic compounds vary dramatically across pumpkin leaf cultivars and growing conditions, flavour has been notoriously difficult to regulate. The new results suggest that this difficulty may be more tractable than previously assumed.

The metabolic consequences of the spray were striking. Of the 28 amino acids and derivatives significantly regulated after treatment, 23 accumulated substantially. The headline result concerned glutamic acid, the amino acid that anchors the savoury umami taste and serves as a fundamental building block of proteins. Glutamic acid rose by 50 percent following foliar feeding, becoming the single most abundant metabolite in the treated leaves. For a vegetable whose culinary appeal depends heavily on savoury depth, that shift represents a meaningful upgrade in eating quality achieved through nothing more exotic than a targeted nutrient spray.

The aroma story proved even more dramatic. The compound 2-acetyl-1-pyrroline, universally abbreviated 2-AP, is the molecule responsible for the taro-like fragrance prized in fragrant pumpkin leaves—and, famously, for the popcorn-like scent of pandan and premium jasmine rice. In the treated leaves, 2-AP levels surged by 189 percent. Simultaneously, (Z)-3-hexen-1-ol, the volatile behind the fresh-cut-grass smell that many consumers find harsh or overly green, dropped by 65.5 percent. The combined effect was a rebalancing of the leaf’s volatile profile toward sweetness and warmth and away from raw vegetal pungency, a shift the authors describe as a prominent improvement in the vegetable’s aroma characteristics.

Understanding how the spray produced these changes required the transcriptomic half of the study. By sequencing gene expression in treated and untreated leaves and integrating those data with the metabolite measurements, the researchers uncovered what appears to be an alternative biosynthetic route to 2-AP—one that runs through the polyamine putrescine rather than the pathways more commonly described in aromatic rice. At the centre of this route sits a gene designated CmoADC, which encodes arginine decarboxylase, the enzyme that channels arginine into putrescine production. Both the metabolite and the gene responded emphatically to foliar feeding: putrescine was up-regulated 2.48-fold, while CmoADC expression jumped 8.33-fold, making it one of the most strongly induced transcripts in the entire dataset.

The regulatory architecture behind these changes appears to involve plant hormones acting through transcription factors. A large proportion of the differentially expressed transcription factors identified in the study were hormone-responsive, hinting that the foliar formulation does not simply dump raw materials into metabolic pools but instead re-tunes the plant’s own signalling networks. Direct measurement of the phytohormone landscape reinforced this interpretation: of the 66 hormone-related compounds the team quantified, 42 were significantly impacted by the treatment, including 18 cytokinin-associated and 11 auxin-associated compounds. Cytokinins are classically linked to nitrogen metabolism and amino acid biosynthesis, which fits neatly with the observed accumulation of glutamic acid and its relatives, while auxin signalling has well-documented connections to secondary metabolism and volatile formation.

For agriculture, the practical message is that flavour quality in leafy vegetables can be engineered through metabolically informed management rather than left to cultivar choice alone. The combined foliar formulation improved amino acid nutrition and umami intensity while simultaneously amplifying the taro-like aroma through a putrescine-dependent 2-AP pathway, giving growers a defined, science-backed lever for quality improvement. Because the treatment acts on the leaf itself and operates within the plant’s existing biochemistry, it offers a relatively low-cost strategy that could be adapted to other fragrant vegetables where 2-AP or related volatiles determine market value.

For plant science, the study adds a compelling piece to the puzzle of how 2-acetyl-1-pyrroline is actually made. The involvement of arginine decarboxylase and putrescine suggests that nitrogen-rich precursors, mobilised in response to nutrient availability and hormone signalling, feed directly into aroma biosynthesis. As pumpkin leaves continue their journey from regional staple to global functional vegetable, work like this demonstrates how metabolomics and transcriptomics together can turn a traditional green into a precisely flavoured, nutritionally optimised crop—one spray at a time.

Subject of Research: Effects of foliar feeding on amino acid and 2-acetyl-1-pyrroline aroma metabolism in fragrant pumpkin leaves

Article Title: Responses of amino acid and aroma metabolism of fragrant pumpkin leaves to foliar feeding: insights from metabolomic and transcriptomic technologies

Article References: Deng, L., Luo, J., Zhao, G., Liu, X., Wu, H., Gong, H., Zheng, X., Wu, X., Dai, Z., Wang, H., Chen, C., Wang, X., Zheng, Y., & Li, J. (2026). Responses of amino acid and aroma metabolism of fragrant pumpkin leaves to foliar feeding: insights from metabolomic and transcriptomic technologies. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10145-0

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10145-0

Keywords: pumpkin leaves, foliar feeding, metabolomics, transcriptomics, 2-acetyl-1-pyrroline, putrescine, glutamic acid, umami, aroma biosynthesis, phytohormones, flavour chemistry, Cucurbita moschata

The Asian longhorned beetle, Anoplophora glabripennis, ranks among the most destructive invasive forest pests in the world. Its larvae tunnel deep into the heartwood of healthy hardwood trees, and outbreaks have forced the destruction of millions of trees across North America, Europe, and Asia. What makes the Russian olive remarkable is its unusual role in the beetle’s ecology. When adult beetles feed on its twigs, the tree responds with defensive gummosis, a sticky resinous exudate that kills the beetle’s eggs and newly hatched larvae. The tree functions as a trap: it attracts the pest, then neutralizes its offspring. But until now, the molecular choreography behind this lethal hospitality remained unresolved.

