Ascorbate Peroxidase Activity Research Articles

Responses of glyoxalase system, ascorbate-glutathione cycle, and antioxidant enzymes in Pontederia cordata to lead stress and its capacity to remove lead

A hydroponic experiment was conducted to investigate the variations in membrane permeabilities, chlorophyll contents, antioxidase activities, the ascorbic acid (AsA)-glutathione (GSH) cycle, and the glyoxalase system in the leaves of Pontederia cordata with 0 ∼ 15.0 mg L−1 lead ion (Pb2+) exposure. The concentrations of Pb2+ accumulated in the plant roots, stems, and leaves were also evaluated. After 7 days of exposure, the plants maintained normal growth, and there was a significant increase in ascorbate peroxidase and dehydroascorbate reductase activities. With 5.0 mg L−1 Pb2+ exposure for 28 days, nearly 66.36% of Pb2+ accumulated in the roots, while excess Pb2+ immobilized in the leaves was not observed. Exposure to 10.0 and 15.0 mg L−1 Pb2+ for 28 days significantly increased Pb2+ contents in the leaves. This led to decrease in chlorophyll a, b, and carotenoid contents, and to increase in the methylglyoxal content in the leaves. With 10 and 15 mg L−1 Pb2+ exposure, NPT and PCs contents in leaves increased. however, the glyoxalase system did not function well in the plant tolerant to Pb2+ at higher concentrations. The AsA-GSH cycle did not cooperate with the glyoxalase system in the plant defense against Pb2+ exposure in the present investigation.

Exploring the response of yellow lupine (Lupinus luteus L.) root to drought mediated by pathways related to phytohormones, lipid, and redox homeostasis.

Yellow lupine (Lupinus luteus L.) is a high-protein crop of considerable economic and ecological significance. It has the ability to fix atmospheric nitrogen in symbiosis with Rhizobium, enriching marginal soils with this essential nutrient and reducing the need for artificial fertilizers. Additionally, lupine produces seeds with a high protein content, making it valuable for animal feed production. However, drought negatively affects lupine development, its mutualistic relationship with bacteria, and overall yield. To understand how lupine responds to this stress, global transcriptome sequencing was conducted, along with in-depth biochemical, chromatography, and microscopy analyses of roots subjected to drought. The results presented here contribute to strategies aimed at mitigating the effects of water deficit on lupine growth and development. Based on RNA-seq, drought-specific genes were identified and annotated to biological pathways involved in phytohormone biosynthesis/signaling, lipid metabolism, and redox homeostasis. Our findings indicate that drought-induced disruption of redox balance characterized by the upregulation of reactive oxygen species (ROS) scavenging enzymes, coincided with the accumulation of lipid-metabolizing enzymes, such as phospholipase D (PLD) and lipoxygenase (LOX). This disruption also led to modifications in lipid homeostasis, including increased levels of triacylglycerols (TAG) and free fatty acids (FFA), along with a decrease in polar lipid content. Additionally, the stress response involved alterations in the transcriptional regulation of the linolenic acid metabolism network, resulting in changes in the composition of fatty acids containing 18 carbons. The first comprehensive global transcriptomic profiles of lupine roots, combined with the identification of key stress-responsive molecules, represent a significant advancement in understanding lupine's responses to abiotic stress. The increased expression of the Δ12DESATURASE gene and enhanced PLD activity lead to higher level of linoleic acid (18:2), which is subsequently oxidized by LOX, resulting in membrane damage and malondialdehyde (MDA) accumulation. Oxidative stress elevates the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT), while the conversion of FFAs into TAGs provides protection against ROS. This research offers valuable molecular and biochemical candidates with significant potential to enhance drought tolerance . It enables innovative strategies in lupine breeding and crop improvement to address critical agricultural challenges.

Novel application of cyclo(-Phe-Pro) in mitigating aluminum toxicity through oxidative stress alleviation in wheat roots

