Seed osmopriming with polyethylene glycol (PEG) enhances seed germination and seedling physiological traits of Coronilla varia L. under water stress.

Water stress can adversely affect seed germination and plant growth. Seed osmopriming is a pre-sowing treatment in which seeds are soaked in osmotic solutions to undergo the first stage of germination prior to radicle protrusion. Seed osmopriming enhances germination performance under stressful environmental conditions, making it an effective method to improve plant resistance and yield. This study analyzed the effect of seed osmopriming with polyethylene glycol (PEG) on seed germination and physiological parameters of Coronilla varia L. Priming treatments using 10% to 30% PEG enhanced germination percentage, germination vigor, germination index, vitality index, and seedling mass and reduced the time to reach 50% germination (T50). The PEG concentration that led to better results was 10%. The content of soluble proteins (SP), proline (Pro), soluble sugars (SS), and malondialdehyde (MDA) in Coronilla varia L. seedlings increased with the severity of water stress. In addition, under water stress, electrolyte leakage rose, and peroxidase (POD) and superoxide dismutase (SOD) activities intensified, while catalase (CAT) activity increased at mild-to-moderate water stress but declined with more severe deficiency. The 10% PEG priming significantly improved germination percentage, germination vigor, germination index, vitality index, and time to 50% germination (T50) under water stress. Across the water stress gradient here tested (8 to 12% PEG), seed priming enhanced SP content, Pro content, and SOD activity in Coronilla varia L. seedlings compared to the unprimed treatments. Under 10% PEG-induced water stress, primed seedlings displayed a significantly lower MDA content and electrolyte leakage than their unprimed counterparts and exhibited significantly higher CAT and POD activities. However, under 12% PEG-induced water stress, differences in electrolyte leakage, CAT activity, and POD activity between primed and unprimed treatments were not significant. These findings suggest that PEG priming enhances the osmotic regulation and antioxidant capacity of Coronilla varia seedlings, facilitating seed germination and seedling growth and alleviating drought stress damage, albeit with reduced efficacy under severe water deficiency.

Silicon regulates phosphate deficiency through involvement of auxin and nitric oxide in barley roots.

MAIN CONCLUSION: Silicon application mitigates phosphate deficiency in barley through an interplay with auxin and nitric oxide, enhancing growth, photosynthesis, and redox balance, highlighting the potential of silicon as a fertilizer for overcoming nutritional stresses. Silicon (Si) is reported to attenuate nutritional stresses in plants, but studies on the effect of Si application to plants grown under phosphate (Pi) deficiency are still very scarce, especially in barley. Therefore, the present work was undertaken to investigate the potential role of Si in mitigating the adverse impacts of Pi deficiency in barley Hordeum vulgare L. (var. BH902). Further, the involvement of two key regulatory signaling molecules--auxin and nitric oxide (NO)--in Si-induced tolerance against Pi deficiency in barley was tested. Morphological attributes, photosynthetic parameters, oxidative stress markers (O2·-, H2O2, and MDA), antioxidant system (enzymatic--APX, CAT, SOD, GR, DHAR, MDHAR as well as non-enzymatic--AsA and GSH), NO content, and proline metabolism were the key traits that were assessed under different treatments. The P deficiency distinctly declined growth of barley seedlings, which was due to enhancement in oxidative stress leading to inhibition of photosynthesis. These results were also in parallel with an enhancement in antioxidant activity, particularly SOD and CAT, and endogenous proline level and its biosynthetic enzyme (P5CS). The addition of Si exhibited beneficial effects on barley plants grown in Pi-deficient medium as reflected in increased growth, photosynthetic activity, and redox balance through the regulation of antioxidant machinery particularly ascorbate-glutathione cycle. We noticed that auxin and NO were also found to be independently participating in Si-mediated improvement of growth and other parameters in barley roots under Pi deficiency. Data of gene expression analysis for PHOSPHATE TRANSPORTER1 (HvPHT1) indicate that Si helps in increasing Pi uptake as per the need of Pi-deficient barley seedlings, and also auxin and NO both appear to help Si in accomplishing this task probably by inducing lateral root formation. These results are suggestive of possible application of Si as a fertilizer to correct the negative effects of nutritional stresses in plants. Further research at genetic level to understand Si-induced mechanisms for mitigating Pi deficiency can be helpful in the development of new varieties with improved tolerance against Pi deficiency, especially for cultivation in areas with Pi-deficient soils.

CsSHMT3 gene enhances the growth and development in cucumber seedlings under salt stress.

