Plant Biology

1. Since plants interact with their environment through complex combinations of phytochemicals rather than metabolites in isolation, quantifying plant chemodiversity is of increasing interest. Although functionally relevant, structural disparity is mostly neglected in measures of chemodiversity because its integration relies on known compound identity, limiting broad application. 2. We established an approach deriving compound dissimilarity from UV-Vis spectra in HPLC-DAD datasets, evaluated how it relates to structure- or biosynthesis-based approaches, and examined whether it provides meaningful contributions to chemodiversity measures. For this, we applied it in an experiment full-factorially testing the effects of drought and herbivory on Solanum dulcamara leaf chemodiversity. 3. UV-Vis spectral dissimilarity aligned well with fMCS-based structural dissimilarity and reflected structural relationships within a set of standards. Incorporating it into chemodiversity analysis improved separation of the effects of drought and herbivory. Especially in the combination of both stresses, their distinct effects on different leaf metabolites were only fully reflected when accounting for compound disparity. 4. Hence, UV-Vis spectral dissimilarity captures chemically meaningful compound relatedness without requiring compound identity. Using it as a proxy for compound disparity adds a biologically relevant dimension to measures of chemodiversity with broader implications when assessing functional consequences of phytochemical diversity.

Fleshy fruits have evolved diverse traits to attract seed dispersers in response to frugivore behavior and sensory capacities. Fruit scent has been suggested to signal ripeness and nutritional quality, yet the volatile components involved and the information they convey remain poorly understood. It is unknown which information is encoded in fruit scent, whether plants actively synthesize these signals, and thus whether scent constitutes an evolved communication system shaping seed-dispersal interactions. Aliphatic esters, chemicals whose odor is often described as fruity, are abundant in some ripe fruits, especially those dispersed by animals which tend to rely on their sense of smell for fruit selection. Moreover, they have been argued to be associated with sugar content, potentially rendering them an honest signal and hence a hotspot of animal-plant chemical communication. We investigated whether aliphatic esters indicate fruit quality honestly and represent an adaptive trait shaped by disperser identity. Using 13 fig species (Ficus spp.; Moraceae) in Madagascar, we quantified seed dispersal by multiple animals using a quantitative ecological network. We then quantified chemical signals and nutritional rewards using thermal desorption gas chromatography-mass spectrometry (TD-GCMS) and high-performance liquid chromatography (HPLC), and used genome-guided transcriptome assembly to identify the candidate genes responsible for ester signaling. Our results show that (a) aliphatic esters occur more frequently in species dispersed primarily by olfactory-oriented mammals than in those dispersed by visually oriented birds; (b) ester abundance correlates positively with soluble sugar across species only in mammal-dispersed species, indicating an honest signal that is activated only when ecologically relevant; and (c) putative AAT gene revealing elevated expression associated with the increased abundance of aliphatic esters, sugars in single mammal-dispersed taxon. Together, these findings support the hypothesis that fruits have evolved to utilize the biochemical link between esters (signals) and sugars (rewards) to provide honest signals to seed dispersers.

Following a severe 2018 drought affecting much of Europe, European beech (Fagus sylvatica) exhibited patchy canopy dieback. To investigate the drivers of this mortality, we used a paired case-control design across Swiss forests, integrating phenotypic assessments and genomic analyses. Phenotypically, crown transparency and discoloration were used to classify tree damage state, while several other characteristics were measured to evaluate whether paired, neighboring damaged and undamaged trees were otherwise comparable, and to identify physiological stress signatures. Elevated leaf calcium content and red edge reflectance in dried leaves emerged as robust indicators of physiological stress. Genomic association models using reference-based SNP markers and reference-free k-mers were heavily confounded by micro-environmental variance and local population stratification even within our geographically limited study region. Our cross-validated genomic outliers showed no spatial overlap with predictive drought-associated loci previously identified in an independent German cohort. These findings indicate that drought survival in European beech is not governed by a universal set of major-effect alleles. Instead, tree performance appears highly context-dependent, likely shaped by micro-environmental heterogeneity and phenotypic condition. However, our results do not exclude polygenic drought responses involving multiple small-effect loci.

