The increasing release of nanoplastics (NPx) and engineered nanoparticles (NPs) into terrestrial ecosystems poses emerging risks to soil biota and the food chain. The effects of NPx contamination on soybean growth and N2 fixation potential in the presence of nickel oxide nanoparticles (NiO-NPs) remain poorly understood. This study investigated the accumulation and phytotoxicity of polystyrene nanoplastic (PS NPx) and NiO-NPs in soybean and their effects on nitrogen fixation potential. Single or co-application of NPx and NiO-NPs (100 mg kg-1) markedly reduced photosynthetic efficiency (8-48%), elevated biochemical stress markers (25-164%), downregulated phytohormone levels (13-54%), and negatively affected nitrogen fixation potential (19-35%), ultimately leading to reduced plant physiological growth (21-57%). This was due to PS-NPx accumulation in the leaves and structural abnormalities in vacuoles (including altered vacuole morphology), cell walls, mitochondria, and chloroplasts. In contrast, NiO-NPs at 50 mg kg-1 significantly increased nodule formation (16%) and biomass (20%), thereby enhancing N2-fixation (14%) in soybean plants. This improvement was attributed to the upregulation of N2 assimilation enzymes in nodules, roots, and shoots that promoted N2 content in the plant, resulting in increased plant growth. This study improves our understanding of the potential environmental risks associated with the accumulation of NPx and NiO-NPs in legumes crops and provides valuable scientific insights into their impacts on plant growth and N2 fixation in soybean.
Programmed cell death and immunity in plants are finely orchestrated to promote antimicrobial defense while preventing autoimmunity. However, the molecular mechanisms involved are not fully understood. Here, we isolated a rice mutant ecdr1 (enhanced cell death and resistance 1) that displayed an autoimmunity phenotype and enhanced resistance to rice blast and bacterial blight, and identified ECDR1 as a new shared component in PI3K and PI4K complexes, linking the hyccin-containing protein with plant defense responses. ECDR1 was expressed at all developmental stages and in all tissues examined. The ECDR1 was highly conserved in function across monocots and dicots. The 113 bp deletion in the ECDR1 promoter reduced its expression, leading to cell death and enhanced disease resistance. The ECDR1 was localized in plasma membrane, and interacted with TPR1 and TPR2 which in turn interacted with both PI4K1 and PI3K1, suggesting that ECDR1 could function as a component associated with not only PI4K complexes but also PI3K complexes to help catalyze PI into PI3P and PI4P. The lethality of all homozygous ecdr1, pi3k1 and tpr1 tpr2 mutants indicated the crucial roles of these genes in plant normal growth, which restricted our understanding of PI3K and PI4K functions. Alternatively, exogenous application of PI3K and PI4K inhibitors could substantially exacerbate the cell death and enhance disease resistance, implying their roles in plant immunity. Our findings provide novel insights into the regulatory mechanisms of ECDR1 in cell death and defense pathways, will aid in understanding the functions of PI3K and PI4K in plant immunity.
Stomatal responses to changes in leaf water status are amongst the most important responses of guard cells for balancing carbon gain with water loss, yet we do not know if guard cells are hydraulically linked to the water status of the leaf across vascular land plants. We combined time-lapsing imaging of leaf tissue in the cuvette of a gas analyzer to provide a dynamic measurement of leaf water potential (Ψl) while simultaneously recording leaf gas exchange to test these questions. Using this method in a representative lycophyte Selaginella moellendorfii we show that stomata respond passively to changes in Ψl by closing as soon as Ψl declines and opening rapidly on rehydration, confirming a close hydraulic connection between guard cells and the leaf in lycophytes. In contrast, in a representative angiosperm Solanum americanum, wrong-way stomatal responses occurred when leaves experienced rapid changes in Ψl. In this species wrong-way responses no longer occurred once Ψl had declined to turgor loss point, at which point stomata will rapidly reopen on rehydration without a wrong-way response. These observations confirm a close hydraulic connection between the guard cell cytosol and leaf apoplast across vascular land plants and rule out a hypothesis that there is a rapid and transient rehydration of leaf tissue from embolized xylem on leaf excision, as an explanation for wrong-way stomatal opening. The ability to simultaneously record leaf gas exchange and Ψl provides a powerful tool for resolving outstanding questions related to the hydraulic regulation of stomatal aperture.
