Small organic compounds (SOCs) are widespread environmental pollutants that pose a significant threat to ecosystem health and human well-being. In this study, the FrmA gene from Escherichia coli was overexpressed alone or in combination with FrmB in Arabidopsis thaliana and their resistance to multiple SOCs was investigated. The transgenic plants exhibited varying degrees of increased tolerance to methanol, formic acid, toluene, and phenol, extending beyond the known role of FrmA in formaldehyde metabolism. Biochemical and histochemical analyses showed reduced oxidative damage, especially in the FrmA/BOE lines, as evidenced by lower malondialdehyde (MDA), H2O2 and O-2(center dot-) levels, indicating improved scavenging of reactive oxygen species (ROS). SOC treatment led to significantly higher levels of glutathione (GSH) and, to a lesser extent, ascorbic acid (AsA) in the transgenic plants than in the wild-types. After methanol exposure, GSH levels increased by 95 % and 72 % in the FrmA/BOE and FrmAOE plants, respectively, while showing no significant increase in the wild-type plants. The transgenic plants also maintained higher GSH:GSSG and AsA:DHA ratios, exhibited upregulated glutathione reductase (GR) and dehydroascorbate reductase (DHAR) activities, and correspondingly increased gene expression. In addition, the photosynthetic parameters of the transgenic plants were less affected by SOC stress, which represents a significant photosynthetic advantage. These results emphasize the potential of genetically engineered plants for phytoremediation and crop improvement, as they exhibit increased tolerance to multiple hazardous SOCs. This research lays the foundation for sustainable approaches to combat pollution and improve plant resilience in the face of escalating environmental problems.

The increasing soil pollution has accelerated the implementation of new agricultural regulations that significantly limit the use of synthetic nitrogen (N) fertilizers. Consequently, plants are likely to experience nutrient stress, leading to decreased productivity and potential threats to food security. To address these critical challenges, microbial-based biostimulant (BS) products, which utilize metabolites from microorganisms, offer a sustainable and eco-friendly solution to mitigate plant nutrient stress. This study evaluated the effects of the radicular application of a microbial-based BS containing L-alpha-amino acids on lettuce and pepper crops under two nitrogen regimes: optimal N availability and N stress (NS). Various parameters, including growth, production, soluble proteins, photosynthetic pigment content, and oxidative stress markers, were assessed. Under optimal N conditions, BS application enhanced commercial biomass in lettuce and vegetative biomass in pepper, indicating that BSs can reduce the need for nitrate uptake and endogenous amino acid synthesis, thereby conserving energy for other physiological processes. Despite BS application, NS conditions significantly reduced vegetative and reproductive growth in both species. However, BS treatment in pepper plants increased chloroplast pigments, improving light absorption and photosynthetic efficiency. The reduction in the carotenoid/chlorophyll ratio suggests efficient N allocation to growth and production. Thus, BS application proved effective in mitigating NS in pepper plants, enhancing pepper production, while under optimal conditions, it improved lettuce yield, particularly commercial biomass. These findings underscore the potential of symbiotic microbial-based BSs as a promising tool for sustainable agriculture under reduced N availability.

Sweet cherry (Prunus avium L.) is a highly valued fruit, and optimal nutrient management is crucial for enhancing yield and fruit quality. However, the over-application of chemical fertilizers in cherry cultivation leads to environmental issues such as soil degradation and nutrient runoff. To address this, foliar application, a more targeted and eco-friendly fertilization method, presents a promising alternative. This study evaluates the effects of pre-harvest foliar application of calcium (Ca) (150 and 300 g hL-1) and seaweed extracts (75 and 150 mL hL-1), both individually and in combination, on the physiological and biochemical responses of 'Burlat' sweet cherry trees. Key physiological parameters, including plant water status, photosynthetic performance, and leaf metabolites, were analyzed. Results show that trees treated with seaweed extracts or with combined Ca and seaweed application had improved water status, higher sugar, starch, and protein content, as well as enhanced antioxidant activity and phenolic content compared to those treated solely with calcium. However, the combined treatment did not significantly enhance overall tree performance compared to individual applications. This study highlights the potential of seaweed-based biostimulants in sustainable cherry production.

Context or problem: As global temperatures steadily increase, the frequent occurrence of extreme hightemperature events has significantly hampered peanut (Arachis hypogaea L.) production in low-latitude regions. Objective or research question: Previously, 24-epibrassinolide (EBR) was identified as a substance capable of mitigating abiotic stress damage in plants. However, it remains unclear whether and by what mechanisms EBR can diminish the yield loss caused by heat stress in peanuts. Methods: During the flowering phase, two distinct peanut cultivars, Qinghua7 (heat-resistant type) and Shanhua101 (heat-sensitive type) were exposed to a 10-day heat stress treatment (+4.2 degree celsius). EBR or water was sprayed on the 1st, 3rd, and 5th days of heating, and water-sprayed natural peanuts was used as control, to assess the effect of EBR on antioxidant capacity, photosynthetic performance, and yield in heat-stressed peanuts. Results: EBR application increased activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase in heat-stressed peanut leaves. Simultaneously, EBR decreased hydrogen peroxide and superoxide anion production, along with a reduction in malondialdehyde content. Additionally, EBR notably alleviated the oxidation damage to chloroplast membranes and grana lamella under heat stress. Thus, an increase in maximum photochemical efficiency, comprehensive performance index, rubisco activity, net photosynthetic rate, and biomass accumulation was observed in heat-stress peanuts. Synergistic enhancement provided by EBR on antioxidant capacity and photosynthetic performance resulted in improved plant growth, kernel weight, and effective pods per plant, led to a reduction in yield loss for heat-stressed cultivars Qinghua7 and Shanhua101 by 26.92 % and 55.18 %, respectively. Conclusions: The application of EBR enhanced the antioxidant capacity of peanut leaves. This, in turn, mitigated oxidative damage to chloroplast membranes, resulting in improved photosynthetic performance. Ultimately, this intervention led to a reduction in yield loss for heat-stressed peanuts, achieved through an increase in kernel weight. Implications or significance: The foliar spraying of EBR holds significant promise in crop production, offering a broad application prospect. This practice is beneficial for enhancing the heat resistance of peanuts and potentially other field crops, equipping them to better withstand the increasingly severe climate challenges anticipated in the future.