Poisonous plants frequently deploy toxic metabolites in an organ- and ontogenetic-specific manner, yet the developmental dynamics of these plant specialised metabolites remain poorly understood. In the Solanaceae, steroidal glycosides (SGs), including steroidal glycoalkaloids (SGAs) and steroidal saponin glycosides (SSGs), are major defence metabolites with potent ecological and pharmacological activities. Here, we investigated how their metabolic profiles are reorganised during flower and fruit development in Solanum dulcamara using untargeted metabolomics and chemometric molecular networking. Non-metric multidimensional scaling (NMDS) using classified metabolite features recovered clear organ-specific and chemotype-specific segregation of samples, which was further strengthened when analyses were restricted to metabolomic features annotated as SGs. In flowers, orthogonal projections to latent structures discriminant analysis (OPLS-DA) separated both floral developmental stage and chemotype, demonstrating that developmental stage and inherited SG polymorphism represent independent axes of chemodiversity in flowers. Chemometric molecular networks showed pronounced diversification of hydroxycinnamate metabolism towards anthesis, including accumulation of caffeoylputrescine in flower buds and progressive acylation of spermidine conjugates across flower development. Upon anthesis, glycosylated hydroxycinnamates and flavonoids, and hydroxycinnamoyl-acylated flavonoid glycosides are accumulated. Fruit ripening followed a contrasting trajectory, in which SGAs were associated with unripe fruit pericarp, whereas ripe pericarp accumulated N- and O-acetylated SGA derivatives, oxidative deamination products, and predicted steroid degradation products, indicating stepwise detoxification of toxic steroidal glycosides during seed maturation. Together, these findings show that the poisonous chemistry in S. dulcamara is highly dynamic and developmentally orchestrated. Flowers accumulate structurally complex metabolites toward anthesis, including conjugates of hydroxycinnamates, whereas fruits metabolise toxic SGAs into less toxic SGs during ripening, linking metabolic remodelling to reproduction and seed dispersal.

Climate change is exposing trees to rising atmospheric water demand. Because stomata regulate plant water loss, understanding stomatal behaviour is critical. However, few comparative studies examine species-specific stomatal responses to atmospheric demand. Here, we quantify stomatal behaviour in 38 temperate tree species (27 broadleaved, 11 conifers) in a German research arboretum during a warm summer without soil drought. We measured the diurnal stomatal conductance (gs) of 787 leaves and modelled gs species-specific responses to leaf-to-air vapour pressure deficit (VPDL). Four descriptors of the gs-VPDL relationship were derived: maximum stomatal conductance (gmax), the VPDL that maximises gs, the VPDL associated with a 50% reduction in gs, and the stomatal closure rate. We relate these metrics to drought-induced shifts of carbon isotope ratios and to leaf functional traits. Large variation in stomatal behaviour exists, ranging from early-closure to VPDL-tolerant strategies. Species maintaining gs at higher VPDL also show weaker physiological responses to past drought. gmax is partly explained by leaf economic traits; other gs-VPDL descriptors are not related to stomatal anatomy and leaf economy. Our interspecific comparison reveals substantial variation in stomatal responses to atmospheric demand that is relevant to drought responses, but cannot be readily inferred from commonly measured leaf traits.

Nectar is a primary floral reward, which can also deter non-specialist pollinators; yet, the role of complex nectar composition in plant-pollinator interactions and its relationship to other floral traits remain understudied, particularly in natural communities. We profiled the nectar metabolome of 43 co-occurring species in an alpine grassland to evaluate relationships among nectar chemistry, phylogeny, floral display traits and pollinator visitation. Field observations revealed a dominant bee vs fly visitation gradient. Several aggregated nectar traits tracked this gradient independently of plant phylogeny, indicating functional convergence: specifically, bee visitation was associated with higher nectar sucrose proportion, greater compound richness, and more divergent profiles of uncommon sugars. Nectar traits exhibited variable relationships to floral display traits, suggesting partial inter-trait phenotypic integration. Together, these findings indicate that detailed features of nectar composition, including phytochemical diversity, play a functional role in floral phenotypes, with previously unappreciated implications for plant-pollinator community ecology.