Salt stress is one of the major factors limiting plant growth and productivity. Many studies have shown that serine hydroxymethyltransferase (SHMT) gene play an important role in growth, development and stress response in plants. However, to date, there have been few studies on whether SHMT3 can enhance salt tolerance in plants. Therefore, the effects of overexpression or silencing of CsSHMT3 gene on cucumber seedling growth under salt stress were investigated in this study. The results showed that overexpression of CsSHMT3 gene in cucumber seedlings resulted in a significant increase in chlorophyll content, photosynthetic rate and proline (Pro) content, and antioxidant enzyme activity under salt stress condition; whereas the content of malondialdehyde (MDA), superoxide anion (H2O2), hydrogen peroxide (O2·-) and relative conductivity were significantly decreased when CsSHMT3 gene was overexpressed. However, the content of chlorophyll and Pro, photosynthetic rate, and antioxidant enzyme activity of the silenced CsSHMT3 gene lines under salt stress were significantly reduced, while MDA, H2O2, O2·- content and relative conductivity showed higher level in the silenced CsSHMT3 gene lines. It was further found that the expression of stress-related genes SOD, CAT, SOS1, SOS2, NHX, and HKT was significantly up-regulated by overexpressing CsSHMT3 gene in cucumber seedlings; while stress-related gene expression showed significant decrease in silenced CsSHMT3 gene seedlings under salt stress. This suggests that overexpression of CsSHMT3 gene increased the salt tolerance of cucumber seedlings, while silencing of CsSHMT3 gene decreased the salt tolerance. In conclusion, CsSHMT3 gene might positively regulate salt stress tolerance in cucumber and be involved in regulating antioxidant activity, osmotic adjustment, and photosynthesis under salt stress. KEY MESSAGE: CsSHMT3 gene may positively regulate the expression of osmotic system, photosynthesis, antioxidant system and stress-related genes in cucumber.

Gamma-aminobutyric acid (GABA) improves salinity stress tolerance in soybean seedlings by modulating their mineral nutrition, osmolyte contents, and ascorbate-glutathione cycle.

BACKGROUND: In plants, GABA plays a critical role in regulating salinity stress tolerance. However, the response of soybean seedlings (Glycine max L.) to exogenous gamma-aminobutyric acid (GABA) under saline stress conditions has not been fully elucidated. RESULTS: This study investigated the effects of exogenous GABA (2 mM) on plant biomass and the physiological mechanism through which soybean plants are affected by saline stress conditions (0, 40, and 80 mM of NaCl and Na2SO4 at a 1:1 molar ratio). We noticed that increased salinity stress negatively impacted the growth and metabolism of soybean seedlings, compared to control. The root-stem-leaf biomass (27- and 33%, 20- and 58%, and 25- and 59% under 40- and 80 mM stress, respectively]) and the concentration of chlorophyll a and chlorophyll b significantly decreased. Moreover, the carotenoid content increased significantly (by 35%) following treatment with 40 mM stress. The results exhibited significant increase in the concentration of hydrogen peroxide (H2O2), malondialdehyde (MDA), dehydroascorbic acid (DHA) oxidized glutathione (GSSG), Na+, and Cl- under 40- and 80 mM stress levels, respectively. However, the concentration of mineral nutrients, soluble proteins, and soluble sugars reduced significantly under both salinity stress levels. In contrast, the proline and glycine betaine concentrations increased compared with those in the control group. Moreover, the enzymatic activities of ascorbate peroxidase, monodehydroascorbate reductase, glutathione reductase, and glutathione peroxidase decreased significantly, while those of superoxide dismutase, catalase, peroxidase, and dehydroascorbate reductase increased following saline stress, indicating the overall sensitivity of the ascorbate-glutathione cycle (AsA-GSH). However, exogenous GABA decreased Na+, Cl-, H2O2, and MDA concentration but enhanced photosynthetic pigments, mineral nutrients (K+, K+/Na+ ratio, Zn2+, Fe2+, Mg2+, and Ca2+); osmolytes (proline, glycine betaine, soluble sugar, and soluble protein); enzymatic antioxidant activities; and AsA-GSH pools, thus reducing salinity-associated stress damage and resulting in improved growth and biomass. The positive impact of exogenously applied GABA on soybean plants could be attributed to its ability to improve their physiological stress response mechanisms and reduce harmful substances. CONCLUSION: Applying GABA to soybean plants could be an effective strategy for mitigating salinity stress. In the future, molecular studies may contribute to a better understanding of the mechanisms by which GABA regulates salt tolerance in soybeans.

Utilizing transcriptomics and proteomics to unravel key genes and proteins of Oryza sativa seedlings mediated by selenium in response to cadmium stress.