A team at the Beijing Key Laboratory for Forest Pest Control at Beijing Forestry University, led by Ruohan Qi, Hanshuo Liu, Keyu Hao, Jiahe Pei, Lili Ren, and Youqing Luo, set out to reconstruct that choreography in real time. Their strategy was to expose Russian olive twigs to continuous adult beetle feeding and then sample the plant tissue at five time points: 0, 6, 12, 24, and 72 hours after the attack began. At each time point, they performed RNA sequencing to capture the full landscape of gene expression, alongside targeted profiling of phytohormones and flavonoids using liquid chromatography with tandem mass spectrometry. This combination allowed them to watch, hour by hour, how chemical signals and defensive metabolites rose and fell in response to the beetle’s feeding.

The transcriptomic data revealed a striking pattern. Gene expression remodeling was most pronounced at the 24-hour mark, a turning point that marked a shift in the tree’s defensive strategy. In the early hours, the dominant response involved salicylic acid and jasmonic acid signaling, the two hormone pathways plants typically deploy as first-line alarms against attackers. By 24 hours, the transcriptional program had pivoted toward the phenylpropanoid and flavonoid biosynthesis pathways, the biochemical assembly lines that produce a diverse family of plant secondary metabolites with well-documented defensive roles. In other words, the tree first sounds the alarm, then builds its chemical arsenal.

To test whether this apparent sequence reflected genuine coordination rather than coincidence, the researchers applied time-lagged correlation analysis, a statistical approach that asks whether changes in one variable reliably precede changes in another. The analysis suggested pathway-specific coordination between hormone accumulation and transcriptional responses, meaning that the buildup of particular phytohormones was followed, with a measurable delay, by the activation of the genes they regulate. This kind of temporal coupling is exactly what one would expect if the hormone signals were functioning as upstream triggers for the downstream biosynthetic machinery, rather than both simply responding in parallel to the damage.

The biochemical measurements confirmed that the transcriptional shift had real chemical consequences. Total flavonoid content increased at 24 hours, and the activity of phenylalanine ammonia-lyase, or PAL, the gateway enzyme that channels carbon from primary metabolism into the phenylpropanoid pathway, rose in parallel. PAL catalyzes the first committed step in the pathway that ultimately yields flavonoids, so its induction is a classic signature of a plant committing resources to secondary chemical defense. Importantly, the individual flavonoid compounds did not all behave identically. The researchers observed distinct accumulation patterns for specific flavonoid aglycones, the core molecular scaffolds, and for their glycosides, the sugar-conjugated forms. This distinction matters because aglycones and glycosides can differ in their biological activity, stability, and transport within plant tissues, suggesting the tree fine-tunes not just how much flavonoid it makes but in which chemical form.

To identify the regulatory masterminds behind this program, the team turned to weighted gene co-expression network analysis, or WGCNA, a computational method that groups genes into modules based on correlated expression patterns across samples and time. Within the modules most tightly linked to flavonoid accumulation, they identified hub transcription factors belonging to three major families: MYB, bHLH, and WRKY. These families are well known in plant biology as central regulators of secondary metabolism and stress responses, but identifying specific hub members co-expressed with flavonoid structural genes in this tree provides concrete candidate switches for the observed chemical shift. The predicted target genes of these transcription factors were enriched in defense-related pathways, reinforcing the link between the regulatory network and the defensive outcome.

Perhaps the most mechanistically suggestive finding came from the promoter analysis. The researchers examined the regulatory DNA upstream of PAL-4, one of the phenylalanine ammonia-lyase genes, and discovered that it contained cognate cis-elements matching the binding motifs of the hub transcription factors. Cis-elements are short DNA sequences that act as docking sites for transcription factor proteins, and their presence in the PAL-4 promoter provides a plausible direct wiring diagram: the MYB, bHLH, and WRKY regulators identified in the co-expression network could physically bind the PAL-4 promoter and drive the enzyme’s induction, thereby opening the metabolic floodgates for flavonoid production. This is a hypothesis the authors present as consistent with their data, and it offers a testable molecular entry point for future functional studies.

The broader significance of the work lies in its temporal resolution. Most studies of plant induced defense capture a snapshot at a single time point, which can obscure the sequential logic of the response. By sampling across a 72-hour window and integrating transcriptomics, hormone profiling, metabolite measurement, and network analysis, this study demonstrates that the Russian olive’s defense is not a single switch but a staged program: early jasmonate and salicylate signaling precedes late-stage flavonoid accumulation, with the transition occurring around the 24-hour mark. The authors describe this as a temporally coordinated defense, and the framing has practical implications. Understanding the timing of each phase could inform breeding or biotechnological strategies aimed at enhancing the trap-tree function of E. angustifolia in integrated pest management against the Asian longhorned beetle.