Orchids exhibit extraordinary floral diversity, yet the molecular mechanisms underlying floral scent evolution remain poorly understood. Guided by recent phylogenomic reconstruction of the Australian orchid subtribe Caladeniinae, we used Glossodia major, an earlier-diverging food-deceptive lineage, as an evolutionary anchor for investigating floral volatile diversification. Scent-producing petals showed coordinated expression of terpene synthase (TPS), carotenoid and carotenoid cleavage dioxygenase (CCD) pathways. Functional characterisation identified GmTPS-b3, GmTPS-b4 and GmTPS-a1 as contributors to floral monoterpene and sesquiterpene production, while GmCCD1 produced geranylacetone, the dominant floral volatile, from {zeta}-carotene. GmCCD4 and GmCCD7a showed additional, partially overlapping apocarotenoid-forming activities. Integration of tissue-specific expression, enzyme activity and subcellular localisation linked these pathways to the emitted floral bouquet. Functional comparisons with characterised Caladenia homologues revealed biochemical conservation and catalytic and compartmental specialisation, while expression profiling across 31 species identified pollination strategy-associated regulatory divergence in TPSa1 and TPSb3, consistent with corresponding shifts in terpenoid-rich floral scent. We propose that differential modification and deployment of conserved biosynthetic pathways contributed to the attenuation and re-emergence of terpenoid-rich floral scent during Caladeniinae diversification. More broadly, our findings provide candidate mechanistic links between molecular evolution, pollinator-mediated selection and floral diversification.

Abstract Tricyclic coumarins (TCs) exhibit defensive properties against herbivorous insects and possess valuable pharmacological properties for humans. They are mainly distributed in the Apiaceae, Rutaceae, Moraceae, and Fabaceae families. The chemical structural diversity of TCs in these families primarily arises from differences in skeletal variety and attachment position of the third ring, as observed in unsaturated furanocoumarins (FCs) and saturated dihydrofuranocoumarins (DHFCs). In TC biosynthesis, the FC and DHFC pathways diverge through distinct oxidation patterns. The product specificity of the reported cytochrome P450 monooxygenase at the branching point suggests that these TC groups are produced in nearly identical ratios; however, some species of the genus Angelica (Apiaceae) accumulate DHFCs at higher levels than FCs. In this study, we investigated the enzymatic mechanism responsible for forming these two TC groups using A. keiskei, a Japanese native species used as a medicinal and edible herb. Organ-specific transcriptome analysis highlighted a P450 member CYP71AJ62 that exhibited a close correlation with TC accumulation across organs. Enzymatic characterization demonstrated that CYP71AJ62 predominantly forms a hydroxylated DHFC, vaginidiol, which may promote DHFC over FC skeletal formation in TC biosynthesis. Phylogenetic analysis suggested that CYP71AJ62 has been derived from a gene responsible for FC formation by functional shift without gene duplication. Subsequent three-dimensional structural modeling and site-directed mutagenesis revealed that two amino acid residues on substrate recognition sites cooperatively determine the product specificity of this P450 enzyme. This study provides new insights into the molecular evolutionary process underlying ring-structure diversification and, more broadly, the adaptation of plants to their environments.

Flower color has primarily been studied in the context of pollinator attraction, although effects on thermal energy balance are also important, especially in the context of global climate change. We used infrared imaging to compare petal temperatures of white versus pigmented cultivars of ten angiosperm taxa under controlled environmental conditions. Excised sets of flowers (n= 6 sets per species) exhibiting white, light, and/or dark anthocyanin (red to purple) coloration were mounted perpendicularly to the sun at mid-day, under clear sky, low wind (<1 m s-1) conditions. Sunlight was filtered through either UV-transparent or UV-opaque film, and petal temperatures were measured using an infrared camera after one minute equilibration. In all species, pigmented flowers were significantly warmer than lighter-colored conspecifics. Mean differences averaged +5.3{degrees}C for darker-colored versus white morphs, +2.9{degrees}C for lighter-colored versus white. Most warming was associated with visible wavelengths, but additional warming under UV-inclusion was also observed in some species. In situ observations of intact landscape plants under low-wind, high-light conditions corroborated experimental results, with differences exceeding 10{degrees}C observed in some taxa. Temperature differences >7{degrees}C were also recorded for purple versus white sections of the same flower in multicolored Viola and Petunia cultivars. Follow-up experiments using dark-pink and white varieties of Impatiens x hybrida corroborated well-known effects of sunlight intensity and wind speed on floral temperatures, helping to explain inconsistent reports in the literature. Our results clearly demonstrate that anthocyanin pigments can have significant and dramatic impacts on floral temperatures, which could be an important factor driving evolution of flower color. In the context of climate change, floral pigments could amplify the effects of rising global temperatures, negatively impacting plant reproduction and crop yields, especially on the warmer end of species ranges. Changes in flower color could also potentially induce shifts in pollinator communities, which could have community-scale effects.