BACKGROUND: Cadmium (Cd) pollution has declined crop yields and quality. Selenium (Se) is a beneficial mineral element that protects plants from oxidative damage, thereby improving crop tolerance to heavy metals. The molecular mechanism of Se-induced Cd tolerance in rice (Oryza sativa) is not yet understood. This study aimed to elucidate the beneficial mechanism of Se (1 mg/kg) in alleviating Cd toxicity in rice seedlings. RESULTS: Exogenous selenium addition significantly improved the toxic effect of cadmium stress on rice seedlings, increasing plant height and fresh weight by 20.53% and 34.48%, respectively, and increasing chlorophyll and carotenoid content by 16.68% and 15.26%, respectively. Moreover, the MDA, ·OH, and protein carbonyl levels induced by cadmium stress were reduced by 47.65%, 67.57%, and 56.43%, respectively. Cell wall metabolism, energy cycling, and enzymatic and non-enzymatic antioxidant systems in rice seedlings were significantly enhanced. Transcriptome analysis showed that the expressions of key functional genes psbQ, psbO, psaG, psaD, atpG, and PetH were significantly up-regulated under low-concentration Se treatment, which enhanced the energy metabolism process of photosystem I and photosystem II in rice seedlings. At the same time, the up-regulation of LHCA, LHCB family, and C4H1, PRX, and atp6 functional genes improved the ability of photon capture and heavy metal ion binding in plants. Combined with proteome analysis, the expression of functional proteins OsGSTF1, OsGSTU11, OsG6PDH4, OsDHAB1, CP29, and CabE was significantly up-regulated under Se, which enhanced photosynthesis and anti-oxidative stress mechanism in rice seedlings. At the same time, it regulates the plant hormone signal transduction pathway. It up-regulates the expression response process of IAA, ABA, and JAZ to activate the synergistic effect between each cell rapidly and jointly maintain the homeostasis balance. CONCLUSION: Our results revealed the regulation process of Se-mediated critical metabolic pathways, functional genes, and proteins in rice under cadmium stress. They provided insights into the expression rules and dynamic response process of the Se-mediated plant resistance mechanism. This study provided the theoretical basis and technical support for crop safety in cropland ecosystems and cadmium-contaminated areas.

Seeds Priming with Melatonin Improves Root Hydraulic Conductivity of Wheat Varieties under Drought, Salinity, and Combined Stress.

Drought and salinity stress reduce root hydraulic conductivity of plant seedlings, and melatonin application positively mitigates stress-induced damage. However, the underlying effect of melatonin priming on root hydraulic conductivity of seedlings under drought-salinity combined remains greatly unclear. In the current report, we investigated the influence of seeds of three wheat lines' 12 h priming with 100 µM of melatonin on root hydraulic conductivity (Lpr) and relevant physiological indicators of seedlings under PEG, NaCl, and PEG + NaCl combined stress. A previous study found that the combined PEG and NaCl stress remarkably reduced the Lpr of three wheat varieties, and its value could not be detected. Melatonin priming mitigated the adverse effects of combined PEG + NaCl stress on Lpr of H4399, Y1212, and X19 to 0.0071 mL·h-1·MPa-1, 0.2477 mL·h-1·MPa-1, and 0.4444 mL·h-1·MPa-1, respectively, by modulating translation levels of aquaporin genes and contributed root elongation and seedlings growth. The root length of H4399, Y1212, and X19 was increased by 129.07%, 141.64%, and 497.58%, respectively, after seeds pre-treatment with melatonin under PEG + NaCl combined stress. Melatonin -priming appreciably regulated antioxidant enzyme activities, reduced accumulation of osmotic regulators, decreased levels of malondialdehyde (MDA), and increased K+ content in stems and root of H4399, Y1212, and X19 under PEG + NaCl stress. The path investigation displayed that seeds primed with melatonin altered the modification of the path relationship between Lpr and leaf area under stress. The present study suggested that melatonin priming was a strategy as regards the enhancement of root hydraulic conductivity under PEG, NaCl, and PEG + NaCl stress, which efficiently enhanced wheat resistant to drought-salinity stress.

Impact of Fe3O4-porphyrin hybrid nanoparticles on wheat: Physiological and metabolic advance.