The transcription activator-like effector Tal12a is widely conserved among Xanthomonas campestris pv. campestris strains that cause black rot in Brassica crops. However, its role in disease remains unclear. To investigate how Tal12a contributes to pathogenesis, we combined transcriptomic profiling of cauliflower leaves infected with Tal12a-expressing strains, prediction of TALE-binding elements, and heterologous expression assays in Nicotiana benthamiana. The aim of this approach was to identify candidate susceptibility genes. Artificial TALEs were further employed to validate the contribution of these candidate targets to disease development. Tal12a enhanced both virulence and bacterial growth in cauliflower. Transcriptome analysis revealed 380 genes that were induced upon infection, nine of which were prioritised as candidates. Seven of these were confirmed as direct Tal12a targets, while the induction of the sugar transporter genes BoSWEET13 and BoSWEET14c likely occurred indirectly. Functional assays demonstrated that these two SWEET genes and the BoIAA7c gene, which encodes auxin-dependent transcriptional regulator, contribute to disease development. These findings identify the first susceptibility genes in cauliflower and reveal that Tal12a promotes disease through a complex transcriptional reprogramming, involving direct and indirect target induction, with several genes functioning as minor susceptibility factors.
The role of RNA splicing as a modulator of the molecular responses to stress is well described. In contrast, its importance in the acclimation of plants to changes in ambient temperatures has only recently started to emerge. Here, we analyzed the role of temperature in regulating the functionality of factors associated with snRNP biogenesis, a key process underlying pre-mRNA splicing. Taking advantage of mutants showing temperature-dependent phenotypes, we conducted a comprehensive study of the role that the methylosome and SMN complexes have in plant development. Genetic, phylogenetic, and confocal analyses, as well as in vivo and in vitro evidence, reveal remarkable differences in the composition and importance of these complexes between plants and vertebrate animals. The SMN complex in Arabidopsis is apparently reduced to a single protein, GEMIN2, that is not essential for plant development, and the existence of a SMN ortholog is uncertain. Similarly, components of the methylosome previously implicated in snRNP biogenesis are not essential for plant viability. Our results suggest that factors considered central to snRNP biogenesis in animals have less crucial roles in plants and highlight how an evolutionarily conserved molecular process like RNA splicing has nevertheless evolved plant specific characteristics.
The symbiotic fungus Serendipita indica confers broad-spectrum beneficial effects on diverse plant hosts. Its key effector SIE141 elicits immunity against Phytophthora and salt tolerance by binding and relocalizing thioredoxin CDSP32 from chloroplast to the nucleus. Here, we show that this functionally essential nuclear transfer process of the SIE141-CDSP32 complex is mediated by the host NTF2 proteins. NTF2 family proteins are direct targets of SIE141, whose knockdown abolished nuclear accumulation of both SIE141 and CDSP32, leading to their rendered accumulation to chloroplasts. The glutamine residue at position 40 of NbNTF2A is critical for its interaction with both SIE141 and Ran GTPase 1. SIE141 modulates NbNTF2-NbRan1 interaction in a dose-dependent manner, without impairing nuclear accumulation of NbRan1 and the NTF2-mediated positive immune function of Ran1. Our results reveal a previously unknown mechanism where a beneficial symbiotic fungal effector utilizes the conserved NTF2 rather than other core nuclear import machinery components to traffic an immune complex and enhance disease resistance. These findings provide a potential strategy for engineering plant immunity by manipulating NTF2-RanGTPase dependent nucleocytoplasmic transport.
The reactive oxygen species (ROS) burst is a hallmark of immune responses, and its fine-tuned regulation is essential for balancing plant immunity and growth. Although mechanistic understanding of ROS production has improved in Arabidopsis, corresponding knowledge remains sparse in crops, particularly in the non-Brassicaceae species that lack PBL13-mediated negative regulation of the ROS burst. Here, we report an RLCK-V subfamily member in potato, StSOAK1, which negatively regulates disease resistance to the oomycete Phytophthora infestans and the fungus Botrytis cinerea. Furthermore, the potato stsoak1 mutants displayed elevated ROS production upon pathogen infection and immune activation. StSOAK1 interacts with and directly phosphorylates the ROS-producing enzyme StRBOHB at Ser849. Notably, the StSOAK1-StRBOHB complex exhibits dynamic changes upon immune activation. Moreover, the phosphorylation status of the S849 site is essential for StRBOHB protein stability and the function of StRBOHB in regulating ROS burst. Together, our study reveals a regulatory mechanism of potato StRBOHB, which occurs in parallel with its paradigmatic AtPBL13-mediated regulation in Arabidopsis.
