Extreme weather conditions driven by climate change have resulted in higher average temperatures, more frequent intense heat waves, increased drought conditions, improper soil conditions, as well as increased pest and disease incidence, posing a unique challenge to plants. Until now, several studies have been performed to reveal how plants can acclimatize or cope with these unfavorable conditions. These studies have majorly focused on how plants respond to an individual stress at a particular point in time. But in nature, no stress occurs in isolation; rather, they act mostly in combination. This condition is referred to as "multifactorial stress combination" or, more precisely, it is termed as "stress matrix". The damages and corresponding responses from individual stresses and stress combinations may entirely be different, leading to complex downstream signaling. Through this review, we have made an attempt to decipher the physiological and molecular responses of different plant species to multiple stress combinations. It is further emphasized that more focus needs to be drawn towards the development of plants that are tolerant to multiple or co-occurring stress factors, keeping in mind the adversities of the consistently challenging environmental conditions.
BACKGROUND:Hypersaline-tolerant bacterial metabolites are believed to play a critical role in sodium detoxification and salt stress tolerance in plants; however, this mechanism needs further investigation. This study aimed to evaluate halophilic bacterial strains from hypersaline environments for their ability to increase salt tolerance in wheat seedlings through sodium‒organic acid complexation, nutrient dissolution, and improved ionic homeostasis. METHODS:The halophilic bacterial strains were isolated from hypersaline conditions of salt mines and were characterized for multiple plant growth-promoting traits. These strains were tested on wheat seedling biomass, chlorophyll, osmolyte accumulation, antioxidant defense, and ion homeostasis under salt stress. The strains were assessed for their ability to produce organic acids and increase nutrient availability by solubilizing insoluble minerals under salt stress. RESULTS:The isolated bacterial strains were salt-tolerant up to 2 M NaCl stress, solubilized insoluble minerals, and produced indole acetic acid, siderophores, ammonia, hydrogen cyanide, exopolysaccharides, and various enzymes. They were identified as Stutzerimonas stutzeri (strains MRK6 and MRK20) and Pseudomonas aeruginosa (strains MRK7 and MRK11). S. stutzeri MRK6 showed the highest increase in wheat seedling growth, chlorophyll, osmolytes accumulation, antioxidant enzymes, and ion homeostasis by increasing potassium uptake and modulating sodium toxicity under 100 mM salt stress. This increased nutrient availability from insoluble minerals. CONCLUSION:The halophilic S. stutzeri MRK6 increased salt tolerance in wheat by increasing soil mineral dissolution, sodium detoxification, and ionic compartmentalization rather than excessive sodium uptake. This mechanism offers a promising approach for mitigating salt stress in salt-affected soils.
Shallot (Allium cepa var. aggregatum) productivity is often limited by fungal diseases, particularly twisted disease caused by Fusarium acutatum. This study evaluated the effects of UV-B pre-exposure (150 min) on enhancing plant resistance under greenhouse conditions using four treatments: control, UV-B, F. acutatum, and UV-B + F. acutatum. UV-B pre-treatment significantly reduced disease incidence, severity, and the area under the disease progress curve (AUDPC) compared with infected plants without UV-B exposure. Although infection suppressed growth, UV-B pre-exposure alleviated these effects by maintaining higher plant height, root length, and biomass. UV-B also increased the photosynthetic pigment content, phenolic accumulation, and the activities of antioxidant enzymes, including catalase and peroxidase. LC-MS/MS metabolomic analysis revealed an increased abundance of metabolites associated with stress signaling, antioxidant responses, and defense-related metabolic pathways. The combined UV-B and pathogen treatment showed coordinated metabolic adjustments, indicating that UV-B priming enhances shallot tolerance to F. acutatum while sustaining growth, offering a sustainable disease management strategy.