Rare earth elements (REEs) have been intentionally used in Chinese agriculture since the 1980s to improve crop yields. Around the world, REEs are also involuntarily applied to soils through phosphate fertilizers. These elements are known to alleviate damage in plants under abiotic stresses, yet there is no information on how these elements act in the physiology of plants. The REE mode of action falls within the scope of the hormesis effect, with low-dose stimulation and high-dose adverse reactions. This study aimed to verify how REEs affect rice plants' physiology to test the threshold dose at which REEs could act as biostimulants in these plants. In experiment 1, 0.411 kg ha(-1) (foliar application) of a mixture of REE (containing 41.38% Ce, 23.95% La, 13.58% Pr, and 4.32% Nd) was applied, as well as two products containing 41.38% Ce and 23.95% La separately. The characteristics of chlorophyll a fluorescence, gas exchanges, SPAD index, and biomass (pot conditions) were evaluated. For experiment 2, increasing rates of the REE mix (0, 0.1, 0.225, 0.5, and 1 kg ha(-1)) (field conditions) were used to study their effect on rice grain yield and nutrient concentration of rice leaves. Adding REEs to plants increased biomass production (23% with Ce, 31% with La, and 63% with REE Mix application) due to improved photosynthetic rate (8% with Ce, 15% with La, and 27% with REE mix), favored by the higher electronic flow (photosynthetic electron transport chain) (increase of 17%) and by the higher F-v/F-m (increase of 14%) and quantum yield of photosystem II (increase of 20% with Ce and La, and 29% with REE Mix), as well as by increased stomatal conductance (increase of 36%) and SPAD index (increase of 10% with Ce, 12% with La, and 15% with REE mix). Moreover, adding REEs potentiated the photosynthetic process by increasing rice leaves' N, Mg, K, and Mn concentrations (24-46%). The dose for the higher rice grain yield (an increase of 113%) was estimated for the REE mix at 0.72 kg ha(-1).

Soil salinization has damaged the soil biological environment and chemical structure, resulting in a decline in soil quality and crop yields, which has caused harm to the ecological environment and human health, and severely hindered the development of the economy. In this experiment, using the 'Ningdan 33' maize seeds as materials, the maize was treated with histidine and salt stress (100 mM NaCl), and photosynthesis, photosynthetic enzyme activity, relative expression of photosynthetic genes of maize were measured. The anatomical structure of the leaves was also observed. The study explored the impact of exogenous histidine treatment on the photosynthesis of maize under salt stress. When the concentration of histidine sprayed on the leaves was 0.5 mM, it had the best effect on promoting photosynthesis in maize under salt stress. 0.5 mM histidine significantly improved the photosynthetic performance ( P N , g s , E , Chl a /Chl b ) of maize under salt stress, significantly improved photosynthesis efficiency (F v /F m , Delta F/F' m , q P were significantly increased. NPQ was significantly decreased), significantly increased the activity of photosynthetic enzymes (PEPC, NADP-ME, PPDK, Rubisco) and the relative expression of photosynthetic genes ( ZmPEPC , ZmNADP-ME , ZmPPDK , ZmRCA ), increased the length of the vascular bundle in the cross- of the leaf, played a certain protective role on the vascular bundle, and improved the efficiency of material transportation under salt stress. Based on the above analysis, 0.5 mM histidine can significantly improve the tolerance of maize under salt stress, which has great application value for planting maize in saline environments.

Melatonin (MT) and reduced glutathione (GSH) roles in mitigating chromium (Cr) toxicity in sweetpotato were explored. Plants, pre-treated with varying MT and GSH doses, were exposed to Cr (40 mu M). Cr severely hampered growth by disrupting leaf photosynthesis, root system, and oxidative processes and increased Cr absorption. However, the exogenous application of 1 mu M of MT and 2 mM of GSH substantially improved growth parameters by enhancing chlorophyll content, gas exchange (Pn, Tr, Gs, and Ci), and chlorophyll fluorescence (Fv/Fm, ETR, qP, and Y(II)). Furthermore, malondialdehyde (MDA), hydrogen peroxide (H2O2), superoxide ion (O-2(center dot-)), electrolyte leakage (EL), and Cr uptake by roots (21.6 and 27.3%) and its translocation to shoots were markedly reduced by MT and GSH application, protecting the cell membrane from oxidative damage of Cr-toxicity. Microscopic analysis demonstrated that MT and GSH maintained chloroplast structure and integrity of mesophyll cells; they also enhanced stomatal length, width, and density, strengthening the photosynthetic system and plant growth and biomass. MT and GSH improved osmo-protectants (proline and soluble sugars), gene expression, and enzymatic and non-enzymatic antioxidant activities, mitigating osmotic stress and strengthening plant defenses under Cr stress. Importantly, the efficiency of GSH pre-treatment in reducing Cr-toxicity surpassed that of MT. The findings indicate that MT and GSH alleviate Cr detrimental effects by enhancing photosynthetic organ stability, component accumulation, and resistance to oxidative stress. This study is a valuable resource for plants confronting Cr stress in contaminated soils, but further field validation and detailed molecular exploration are necessary.