The phenylpropanoid pathway varies across species and environments, producing diverse metabolites. The transcriptional regulation governing precursor feeding into this pathway remains largely unexplored. Here, we characterize OscWRKY7 TF from Ocimum sanctum as a positive regulator of arogenate dehydratase-5, a key shikimate pathway gene catalyzing the conversion of arogenate into phenylalanine. Phenylalanine treatment in O. sanctum induced key genes and metabolites of the phenylpropanoid pathway, with OscWRKY7 showing early induction. Recombinant OscWRKY7 interacts with the canonical W-box cis element and transactivates the reporter gene in yeast. Ectopic expression of OscWRKY7 in Arabidopsis thaliana induced transcriptomic changes in the shikimate and phenylpropanoid pathways, leading to upregulation of arogenate dehydratase-5 transcripts and enhanced accumulation of phenylalanine and downstream metabolites. The biological function of OscWRKY7 was determined in Ocimum sanctum using gain- and loss-of-function approaches via hairy root-mediated overexpression and tobacco rattle virus (TRV)-based VIGS. Overexpression of OscWRKY7 upregulated OscADT5 and enhanced phenylalanine accumulation, along with downstream phenylpropanoid metabolites, whereas silencing reduced them, providing evidence of OscWRKY7-mediated regulation of phenylpropanoid metabolism in O. sanctum. OscWRKY7 exhibits dual cis-element specificity, binding the W-box and a noncanonical WT-box variant (TAACTTTT) in the OscADT5 promoter, suggesting a novel regulatory module. The Electrophoretic Mobility Shift Assay and the Yeast One-Hybrid Assay demonstrated binding, while dual luciferase suggests the transactivation of OscADT5 by OscWRKY7 through a noncanonical WT-box. OscWRKY7 further modulates phenylpropanoid pathway-associated genes to alter the accumulation of anthocyanin and salicylic acid, thereby enhancing plant defense response in Arabidopsis. Overall, our study suggests that OscWRKY7 promotes phenylpropanoid accumulation by facilitating the availability of phenylalanine, a precursor of the phenylpropanoid pathway.
Guard cell pairs form dynamic stomatal gas exchange pores in aerial tissues of plants. Guard cells regulate CO2 influx and water loss through stomata by integrating multiple environmental and internal signals. Guard cells serve as highly specialized sensory and signal processing cells, thereby orchestrating stomatal movements in response to changing conditions. This review describes recent advances and early discoveries in elucidation of guard cell signaling networks. Present day understanding of the molecular and cellular mechanisms mediating stomatal opening by blue light, red light, heat stress and photosynthesis-mediated low CO2 in intercellular leaf spaces are reviewed. Furthermore, up-to-date knowledge of the molecular mechanisms and pathways that trigger stomatal closing by abscisic acid (ABA), elevated CO2 and low humidity/high vapor pressure difference is synthesized. These pathways promote stomatal closure and water conservation. Critical functions of other tissues are described, including mesophyll cells as producers of messengers for red light-induced stomatal opening and vascular tissues in drought-induced ABA synthesis and transport. Guard cell ion channels and pumps drive the ion fluxes required for the cellular osmotic motor that opens and closes stomatal pores. Roles of and recent advances toward understanding the regulatory mechanisms of these membrane transporters as downstream targets of guard cell signaling cascades are described. Synthesis of these signaling cascades into signaling networks is reviewed and open questions for future research are highlighted throughout. Understanding these integrated mechanisms is critical for future improvement of plant water use efficiency and crop environmental stress resilience.