Rice is one of the most important food crops and feeds more than half of the world's population. Enhancing grain quality is currently a highly important issue since consumers are now more concerned with the taste, appearance, and nutritional value of the grain. The quality of grain in rice is complex and regulated by a multitude of genes that influence qualities such as amylase content, grain size and shape, chalkiness, aroma and nutrient content. The traditional forms of breeding, such as hybridization and marker-assisted selection, are slow and less effective since such characteristics are regulated by many genes and are influenced by environmental conditions. CRISPR/Cas genome editing has become a potent tool that enables scientists to directly and specifically edit grain quality-related genes. Important genes such as Wx (amylose), GS3, GW8, and TGW3 (grain size), Chalk5 (chalkiness), BADH2 (aroma), and nutrient-related grain size genes such as OsAAP6, OsAAP10, and OsVIT1/2, have been successfully edited to enhance the quality of rice. Newer methods, such as base editing and prime editing, enable this process to become even more precise by modifying the specific bases of DNA without cutting the DNA. CRISPR has assisted in the improvement of rice by controlling the amylose content, reducing chalkiness, enhancing aroma, and improving nutritional quality. It is more accurate and quicker than traditional breeding, and it can enhance various traits simultaneously. Nonetheless, other challenges, such as off-target effects, regulatory concerns, and acceptance by the people, still have to be overcome. Combining CRISPR with artificial intelligence and genomic selection in the future will aid in creating superior versions of rice in shorter periods of time. Overall, CRISPR/Cas genome editing is a potential method to enhance the quality of rice and secure food security in the whole world.
Live fuel moisture content is a key determinant of live fuel flammability, yet its destructive and discontinuous measurement limits high-temporal-resolution monitoring. This study evaluated whether leaf electrical potential can serve as a non-invasive proxy for LFMC and flammability-related traits under natural drought conditions. From February to July 2025, leaf and trunk electrical potentials were monitored weekly in Salvia rosmarinus individuals from a Mediterranean shrubland, while LFMC, essential oil yield, fatty-acid fraction, and laboratory-based flammability metrics-ignition time, combustion duration, and flame height-were assessed bi-weekly. Leaf electrical potential was strongly associated with LFMC (R2 = 0.64, p < 0.001), decreasing as plants underwent seasonal drought-induced dehydration. Periods of high temperature and low rainfall reduced both LFMC and electrical potential, coinciding with shorter ignition times, which declined to approximately 20-30 s during the driest period. Based on the observed shifts in ignition time, combustion duration, and flame height, three empirical LFMC response zones were identified, with leaf electrical potential closely tracking transitions in plant hydration and flammability. These results suggest that plant electrophysiology may provide a promising non-invasive indicator of live fuel water status and seasonal flammability dynamics, with potential applications in wildfire risk monitoring when combined with conventional LFMC, meteorological, and remote-sensing approaches.
To elucidate the light adaptation mechanism and optimal cultivation light regime for Paris polyphylla var. yunnanensis, a two-year continuous field positioning trial was conducted with five light gradients (20%, 40%, 60%, 80%, and 100% natural light, PAR = 300-2200 μmol·m-2·s-1). We systematically investigated the regulatory effects of light intensity on leaf phenotypic traits, anatomical and physiological functions, photosynthetic performance, vegetative growth and rhizome biomass accumulation. Significant differences in plant growth, leaf morphology and all functional trait indices were detected among the treatments (p < 0.05). The plants cultivated under 40%-60% natural light (PAR = 700-1400 μmol·m-2·s-1) exhibited balanced leaf anatomy, maximum photosynthetic efficiency and the highest rhizome fresh biomass. Compared with CK (100% natural light), plants under 40%-60% natural light showed 164.8% greater plant height, 35.5% thicker stem diameter, 50.0% larger rhizome diameter and 124.4% higher rhizome fresh weight. In contrast, 20% natural light induced excessive elongation, slender stems and underdeveloped mechanical tissues, with rhizome fresh weight, length and diameter decreasing by 52.2%, 61.4%, and 62.1%, respectively, relative to CK. Treatments of 80%-100% natural light triggered severe high-light stress, causing leaf scorch, chlorosis and suppressed stomatal development, with most assimilates allocated to antioxidant defense and thermal dissipation rather than rhizome carbon partitioning. In conclusion, P. polyphylla var. yunnanensis exhibits a clear light adaptation threshold with distinct gradient-specific responses: 80%-100% natural light induces photoinhibition and suppresses stomatal development; 20% natural light causes excessive elongation, slender stems and reduced rhizome biomass; while 40%-60% natural light optimizes leaf morphology, photosynthetic physiology and biomass allocation, resulting in the highest rhizome fresh weight (63.54-64.4 g) and overall growth performance. The 40%-60% natural light regime (PAR 700-1400 μmol·m-2·s-1) coordinates leaf morphogenesis, photosynthetic carbon fixation and dry matter accumulation, and is therefore identified as the optimal light condition for high-yield and high-quality medicinal production. This study provides quantitative light regulation parameters (PAR thresholds and corresponding growth responses) for understory bionic cultivation and precise light environment management in facility cultivation of this medicinal herb.