The study also contributes to a growing appreciation that time-dependent induced defenses are a general feature of woody plants, not just annual herbs. Trees face herbivores that feed continuously over days and weeks, and their defenses must therefore be sustained, not just triggered. The Russian olive’s two-phase response, alarm first, arsenal second, may represent an evolutionary solution to that challenge, allocating costly chemical production only after an attack is confirmed to be ongoing. As the researchers conclude, their findings provide molecular insights into trap-tree defense mechanisms and advance the broader understanding of how the timing of a plant’s internal chemistry can mean the difference between hosting a pest and destroying its next generation. For a beetle that has devastated forests on multiple continents, that difference could prove decisive.

Subject of Research: Temporal dynamics of jasmonate signaling and flavonoid biosynthesis in Russian olive during sustained Asian longhorned beetle herbivory

Article Title: Temporal dynamics of jasmonate signaling and flavonoid biosynthesis in Elaeagnus angustifolia during sustained adult Anoplophora glabripennis herbivory

Article References: Qi, R., Liu, H., Hao, K., Pei, J., Ren, L., & Luo, Y. (2026). Temporal dynamics of jasmonate signaling and flavonoid biosynthesis in Elaeagnus angustifolia during sustained adult Anoplophora glabripennis herbivory. BMC Plant Biology. https://doi.org/10.1186/s12870-026-10185-6

Image Credits: AI Generated

DOI: 10.1186/s12870-026-10185-6

Keywords: Asian longhorned beetle, Russian olive, Elaeagnus angustifolia, jasmonate signaling, flavonoid biosynthesis, plant defense, phytohormones, RNA sequencing, transcription factors, phenylalanine ammonia-lyase, trap tree, induced defense

The study focused on one of the most studied relationships in plant pathology: the encounter between Arabidopsis thaliana, the diminutive mustard weed that serves as botany’s laboratory workhorse, and Pseudomonas syringae pv. tomato DC3000, the bacterial pathogen famous for disarming plant defences. When these two meet, a rapid and intricate chemical exchange begins. The plant deploys salicylic acid as its primary alarm signal against biotrophic bacteria, while jasmonic acid, abscisic acid, auxin and an assortment of cytokinins modulate growth, stress responses and defence trade-offs. Each of these hormones exists at vanishingly low concentrations, and each is accompanied by structurally near-identical relatives, metabolites and isomers that confound straightforward detection. Understanding where in the leaf each signal rises, and how quickly, has long been beyond the reach of conventional analysis.

Conventional liquid chromatography-mass spectrometry, or LC-MS, remains the gold standard for hormone quantification. It separates compounds in a liquid column before weighing them in a mass spectrometer, delivering exquisitely sensitive numbers. But those numbers describe an entire extracted sample. A single reading might blend a hot spot of defence signalling at the infection margin with the quiet metabolism of healthy tissue several millimetres away, erasing exactly the spatial patterns that biologists most want to see. Wounding and infection make the problem worse, because localised responses at wound sites or lesion edges get averaged into invisibility. The Olomouc- and Prague-based team, led by corresponding author Chao Zhang of the Laboratory of Growth Regulators, set out to recover that lost geography.

Their instrument of choice was ion mobility-assisted desorption electrospray ionisation mass spectrometry imaging, abbreviated DESI-IM-MSI. The technique works like a molecular paint stripper. A charged spray of solvent is directed at the intact leaf surface, gently nudging molecules off the tissue without grinding, staining or embedding it. The desorbed ions are then drawn into the mass spectrometer, and the instrument scans across the leaf pixel by pixel, recording what it finds at every position. The result is a map: a picture in which brightness at each point corresponds to the abundance of a chosen molecule. Crucially, before ions reach the mass analyser they pass through an ion mobility region, where they are separated in milliseconds according to how their size and shape affect their drift through a buffer gas under an electric field.

That ion mobility step is what elevates the method from useful to decisive. Plant tissues are chemical jungles, crowded with isomers, compounds that share the same molecular formula and mass but differ in three-dimensional arrangement. In a conventional imaging experiment, two isomers arriving together at the same mass-to-charge ratio produce a single overlapping signal, making it impossible to say which of them occupies a given spot on the leaf. Ion mobility separates them by drift time, and each species acquires a characteristic collision cross section, a measurable fingerprint of its shape that can be compared against reference values. The researchers observed distinct drift-time distribution patterns for their targeted hormones and their metabolites, allowing salicylic acid, jasmonic acid, auxin, abscisic acid and cytokinins, including specific cytokinin forms such as isopentenyladenine and a mixture of cis- and trans-zeatin, to be localised in situ while interference from background isomers was minimised.

The sophistication of the analysis extended to the full metabolic entourage of salicylic acid, the hormone that anchors plant immunity against this class of bacteria. The team tracked not only the free acid but a constellation of its conjugates and derivatives: salicylic acid 2-O-β-D-glucoside, the storage form in which the hormone is locked away; 1-O-salicyl-D-glucosyl ester; methyl salicylate 2-O-β-D-glucoside, a volatile-related conjugate implicated in long-distance signalling; salicylic acid aspartate; and dihydroxybenzoic acid. Each of these carries distinct biological meaning, marking different stages of hormone activation, sequestration or transport, and each presents its own analytical challenge. Resolving them simultaneously on an intact leaf, rather than in separate chromatographic runs on extracted tissue, represents a meaningful advance for what the field calls hormonomics, the systematic study of hormone networks.