Central to understanding biodiversity is the systematic classification of biological taxa where concepts on integrating omics data have not yet been comprehensively executed. The data-driven approach is aiming at integrating phylogenetic data from three or more scales aiming at enriching the robustness of species delimitations while also revealing evolutionary drivers of diversification and speciation. This study investigates complex-thallose liverworts as reference and combines the analysis of DNA marker sequencing, morphometrics utilizing bioimaging measurements and chemometrics using liquid chromatography high-resolution mass-spectrometry (UPLC/ESI-QTOF-MS) with data-dependent acquisition of tandem mass-spectra (DDA-MS), with character variation evaluated with dendrograms and data mining. The comparative analysis revealed similar tree topologies albeit with diverging positions of taxa that were attributed to flavonoid-glycosides, auronidins and phenanthrenes resulting from evolutionary radiation and adaptations to stressful bioclimatic conditions, whereas unique fatty acyls in Riccia link to ecological causes of speciation. Characteristic amino acid motifs confirm the intermediary position of liverworts between algae and land plants. By functionally attributing and mapping chemometric markers to the taxonomy, the data-driven approach integrating omics into integrative taxonomy is opening opportunities for plant systematics to identify evolutionary drivers and form new hypotheses on the diversification and speciation of species.

Temperate forests increasingly face extreme air temperature, but plant physiological responses, particularly alterations in carbon allocation or protection via volatile organic compound (VOC) emissions, remain poorly understood. We pulse-labelled well-watered saplings of Fagus sylvatica and Pseudotsuga menziesii in a controlled heat stress experiment with 13CO2 to quantify heat-induced shifts in CO2, VOC and C pool exchange, specifically analyzing compound-specific {delta}13C of terpenoids, water-soluble organic matter (WSOM) and dark respiration. Under heat stress, up to 50% of fresh assimilates were directed to maintenance respiration and 1-2% to VOC emissions, while net assimilation and water use efficiency decreased by 50-75% in both species. Heat directly affected metabolic processes and reduced turnover rates of fresh assimilates in F. sylvatica, but accelerated them in P. menziesii. Strong 13C labelling of some compounds, particularly acyclic ones, suggested increased de novo synthesis of specific terpenoids for heat stress protection. By tracing the fate of recently assimilated 13CO2 we demonstrate that heat stress reduces net carbon uptake and water use efficiency, disrupts turnover of C pools and increases carbon loss via respiration and de novo synthesis of specific VOCs, potentially diminishing net carbon uptake of forests under future heat extremes.

Vegetative desiccation tolerance requires specialised cell wall (CW) adaptations to withstand severe mechanical stress during dehydration and rehydration. While intracellular protective strategies in resurrection plants, including Ramonda serbica, are well documented, the CW response remains poorly understood. Here, we integrated immunocytochemical profiling, FTIR spectroscopy, quantification of CW-bound phenolics, transcriptomics, and ionically bound CW proteomics across hydrated (HL), desiccated (DL), and rehydrated states (R1-1h, R2-24h, R3-48h). Reversible CW folding was facilitated by condensed arabinogalactan-proteins (AGPs) and extensins, alongside a site-specific balance between pectin methylesterification and demethylesterification. Structural compaction was further reinforced by the accumulation of CW-bound hydroxycinnamates, which persisted through R1 phase. Moreover, basic 7S globulin, miraculin, -galactosidase, and two LEA4 protein family members were strongly accumulated during DL and R1, providing the first evidence of ionically CW-bound LEA proteins. Initial rewatering (R1) triggered a rapid transcriptomic reactivation of pectin-degrading/modifying enzymes, carbohydrate-active enzymes, and subtilases, accompanied by unesterified pectin enrichment. By 24-48 h (R2-R3), CW-bound hydroxycinnamic acids declined, and CW architecture, gene expression, and proteome profiles returned to baseline levels. Overall, our findings reveal a coordinated spatiotemporal apoplastic network - driven by glycoproteins, pectin modulation, CW-bound hydroxycinnamates, and LEA4 proteins - essential for rapid desiccation recovery.

