Salinity stress is one of the most detrimental abiotic factors affecting plant development, harming vast swaths of agricultural land worldwide. Silicon is one element that is obviously crucial for the production and health of plants. With the advent of nanotechnology in agricultural sciences, the application of silicon oxide nanoparticles (SiO-NPs) presents a viable strategy to enhance sustainable crop production. The aim of this study was to assess the beneficial effects of SiO-NPs on the morpho-physio-biochemical parameters of rice (Oryza sativa L., variety: DRR Dhan 73) under both normal and saline conditions. To create salt stress during transplanting, 50 mM NaCl was injected through the soil. 200 mM SiO-NPs were sprayed on the leaves 25 days after sowing (DAS). It was evident that salt stress significantly hindered rice growth because of the reductions in shot length (41 %), root length (38 %), shot fresh mass (40 %), root fresh mass (47 %), shoot dry mass (48 %), and root dry mass (39 %), when compared to controls. Together with this growth inhibition, elevated oxidative stress markers including a 78 % increase in malondialdehyde (MDA) and a 67 % increase in hydrogen peroxide (H2O2) indicating enhanced lipid peroxidation were noted. Increasing the chlorophyll content (14 %), photosynthetic rate (11 %), protein levels, total free amino acids (TFAA; 13 %), and total soluble sugars (TSS; 11 %), all help to boost nitrogen (N; 16 %), phosphorous (P; 14 %), potassium (K; 12 %), and vital nutrients. The adverse effects of salt stress were significantly reduced by exogenous application of SiO-NPs. Additionally; SiO-NPs dramatically raised the activity of important antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POX), and catalase (CAT), improving the plant's ability to scavenge reactive oxygen species (ROS) and thereby lowering oxidative damage brought on by salt. This study highlights SiO-NPs' potential to develop sustainable farming practices and provides significant new insights into how they enhance plant resilience to salinity, particularly in salt-affected regions worldwide.

The global escalation of soil salinization has led to increased water erosion, adversely impacting plant growth and development. Heat shock proteins (HSPs) are highly conserved proteins found across a wide range of organisms. When biological organisms are stimulated by the external environment, they will express themselves in large quantities. HSPs play a pivotal role in mediating plant responses to abiotic stress. This study identified 22 members of the PcHsp20 gene family with complete open reading frames (ORFs) through transcriptomic analysis conducted under Pugionium cornutum salt stress, and evaluated their expression levels. Notably, PcHsp18.1 was significantly upregulated in the leaves of Pugionium cornutum (L.) Gaertn. Based on this, we cloned the PcHsp18.1 gene and determined through subcellular localization that PcHsp18.1 is localized in both the cytoplasm and nuclear membrane. Subsequently, we transformed the PcHsp18.1 gene into Arabidopsis thaliana to investigate its involvement in the response to salt stress. The results indicated that the overexpressing (OE) plants exhibited improved growth conditions, higher seed germination rates, increased root lengths, a greater number of lateral roots, reduced relative conductivity, and elevated relative chlorophyll content compared to the wild-type (WT) plants. These findings suggesting that the transgenic line possesses enhanced salt tolerance. Moreover, the concentrations of malondialdehyde (MDA) and relative conductivity in the overexpressing (OE) plants were significantly lower than those observed in the wild-type (WT) plants, suggesting a reduced extent of damage to their cell membranes. In comparison to the wild type (WT), the transgenic line (OE) exhibited elevated activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), along with increased proline content, suggesting that the transgenic plants possess enhanced resistance to abiotic stress and a greater capacity for scavenging reactive oxygen species (ROS). Meanwhile, salt treatment resulted in the significant expression of stress-related genes in the transgenic plants. These results indicate that PcHsp18.1 positively regulates salt stress in Arabidopsis.