Iron-magnetic nanoparticles (Fe-NMPs) are widely used in environmental remediation, while porphyrin-based hybrid materials anchored to silica-coated Fe3O4-nanoparticles (Fe3O4-NPs) have been used for water disinfection purposes. To assess their safety on plants, especially concerning potential environmental release, it was investigated for the first time, the impact on plants of a silica-coated Fe3O4-NPs bearing a porphyrinic formulation (FORM) - FORM@NMP. Additionally, FORM alone and the magnetic nanoparticles without FORM anchored (NH2@NMP) were used for comparison. Wheat (Triticum aestivum L.) was chosen as a model species and was subjected to three environmentally relevant doses during germination and tiller development through root application. Morphological, physiological, and metabolic parameters were assessed. Despite a modest biomass decrease and alterations in membrane properties, no major impairments in germination or seedling development were observed. During tiller phase, both Fe3O4-NPs increased leaf length, and photosynthesis exhibited varied impacts: both Fe3O4-NPs and FORM alone increased pigments; only Fe3O4-NPs promoted gas exchange; all treatments improved the photochemical phase. Regarding oxidative stress, lipid peroxidation decreased in FORM and FORM@NMP, yet with increased O2-• in FORM@NMP; total flavonoids decreased in NH2@NMP and antioxidant enzymes declined across all materials. Phenolic profiling revealed a generalized trend towards a decrease in flavones. In conclusion, these nanoparticles can modulate wheat physiology/metabolism without apparently inducing phytotoxicity at low doses and during short-time exposure. ENVIRONMENTAL IMPLICATION: Iron-magnetic nanoparticles are widely used in environmental remediation and fertilization, besides of new applications continuously being developed, making them emerging contaminants. Soil is a major sink for these nanoparticles and their fate and potential environmental risks in ecosystems must be addressed to achieve more sustainable environmental applications. Furthermore, as the reuse of treated wastewater for agricultural irrigation is being claimed, it is of major importance to disclose the impact on crops of the nanoparticles used for wastewater decontamination, such as those proposed in this work.

Nanobiostimulant action of trigolic formulated zinc sulfide nanoparticles (ZnS-T NPs) on rice seeds by triggering antioxidant defense network and plant growth specific transcription factors.

Under a changing climate, nanotechnological interventions for climate resilience in crops are critical to maintaining food security. Prior research has documented the affirmative response of nano zinc sulfide (nZnS) on physiological traits of fungal-infested rice seeds. Here, we propose an application of trigolic formulated zinc sulfide nanoparticles (ZnS-T NPs) on rice seeds as nanobiostimulant to improve physiological parameters by triggering antioxidative defense system, whose mechanism was investigated at transcriptional level by differential expression of genes in germinated seedlings. Nanopriming of healthy rice seeds with ZnS-T NPs (50 µg/ml), considerably intensified the seed vitality factors, including germination percentage, seedling length, dry weight and overall vigor index. Differential activation of antioxidant enzymes, viz. SOD (35.47%), APX (33.80%) and CAT (45.94%), in ZnS-T NPs treated seedlings reduced the probability of redox imbalance and promoted the vitality of rice seedlings. In gene expression profiling by reverse transcription quantitative real time PCR (qRT-PCR), the notable up-regulation of target antioxidant genes (CuZn SOD, APX and CAT) and plant growth specific genes (CKX and GRF) in ZnS-T NPs treated rice seedlings substantiates their molecular role in stimulating both antioxidant defenses and plant growth mechanisms. The improved physiological quality parameters of ZnS-T NPs treated rice seeds under pot house conditions corresponded well with in vitro findings, which validated the beneficial boosted impact of ZnS-T NPs on rice seed development. Inclusively, the study on ZnS-T NPs offers fresh perspectives into biochemical and molecular reactions of rice, potentially positioning them as nanobiostimulant capable of eliciting broad-spectrum immune and growth-enhancing responses.

Exogenous 5-Aminolevulinic acid improved low-temperature tolerance tomato seedling by regulating starch content and phenylalanine metabolism.

Tomato is an important horticultural cash crop, and low-temperature stress has seriously affected the yield and quality of tomato. 5-Aminolevulinic acid (ALA) is widely used in agriculture as an efficient and harmless growth regulator. It is currently unclear whether exogenous ALA can cope with low-temperature stress by regulating tomato starch content and phenylalanine metabolism. In this study, exogenous ALA remarkably improved the low-temperature tolerance of tomato seedlings. RNA-sequencing results showed that exogenous ALA affected starch metabolism and phenylalanine metabolism in tomato seedling leaves under low-temperature stress. Subsequently, we used histochemical staining, observation of chloroplast microstructure, substance content determination, and qRT-PCR analysis to demonstrate that exogenous ALA could improve the low-temperature tolerance of tomato seedlings by regulating starch content and phenylalanine metabolism (SlPAL, SlPOD1, and SlPOD2). Simultaneously, we found that exogenous ALA induced the expression of SlMYBs and SlWRKYs under low-temperature stress. In addition, dual luciferase, yeast one hybrid, and electrophoretic mobility shift assays indicate that SlMYB4 and SlMYB88 could regulate the expression of SlPOD2 in phenylalanine metabolism. We demonstrated that exogenous ALA could improve the low-temperature tolerance of tomato seedlings by regulating starch content and phenylalanine metabolism.

Cu-II-directed self-assembly of fullerenols to ameliorate copper stress in maize seedlings.