Reports that the South American climbing vine Boquila trifoliolata modifies its leaf shape to mimic leaves of its host plant have raised considerable attention. Boquila leaf development was proposed to reflect visual inputs perceived in an unknown manner. However, the very existence of Boquila leaf shape mimicry remains inconclusive, since the reported observations are open to alternative explanations. We performed an initial quantitative characterization of leaf shape variability in glasshouse-cultured clonal Boquila plants grown without close host contact, and attempted to reproduce the leaf shape mimicry phenomenon under controlled culture conditions using live olive (Olea europaea) plants, artificial (decoy) olive or artificial ivy plants as supports. While we found leaves of variable shape (including those resembling ivy leaves) both in plants grown without host contact and in those climbing on live or decoy hosts, we did not observe any link between leaf shape and host presence or character. Instead, the leaf shape appears to be affected by environmental conditions including the season. Although our study was limited to a single Boquila genotype and an ecologically unrealistic host selection, our observations suggest that the alleged mimicry might originate from unintentional misinterpretation of intrinsic discontinuous leaf shape plasticity in field observations.

Fire-dependent or fire-influenced ecosystems harbor species with diverse response strategies, such as smoke-stimulated germination and dormancy release through heat shocks. Although these cues influence germination in many fire-prone ecosystems, their effects on seeds of woody species from tropical dry forests (TDFs) remain poorly understood. We evaluated the germination response of twelve TDF woody species to three heat-shock temperatures (80, 120, and 160C), two exposure times (3 and 5 min), and two smoke conditions (with and without smoke water), plus dry and wet controls. We also assessed the relationship between germination and functional seed traits, including permeability, seed-coat thickness, mass, and shape index. Of the eleven species that germinated, four showed broad tolerance, with no significant reduction in germination even at 160C for 5 min, which was associated with lower permeability, thicker seed coats, and greater mass. Four other species showed restricted tolerance to heat, with significant declines in germination at higher temperatures or longer exposure times, and were associated with higher permeability, thinner seed coats, and lower seed mass. The remaining three species showed heat-stimulated germination between 80 and 120C and tended to have lower shape-index values. Smoke treatments significantly increased germination in three species, Ceiba pentandra, Guazuma ulmifolia, and Samanea saman. In the remaining species, significant differences were either absent or attributable to moisture or imbibition effects rather than to smoke itself. Overall, germination responses to heat were associated with variation in functional seed traits, whereas responses to smoke were less widespread and showed a less consistent functional pattern.

Apple scar skin disease (ASSD), caused by Apple scar skin viroid (ASSVd), is characterized by peel scarring, cracking, dappling, and fruit deformation, resulting in reduced fruit quality and marketability. Despite its economic importance, the physicochemical and metabolic alterations underlying disease progression remain poorly understood. To address this knowledge gap, apple fruits representing four stages of ASSD (healthy, lightly infected, moderately infected, and highly infected) were comprehensively characterized. ASSVd infection was confirmed by RT-PCR, amplicon sequencing, and phylogenetic analysis. Fruit morphology and quality attributes, including firmness, total soluble solids (TSS), pH, titratable acidity (TA), and total phenolic content (TPC), were evaluated. ASSVd infection significantly reduced fruit weight and firmness and altered TSS and TA, indicating progressive deterioration of fruit quality. To investigate the underlying metabolic changes, peel and pulp tissues were analysed separately using gas chromatography-mass spectrometry (GC-MS), while major soluble sugars were quantified by 1H nuclear magnetic resonance (1H NMR) spectroscopy. Integrated metabolomic analyses revealed distinct tissue-specific metabolic reprogramming during disease progression. Major soluble sugars declined significantly during early infection, followed by tissue-dependent recovery at later stages, whereas organic acids, amino acids, phenolics, lipids, polyols, and pentacyclic triterpenoids exhibited dynamic stage-dependent changes. Notably, lupeol accumulated progressively, whereas ursolic acid and oleanolic acid declined, indicating disease-associated alterations in host triterpenoid metabolism. Multivariate analyses demonstrated clear metabolic separation among disease stages. Lupeol, ursolic acid, and chlorogenic acid were identified as candidate discriminatory metabolites in the peel, whereas myo-inositol, chlorogenic acid, and aspartic acid were identified in the pulp. Collectively, these findings demonstrate that ASSD induces coordinated, tissue-specific physicochemical and metabolic reprogramming that compromises postharvest fruit quality and reshapes defence-associated metabolism. This study provides the first integrated metabolomic characterization of ASSD progression and identifies potential metabolic biomarkers for disease diagnosis and severity assessment. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/741181v1_ufig1.gif" ALT="Figure 1"> View larger version (56K): org.highwire.dtl.DTLVardef@92e453org.highwire.dtl.DTLVardef@1cc2436org.highwire.dtl.DTLVardef@15d7e27org.highwire.dtl.DTLVardef@1056568_HPS_FORMAT_FIGEXP M_FIG C_FIG