Salinity is a common environmental stress that disrupts physiological and biochemical processes in plants, inhibiting growth. Silicon is a key element that enhances plant tolerance to such abiotic stresses. This study examined the effects of silicon supplementation on physiological, biochemical, and molecular responses of GF677 and GN15 rootstocks under NaCl-induced salinity stress. The experiment was conducted in a greenhouse using a factorial design with two rootstocks, three NaCl concentrations (0, 50, and 100 mM), and three silicon levels (0, 1, and 2 mM) in a randomized complete block design with three replicates. Salinity significantly reduced growth parameters, including shoot and root fresh and dry weights, RWC, and photosynthetic activity, with GN15 being more sensitive to salt stress than GF677. Silicon supplementation, especially at 2 mM, alleviated NaCl-induced damage, enhancing biomass retention and RWC under moderate and high NaCl levels. Additionally, silicon reduced electrolyte leakage, lipid peroxidation, and hydrogen peroxide accumulation, suggesting a protective role against oxidative stress. Biochemical analyses showed that silicon increased the accumulation of osmolytes such as proline, soluble sugars, glycine betaine, and total soluble protein, particularly in GF677. Silicon also boosted antioxidant enzyme activities, mitigating oxidative damage. In terms of mineral nutrition, silicon reduced Na+ and Cl- accumulation in leaves and roots, with the greatest reduction observed at 2 mM Si. Gene expression analysis indicated that NaCl stress upregulated key salt tolerance genes, including HKT1, AVP1, NHX1, and SOS1, with silicon application further enhancing their expression, particularly in GF677. The highest levels of gene expression were found in plants treated with both NaCl and 2 mM Si, suggesting that silicon improves salt tolerance by modulating gene expression. In conclusion, this study demonstrates the potential of silicon as an effective mitigator of NaCl stress in GF677 and GN15 rootstocks, particularly under moderate to high salinity conditions. Silicon supplementation enhances plant growth, osmotic regulation, reduces oxidative damage, and modulates gene expression for salt tolerance. Further research is needed to assess silicon's effectiveness under soil-based conditions and its applicability to other rootstocks and orchard environments. This study is the first to concurrently evaluate the physiological, biochemical, and molecular responses of GF677 and GN15 rootstocks to silicon application under salt stress conditions.

This study aimed to evaluate the synergistic effects of zinc sulfate and Pseudomonas spp. in terms of mitigating drought stress in maize (Zea mays L.) by analyzing physiological, biochemical, and morphological responses under field conditions. A two-year (2018-2019) field experiment investigated two irrigation levels (optimal and moderate stress) and twelve treatment combinations of zinc sulfate application methods (without fertilizer, soil, foliar, and seed priming) with zinc-solubilizing bacteria (no bacteria, Pseudomonas fluorescens, and Pseudomonas aeruginosa). Drought stress significantly reduced chlorophyll content, increased oxidative damage, and impaired membrane stability, leading to a 42.4% increase in electrolyte leakage and a 10.9% reduction in leaf area index. However, the combined application of zinc sulfate and P. fluorescens, and P. aeruginosa mitigated these effects, with seed priming showing the most significant improvements. Specifically, seed priming with zinc sulfate and P. fluorescens increased catalase activity by 76% under non-stress conditions and 24% under drought stress. Principal component analysis revealed that treatments combining zinc sulfate and P. fluorescens, and P. aeruginosa were strongly associated with improved chlorophyll content, carotenoid content, and grain yield while also enhancing osmotic adjustment and antioxidant enzyme activity. These findings highlight the potential of the use of zinc sulfate and P. fluorescens as well as P. aeruginosa as sustainable strategies for enhancing maize drought tolerance, mainly through seed priming and soil application methods.