Widespread use of copper-based agrochemical may cause copper excessive accumulation in agricultural soil to seriously threaten crop production. Recently, fullerenols are playing important roles in helping crops build resistance to abiotic stresses by giving ingenious and successful resolutions. However, there is a lack of knowledge on their beneficial effects in crops under stresses induced by heavy metals. Herein, the visual observation of Cu2+-mediated assembly of fullerenols via electrostatic and coordination actions was carried out in vitro, showing that water-soluble nanocomplexes and water-insoluble cross-linking nanohybrids were selectively fabricated by precisely adjusting feeding ratios of fullerenols and CuSO4. Furthermore, maize simultaneous exposure of fullerenols and CuSO4 solutions was tested to investigate the comparative effects of seed germination and seedling growth relative to exposure of CuSO4 alone. Under moderate Cu2+ stresses (40 and 80 µM), fullerenols significantly mitigated the detrimental effects of seedlings, including phenotype, root and shoot elongation, biomass accumulation, antioxidant capacity, and Cu2+ uptake and copper transporter-related gene expressions in roots. Under 160 µM of Cu2+ as a stressor, fullerenols also accelerated germination of Cu2+-stressed seeds eventually up to the level of the control. Summarily, fullerenols can enhance tolerance of Cu2+-stressed maize mainly due to direct detoxification through fullerenol-Cu2+ interactions restraining the Cu2+ intake into roots and reducing free Cu2+ content in vivo, as well as fullerenol-maize interactions to enhance resistance by maintaining balance of reactive oxygen species and optimizing the excretion and transport of Cu2+. This will unveil valuable insights into the beneficial roles of fullerenols and its mechanism mode in alleviating heavy metal stress on crop plants.

Exogenous melatonin delays leaves senescence and enhances saline and alkaline stress tolerance in grape seedlings.

Saline and alkaline stress is one of the major abiotic stresses facing agricultural production, which severely inhibits the growth and yield of plant. The application of plant growth regulators can effectively prevent crop yield reduction caused by saline and alkaline stress. Exogenous melatonin (MT) can act as a signaling molecule involved in the regulation of a variety of physiological processes in plants, has been found to play a key role in enhancing the improvement of plant tolerance to abiotic stresses. However, the effects of exogenous MT on saline and alkaline tolerance of table grape seedlings and its mechanism have not been clarified. The aim of this study was to investigate the role of exogenous MT on morphological and physiological growth of table grape seedlings (Vitis vinifera L.) under saline and alkaline stress. The results showed that saline and alkaline stress resulted in yellowing and wilting of grape leaves and a decrease in chlorophyll content, whereas the application of exogenous MT alleviated the degradation of chlorophyll in grape seedling leaves caused by saline and alkaline stress and promoted the accumulation of soluble sugars and proline content. In addition, exogenous MT increased the activity of antioxidant enzymes, which resulted in the scavenging of reactive oxygen species (ROS) generated by saline and alkaline stress. In conclusion, exogenous MT was involved in the tolerance of grape seedlings to saline and alkaline stress, and enhanced the saline and alkaline resistance of grape seedlings to promote the growth and development of the grape industry in saline and alkaline areas.

Temperature fluctuation in soil alters the nanoplastic sensitivity in wheat.

Despite the wide acknowledgment that plastic pollution and global warming have become serious agricultural concerns, their combined impact on crop growth remains poorly understood. Given the unabated megatrend, a simulated soil warming (SWT, +4 °C) microcosm experiment was carried out to provide a better understanding of the effects of temperature fluctuations on wheat seedlings exposed to nanoplastics (NPs, 1 g L-1 61.71 ± 0.31 nm polystyrene). It was documented that SWT induced oxidative stress in wheat seedlings grown in NPs-contaminated soil, with an 85.56 % increase in root activity, while decreasing plant height, fresh weight, and leaf area by 8.72 %, 47.68 %, and 15.04 % respectively. The SWT also resulted in reduced photosynthetic electron-transfer reaction and Calvin-Benson cycle in NPs-treated plants. Under NPs, SWT stimulated the tricarboxylic acid (TCA) metabolism and bio-oxidation process. The decrease in photosynthesis and the increase in respiration resulted in an 11.94 % decrease in net photosynthetic rate (Pn). These results indicated the complicated interplay between climate change and nanoplastic pollution in crop growth and underscored the potential risk of nanoplastic pollution on crop production in the future climate.

Perfluorobutanoic acid triggers metabolic and transcriptional reprogramming in wheat seedlings.