Microbial secondary metabolites are crucial in plant-microorganism interactions, regulating plant growth and stress responses. In this study, we found that cyclo(-Phe-Pro), a proline-based cyclic dipeptide secreted by many microorganisms, alleviated aluminum toxicity in wheat roots by increasing root growth, decreasing callose deposition, and decreasing Al accumulation. Cyclo(-Phe-Pro) also significantly reduced Al-induced reactive oxygen species (ROS) with H2O2, O2•-, and •OH levels decreasing by 19.1%, 42.8%, and 17.9% in root tips, thus protecting the plasma membrane from oxidative damage. Although Al stress increased the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX) in wheat roots, cyclo(-Phe-Pro) application reduced these enzyme activities. However, compared to the Al treatment, cyclo(-Phe-Pro) application increased DPPH and FRAP activities by 16.8% and 14.9%, indicating increased non-enzymatic antioxidant capacity in wheat roots. We observed that Al caused the oxidation of ascorbate (AsA) and glutathione (GSH) to dehydroascorbate (DHA) and glutathione disulfide (GSSG), respectively. Under Al stress, cyclo(-Phe-Pro) treatment maintained reduced AsA and GSH levels, as well as high AsA/DHA and GSH/GSSG redox pair ratios in wheat roots. High AsA/DHA and GSH/GSSG ratios can reduce Al toxicity by neutralizing free radicals and restoring redox homeostasis via antioxidant properties. These results suggest that cyclo(-Phe-Pro) maintains ASA- and GSH-dependent redox homeostasis to alleviate oxidative and Al stress in wheat roots. Findings of this study establishes a theoretical foundation for using microbial metabolites to mitigate Al toxicity in acidic soils, highlighting their potential in sustainable agriculture.

Changes in Postharvest Quality and Physiological Attributes of Strawberry Fruits Influenced by L‐Phenylalanine

ABSTRACTStrawberry (Fragaria × ananassa) is a popular fruit with rich nutrients and a delicious taste. But this fruit is very vulnerable to diseases and decay. Therefore, L‐phenylalanine (Phe) (0, 4, 8 mM) was considered to improve biochemical characteristics and activity of antioxidant enzymes in strawberry fruit cv. Sabrina under cold storage (5, 10, 15 days). After treatment and storage, traits including weight loss, total phenol (TP), antioxidant capacity, ascorbic acid, total anthocyanin (TA), total flavonoid (TF), malondialdehyde (MDA), soluble protein content and antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (POD) and phenylalanine ammonialyase (PAL) were evaluated at 5‐day intervals. Our findings showed that the treatment of L‐phenylalanine in different concentrations prevented the weight loss of the fruit compared to the control and maintained and increased TP, antioxidant capacity, ascorbic acid, TA, TF, soluble protein and SOD, CAT, APX, POD, and PAL enzymes activity. Also, Phe decreased the MDA content and peroxidation of lipid. The results showed that 4 mM Phe is the best treatment for improving phytochemical characteristics and maintaining fruit quality. The findings indicated that Phe treatment may be useful to improve quality and increase postharvest shelf life in strawberry fruits.

Effects of Bacillus spp. inoculation on suggested shoot tolerance mechanisms in lowland rice (Oryza sativa L.) grown under iron toxicity

AbstractBackgroundIn areas of lowland rice production, high iron concentrations in the soil often lead to yield reductions. Local adapted varieties possess different adaptation mechanisms, which, however, are not fully understood. Previous studies have shown that endophytic bacteria can influence plant tolerance to abiotic stresses, including iron toxicity.AimThis study aims at analyzing the effects of different Bacillus isolates on distinct shoot tolerance mechanism in different rice cultivars grown under iron toxicity.MethodsThree lowland rice cultivars, varying in their tolerance against iron toxicity (IR31785‐58‐1‐2‐3‐3, Sahel 108, Suakoko 8), were inoculated with three Bacillus strains (two of B. pumilus and one of B. megaterium). One week after Bacillus inoculation plants were subjected to high iron levels (1000 ppm) for 7 days. Leaf symptom scoring was used to assess tolerance levels. Activities of ascorbate peroxidase (APX), glutathione reductase (GR), catalase (CAT), superoxide dismutase (SOD), and guaiacol peroxidase (PRX) were measured by spectrophotometric assays. Transcription of genes related to iron toxicity (OsFER, OsFRO1, OsNRAMP6) was determined by RT‐qPCR. Bacterial production of NO was evaluated by measuring nitrite levels in the culture supernatants.ResultsIn general, iron toxicity affected the activities of APX, GR, CAT, and PRX but not SOD activity. Only PRX activity in response to iron differed between cultivars with a significantly stronger increase in IR31785‐58‐1‐2‐3‐3. Inoculation with B. pumilus Ni9MO12 led to higher activity of CAT in the leaf sheaths of all cultivars and an increase in GR activity in the sheaths that was significantly higher in Suakoko 8. In the young leaf blades of IR31785‐58‐1‐2‐3‐3, transcription of OsFRO1 and OsNRAMP6 was not significantly affected by Bacillus inoculation, whereas accumulation of OsFER mRNA was significantly higher in iron‐stressed, B. pumilus Ni9MO12 inoculated plants compared to non‐inoculated, non‐iron‐stressed plants. Nitrite concentration as an indicator for NO production was increased in B. pumilus Ni9MO12 culture supernatants.ConclusionOur results show that in the sensitive cultivar IR31785‐58‐1‐2‐3‐3 tolerance to iron toxicity increases when inoculated with B. pumilus Ni9MO12, coinciding with higher levels of ferritin transcription. NO production by the Bacillus isolate might confer the promotion of OsFER gene transcription in the inoculated plants.