Perhaps the most important validation in the study was a direct comparison with the established method. The researchers ran parallel LC-MS analyses on matching samples and found that the changes they observed in salicylic acid and its metabolites by imaging were consistent with the conventional measurements. This agreement matters enormously, because a new imaging technique is only as credible as its numbers. Spatially resolved data could easily trade accuracy for location, producing beautiful maps of unreliable intensities. The consistency demonstrated here suggests the opposite: DESI-IM-MSI can deliver spatially resolved measurements that stand up against the quantitative rigour of chromatography-based profiling, at least for the salicylic acid pathway where the comparison was made.

The implications reach well beyond a single model plant and pathogen. Plant hormones act as a communication grid, and defence is fundamentally a spatial negotiation. A bacterial colony colonising one sector of a leaf triggers signals that radiate outward, priming distant cells for attack, while the pathogen in turn manipulates hormone balances, often suppressing salicylic acid defences while coaxing growth-related pathways. Capturing that negotiation as it happens, on the tissue rather than in the test tube, could reshape how researchers understand susceptibility, lesion formation and systemic acquired resistance. The authors position the approach as a route toward comprehensive hormononomic and metabolomic maps of plant responses to pathogen attack, offering an alternative to conventional LC-MS profiling where spatial and temporal context is what matters.

There are honest limitations, and the method does not yet replace extraction-based quantification across the board. Imaging techniques of this kind generally trade some sensitivity and quantitative precision for spatial information, and the low natural abundance of many hormones remains a formidable challenge, as the authors themselves note in framing the study’s motivation. The comparison with LC-MS covered selected targets, chiefly the salicylic acid pathway, and extending that validation to the other hormone families will be the obvious next step. Collision cross section libraries for plant metabolites are also still maturing, meaning confident identification of less-studied compounds may require supporting experiments. The work was supported by Czech and European funding programmes, including projects under the Czech Science Foundation, the ERDF Programme Johannes Amos Comenius and an ERC Synergy grant focused on auxin redistribution, signalling a sustained institutional investment in spatial plant chemistry.

Even so, the trajectory is clear. Mass spectrometry imaging has already transformed how biologists visualise lipids, drugs and metabolites in animal tissues, and the addition of ion mobility has steadily pushed the technique toward the complexity of real biological samples. Applying it to the hormone signalling of an infected leaf, one of the most chemically dynamic environments in biology, closes a long-standing gap between molecular biology, which knows which genes are switched on, and biochemistry, which knows what the resulting molecules actually do and where. If the approach scales as its developers hope, future plant pathologists may routinely read infection maps the way meteorologists read weather charts, watching defence signals sweep across a leaf and pinpointing precisely where a pathogen bends the plant’s chemistry to its own ends. For a field that has spent half a century averaging away the very patterns it needed to see, that is a genuinely new way of looking.

Subject of Research: Spatial mapping of phytohormone changes in Pseudomonas syringae-infected Arabidopsis leaves using ion mobility mass spectrometry imaging

Article Title: Ion mobility mass spectrometry imaging for in situ characterisation of phytohormone changes within Pseudomonas syringae-infected Arabidopsis thaliana

Article References: Zhang, C., Kalachova, T., Žukauskaitė, A., Antonova, A., Burketová, L., Kaczorová, D., Bieleszová, K., Doležal, K., Novák, O., & Široká, J. (2026). Ion mobility mass spectrometry imaging for in situ characterisation of phytohormone changes within Pseudomonas syringae-infected Arabidopsis thaliana. Plant Methods. https://doi.org/10.1186/s13007-026-01604-8

Image Credits: AI Generated

DOI: 10.1186/s13007-026-01604-8

Keywords: phytohormones, mass spectrometry imaging, ion mobility, DESI, Arabidopsis thaliana, Pseudomonas syringae, salicylic acid, jasmonic acid, plant immunity, metabolomics, abscisic acid, cytokinins

At the heart of floral architecture lies the famous ABCDE model, first sketched out in the early 1990s from studies of Arabidopsis thaliana and snapdragon. According to this framework, five classes of homeotic genes act in overlapping combinations across the concentric whorls of a flower. A-class genes specify sepals, A plus B specifies petals, B plus C specifies stamens, C alone specifies carpels, D-class genes govern ovule identity, and E-class SEPALLATA proteins act as essential partners that allow the other classes to function at all. Nearly all of these genes encode MADS-box transcription factors, proteins carrying a conserved 58 to 60 amino acid DNA-binding domain that recognizes specific regulatory sequences called CArG boxes. When any class is lost, the flower transforms dramatically: Arabidopsis plants lacking C-class AGAMOUS function produce double flowers, a trait breeders have deliberately induced in ornamental species such as morning glory and chrysanthemum.