Tellurium toxicity severely impairs soil health, plant physiology and crop productivity, posing a critical threat to global food security, ecosystem sustainability and human health. The exogenous application of phytohormones and osmoprotectants offers a sustainable strategy for mitigating heavy metal-induced phytotoxicity and restoring agricultural viability. A comprehensive experiment was conducted to evaluate the synergistic efficacy of serotonin (5-HT) and allantoin (ALL) in ameliorating tellurite stress in quinoa plants. Plants subjected to 50 µM sodium tellurite soil drenching were treated with 50 µM 5-HT and 100 µM ALL via foliar spray under a randomized complete block design with a factorial arrangement and four replications. Tellurite stress alone drastically reduced morphological traits and overall yield, while simultaneously elevating oxidative damage. However, combined 5-HT and ALL application under stress increased grain yield by 90.41%, photosynthetic rate by 78.68%, stomatal conductance by 80.30%, relative water content by 33.52%, and antioxidant enzyme activities by up to 84.86%. Furthermore, it decreased malondialdehyde content by 58.20%, hydrogen peroxide by 61.16%, tellurium root accumulation by 52.48%, shoot translocation by 60.41%, and grain residue by 66.74% compared to stressed controls, while concurrently improving soil microbial biomass carbon by 63.71%, dehydrogenase activities by 88.49%, and available nitrogen by 39.48%. The integrated treatment significantly restored cellular ion homeostasis, enhanced complex root architectural traits, and effectively restricted heavy metal translocation to the edible harvested grains. Consequently, the co-application of 5-HT and ALL is highly recommended as a robust agronomic intervention to safeguard crop productivity, improve soil health, and ensure long-term food safety in severely Te-contaminated agricultural environments.
Although the term anesthesia is mainly associated with animals, it is well known that anesthetics also affect plants through their actions on membrane properties and protein function. Here, we show that the anesthetic diethyl ether inhibits the phototropic response of Arabidopsis thaliana hypocotyls to unidirectional, low-intensity blue light. Diethyl ether acts not only on the inhibition of hypocotyl elongation but also specifically on the inhibition of phototropic signalling. This complex process consists of initial steps, defined by photoactivation of blue-light receptors, phototropins (PHOTs), and further regulators, followed by later steps involving differential accumulation of the plant growth regulator auxin on the organ’s shaded and illuminated sides, leading to heterogeneous cell elongation and bending towards light. Our data reveal that the early steps of phototropic signalling, such as PHOT1 phosphorylation, are insensitive to diethyl ether anesthesia, whereas auxin redistribution was significantly inhibited, as evidenced by the DR5:GUS assay and inhibition of auxin transporter PIN3 relocalization. This study therefore provides the first evidence about the inhibitory effect of anesthetics on auxin-mediated growth responses in plants.
Fluoride, a hazardous air and soil contaminant, poses significant risks to agricultural productivity and plant health. Its accumulation in soil and subsequent uptake by plant roots and mesophyll cells interfere with critical morphological, physiological, and biochemical processes essential for growth and development. Fluoride toxicity affects germination, respiration, photosynthesis, mineral nutrition, enzyme activity, and reproduction, ultimately reducing crop yield. It disrupts cell signaling pathways, impairs antioxidant enzyme function (e.g., superoxide dismutase), and interacts antagonistically with calcium, a key element in fertilization and pollen tube growth. The resulting toxicity manifests as chlorosis, necrosis, growth inhibition, leaf and fruit abscission, and reduced seed production. This review provides a comprehensive evaluation of fluoride-induced stress in plants, highlighting recent advances in understanding its mechanisms and potential mitigation strategies. By synthesizing current findings, this study offers insights into developing fluoride-resistant crops and improving management practices to safeguard agricultural productivity in contaminated regions.