Tetranychus ludeni (Acari: Tetranychidae) infestation triggers a spatiotemporal redox response dependent on soybean genotypes.

The redox homeostasis and photosynthetic pigments changes vary with Tetranychus ludeni infestation, with longer-cycle genotypes showing greater tolerance and efficiency in antioxidant defense. Infestations of Tetranychus ludeni Zacher (Tetranychidae) have been frequently observed in soybean plants. In this context, understanding the oscillation of redox homeostasis is crucial for detecting and assessing the stress levels caused in the plants by these organisms. The impacts of these infestations on redox metabolism and photosynthetic pigments are currently unknown. Therefore, we examined the hypothesis that T. ludeni infestations in soybean plants can influence redox homeostasis and photosynthetic pigments in a spatiotemporal manner, varying between different infestation times, modules and genotypes. For this purpose, soybean plants of the genotypes Monsoy, maturity group 5.7, and Brasmax, maturity group 6.3, grown in a controlled environment, were exposed to infestation and evaluated at two periods: 14 and 24days. A variation in the distribution of T. ludeni within the infested plants over time increased the activity of ascorbate peroxidase and catalase, especially in Monsoy, reducing the content of hydrogen peroxide and superoxide, which prevented lipid peroxidation in the apical region in both genotypes. In the basal region, low chlorophyll indices corroborated by the yellow coloration of trifoliate leaves, high levels of membrane stability loss, and accumulation of hydrogen peroxide and superoxide characterized senescent trifoliate leaves in Brasmax, 24days post infestation. Thus, the infestation of T. ludeni has a complex and significant impact on the redox metabolism of soybean plants, especially in shorter-cycle genotypes such as Brasmax. Furthermore, the oscillation of homeostasis can be considered as a good biochemical marker for selecting more suitable genotypes that are less sensitive and prone to infestations.

Inoculation with multifunctional Bacillus sp. NEAU-DCB1-2 mitigates chromium toxicity in pakchoi (Brassica rapa ssp. chinensis) through a multi-level mechanism

Soil chromium (Cr) accumulation is escalating, severely hindering plant growth and development. Plant growth-promoting bacteria (PGPB) have shown potential in enhancing plant tolerance to heavy metals. However, the role and mechanisms of Cr(VI)-reducing PGPB strains in improving the growth of pakchoi under Cr toxicity remain unclear. This study aimed to isolate a Cr(VI)-reducing PGPB strain from Cr-contaminated soil, evaluate its effect on pakchoi growth under Cr(VI) stress, and investigate the mechanisms involved. Our findings showed that Bacillus sp. NEAU-DCB1-2 effectively reduce Cr(VI) to Cr(III) and produced indole-3-acetic acid and siderophores. Under Cr(VI) stress, inoculation with NEAU-DC1-2 significantly promoted seed germination and early growth of pakchoi. In pot experiments, NEAU-DCB1-2 significantly increased biomass accumulation, plant height, and root length of Cr(VI)-treated pakchoi seedlings, while reducing the Cr(VI) content in root, shoot and soil. Moreover, NEAU-DCB1-2 greatly increased catalase, superoxide dismutase, peroxidase, and ascorbate peroxidase activities in seedlings under Cr(VI) stress, thereby reducing malondialdehyde content. Transcriptome analysis indicated substantial alterations in gene expression patterns after inoculation with NEAU-DCB1-2 under Cr(VI) stress. Further analyses revealed that NEAU-DCB1-2 mainly affected the responses of antioxidant system, metal chelation and transport, together with auxin, abscisic acid, and jasmonic acid signaling to Cr(VI) stress. Conclusively, the Cr(VI)-reducing PGPB strain NEAU-DCB1-2 significantly enhances the growth and Cr tolerance of pakchoi through multiple mechanisms, offering a valuable microbial resource for mitigating the adverse effects of heavy metal contamination in agricultural soils on the yield and safety of vegetable crops.