The review emphasizes that the classical model is now only the skeleton of a much richer regulatory body. Revised interpretations, including the so-called (A)BC framework, assign APETALA2 a broader, more context-dependent role than the original model predicted. Beyond the ABCDE genes, an expanding cast of regulators refines floral patterning. AGL6-type MADS-box proteins interact with B-class factors in orchids to form complexes that determine whether a sepal, petal or lip develops, a finding that has reshaped understanding of orchid floral evolution. In tomato, silencing the SlAGL6 gene causes fused sepals and pale, shrunken petals. Other families contribute too: NAC-type NAP genes affect petal and stamen elongation, SPL proteins accelerate the transition to flowering, TGA factors with their glutaredoxin partners ROXY1 and ROXY2 are required for proper anther development, and WOX genes influence everything from gynoecium structure to flowering time, with rice OsWOX13 overexpression triggering flowering seven to ten days early.

Deciding when to flower is an equally intricate calculation. Plants integrate photoperiod, temperature, vernalization, age, hormones and metabolic status through interconnected genetic pathways. In the photoperiod pathway, circadian regulation of GIGANTEA and CDF1 activates CONSTANS, which in turn induces the floral integrator FLOWERING LOCUS T, the mobile signal that travels from leaf to shoot apex. Vernalization works through epigenetic silencing of the floral repressor FLOWERING LOCUS C: weeks of cold trigger chromatin changes, including Polycomb-mediated histone methylation, that lock FLC into a repressed state and release the brake on flowering. The FRIGIDA protein, recognizing H3K4me3 marks at the FLC locus, does the opposite, keeping FLC active and delaying bloom in winter annuals. Temperature responses also flow through FCA, FLM and SVP, which modulate FT expression depending on ambient conditions, a mechanism illustrated in osmanthus, where OfFCA expression rises at 19 degrees Celsius and flowering is advanced.

A particularly elegant layer of control involves microRNAs that track a plant’s age. miR156, abundant in seedlings, represses SPL transcription factors and keeps the plant vegetative. As the plant matures, miR156 declines and miR172 rises, together flipping the developmental switch toward reproduction. This miR156-miR172 module is conserved from Arabidopsis to maize, and the review highlights how long non-coding RNAs and circular RNAs add further post-transcriptional regulation that is only now being mapped through transcriptome-wide sequencing.

Hormones and metabolites complete the picture. Gibberellin promotes flowering by degrading DELLA repressor proteins, and in Arabidopsis the active gibberellin GA4 accumulates at the shoot apex alongside sucrose under short days, driving expression of the meristem identity gene LEAFY. Cytokinins and gibberellin jointly activate MADS-box genes that promote bud formation, while auxin’s polar transport is essential for flower bud initiation, with AUXIN RESPONSE FACTOR 3 helping establish the ovary boundary. Even gaseous and nutritional signals matter: nitric oxide delays flowering by inhibiting GI and CO, sucrose antagonizes this effect by reducing S-nitrosylation of those same proteins, and sulfur can reverse NO-induced late flowering. The carbon-nitrogen balance thus acts as a metabolic gauge, ensuring that a plant only commits to the costly business of reproduction when resources permit.

Sex differentiation adds a further dimension of complexity. Although most angiosperms are hermaphroditic, roughly seven percent of species are dioecious, bearing male and female flowers on separate plants, and this breeding system has evolved repeatedly from hermaphroditic or monoecious ancestors. Unlike animals, plants rarely possess well-defined XY or WZ sex chromosome systems, but where they do occur, sex-linked genes accumulate in recombination-suppressed genomic regions. In the white campion Silene latifolia, the Y-linked SlAP3 gene encodes a B-class MADS-box protein expressed in developing male buds, while X-linked genes such as MROS3X and SlMF1 show elevated expression in female flowers. In persimmon, the HD-Zip gene MeGI acts as a key regulator of anther fertility, and in melon, a C2H2 zinc finger protein called CmWIP1 promotes stamens while suppressing carpels, a system famously traced to a transposon insertion that rewired hormone signaling.

Methodological advances are transforming the field. Early candidate-gene approaches have given way to RNA sequencing, which in cucumber identified roughly 200 differentially expressed genes linked to sex determination, and in melon revealed 1,259 genes associated with male fertility. Long-read platforms from PacBio and Oxford Nanopore now resolve full-length transcripts and complex splice isoforms, while single-cell and single-nucleus transcriptomics can distinguish developmental trajectories within floral meristems, stamens, ovules and other reproductive tissues. Spatial transcriptomics preserves the positional context of gene expression, allowing researchers to connect transcriptional states to specific floral domains rather than averaging across whole organs. The review argues that combining these approaches will finally reveal when, where and in which cell types the key regulatory genes act.

The stakes extend well beyond basic biology. Flowering time and sex expression directly determine crop yield, and climate change is making these traits less predictable, as drought, salinity and heat increasingly stress plants during reproduction. Studies in rice show that OsWOX13 enhances drought tolerance while promoting early flowering, hinting that stress adaptation and flowering control are mechanistically entangled. The authors call for integrating genomics, epigenomics, machine learning and CRISPR-based functional validation to build predictive models of reproductive development. If that integration succeeds, breeders could engineer flowering stability and climate resilience into the crops that feed the world, turning the molecular secrets of the flower into agricultural insurance.