The soybean plant (Glycine max L.) is an important crop for valuable food source because of its high levels of protein and oil, thus contributing greatly to a sustainable system for producing food through biological nitrogen fixation. Recent research supports the theory that the soybean-associated microbiome located in the rhizosphere is a crucial regulatory mechanism governing plant growth, nutrient acquisition, and stress tolerance. Additionally, advances in metagenomics, metatranscriptomics, metabolomics, and root exudate profiling via LC‒MS have shown that soybean roots alter the microbial communities found in their rhizosphere by utilizing dynamic chemical signaling and targeted microbial recruitment, thereby enhancing the ecological interpretation of the processes that drive microbiome assembly. Microbial consortia (AMF & PGPR) assess cycling through nutrients, phytohormones, suppressing diseases, as well as having a legacy effects on the productivity of agroecosystems. Factors such as plant genotype, physical and chemical soil properties, and environmental conditions greatly affect the assembly and functioning of the soybean microbiome, thus this is difficult to transfer this information to field applications. Unlike previous reviews focused primarily on biological nitrogen fixation, this review integrates recent advances in multi-omics technologies, species-level microbiome characterization, root exudate chemistry, microbiome-assisted breeding, and translational microbiome engineering approaches to provide a systems-level perspective of soybean-microbiome interactions. while also identifying significant knowledge gaps and future areas of research within this aspect of agriculture.
Salt stress severely limits wheat growth by disturbing photosynthesis, osmotic balance, and cellular redox homeostasis. This study evaluated whether agmatine and N-hydroxy pipecolic acid, applied alone or in combination, could improve wheat tolerance under 200 mM NaCl stress. Wheat plants were grown under greenhouse conditions and treated with agmatine at 100 µM, N-hydroxypipecolic acid at 0.01 µM, or their combined application. Salt stress reduced growth, leaf area, leaf relative water content, chlorophyll content, gas exchange, Rubisco activity, and biomass accumulation while increasing hydrogen peroxide, lipid peroxidation, and electrolyte leakage. Both compounds improved wheat performance under salinity, but their combined application produced the strongest response across the measured growth, photosynthetic, osmotic, and antioxidant traits. The combined treatment improved root and shoot growth, maintained higher chlorophyll content and Rubisco activity, supported gas exchange, and increased soluble sugar accumulation. It also reduced oxidative injury by strengthening catalase, peroxidase, superoxide dismutase, and glutathione reductase activities. In addition, the combined treatment increased proline accumulation and activated key enzymes involved in proline metabolism, indicating improved osmotic adjustment under salt stress. These findings suggest that agmatine and N-hydroxy pipecolic acid act through complementary physiological and biochemical pathways to improve wheat salt tolerance. The combined treatment may offer a useful foliar strategy for improving wheat performance under saline conditions, although field validation and dose optimization are needed before practical recommendation.
The accumulation of plant hormones in different tissues leads to transcriptional reprogramming that guides the downstream phenotypic response. Current models are largely derived from Arabidopsis, and increasing evidence indicates that monocots only partially conform to these canonical pathways, with additional variability even within the clade. In cereals, salicylate (SA), jasmonate (JA), and ethylene (ET) signaling play important roles in both inflorescence development and pathogen defense. This communication focuses on the transcriptional responses of wheat inflorescence tissue in three genotypes 8 h following exogenous applications of salicylic acid (SA), methyl jasmonate (MeJA), and the ethylene-releasing compound, ethephon (ETp). Nearly 8000 differentially expressed genes (DEGs) were detected in response to MeJA, approximately half of which were conserved across all three genotypes. In contrast, SA and ETp elicited limited responses, each inducing fewer than 100 DEGs with little to no overlap among genotypes. The comparatively feeble response to SA and ETp suggests a delayed response compared to MeJA. Other studies have assessed differential transcriptomes at 24 h or later. Notably, other studies in cereals, including wheat, have also reported less pronounced transcriptional changes to salicylate and ethylene signaling. These findings demonstrate both conservation and genotype-specific variation in the transcriptional response to plant hormones.