Polyethylene microplastic modulates the toxicity of pentachlorophenol to the microalgae Isochrysis galbana, clone t-ISO

Pentachlorophenol (PCP) and polyethylene microplastic (PE-MP) have been designated as emerging and persistent pollutants, respectively. The combined effects of those pollutants are still unknown, especially to organisms like phytoplankton that may adsorb to their surface. Therefore, the purpose of this study was to investigate for the first time the effects of PE-MP alone and in combination with PCP on the microalgae Isochrysis galbana, clone t-ISO following 72 h of exposure. Photosynthetic pigments amounts, carotenoid, protein, carbohydrate and fatty acids have been assessed. Acute toxicity test showed that the 72 h median inhibition concentration (72 h-EC50) was 148.2, 0.66 and 087 mg L−1 for PE-MP, PCP and their mixture. The utmost effects in growth inhibition rates were noted with 0.5 and 1.25 mg L−1 PCP (23% and 85%, respectively), and 100 and 300 mg L−1 PE-MP (49% and 64%, respectively). Moreover, it was found that those concentrations had a major impact on the photosynthetic pigments, protein, carbohydrate, and fatty acids amounts in algal cells. Furthermore, levels of H2O2 and Malondialdehyde (MDA), as well as the activities of catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX), indicated the induction of an oxidative stress in algal cells. It appears that adding PE-MP at a no-effect concentration (25 mg L−1) reduces the toxicity caused by PCP due to its adsorption to polyethylene microplastics.

Copper sulfate-induced stress in Spinach: Metabolic pathway disruption and plant response

Copper sulfate (CuSO4) stress profoundly affects plant growth by interfering with key metabolic pathways. This disruption leads to significant alterations in various physiological parameters, ultimately impacting the overall health and productivity of the plant. This study assessed the impact of CuSO4 stress on spinach (Spinacia oleracea L.) through a pot experiment using CuSO4 concentrations of 0, 75, 125, and 175 ppm. We noticed that at 75 ppm, CuSO4 improved plant height and the concentration of soluble sugar and ascorbic acid compared to the control. Additionally, amino acid, phenol, proline, fresh weight, and moisture content peaked at 175 ppm. Conversely, at 125 and 175 ppm, plant height, dry weight, leaf area, and concentrations of ascorbic acid and sugar significantly decreased. Moreover, at 175 ppm, there were substantial decreases in chlorophyll a (14.8%), chlorophyll b (73.6%), carotenoids (15%), and photosynthetic rates compared to the control. However, the chlorophyll a to chlorophyll b ratio increased by 29.53% at 175 ppm. In addition, protein and phenol contents diminished at 75 and 125 ppm. Elevated CuSO4 levels increased non-protein thiol levels while reducing the activities of superoxide dismutase, catalase, ascorbate peroxidase, and glutathione peroxidase. Stress hormones such as abscisic acid, jasmonic acid, and ethylene increased with CuSO4 stress, whereas growth hormones indol-acetic acid and gibberellic acid declined. This study demonstrates that spinach shows improved growth and metabolic function at 75 ppm CuSO4, indicating tolerance to mild stress. However, higher CuSO4 concentrations (125 and 175 ppm) significantly reduce growth parameters, chlorophyll content, and enzyme activities, highlighting the need for careful CuSO4 management in agriculture to avoid adverse effects on plant health and productivity.

Unlocking the potential of green synthesis: biogenic silver nanoparticles enhance biomass and bioactive chemicals in Ricinus communis Callus

Harnessing the power of nature, this study delves into the remarkable influence of biosynthesized silver nanoparticles (AgNPs) on biomass production and bioactive chemical synthesis in Ricinus communis callus. Leveraging the eco-friendly properties of Calligonum comosum leaf aqueous extract as both reducing and capping agents, the synthesis of AgNPs was meticulously characterized through an array of analytical techniques, including FTIR, UV-vis spectroscopy, XRD, SEM, TEM, and EDS, confirming the triumphant creation of biogenic AgNPs. Unveiling a landscape of possibilities, the assessment of R. communis biomass and phytochemical substances unraveled intriguing insights. Results unveiled a resounding enhancement in biomass production upon the introduction of biosynthesized AgNPs to the plant media. Noteworthy is the revelation that increasing concentrations of silver NPs acted as catalysts for heightened plant growth and enriched physiological parameters. Moreover, the application of silver nitride elicited a profound amplification in both biomass and antioxidant enzyme activities within plant cells. However, amidst these triumphs, a curious observation emerged: the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) exhibited a notable decline with escalating doses of AgNPs. In essence, this groundbreaking study not only underscores the potential of biosynthesized AgNPs to orchestrate a symphony of growth and biochemical synthesis within R. communis callus but also beckons forth an era of exploration. By charting a course for future research, it beckons scientists to delve deeper into the intricate pathways of phytochemical production and bioactive molecule synthesis under the influence of AgNPs.