The 1988 papers by Mauch, Mauch-Mani, Hadwiger and Boller on pea antifungal hydrolases captured a simple but powerful idea: plants can attack pathogens by directly targeting the structural polymers that hold their cell walls together. At that time, chitinases and β-1,3-glucanases were known to accumulate after infection, wounding and ethylene treatment, but whether these proteins actually restricted fungal growth remained unclear. By resolving distinct hydrolase isoforms and showing that inducible chitinase and β-1,3-glucanase act synergistically to inhibit fungal growth and lyse hyphal tips, these studies transformed infection-induced enzyme accumulation into a mechanistic model of antifungal activity. We now recognize that fungal cell wall hydrolysis also releases glycan fragments that act as immune signals and are perceived by plant immune receptors, linking pathogen damage to immune activation in plants. At the same time, pathogens have evolved counterstrategies to mask, modify or protect these cell wall components, limiting both enzymatic access and immune detection. Thus, the Boller studies anticipated a central theme of modern molecular plant pathology: plant-pathogen interactions are dynamic interfaces where host enzymes, pathogen wall fragments, immune receptors and pathogen counterstrategies converge.
Panax notoginseng is an economically vital medicinal plant, prized for its bioactive P. notoginseng saponins (PNS) which possess significant therapeutic effects in cardiovascular and cerebrovascular diseases. Despite the elucidation of the core enzymatic steps in PNS biosynthesis, the post-transcriptional mechanisms that coordinate these metabolic fluxes remain largely obscure. This study explored the Pn-miR160a-ARF4 module as a pivotal regulation mode in the biosynthesis of PNS. Under methyl jasmonate (MeJA) stimulation, Pn-miR160a was significantly upregulated, subsequently targeting and cleaving the transcripts of auxin response factor 4 (PnARF4). This targeted silencing of PnARF4 effectively relieves its transcriptional repression, thereby promoting the expression of downstream biosynthetic genes and increasing PNS yield. By integrating hormonal signaling with miRNA-mediated gene silencing, these results uncover a sophisticated regulatory axis that governs specialized metabolism. Furthermore, this work expands the known functional scope of the evolutionarily conserved miR160-ARF module beyond its traditional role in plant architecture and auxin signaling, repositioning it as a central component of secondary metabolic regulation. These findings provide a theoretical foundation and a robust molecular target for the metabolic engineering and genetic improvement of P. notoginseng quality.
Eukaryotic organisms organize their genetic material in chromatin rather than naked DNA. Efficient chromatin assembly is essential for all DNA-templated processes, including replication, transcription, and DNA repair. Our research focused on two major histone H3 deposition complexes: Chromatin Assembly Factor (CAF-1) and Histone Regulator A (HIRA). CAF-1 deposits canonical H3 on naked DNA immediately after replication during the S-phase in yeast and metazoans, and HIRA is thought to incorporate the H3.3 variant in a replication-independent manner. By combining biochemical, genetic, genomic, and proteomic data, we revealed that CAF-1 activity might be associated with the maintenance of the histone variant H3.3 in Arabidopsis chromatin. Moreover, this CAF-1's potential function in H3.3 homeostasis may be particularly significant in the transcribed regions of the genome.
Vernicia montana possesses a robust root system and exhibits high resistance to the soil-borne fungus Fusarium. The molecular mechanism underlying this resistance remains largely elusive. Here, we identified the species-specific UDP-glucosyltransferase coding genes VmUGT88A65 and VmUGT88A66 in V. montana through evolutionary analysis. These genes displayed exclusively root-specific expression patterns and were significantly upregulated upon infection with Fof-1. Transgenic tung trees overexpressing VmUGT88A65 and VmUGT88A66 exhibited a substantial increase in root index from 1.59 g to 2.16 g and enhanced resistance to Fof-1, which was associated with elevated levels of flavonoid and lignin glycosides. Conversely, RNAi-mediated suppression of VmUGT88A65 and VmUGT88A66 resulted in increased susceptibility to Fof-1, reduced root size, and decreased glycoside accumulation. In vitro and in vivo experiments further confirmed that VmUGT88A65 and VmUGT88A66 catalyze the glycosylation of specific compounds, producing flavonoid glycosides (N7G and Q7G) and lignin glycosides (CA4G and FA4G). Exogenous application of a combination of N7G and Q7G significantly inhibited Fof-1 mycelial growth and host infection in vitro. Additionally, CA4G and FA4G contributed to enhanced lignin deposition in roots, thereby strengthening the physical barrier against Fof-1. Our findings reveal a pathway through which VmUGT88A65 and VmUGT88A66 overexpression enhances the accumulation of flavonoid and lignin glycosides and promotes root growth, collectively contributing to improved disease resistance in tung trees.