Chloroplast division is a complex process influenced by various proteins, among which bacteria-derived MinE plays a vital role in correctly placing the FtsZ-based division apparatus and initiating the division. This study aimed to elucidate the intrachloroplastic localization of MinE in the living mesophyll cells of Arabidopsis thaliana using the MinE-yellow fluorescent protein (YFP) fusion. Fluorescence microscopy of the complemented A. thaliana minE mutant, expressing MinE-YFP under the native MinE promoter, showed normal chloroplast division and revealed a mid-chloroplast MinE ring composed of array-of-dots and filaments, as well as other distinct localization patterns of MinE during chloroplast division. The MinE ring relatively maintained its configuration during chloroplast constriction, as does the FtsZ ring, suggesting a dynamic protein dissociation correlating with division progression. We also observed a unique “twin dot” structure and one-sided distribution of MinE in chloroplasts with slight over-accumulation of MinE-YFP in transgenic tissues. These observations deviate from the well-accepted model of the MinE behavior during Escherichia coli cytokinesis, suggesting fundamental differences in the division mechanisms between chloroplasts and bacteria. The present findings deepen our understanding of the protein organization at the chloroplast division site and highlight the distinctive nature of the MinE protein’s behavior in plants.
Cadmium (Cd) contamination of agricultural soils disrupts plant signaling networks, impairing nutrient communication, photosynthetic efficiency, and stress responses. Microbial inoculants offer eco-biotechnological solutions by modulating signal perception and transduction under heavy metal stress. This field study investigated the role of Acinetobacter schindleri strain SR-5-1 in influencing pea (Pisum sativum L.) signaling pathways under Cd toxicity. Plants exposed to environmentally relevant Cd concentrations (250 and 500 µM) exhibited disrupted chlorophyll biosynthesis, elevated oxidative stress markers, and impaired nutrient signaling. Inoculation with SR-5-1 restored chlorophyll levels, enhanced ROS-scavenging enzyme activities, and reduced lipid peroxidation, indicating microbial effects on oxidative signaling cascades. Importantly, the inoculated plants accumulated less Cd in the roots and leaves, reflecting microbial mediation of ion transporter activity and rhizosphere detoxification. SR-5-1 also improved nitrogen, iron, zinc, potassium, and magnesium acquisition, highlighting its role in nutrient uptake and homeostasis. These findings demonstrate that SR-5-1 functions as a bio-communicator, alleviating xenobiotic stress by modulating ROS and nutrient signaling pathways. The study underscores the ecological relevance of microbial inoculants in supporting integrative plant communication and resilience, positioning SR-5-1 as a promising bioresource for signaling-driven sustainable agriculture in Cd-affected soils.
Paphiopedilum malipoense, a critically endangered orchid, depends entirely on mycorrhizal fungi for germination, complicating its conservation. This study isolated 12 fungal strains from wild roots, all identified as Tulasnella, confirming strict host specificity. Cross-species germination assays revealed functional divergence: strains MLP116, MLP027, and MLP232 supported full protocorm-to-seedling development with germination rates of 54.27%, 54.88%, and 62.01%, respectively, while others induced developmental arrest. Seedling symbiosis showed stage-specific effects: MLP217, ineffective during germination, increased seedling biomass by 131%. MLP232 performed excellently in both stages, achieving the highest germination rate and 98% biomass increase, with elevated IAA and soluble protein. Physiological profiling demonstrated functional complementarity: MLP161 enhanced nutrient acquisition; MLP246 boosted chlorophyll and antioxidants; and MLP281 increased antioxidant activity but suppressed growth. These results indicate that part Tulasnella strains exhibit stage-specific efficiency and functional complementarity. We recommend using tailored fungal consortia in orchid conservation to synergistically support complete life cycle development, providing a practical framework for safeguarding endangered species like P. malipoense.