Climate change is increasing the frequency and intensity of heatwaves and droughts, threatening medicinal and aromatic plants (MAP) production. Temporary shading during the hottest part of the day may reduce heat and radiative stress while limiting the reduction in light availability. We evaluated this strategy in a field experiment using three MAP species with contrasting ecological requirements and harvested organs: lavandin (Lavandula x intermedia), curly parsley (Petroselinum crispum) and valerian (Valeriana officinalis). Vertical shade nets provided midday shading and effects on crop microclimate, leaf temperature, water status, PSII photochemical efficiency, plant growth and biomass and essential oil production were assessed over two growing seasons. Midday shading reduced daily photosynthetically active radiation by 19.9-55.9 %, with weak effects on air temperature and vapor pressure deficit. In contrast, leaf temperature at solar noon decreased by 6.9 degrees C, 5.6 degrees C and 3.0 degrees C in lavandin, valerian and parsley, respectively. Midday shading improved light-adapted and maximum PSII photochemical efficiencies in all three species and reduced branch dehydration in lavandin during heatwave periods. However, agronomic responses were species-dependent. Floral biomass decreased in lavandin, whereas parsley leaf biomass and valerian root biomass increased. Essential oil concentration was unaffected in lavandin and valerian. Overall, our results show that midday shading primarily reduced leaf-level thermal and radiative stress rather than modifying the surrounding air microclimate, and suggest that its agronomic effects may reflect a balance between stress alleviation and reduced carbon acquisition, that varies with species ecology and production objectives.

Seed ecophysiology is essential for understanding plant regeneration and developing effective conservation and ecological restoration strategies, yet knowledge remains scarce for most threatened Cerrado species. We characterised the germination niche, desiccation tolerance and storage behaviour of Xyris paradisiaca (Xyridaceae), an Endangered species endemic to Central Brazil, to assess whether its restricted distribution is associated with narrow germination requirements and to inform seed-based conservation. Germination was tested across light regimes, constant temperatures, decreasing water potentials and short-duration heat shocks, while thermal- and hydro-time models were used to quantify thermal and hydric thresholds. Seeds exhibited an absolute light requirement but broad abiotic tolerances. Germination remained >87% between 15 and 40 {degrees}C, with estimated cardinal temperatures of Tb = 8.94 {degrees}C, To = 33.13 {degrees}C and Tc = 45.53 {degrees}C. Germination remained similar to the control down to -0.6 MPa and exceeded 40% at -1.0 MPa, with a median base water potential of {Psi}b = -1.03 MPa. Germination also remained high after 1-min heat shocks up to 200 {degrees}C. Seeds were desiccation tolerant, with 100% germination after drying and a viability loss index of -0.04, and germination remained >90% after 24 months of ambient storage. Thus, the highly restricted distribution of X. paradisiaca is not driven by a narrow physiological germination niche. Its broad environmental tolerances, desiccation tolerance and favourable storage behaviour also highlight its unexplored potential for seed-based restoration, propagation and ex situ conservation.