Understanding the relative roles of phenotypic plasticity and genetic differentiation in shaping plant phenological responses is essential for predicting forest tree responses to climate warming. Although spring and autumn phenophases respond sensitively to rising temperatures, the underlying regulatory mechanisms may differ substantially, particularly across environmental gradients. We investigated intra-specific phenological variation in Quercus petraea across the French Pyrenees using a multi-environment experimental framework. This approach integrated 15 years of in situ phenological monitoring with common garden (CG) and reciprocal transplant experiments spanning an elevational gradient. We quantified key phenological traits-leaf unfolding, leaf senescence, and growing season length-and applied generalized linear mixed models to evaluate the relative effects of temperature, provenance-level differentiation, and their interactions. Leaf unfolding showed strong temperature-associated plastic responses and comparatively limited provenance-level differentiation. In contrast, leaf senescence showed weaker and less consistent temperature responses. Growing season length increased under warmer conditions, largely reflecting the combined effects of earlier leaf unfolding and variable senescence timing. Our findings reveal phase-specific differences in phenological responses, with stronger temperature-associated plasticity in spring than in autumn phenology. These results highlight the need for long-term, multi-environmental data for understanding tree phenology under a changing climate and provide insights for developing adaptive forest management strategies that maintain adaptive capacity.
Balancing growth and defense is critical for plant fitness and crop productivity, yet how viruses manipulate this trade-off remains unclear. Here, we identified the trihelix transcription factor Oryza sativa GT2-like 1 (OsGTL1) as a central regulator of the growth-defense trade-off in rice (Oryza sativa L.). Loss-of-function osgtl1 mutants displayed increased grain size but heightened susceptibility to rice stripe virus (RSV). We showed that miR159a.2 directly targets OsGTL1, and disrupting the miRNA binding site abolished its repression. RSV infection strongly induced miR159a.2, resulting in reduced OsGTL1 levels; rice grassy stunt virus elicited a similar response, whereas other rice viruses did not. These findings reveal that RSV hijacks a miRNA-transcription factor regulatory module to weaken immunity while redirecting resources toward growth, thereby manipulating the growth-defense trade-off. Our study identifies the miR159a.2-OsGTL1 node as a pathogen-sensitive hub with potential for molecular breeding strategies that optimize yield and disease resistance.
Early-spring nitrogen (N) acquisition in perennial fruit trees represents a critical physiological bottleneck determining vegetative-reproductive balance, as remobilized woody-tissue N supports initial growth but excessive depletion compromises reproductive performance. The interactive effects of N form (NH4+ or NO3-) and soil moisture on root morphological plasticity and whole-plant N allocation during this period remain poorly characterized. We subjected two-year-old apple trees to five NH4+/NO3- ratios under contrasting soil moisture regimes spanning budbreak to shoot elongation. Combined NH4+/NO3- supply, particularly at 25:75, optimized root architecture by maintaining high absorptive-to-structural root length ratios at moderate total root length, enhancing whole-plant total N accumulation by 59% and 21% over sole nitrate and ammonium, respectively, under moderate drought (50% FC). Balanced N supply decoupled carbon (C) and N partitioning, achieving the highest C-N allocation deviation index (0.68), facilitating preferential N enrichment in shoots while minimizing root C investment. Leaf nitrate reductase activity under drought reached maximum values under balanced supply despite reduced substrate availability, indicating that whole-plant photosynthetic status rather than substrate concentration determined assimilation capacity under water limitation. Partial least squares path modeling revealed soil moisture functions as a mechanistic switch determining N acquisition pathways: under drought, N accumulation was driven predominantly by root morphological quality (absorptive root proportion and specific root length; β=0.76), whereas under adequate moisture, absorptive root length became the primary driver (β=0.80). These findings demonstrate that coordinating NH4+/NO3- ratio with soil water availability provides a mechanistic basis for climate-adapted fertigation strategies supporting early-season N acquisition under intensifying spring drought.