The environmental risks of fluorinated alternatives are of great concern with the phasing out of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate. Here, multi-omics (i.e., metabolomics and transcriptomics) coupled with physiological and biochemical analyses were employed to investigate the stress responses of wheat seedings (Triticum aestivum L.) to perfluorobutanoic acid (PFBA), one of the short-chain per- and polyfluoroalkyl substances (PFAS) and PFOA alternatives, at environmentally relevant concentrations (0.1-100 ng/g). After 28 days of soil exposure, PFBA boosted the generation of OH and O2- in wheat seedlings, resulting in lipid peroxidation, protein perturbation and impaired photosynthesis. Non-enzymatic antioxidant defense systems (e.g., glutathione, phenolics, and vitamin C) and enzymatic antioxidant copper/zinc superoxide dismutase were strikingly activated (p < 0.05). PFBA-triggered oxidative stress induced metabolic and transcriptional reprogramming, including carbon and nitrogen metabolisms, lipid metabolisms, immune responses, signal transduction processes, and antioxidant defense-related pathways. Down-regulation of genes related to plant-pathogen interaction suggested suppression of the immune-response, offering a novel understanding on the production of reactive oxygen species in plants under the exposure to PFAS. The identified MAPK signaling pathway illuminated a novel signal transduction mechanism in plant cells in response to PFAS. These findings provide comprehensive understandings on the phytotoxicity of PFBA to wheat seedlings and new insights into the impacts of PFAS on plants.

Biosynthetic selenium nanoparticles (Bio-SeNPs) mitigate the toxicity of antimony (Sb) in rice (Oryza sativa L.) by limiting Sb uptake, improving antioxidant defense system and regulating stress-related gene expression.

Nanotechnology offers a promising and innovative approach to mitigate biotic and abiotic stress in crop production. In this study, the beneficial role and potential detoxification mechanism of biogenic selenium nanoparticles (Bio-SeNPs) prepared from Psidium guajava extracts in alleviating antimony (Sb) toxicity in rice seedlings (Oryza sativa L.) were investigated. The results revealed that exogenous addition of Bio-SeNPs (0.05 g/L) into the hydroponic-cultured system led to a substantial enhancement in rice shoot height (73.3%), shoot fresh weight (38.7%) and dry weight (28.8%) under 50 µM Sb(III) stress conditions. Compared to Sb exposure alone, hydroponic application of Bio-SeNPs also greatly promoted rice photosynthesis, improved cell viability and membrane integrity, reduced reactive oxygen species (ROS) levels, and increased antioxidant activities. Meanwhile, exogenous Bio-SeNPs application significantly lowered the Sb accumulation in rice roots (77.1%) and shoots (35.1%), and reduced its root to shoot translocation (55.3%). Additionally, Bio-SeNPs addition were found to modulate the subcellular distribution of Sb and the expression of genes associated with Sb detoxification in rice, such as OsCuZnSOD2, OsCATA, OsGSH1, OsABCC1, and OsWAK11. Overall, our findings highlight the great potential of Bio-SeNPs as a promising alternative for reducing Sb accumulation in crop plants and boosting crop production under Sb stress conditions.

Effects of Cu2O nanoparticles on the kinetic characteristics of rapid chlorophyll fluorescence induction and related genes in wheat seedlings.

Metal nanoparticles could be accumulated in soils, which threatens the ecological stability of crops. Investigating the effects of cuprous oxide nanoparticles (Cu2O-NPs) on photosystem Ⅱ (PSⅡ) of wheat seedling leaves holds considerable importance in comprehending the implications of Cu2O-NPs on crop photosynthesis. Following the hydroponic method, we investigated the effects of 0, 10, 50, 100, and 200 mg·L-1 Cu2O-NPs on chlorophyll fluorescence induction kinetics and photosynthetic-related genes in wheat seedlings of "Zhoumai 18". The results showed that, with the increases of Cu2O-NPs concentrations, chlorophyll contents in wheat leaves decreased, and the standardization of the OJIP curve showed a clearly K-phase (ΔK＞0). Cu2O-NPs stress increased the parameters of active PSⅡ reaction centers, including the absorption flux per active RC (ABS/RC), the trapping flux per active RC (TRo/RC), the electron transport flux per active RC (ETo/RC), and the dissipation flux per active RC (DIo/RC). Cu2O-NPs stress decreased the parameters of PSⅡ energy distribution ratio including the maximum quantum yield of PSⅡ (φPo), the quantum yield of electron transport from QA (φEo), and the probability that a trapped exciton moved an electron further than QA (Ψo), while increased the quantum ratio for heat dissipation (φDo). Moreover, there was a decrease in photosynthetic quantum yield Y(Ⅱ), photochemical quenching coefficient (qP), net photosynthetic rate (Pn), stomatal conductance (gs), intercellular CO2 concentration (Ci), and transpiration rate (Tr) of leaves with the increases of Cu2O-NPs concentration. Under Cu2O-NPs stress, the expression levels of genes which included PSⅡ genes (PsbD, PsbP, Lhcb1), Rubisco large subunit genes (RbcL), cytochrome b6/f complex genes (PetD, Rieske), and ATP synthase genes (AtpA, AtpB, AtpE, AtpI) were downregulated. These results indicated that Cu2O-NPs stress altered the activity and structure of PSⅡ in wheat seedlings, affected the activity of PSⅡ reaction centers, performance parameters of PSⅡ donor and acceptor sides. PSⅡ related genes were downregulated and exhibited significant concentration effects.