Subject of Research: Molecular and environmental regulation of floral development, flowering time and sex differentiation in angiosperms

Article Title: Molecular and environmental regulation of floral development, flowering, and sex differentiation in angiosperms

Article References: Iqbal, S., Tariq, K., Elatafi, E., Yu, H., Ali, S., Elhendawy, B., Aziz, R. B., Khan, I. A., Baz, N. M., Hussain, A., & Fang, J. (2026). Molecular and environmental regulation of floral development, flowering, and sex differentiation in angiosperms. Discover Plants, 3(1), Article 450. https://doi.org/10.1007/s44372-026-00925-1

Image Credits: AI Generated

DOI: 10.1007/s44372-026-00925-1

Keywords: flowering, MADS-box transcription factors, ABCDE model, floral organ identity, sex differentiation, vernalization, photoperiod, microRNA, phytohormones, epigenetics, single-cell transcriptomics, crop improvement

The study focused on the ‘Kırik’ wheat cultivar, a landrace population traditionally grown in eastern Türkiye and valued for its cold tolerance and bread-making quality. Rather than applying bacteria directly to the soil, where survival rates can be poor, the team used tuff as a carrier material. Tuff is a porous volcanic stone with high water-holding capacity and a strong cation exchange capacity, properties that allow it to retain moisture and nutrients while providing a protective habitat for microbial communities. Large tuff granules measuring approximately 9 by 14 by 11 millimeters were inoculated with a PGPR consortium at a concentration of roughly 4.8 × 10^10 colony-forming units per gram and then applied directly to the root zone of each plant.

Across two growing seasons, the inoculated plants consistently outperformed the non-inoculated controls. Grain yield rose by just over 20 percent, a substantial gain for a treatment that involved no additional synthetic fertilizer. The physiological measurements behind that yield boost tell a coherent story. Chlorophyll content increased, stomatal conductance improved, membrane permeability was enhanced, and photosynthetic rate climbed significantly. In practical terms, the treated plants were able to capture more light energy, exchange gases more efficiently, and maintain healthier cellular membranes, all of which feed directly into the carbon budget that ultimately determines how many grains a wheat head can fill.

One of the most striking aspects of the research is the detailed biochemical profiling the team performed. Antioxidant enzyme activities rose across the board: catalase increased by 11.43 percent, superoxide dismutase by 14.83 percent, and peroxidase by 10.71 percent. These enzymes form the front line of the plant’s defense against reactive oxygen species, unstable molecules that damage membranes, proteins, and DNA when photosynthesis and metabolism run under stress. Higher antioxidant capacity means the bacterial treatment did not merely push plants to grow faster; it also strengthened the cellular machinery that keeps growth sustainable under the oxidative pressures that inevitably accompany rapid metabolism and fluctuating environmental conditions.

The hormone data reveal how the bacteria reprogrammed plant signaling. Levels of indole-3-acetic acid, the principal auxin that drives cell elongation and root development, rose by 13.59 percent. Gibberellic acid, which governs stem elongation and germination, increased by 7 percent, and salicylic acid, a key immune signaling molecule, climbed by 9.27 percent. Meanwhile, abscisic acid, the stress hormone that typically signals plants to close stomata and slow growth, dropped by 16.67 percent. That simultaneous pattern, more growth-promoting hormones and less stress hormone, is precisely what a plant in a comfortable, well-nourished state would be expected to show, and it helps explain why the treated wheat could sustain higher photosynthetic rates and greater yield.

Nutrient analysis added another layer to the mechanism. Concentrations of essential elements rose significantly, most notably phosphorus by 18.49 percent, copper by 10.61 percent, and iron by 9.99 percent. Phosphorus is often the most limiting nutrient in agricultural soils because it binds tightly to minerals and becomes unavailable to roots; many PGPR strains solubilize it by excreting organic acids. The study also documented generally enhanced amino acid and organic acid contents in the treated plants, consistent with improved nitrogen assimilation and metabolic activity. Notably, sodium and boron concentrations decreased by 5 percent and 3.48 percent respectively, suggesting the treatment may help plants exclude potentially harmful elements, an effect with implications for salt-affected and marginal soils.

The choice of carrier material is more than a technical footnote. Liquid bacterial inoculants often fail in the field because desiccation, UV exposure, and competition with native soil microbes rapidly reduce viable cell counts. Tuff addresses several of these problems at once: its porous structure shelters bacteria, buffers moisture, and slowly releases nutrients through cation exchange, effectively turning each granule into a microhabitat that seeds the rhizosphere over time. The approach has precedent in the same research group’s earlier work, which showed that bacterially inoculated tuff improved yield and physiological parameters in grape and tomato, but the new study extends the concept to the world’s most important cereal crop with a far deeper biochemical characterization.

The broader context makes the result timely. Wheat provides roughly a fifth of the calories and protein consumed globally, and demand continues to rise with population growth, while the environmental costs of synthetic nitrogen and phosphorus fertilizers, from greenhouse gas emissions to eutrophication of waterways, face increasing regulatory pressure, including under the European Green Deal. Biological inputs such as PGPR are attractive precisely because they work with existing plant physiology: they solubilize locked-up nutrients, produce growth-promoting compounds, and prime antioxidant defenses, all at a fraction of the energy cost of industrial fertilizer synthesis. The tuff carrier adds the advantage of being an abundant, inexpensive volcanic material in regions like Anatolia where it occurs naturally.