Effect of lead on photosynthetic pigments, antioxidant responses, metabolomics, thalli morphology and cell ultrastructure of Iridaea cordata (Rhodophyta) from Antarctica

Over the past decades, the concern about lead pollution in marine environments has increased due to its remarkable toxicity, even at low concentrations. Lead is one of the significant contaminants arising from human activities in Antarctica. However, its effects on polar photosynthetic organisms are poorly known. This work aims to evaluate the effects of two different environmental concentrations of lead (10 μg/L and 50 μg/L) on pigment content, antioxidant enzyme activities (catalase, superoxide dismutase, ascorbate peroxidase and glutathione–S–transferase), metabolome, thalli morphology and cell ultrastructure of the red seaweed Iridaea cordata (Turner) Bory from Terra Nova Bay (Ross Sea, Antarctica). The results highlighted that lead exposure decreased phycocyanin and phycoerythrin content, starting from 10 μg/L, while induced carotenoid accumulation at 50 μg/L. Catalase, ascorbate peroxidase, and superoxide dismutase activities generally increased after lead exposure and distinct biochemical features were identified in the control and treatment groups. Further lead–related effects on cell ultrastructure comprised floridean starch accumulation and plastoglobuli formation. Overall, our results suggested that the enhanced formation of reactive oxygen species in response to lead altered the photosynthetic pigment pattern, antioxidant defenses, metabolome and ultrastructure of I. cordata.

Zinc oxide nanoparticles at low dose mitigate lead toxicity in pea (Pisum sativum L.) seeds during germination by modulating metabolic and cellular defense systems

Addressing lead (Pb) pollution and contamination in soil and agriculture is urgent due to its widespread and long-lasting impacts on human health, food safety, and the environment. In the current study, we assessed the potential use of Zinc oxide nanoparticles (ZnONPs) in alleviating Pb toxicity in germinating seedlings. Pea (Pisum sativum L.) seedlings were exposed to Pb (83 mg/L) over a 7-day period, without and with ZnONPs amendment. Our results showed that the application of ZnONPs at 10 mg/L restored the morphological parameters affected by Pb, 34 %, 26 % and 23 %, for the length, fresh, and dry biomass of embryonic axis, respectively. ZnONPs decreased the activities of antioxidative enzymes of catalase (87.5 %), guaiacol peroxidase (60 %), and glutathione peroxidase (25 %), but increased the activities of ascorbate peroxidase (60 %) and glutathione reductase (25 %). These changes were associated with the increase (7 %) in the thiol groups, and reductions in the malondialdehyde (23 %), hydrogen peroxide (33 %), and carbonyl group levels (78 %), in addition to the stimulation of the activities of ROS-associated enzymes, including glycolate oxidase (40 %) and NADPH oxidase (by 89 %). Consequently, cell viability was increased by 66 %, while cellular death was reduced by 10 %, with ZnONPs, relative to the Pb-stressed seedlings. These findings highlight the mechanisms surrounding the ability of nanosized ZnO to mitigate the harmful effects of Pb on the growth and physiology of plants. Further investigation is needed to understand the mitigating effects of ZnONPs on Pb on the molecular and genomic levels in seedlings and plants, and ensure the sustainability of agricultural practices and food safety. Besides, site and source-specific integrated approaches must be practiced to formulate suitable remediation strategies.

Carvacrol enhances antioxidant activity and slows down cell wall metabolism by maintaining the energy level of 'Guifei' mango.