Allelopathy and potential allelochemicals of Ligularia sagitta as an invasive plant.

Allelopathy is the main chemical means in the invasion process of exotic plants and one of the key factors in grassland degradation. In this experiment, we investigated the effects of ethyl acetate phase extract (EAE), n-butanol phase extract (BE) and aqueous phase extract (AE) from the aboveground (stems and leaves) and roots of Ligularia sagitta on seed germination and seedling growth of four Gramineae forages (Poa pratensis L. Festuca ovina L. Elymus nutans Griseb. Agropyron cristatum (L.) Gaertn.) in their sympatric domains and one Legosuminae forage (Medicago sativa L.). The chemical components in each phase extract of L. sagitta were determined with UHPLC-MS/MS non-targeted metabolomics, and the differential compounds were screened using Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA). Within a set concentration range, EAE significantly inhibited seed germination and seedling growth of four Gramineae forages. BE and AE acted mainly in the seedling growth stage and did not significantly inhibit forage seed germination. P. pratensis was most sensitive to L. sagitta extracts; at 2.0 mg/mL of EAE from roots, germination energy and germination rate of P. pratensis seeds were 0. L. sagitta extracts inhibited the growth of M. sativa seedlings and did not inhibit its seed germination. A total of 904 compounds were identified with UHPLC-MS/MS, among which 31, 64, 81 and 66 metabolites displayed different accumulation patterns in the four comparison groups (R.EAE vs. R.BE, R.EAE vs. R.AE, SL.EAE vs. SL.BE, SL.EAE vs. SL.AE), respectively. In particular, 9 compounds were found to be common up-regulated differential metabolites in the four comparison groups and were enriched in EAE. Additionally, N,N-dimethylaniline, Caffeic acid, 4-Hydroxybenzoic acid, 4-Hydroxybenzaldehyde and cis-9-Octadecenoic acid as potential allelochemicals in L. sagitta. The results of this study support efforts at finding alternative control plants for the restoration of poisonous grass-type degraded grasslands.

Physiological and proteomic characterization revealed the response mechanisms underlying aluminium tolerance in lentil (Lens culinaris Medikus).

Aluminium (Al) toxicity causes major plant distress, affecting root growth, nutrient uptake and, ultimately, agricultural productivity. Lentil, which is a cheap source of vegetarian protein, is recognized to be sensitive to Al toxicity. Therefore, it is important to dissect the physiological and molecular mechanisms of Al tolerance in lentil. To understand the physiological system and proteome composition underlying Al tolerance, two genotypes [L-4602 (Al-tolerant) and BM-4 (Al-sensitive)] were studied at the seedling stage. L-4602 maintained a significantly higher root tolerance index and malate secretion with reduced Al accumulation than BM-4. Also, label-free proteomic analysis using ultra-performance liquid chromatography-tandem mass spectrometer exhibited significant regulation of Al-responsive proteins associated with antioxidants, signal transduction, calcium homeostasis, and regulation of glycolysis in L-4602 as compared to BM-4. Functional annotation suggested that transporter proteins (transmembrane protein, adenosine triphosphate-binding cassette transport-related protein and multi drug resistance protein), antioxidants associated proteins (nicotinamide adenine dinucleotide dependent oxidoreductase, oxidoreductase molybdopterin binding protein & peroxidases), kinases (calmodulin-domain kinase & protein kinase), and carbohydrate metabolism associated proteins (dihydrolipoamide acetyltransferase) were found to be abundant in tolerant genotype providing protection against Al toxicity. Overall, the root proteome uncovered in this study at seedling stage, along with the physiological parameters measured, allow a greater understanding of Al tolerance mechanism in lentil, thereby assisting in future crop improvement programmes.

Application of prohexadione-calcium priming affects Brassica napus L. seedlings by regulating morph-physiological characteristics under salt stress.

Salinity stress imposes severe constraints on plant growth and development. Here, we explored the impacts of prohexadione-calcium (Pro-Ca) on rapeseed growth under salt stress. We designed a randomized block design pot experiment using two rapeseed varieties, 'Huayouza 158R' and 'Huayouza 62'. We conducted six treatments, S0: non-primed + 0 mM NaCl, Pro-Ca+S0: Pro-Ca primed + 0 mM NaCl, S100: non-primed + 100 mM NaCl, Pro-Ca+S100: Pro-Ca primed + 100 mM NaCl, S150: non-primed + 150 mM NaCl, Pro-Ca+S150: Pro-Ca primed + 150 mM NaCl. The morphophysiological characteristics, and osmoregulatory and antioxidant activities were compared for primed and non-primed varieties. Our data analysis showed that salt stress induced morph-physiological traits and significantly reduced the antioxidant enzyme activities in both rapeseed varieties. The Pro-Ca primed treatment significantly improved seedlings, root, and shoot morphological traits and accumulated more dry matter biomass under salt stress. Compared to Huayouza 158R, Huayouza 62 performed better with the Pro-Ca primed treatment. The Pro-Ca primed treatment significantly enhanced chlorophyll content, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and actual photochemical quantum efficiency (ФPSII). Furthermore, the Pro-Ca primed treatment also improved ascorbic acid (ASA) content, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) activity, and stimulated the accumulation of soluble proteins. These findings strongly suggested that the Pro-Ca primed treatment may effectively counteract the negative impacts of salinity stress by regulating the morph-physiological and antioxidant traits.