OBJECTIVE:This study aimed to investigate the response patterns of root-associated fungal communities in the rare and endangered species Paphiopedilum barbigerum across different habitat types, and to identify key taxonomic groups that differentiate natural habitats from reintroduction sites, thereby providing a theoretical basis for the species artificial propagation and field reintroduction. METHODS:Using PacBio high-throughput sequencing, we sequenced the ITS region of 21 root samples of P. barbigerum collected from seven sites representing three habitat categories: natural habitats within a nature reserve (SL, DE, YL, KL), natural habitats outside the reserve (FQ, KY), and a field reintroduction site (HG). Alpha diversity, beta diversity, LEfSe analysis, and co-occurrence network analysis were employed to characterize root-associated fungal community structure, diversity, and habitat-driven assembly patterns. RESULTS:A total of 792,178 clean reads were obtained and classified into 8 phyla, 37 classes, 134 orders, 352 families, 1,012 genera, and 2,311 species. The communities were dominated by Ascomycota (52.90%-91.41%) and Basidiomycota (7.79%-54.33%). Key findings include: (1) Fungal species richness was significantly higher in natural habitats within the reserve than at the reintroduction site and natural habitats outside the reserve, with specific enrichment of desiccation-tolerant taxa such as Chaetothyriales and Exophiala (relative abundance 12.58%-33.53%). (2) The fungal community structure at the reintroduction site converged with that of natural habitats outside the reserve. Core OTUs included Epulorhiza sp., Cladosporium sp., and Lachancea thermotolerans, all of which exhibited significantly higher relative abundances in these two habitat types; notably, Epulorhiza sp. reached a relative abundance of 44.79% at the reintroduction site, suggesting a key role in host growth and development. CONCLUSION:Habitat heterogeneity is associated with adaptive restructuring of the root-associated fungal community by selecting for distinct functional guilds: desiccation-tolerant taxa are enriched in natural habitats within the reserve, whereas growth-promoting taxa are enriched in disturbed habitats. We recommend prioritizing the conservation of natural habitats within the reserve to preserve high fungal diversity and stress-tolerant guilds, and emphasize the targeted utilization and monitoring of core growth-promoting fungi such as Epulorhiza during reintroduction programs.
Floral scent is a primary determinant of pollinator attraction and reproductive success in the Orchidaceae family. In the genus Phalaenopsis, floral volatiles are typically dominated by terpenoids; however, this study identifies a significant exception in the novel cultivar Phalaenopsis DSM2049. Utilizing thin film solid phase microextraction (TF SPME) coupled with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS), Methoxy-Phenyl-Oxime (MPO) was identified as the predominant floral volatile. Mass spectrometry confirmed a molecular formula of C₈H₉NO₂, characterized by a molecular ion at m/z 151 [M]⁺, a base peak at m/z 133 [M-H₂O]⁺, and a phenyl ring at m/z 77. The compound was detected as two distinct E/Z geometric isomers with retention times of 12.35 and 12.32 minutes. MPO emission followed an extreme diurnal ON/OFF rhythm, with peak levels at 07:30-09:00 being 13.4-fold higher than those recorded at 01:30-03:00, while only trace amounts were detectable by mid-afternoon. These findings represent the first report of an oxime as the dominant scent component in Phalaenopsis, challenging the conventional view of terpenoid exclusivity in the genus and suggesting a highly regulated biosynthetic mechanism with specialized ecological implications for pollinator recruitment.
Neodymium (Nd) contamination is an emerging environmental challenge that threatens crop productivity and food quality in agroecosystems. Although taurine (Tau) and spermidine (Spd) are recognized as important regulators of plant stress responses, their interactive role in mitigating rare-earth-element toxicity remains largely unexplored. The present study evaluated the potential of foliar-applied (Tau 10 mM) and (Spd 1 mM), applied individually and in combination, to alleviate Nd toxicity (150 mg kg-1 NdCl3·6H2O) in wheat (Triticum aestivum L.) cv. Faisalabad-2008. Nd exposure significantly (p ≤ 0.05) impaired soil physico-chemical properties, depressed microbial biomass carbon and dehydrogenase, urease, alkaline phosphatase and β-glucosidase activities, restricted root architecture and shoot biomass, suppressed gas exchange and pigment biosynthesis and triggered oxidative damage, as evidenced by elevated malondialdehyde (MDA) and hydrogen peroxide (H2O2). The combined Tau + Spd foliar spray restored the soil quality and microbial functionality, enhanced the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), and ascorbate peroxidase (APX), increased the proline, glutathione and total soluble sugars and improved the photosynthetic pigments and stomatal conductance relative to the Nd-only treatment. The dual application also reduced Nd accumulation in roots, shoots, and grains, restored the K+/Na+ ratio and macronutrient acquisition and improved the grain yield, protein, starch, and micronutrient density. Pearson correlation, radar, and principal component analyses confirmed coordinated recovery across soil, physiological, and grain-quality traits. These findings demonstrate that taurine and spermidine act synergistically to enhance wheat tolerance to Nd toxicity through the modulation of antioxidant defenses, osmotic adjustment, nutrient homeostasis, and metal exclusion mechanisms, highlighting their potential as sustainable biostimulants for crop production in rare-earth-element-contaminated soils.