Heavy metals (HMs) contamination is a major issue produced by industrial and mining processes, among other human activities. The capacity of fungi to eliminate HMs from the environment has drawn attention. However, the main process by which fungi protect the environment against the damaging effects of these HMs, such as cadmium (Cd), is still unknown. In this study, some fungi were isolated from HMs-polluted soil. The minimum inhibitory concentrations (MICs) and the tolerance indices of the tested isolates against Cd were evaluated. Moreover, molecular identification of the most tolerant fungal isolates (Aspergillus niger and A. terreus) was done and deposited in the GenBank NCBI database. The results showed that the colony diameter of A. niger and A. terreus was decreased gradually by the increase of Cd concentration. Also, all the tested parameters were influenced by Cd concentration. Lipid peroxidation (MDA content) was progressively increased by 12.95-105.95% (A. niger) and 17.27-85.38% (A. terreus), respectively, from 50 to 200 mg/L. PPO, APX, and POD enzymes were elevated in the presence of Cd, thus illustrating the appearance of an oxidative stress action. Compared to the non-stressed A. niger, the POD and PPO activities were enhanced by 92.00 and 104.24% at 200 mg/L Cd. Also, APX activity was increased by 58.12% at 200 mg/L. Removal efficiency and microbial accumulation capacities of A. niger and A. terreus have also been assessed. Production of succinic and malic acids by A. niger and A. terreus was increased in response to 200 mg/L Cd, in contrast to their controls (Cd-free), as revealed by HPLC analysis. These findings helped us to suggest A. niger and A. terreus as the potential mycoremediation microbes that alleviate Cd contamination. We can learn more about these fungal isolates' resistance mechanisms against different HMs through further studies.

The increasing global temperatures, driven largely by anthropogenic activities, pose a significant threat to crops worldwide, with heat stress (HS) emerging as one of the most severe challenges to agricultural productivity. Among the numerous human-induced pressures threatening terrestrial ecosystems globally, microplastics (MPs) represent one of the most persistent and urgent concerns. This study investigated the effects of heat stress (HS) at 35 degrees C and 40 degrees C (12 h exposure) on wheat (Triticum aestivum) and maize (Zea mays) grown in soil contaminated with polyethylene microplastics (PE-MPs; 0.01%, 0.1%, and 1% w/w), assessing their physiological and biochemical responses. The results indicated a significant (p < 0.05) reduction in plant height, root length, leaf area, chlorophyll content, and biomass of the selected plants due to MPs application. HS alone and in co-exposure with MPs caused damage to plant tissues as shown by significant (p < 0.05) reactive oxygen species (ROS) production, and lipid peroxidation. Under ROS induction, proline and antioxidant enzymes (CAT, POD, SOD) exhibited significantly (p < 0.05) higher levels in combined stress (HS + MPs) than in individual treatments. In conclusion, wheat exhibited higher levels of H2O2 and MDA stress markers indicating increased oxidative stress compared to maize. In contrast, maize showed elevated levels of proline, CAT, POD, and SOD, suggesting greater resistance to environmental stresses than wheat. Our results provide new understandings of sustainable agriculture practices and hold vast promise in addressing the challenges of HS and MP stresses in agricultural soils.

Soil salinization is increasingly recognized as a critical environmental challenge that significantly threatens plant survival and agricultural productivity. To elucidate the mechanism of salt resistance in poplar, physiological and transcriptomic analyses were conducted on 84K poplar (Populus alba x Populus glandulosa) under varying salt concentrations (0, 100, 200 and 300 mM NaCl). As salt levels increased, observable damage to poplar progressively intensified. Differentially expressed genes under salt stress were primarily enriched in photosynthesis, redox activity and glutathione metabolism pathways. Salt stress reduced chlorophyll content and net photosynthetic rate, accompanied by the downregulation of photosynthesis-related genes. NaCl (300 mM) significantly inhibited the photochemical activity of photosystems. The higher photochemical activity under 100 and 200 mM NaCl was attributed to the activated PGR5-cyclic electron flow photoprotective mechanism. However, the NAD(P)H dehydrogenase-like (NDH)-cyclic electron flow was inhibited under all salt levels. Salt stress led to reactive oxygen species accumulation, activating the ASA-GSH cycle and antioxidant enzymes to mitigate oxidative damage. Weighted gene co-expression network analysis showed that five photosynthesis-related hub genes (e.g., FNR and TPI) were down-regulated and nine antioxidant-related hub genes (e.g., GRX, GPX and GST) were up-regulated under salt stress conditions. PagGRXC9 encodes glutaredoxin and was found to be differentially expressed during the salt stress condition. Functional studies showed that overexpressing PagGRXC9 enhanced salt tolerance in yeast, and in poplar, it improved growth, FV/FM, non-photochemical quenching values and resistance to H2O2-induced oxidative stress under salt stress. This study constructed the photosynthetic and antioxidant response network for salt stress in poplar, revealing that PagGRXC9 enhances salt tolerance by reducing photoinhibition and increasing antioxidant capacity. These findings provide valuable insights for breeding salt-tolerant forest trees.