Hollow Mesoporous Silica Nanoparticles as a New Nanoscale Resistance Inducer for Fusarium Wilt Control: Size Effects and Mechanism of Action.

In agriculture, soil-borne fungal pathogens, especially Fusarium oxysporum strains, are posing a serious threat to efforts to achieve global food security. In the search for safer agrochemicals, silica nanoparticles (SiO2NPs) have recently been proposed as a new tool to alleviate pathogen damage including Fusarium wilt. Hollow mesoporous silica nanoparticles (HMSNs), a unique class of SiO2NPs, have been widely accepted as desirable carriers for pesticides. However, their roles in enhancing disease resistance in plants and the specific mechanism remain unknown. In this study, three sizes of HMSNs (19, 96, and 406 nm as HMSNs-19, HMSNs-96, and HMSNs-406, respectively) were synthesized and characterized to determine their effects on seed germination, seedling growth, and Fusarium oxysporum f. sp. phaseoli (FOP) suppression. The three HMSNs exhibited no side effects on cowpea seed germination and seedling growth at concentrations ranging from 100 to 1500 mg/L. The inhibitory effects of the three HMSNs on FOP mycelial growth were very weak, showing inhibition ratios of less than 20% even at 2000 mg/L. Foliar application of HMSNs, however, was demonstrated to reduce the FOP severity in cowpea roots in a size- and concentration-dependent manner. The three HMSNs at a low concentration of 100 mg/L, as well as HMSNs-19 at a high concentration of 1000 mg/L, were observed to have little effect on alleviating the disease incidence. HMSNs-406 were most effective at a concentration of 1000 mg/L, showing an up to 40.00% decline in the disease severity with significant growth-promoting effects on cowpea plants. Moreover, foliar application of HMSNs-406 (1000 mg/L) increased the salicylic acid (SA) content in cowpea roots by 4.3-fold, as well as the expression levels of SA marker genes of PR-1 (by 1.97-fold) and PR-5 (by 9.38-fold), and its receptor gene of NPR-1 (by 1.62-fold), as compared with the FOP infected control plants. Meanwhile, another resistance-related gene of PAL was also upregulated by 8.54-fold. Three defense-responsive enzymes of POD, PAL, and PPO were also involved in the HMSNs-enhanced disease resistance in cowpea roots, with varying degrees of reduction in activity. These results provide substantial evidence that HMSNs exert their Fusarium wilt suppression in cowpea plants by activating SA-dependent SAR (systemic acquired resistance) responses rather than directly suppressing FOP growth. Overall, for the first time, our results indicate a new role of HMSNs as a potent resistance inducer to serve as a low-cost, highly efficient, safe and sustainable alternative for plant disease protection.

Antifungal Properties of Bio-AgNPs against D. pinodes and F. avenaceum Infection of Pea (Pisum sativum L.) Seedlings.

Ascochyta blight and Fusarium root rot are the most serious fungal diseases of pea, caused by D. pinodes and F. avenaceum, respectively. Due to the lack of fully resistant cultivars, we proposed the use of biologically synthesized silver nanoparticles (bio-AgNPs) as a novel protecting agent. In this study, we evaluated the antifungal properties and effectiveness of bio-AgNPs, in in vitro (poisoned food technique; resazurin assay) and in vivo (seedlings infection) experiments, against D. pinodes and F. avenaceum. Moreover, the effects of diseases on changes in the seedlings' metabolic profiles were analyzed. The MIC for spores of both fungi was 125 mg/L, and bio-AgNPs at 200 mg/L most effectively inhibited the mycelium growth of D. pinodes and F. avenaceum (by 45 and 26%, respectively, measured on the 14th day of incubation). The treatment of seedlings with bio-AgNPs or fungicides before inoculation prevented the development of infection. Bio-AgNPs at concentrations of 200 mg/L for D. pinodes and 100 mg/L for F. avenaceum effectively inhibited infections' spread. The comparison of changes in polar metabolites' profiles revealed disturbances in carbon and nitrogen metabolism in pea seedlings by both pathogenic fungi. The involvement of bio-AgNPs in the mobilization of plant metabolism in response to fungal infection is also discussed.