The authors are careful about the limits of their evidence. The work was conducted in a greenhouse over two years, and they explicitly note that further field studies comparing the PGPR-tuff approach with standard chemical fertilization are needed to confirm its practical applicability and support broader adoption. Greenhouse conditions rarely reproduce the temperature swings, pest pressure, and soil heterogeneity of open fields, and yield gains of 20 percent under controlled conditions often shrink when translated to farm scale. Still, the consistency of the response across two seasons, and the breadth of the measured effects spanning physiology, hormones, antioxidants, and nutrition, give the finding unusual robustness for an early-stage study.

If field trials bear out the greenhouse results, the implications could extend well beyond wheat. A scalable, low-cost delivery system for beneficial bacteria would be relevant to barley, maize, rice, and horticultural crops alike, and the demonstrated reductions in sodium accumulation hint at applications in salt-stressed soils that are expanding worldwide. For now, the study stands as a compelling proof of concept: that a chunk of volcanic rock and a community of root-dwelling bacteria, working together, can measurably rewire a plant’s chemistry toward growth. As agriculture searches for ways to maintain yields while cutting chemical inputs, solutions drawn from the rhizosphere, the teeming microbial world just beneath our feet, are proving they deserve a central place in the conversation.

Subject of Research: Effects of PGPR-enriched volcanic tuff on wheat yield, physiology, and biochemical profiles

Article Title: Enhanced wheat (Triticum aestivum) performance: effects of PGPR-enriched on yield and biochemical profiles

Article References: Yıldıran Söğürtlüpınar, S., İnanç, M., Keçe, Y. M., Tarhan, L., Soğutmaz Özdemir, B., Şahin, F., Turan, M., & Güneş, A. (2026). Enhanced wheat (Triticum aestivum) performance: effects of PGPR-enriched on yield and biochemical profiles. Plant Biosystems, 160(5), Article 279. https://doi.org/10.1007/s44473-026-00291-6

Image Credits: AI Generated

DOI: 10.1007/s44473-026-00291-6

Keywords: PGPR, wheat, volcanic tuff, plant growth-promoting rhizobacteria, grain yield, antioxidant enzymes, phytohormones, photosynthesis, nutrient uptake, sustainable agriculture, biochemical profile, Triticum aestivum

The story of dopamine in plants is older than many researchers realise. The molecule was first detected in plant tissue in the saguaro cactus, where scientists observed a spike in endogenous dopamine within five minutes of tissue wounding, hinting at a protective role. Earlier work in 1958 had already identified catecholamines and serotonin in bananas, and dopamine was subsequently confirmed in banana peel and pulp, plantains and avocados. Bananas remain one of the richest known plant sources of the compound, and its antioxidant power there is striking: dopamine outperforms glutathione, ascorbic acid, catechin gallate and common synthetic antioxidants in free-radical scavenging assays. What has changed in recent years is the depth of mechanistic understanding, with studies now tracing dopamine’s effects from gene expression to whole-plant physiology.

Chemically, dopamine is identical across kingdoms. It is a benzene ring bearing two adjacent hydroxyl groups, the catechol moiety characteristic of catecholamines, attached to an ethylamine side chain. That catechol group is the secret of its antioxidant behaviour, donating electrons and hydrogen atoms to neutralise reactive oxygen species and, in some cases, chelating metals to disarm free radicals. The primary amine makes dopamine an organic base capable of forming salts in acidic conditions, while both functional groups hydrogen-bond readily with water, making the molecule highly polar. In animals, dopamine is synthesised from the amino acid tyrosine through a single route in which tyrosine hydroxylase acts as the rate-limiting enzyme. Plants, remarkably, run two alternative pathways: one decarboxylates tyrosine to tyramine via tyrosine decarboxylase before hydroxylation by monophenol hydroxylase, while the other hydroxylates tyrosine to L-DOPA first and then decarboxylates it with DOPA decarboxylase. Which route dominates depends on enzyme availability and plant species.

Inside the plant cell, dopamine appears to accumulate mainly in the vacuole, which serves as a storage compartment, with smaller quantities detected in the cytoplasm. Its production sites shift with need, from roots to leaves, and its concentration ranges from nanograms to micrograms depending on species and developmental stage. In opium poppy, dopamine is synthesised in young rosette leaves and declines as flowering begins. This spatial and temporal flexibility underscores a key theme of the review: dopamine is not a static metabolite but a dynamic, stress-responsive signal whose behaviour is tailored to the tissue, the species and the threat at hand.

The physiological reach of dopamine in plants is broad. Under stress, photosynthesis typically collapses as reactive oxygen species oxidise the pigments that capture light, forcing plants to close their stomata and conserve energy at the cost of growth. Dopamine intervenes at multiple points in this cascade. It stabilises the light-dependent reactions of photosynthesis, maintains stomatal conductance, preserves chlorophyll and supports optimal transpiration and carbon assimilation. In apple seedlings exposed to drought, a treatment of 100 micromolar dopamine enhanced net photosynthetic rate, relative water content, stomatal conductance and the content of chlorophyll a and b. Dopamine also reshapes root architecture, stimulating root vigour and elongation so that plants can explore soil for water and nutrients more effectively. Intriguingly, roots themselves secrete dopamine as a major exo-metabolite, suggesting it plays an active role at the root-soil-microbe interface.