The root-knot nematode (RKN), Meloidogyne javanica, causes severe damage to a wide variety of crops. These nematodes significantly reduce tomato yield globally, causing symptoms such as stunted growth, galls on roots, chlorosis, and wilting, ultimately leading to host death. Classical nematode control methods, such as the application of chemical nematicides, are very effective; however, their use is limited due to conflicts with sustainable agriculture. Therefore, biological methods, are gaining attention as more environmentally friendly options. In the present study, 47 strains of bacteria were isolated from the rhizosphere of RKN-infected plants. The effect of these strains was studied on egg hatching and second stage infective juveniles (J2s) mortality of M. javanica, in vitro. Then, three holes were made in the soil around the roots of non-inoculated and nematode inoculated tomato plants and a suspension of 15 mL of three isolates with the greatest negative effect on hatching and J2s mortality (107 CFU/ml), was poured into the holes. Stenotrophomonas maltophilia CPHE1, Peribacillus frigoritolerans Rhs-L31 and Bacillus cereus Pt0-RL12 improved the vegetative indices of inoculated plants compared to control plants. These strains significantly reduced nematode hatching and significantly increased mortality of nematode J2s; and in greenhouse pot experiments significantly reduced the number of nematode eggs and egg masses, root galls, and nematode reproduction factor. In each case, inoculation with the bacterial strains significantly increased peroxidase and superoxide dismutase activity, and decreased catalase activity in tomato roots infected with M. javanica. The present study indicates the potential of these bacterial strains for biocontrol of M. javanica on tomato.

Nickel (Ni) is a trace element that is toxic to plants and consequently results in toxicity symptoms and hazardous fitness problems in human beings through food chains. Nanoparticles (NPs) are being used in new ways to directly help plants handle Ni stress and act as nano-fertilizers. The purpose of the current study was to establish the use of biogenically produced zinc oxide nanoparticles (ZnONPs) to reduce Ni-induced toxic effect on the growth and development of watermelon (Citrullus lanatus). Watermelon seeds were sown in pot filled with five kg of soil and placed in a greenhouse. The watermelon plants were treated with Ni stress (70 mg/kg soil) at 20 DAS (days after sowing), and the treatment was applied directly into the soil. The supply of ZnONPs (100 mg/L) as foliar spray was given at 30 DAS and 38 DAS, and the sampling was performed at 55-60 DAS for biochemical and physiological analysis. The results showed that watermelon plants that were exposed to Ni had oxidative damage, which was shown by more electrolyte leakage, hydrogen peroxide, lipid peroxidation, pigment and osmolyte loss, and a loss of ultrastructural integrity in the chloroplasts. However, watermelon plants supplemented with ZnONPs under the Ni toxicity revealed significantly increased plant fresh weight (53.18%), plant dry weight (51.25%), and root length (32.14%). Moreover, the ZnONPs supplement has beneficial impacts on photosynthesis attributes, SPAD value (21.93%), and chloroplast structure observed by transmission electron microscopy (TEM) under Ni stress. Application of ZnONPs also substantially reduced the oxidative stress by lowering the levels of superoxide radical (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\:{\text{O}}_{2}{-\cdot\:}$$\end{document}; 22.68%), hydrogen peroxide (H2O2; 21.18%), malondialdehyde (MDA; 21.34%), and electrolyte leakage (EL; 34.613%). The results showed that ZnONPs enhanced enzymatic activities of superoxide dismutase (SOD; 39.95%), peroxidase (POD; 19.95%), catalase (CAT; 32.85%), ascorbate peroxidase (APX; 25%) that metabolize reactive oxygen species (ROS); these increases correlated with the changes observed in the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\:{\text{O}}_{2}{-\cdot\:}$$\end{document}, H2O2 and MDA after ZnONPs application. Application of ZnONPs increased the transcriptional levels of antioxidant defense genes as compared to the Ni plants alone. In conclusion, spraying ZnONPs on foliage has high effectiveness in increasing biomass, photosynthesis, protein and antioxidant enzymes, mineral nutrient concentrations, and lowering Ni concentrations in watermelon. The results indicate biogenically produced ZnONPs can be a promising technique for the remediation of Ni-contaminated soils.