Distinct from plants which directly parasitise other plants (parasites), non-photosynthetic mycoheterophic plants (MHPs, previously known as achlorophyllous mycotrophs or saprophytes) depend upon fungal hyphae for their carbon and have been viewed as cheaters or parasites in their fungal partnerships rather than mutualistic as in most other plant-mycorrhizal interactions. Over 400 such species in 87 genera and 11 families are recorded which maintain this lifeform through their life-cycle, while an estimate 30,000 further species, mainly orchids, depend on this mode of life to establish themselves from seeds. In most cases the fungal partners and the ultimate carbon sources, usually autotrophic plants, are unknown. High fungal specificity is the norm in those MHPs researched. We describe a new MHP genus and species, Denisea fonensis that we discovered in the Simandou range of the Republic of Guinea, West Africa in October 2025 on the footprint of a mining project. While clearly placed in Dioscoreales (which has three MHP families), the features of Denisea are so unusual that it was not initially clear in which family to place it. Finally, with molecular data we placed Denisea in Thismiaceae, corroborated by morphology. The new discovery is all the more unexpected as this is the first record of Thismiaceae from West Africa. Until now the family has only been recorded in Africa from three species of the very different genus Oxygyne, of Cameroon and Central African Republic. We provisionally assess Denisea fonensis as Critically Endangered since less than ten individuals are recorded in only a few square metres at one site, where there are imminent threats from animals. We propose urgent measures to conserve this species to reduce the risk of global extinction that has eliminated other African MHP species such as Oxygyne triandra, and further research to determine the fungal and autotrophic plant partners of this remarkable plant genus.

O_LIC4 photosynthesis and the crassulacean acid metabolism (CAM) rarely co-evolved in a single lineage, but Portulaca can switch from C4 to CAM under drought stress. Little is known about CAM responses to nutrient availability, hence the goal of this work was to assess the influence of macronutrients over C4-CAM. C_LIO_LIP. oleracea was grown hydroponically and subjected to treatments (+/- PEG) for: nitrate deficiency (-NO3-), ammonium (NH4+), NO3- + NH4+, magnesium (-Mg), phosphorus (-P), calcium (-Ca), potassium (-K), and sulphur (-S) deficiencies, and salt stress. Samples were monitored for diurnal titratable acidity ({Delta}H+), osmotic potential, and gene relative expression for core C4/CAM and signaling genes. C_LIO_LI-NO3- induced CAM even without PEG, a process probably without the mediation of abscisic acid (ABA). Notably, -P showed a trend to induce CAM without PEG and -Ca prevented CAM induction even with PEG. Salt stress induced CAM, and NH4+ was not toxic for P. oleracea. Other treatments showed less conspicuous responses. C_LIO_LIThis work brings an unprecedented overview of the nutrition of C4 and CAM, suggesting perspectives for deepening the study of C4-CAM. Understanding the molecular mechanisms and environmental signaling of C4-CAM is essential for realizing the evolution of two CCMs in a single plant. C_LI

Background and AimsThe genus Solanum including the wild species S. dulcamara, is rich in specialized metabolites such as steroidal glycoalkaloids (SGAs). Yet, much of this chemical diversity remains poorly characterized. This study aims to provide a comprehensive assessment of intra-specific chemodiversity in S. dulcamara. Using a dataset generated from 42 globally distributed accessions, we tested whether metabolic profiles differ among plant organs. We postulated that metabolic richness and abundance vary across accessions. Additionally, we hypothesized that differences in geographic origin or altitude affect SGA chemodiversity. MethodsAn untargeted metabolomic approach was applied to leaf, flower and root samples of 42 S. dulcamara accessions. Plants were grown in the greenhouse, and the extracted metabolites were analyzed using UHPLC-HRMS/MS in positive and negative ionization modes. Data processing and metabolite annotation were performed with a tailored bioinformatics workflow. Multivariate analyses were performed to evaluate chemical variation across organs and accessions. Key ResultsOur analyses revealed both organ and accession-specific metabolic diversity. Principal component analysis and clustering analyses revealed metabolic differentiation between leaves, flowers and roots. Leaves showed the highest metabolite richness and abundance, while roots showed the lowest. Alkaloids, especially SGAs, dominated positive mode profiles in roots, whereas shikimates and phenylpropanoids were prominent in negative mode profiles. Based on the leaf and flower SGAs profiles, four chemotypes were identified. Analyses of flavonoid and cinnamic acid derivatives, however, did not reveal chemotypes. Feature-based molecular network analyses confirmed that metabolite clusters are associated with plant organs, but not with altitude or geographic origin of the accessions. ConclusionsThe intraspecific chemodiversity within S. dulcamara is mainly driven by organ and accession-specific metabolic differences. We identified four SGA leaf and flower chemotypes, suggesting possible functional and ecological roles of this aboveground chemodiversity. These insights may contribute to applied research in plant resistance breeding and crop production.