At the molecular level, dopamine’s influence extends deep into gene regulation. Transcriptomic analysis of drought-stressed apple plants treated with dopamine revealed upregulation of calmodulin and calmodulin-like genes and cyclic nucleotide-gated channels involved in calcium signalling. The transient elevation of cytosolic calcium during stress initiates a cascade of adaptive cellular responses that activate downstream transcription factors, including MYBs and WRKYs. Because superoxide dismutase is a calmodulin-dependent enzyme, and glutathione peroxidase activation is also linked to calmodulin, dopamine’s calcium signalling effectively amplifies the plant’s antioxidant arsenal. The review also documents dopamine’s extensive crosstalk with phytohormones, including auxin, gibberellic acid, melatonin, abscisic acid, jasmonic acid and ethylene, fine-tuning the growth-defence trade-offs that determine how a plant allocates its limited resources under threat.

Each stress type reveals a different facet of dopamine’s versatility. Under salinity, exogenous dopamine in Malus hupehensis inhibited excess sodium and chloride uptake while enhancing the acquisition of potassium, nitrogen, phosphorus, sulphur, copper and manganese. Upregulation of genes such as MdHKT1, MdNHX1 and MdSOS1 shows dopamine engaging the salt overly sensitive pathway, the core salt-defence system in plants, pumping sodium into vacuoles and expelling it from root cells. In tomato seedlings, 100 micromolar dopamine maintained calcium-to-sodium and potassium-to-sodium ratios and produced striking gains: root dry weight increased by 286.84 percent, plant height by 108.37 percent and leaf area by 158.28 percent compared with untreated controls. Under cadmium stress in apple, dopamine reshaped the rhizosphere microbial community, enriching beneficial bacteria such as Frankia, Bradyrhizobium and Streptomyces and shifting keystone species in ways that helped the plant resist the metal.

Nitrogen stress and temperature extremes add further chapters. In cucumber grown under excess nitrate, 150 micromolar dopamine improved root growth, photosynthesis and antioxidant activity while upregulating genes for sucrose phosphate synthase, nitrate reductase and other enzymes that coordinate carbon and nitrogen metabolism. In apple, dopamine under low-nitrogen conditions increased expression of nitrate transporter genes and activated MdORG2, a transcription factor that boosts the plant’s own dopamine-synthesising machinery. Against cold, dopamine protected watermelon and grape seedlings by accumulating polyamines and osmolytes and bolstering antioxidant systems. Perhaps most commercially intriguing are the postharvest results: dopamine treatment significantly mitigated chilling injury in bananas stored at 7 degrees Celsius for 21 days and kiwifruits stored at 1 degree Celsius for 120 days, by activating the phenylpropanoid pathway, raising endogenous proline, GABA and glycine betaine, and preserving membrane integrity.

Dopamine also strengthens plant immunity against pathogens. In apple replant disease caused by Fusarium solani, 150 micromolar dopamine enhanced endogenous dopamine biosynthesis, reduced root damage and upregulated defence genes encoding chitinase and beta-1,3-glucanase, while increasing tyramine content and cell wall-bound amine deposition. Against Valsa mali infection in apple, resistance came through elevated phenolic content and salicylic acid. In pear, a foliar spray of 100 micromolar dopamine imparted resistance to Botryosphaeria dothidea by enhancing autophagy activity in host cells. Even allelopathic threats fall within its scope: dopamine counteracted phloridzin, a growth-inhibiting compound that disrupts apple rhizosphere communities, by lowering reactive oxygen species and enriching beneficial nitrogen-cycling microbes.

Significant gaps remain before dopamine can be deployed at scale. Research has concentrated on a narrow set of crops, chiefly apple rootstocks, tomato, cucumber and duckweed, while cereals, legumes and tropical fruits remain largely unexplored. Unlike in animals, no dopamine receptors have been identified or characterised in plants, leaving open the fundamental question of how the molecule is perceived. The threshold between beneficial and phytotoxic doses is poorly defined, and there is no regulatory framework governing exogenous dopamine use in agriculture. The review’s authors point to biotechnology as one promising route: overexpressing the tyrosine decarboxylase gene could raise endogenous dopamine levels and confer climate resilience without repeated spraying. Combined applications with melatonin, brassinosteroids and beneficial microbes offer further synergistic potential. If those mechanistic and safety questions can be answered, dopamine may graduate from laboratory curiosity to a next-generation regulator of crop resilience, extending its celebrated career from the animal brain to the world’s fields and orchards.

Subject of Research: The role of dopamine as a stress-regulating signalling molecule in plants

Article Title: Beyond neurotransmission: dopamine as an emerging biotic and abiotic stress regulator in plants

Article References: Shinde, D., & Pareek, S. (2026). Beyond neurotransmission: dopamine as an emerging biotic and abiotic stress regulator in plants. Stress Biology, 6(1), Article 24. https://doi.org/10.1007/s44154-026-00291-8

Image Credits: AI Generated

DOI: 10.1007/s44154-026-00291-8

Keywords: dopamine, plant stress, abiotic stress, biotic stress, antioxidant, reactive oxygen species, calcium signalling, phytohormones, salinity tolerance, drought tolerance, postharvest, plant signalling