Simple Summary: To reduce the influence of chemical fertilizers and pesticides on the cultivation of Fritillaria taipaiensis P. Y. Li, this study adopted the application of microbial fertilizer to mitigate soil damage and enhance the plant's stress resistance. In this experiment, the growth index, enzyme activity, and gene expression of F. taipaiensis leaves were measured by applying nitrogen-fixing bacteria. The results showed that nitrogen-fixing bacteria could promote the growth and development of F. taipaiensis. This study not only provides a theoretical foundation for the subsequent cultivation technology of F. taipaiensis but also provides a new idea in terms of the realization of green planting of Chinese medicinal materials. The widespread application of chemical fertilizers and pesticides has resulted in environmental pollution. With the growing emphasis on ecological agriculture in traditional Chinese medicine, microbial fertilizers are increasingly recognized for their potential. The aim of this study is to investigate the effect of inoculating nitrogen-fixing bacteria on the soil (yellow loam, river sand, and organic fertilizer in a 2:1:1 ratio) of Fritillaria taipaiensis, with a focus on the leaf changes in terms of physiological parameters, antioxidant enzyme activity, and corresponding gene expression levels. The experiment involved three nitrogen-fixing bacteria, namely Rahnella aquatilis, Pseudomonas chlororaphis, and Paenibacillus stellifer, with a total of eight treatment groups. The objective was to assess how these bacterial treatments influenced physiological parameters, photosynthetic characteristics, pigment content, and both antioxidant enzyme activities and gene expression in the leaves of F. taipaiensis. The experimental results demonstrated statistically significant reductions (p < 0.05) in malondialdehyde (MDA) content and stomatal limitation value (LS) in F. taipaiensis leaves under treatment conditions relative to the control group (CK). The most substantial decreases were observed dual-inoculation with R. aquatilis and P. stellifer (N5), showing reductions of 38.24% and 20.94% in MDA and LS compared to CK values. Additionally, leaf area, leaf thickness, stem thickness, plant height, photosynthetic parameters, pigment content, soluble sugars, soluble proteins, proline levels, and the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) exhibited varying degrees of increase. Compared to the CK group, the SOD, POD, and CAT activities of the N5 group increased by 141.06%, 160.59%, and 106.23%, respectively. The relative gene expression patterns of SOD, POD, and CAT corresponded with the trends observed in their respective antioxidant enzyme activities. Pearson correlation analysis further demonstrated that leaf area and net photosynthetic rate (Pn) were significantly correlated with respect to SOD, POD, and CAT activities, as well as their corresponding gene expression levels. In conclusion, inoculation with nitrogen-fixing bacteria improved the growth and stress tolerance of F. taipaiensis, with the combined application of Rahnella aquatilis and Pseudomonas stellifer yielding the most effective results. This study establishes that different rhizosphere nitrogen-fixing bacteria, either individually or in combination, influence the photosynthetic characteristics, physiological and biochemical parameters, and protective enzyme systems of F. taipaiensis. These findings provide a theoretical foundation for the selection of nitrogen-fixing bacteria as biofertilizers in the artificial cultivation of F. taipaiensis and highlight their potential application in the cultivation of traditional Chinese medicinal materials.