Salvia miltiorrhiza is a valuable medicinal plant with diverse pharmacological applications and high market demand. Light quality is a critical environmental factor regulating plant growth, secondary metabolism, and interactions with rhizosphere microorganisms. However, the effects of short-term, pure monochromatic light exposure on S. miltiorrhiza remain largely unexplored. In this study, we employed integrated transcriptomic, metabolomic, and rhizosphere metagenomic analyzes to investigate the responses of S. miltiorrhiza under different monochromatic light conditions: ultraviolet (UV), blue (B), red (R), and far-red (FR), with white light (WL) as the control. GO enrichment analysis indicated that all monochromatic light treatments activated defense responses, while specific pathways related to light stimulus, wounding, and reactive oxygen species were uniquely enriched under B, R, and FR light. Metabolomic analysis showed a general decrease in metabolite abundance under monochromatic light compared to WL, with the R treatment inducing the highest number of significantly upregulated metabolites. Integrated KEGG pathway analysis of differential transcripts and metabolites highlighted the enrichment of secondary metabolic pathways, including diterpenoid, monoterpenoid, and phenylpropanoid biosynthesis. Notably, quantitative HPLC analysis confirmed that UV, R, and FR light significantly promoted the accumulation of dihydrotanshinone I and tanshinone IIA, while decreasing salvianolic acid A content. Metagenomic analysis revealed that monochromatic light, especially B light, reduced rhizosphere microbial alpha diversity and altered the abundance of specific bacterial families and species. Functional gene annotation also showed treatment-specific shifts in microbial metabolic potential and virulence factors. In conclusion, short-term monochromatic light culture, particularly R and FR, effectively modulates the transcriptome and metabolome of S. miltiorrhiza, enhancing the accumulation of key bioactive tanshinones, while simultaneously reshaping its rhizosphere microbial community. These findings offer a potential light-based strategy for improving the quality of S. miltiorrhiza.
Nitrogen (N) deficiency-induced leaf senescence is a genetically programmed process that facilitates plant adaptation to nutrient-limited conditions. Although numerous transcription factors (TFs) involved in N deficiency-induced leaf senescence have been identified, how they are regulated remains largely unknown. Here, we discovered that a plant-specific small GTPase, RHO of Plant 2 (ROP2), acts as an upstream positive regulator that bridges N starvation to leaf senescence by modulating key leaf senescence-associated TFs. Plants expressing constitutively active ROP2 (CA-ROP2) promote cotyledon early senescence under N-deficient conditions, by inducing the expression of key senescence-promoting NAC family TFs (ORE1, NAP, ANAC005), while strongly suppressing the expression of these TFs' inhibitory regulators (HASTY and NLA). On the contrary, CA-ROP2 suppresses the expression of the negative regulation TFs of N limitation-induced leaf senescence, like WRKY53 and NIGT1. The two opposing regulatory axes of CA-ROP2 coordinately accelerate premature cotyledon senescence under N starvation. Furthermore, phenotypic and time-series transcriptomic analysis revealed that CA-ROP2, relative to the wild type (WT), maintains shoot growth and elevated expression of growth- and development-related genes during early N starvation, yet later induces premature cotyledon senescence and drives a pronounced transcriptional switch to upregulate senescence-associated genes. Together, ROP2 converts from a "growth promoter" to a "senescence-initiating regulator" depending on environmental nitrogen status, unveiling a novel mechanism by which plants balance growth and senescence to adapt to nutrient stress.