Postharvest mango fruit are highly susceptible to rapid ripening, softening and senescence, greatly limiting their distribution. In this study, we evaluated the potential effects of carvacrol (0.06 g L-1) on mango (25 ± 1 °C) and the mechanisms by which it regulates antioxidant activity, energy and cell wall metabolism. The results showed that carvacrol treatment delayed the 'Guifei' mango color transformation (from green to yellow) and the decrease in firmness, titratable acidity, weight loss and soluble solids content, and suppressed the increase in relative conductivity, malondialdehyde content and reactive oxygen species (H2O2 and O2 ·-) as well as enhancing antioxidant activity. In addition, carvacrol treatment increased ascorbic acid and reduced glutathione levels, ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase and dehydroascorbate reductase activities in mango. Meanwhile, energy level (adenosine triphosphate, adenosine diphosphate, adenosine monophosphate and energy charge) content and energy metabolizing enzyme activities (H+-ATPase, Ca2+-ATPase, succinate dehydrogenasepears and cytochrome C oxidase) were increased on carvacrol treatment, which resulted in the maintenance of higher energy levels. Finally, the application of carvacrol was effective in maintaining firmness and cell wall components by inhibiting the activities of polygalacturonase, cellulase, pectin methyl esterase and β-galactosidase. The current study demonstrates that carvacrol effectively delays the ripening and softening of mangoes by modulating energy metabolism and cell wall dynamics through the attenuation of oxidative stress. © 2024 Society of Chemical Industry.

Exogenous hydrogen sulfide increased Nicotiana tabacum L. resistance against drought by the improved photosynthesis and antioxidant system

Drought stress is an abiotic stressor that impacts photosynthesis, plant growth, and development, leading to decreased crop yields. Sodium hydrosulfide (NaHS), an exogenous additive, has demonstrated potential regulatory effects on plant responses to polyethylene glycol-induced drought stress in tobacco seedlings. Compared to the control, drought stress induced by 15 g/L PEG-6000 significantly reduced several parameters in tobacco seedlings: shoot dry weight (22.83%), net photosynthesis (37.55%), stomatal conductance (33.56%), maximum quantum yield of PSII (Fv/Fm) (11.31%), photochemical quantum yield of PSII (ΦPSII) (25.51%), and photochemical quenching (qP) (18.17%). However, applying NaHS, an H2S donor, mitigated these effects, ultimately enhancing photosynthetic performance in tobacco seedlings. Furthermore, optimal NaHS concentration (0.4 mM) effectively increased leaf stomatal aperture, relative water content (RWC) and root activity, as well as facilitated the absorption of N, K, Mg and S. It also enhanced the accumulation of soluble sugar and proline content to maintain osmotic pressure balance under drought stress. Compared to drought alone, pretreatment with NaHS also bolstered the antioxidant defense system in leaves, leading to 22.93% decrease in hydrogen peroxide (H2O2) content, a 22.19% decrease in malondialdehyde (MDA) content and increased activities of ascorbate peroxidase (APX) by 28.13%, superoxide dismutase (SOD) by 17.07%, peroxidase (POD) by 46.99%, and catalase (CAT) by 65.27%. Consequently, NaHS protected chloroplast structure and attenuated chlorophyll degradation, thus mitigating severe oxidative damage. Moreover, NaHS elevated endogenous H2S levels, influencing abscisic acid (ABA) synthesis and the expression of receptor-related genes, collaboratively participating in the response to drought stress. Overall, our findings provide valuable insights into exogenous NaHS’s role in enhancing tobacco drought tolerance. These results lay the foundation for further research utilizing H2S-based treatments to improve crop resilience to water deficit conditions.

Enhancing cold tolerance in tobacco through endophytic symbiosis with Piriformospora indica.

Tobacco, a warm-season crop originating from the Americas, is highly susceptible to cold stress. The utilization of symbiotic fungi as a means to bolster crops' resilience against abiotic stresses has been proven to be a potent strategy. In this study, we investigated the effect of endophytic fungus Piriformospora indica on the cold resistance of tobacco. When exposed to cold stress, the colonization of P.indica in tobacco roots effectively stimulates the activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX). This, in turn, reduces the accumulation of reactive oxygen species (ROS), thereby mitigating oxidative damage. Additionally, P. indica elevates the levels of osmolytes, such as soluble sugars, proline, and soluble proteins, thus facilitating the restoration of osmotic balance. Under cold stress conditions, P. indica also induces the expression of cold-responsive genes. Furthermore, this fungus not only enhances photosynthesis in tobacco by stimulating the synthesis of photosynthetic pigments, strengthening Rubisco activity, and elevating PSII efficiency, but also fortifies tobacco's nitrogen assimilation by inducing the expression of nitrate transporter gene and activating enzymes related to nitrogen assimilation. Consequently, this synergistic optimization of nitrogen and carbon assimilation provides a solid material and energetic foundation for tobacco plants to withstand cold stress. Our study demonstrates that a mycorrhizal association between P. indica and tobacco seedlings provides multifaceted protection to tobacco plants against low-temperature stress and offers a valuable insight into how P. indica enhances the cold tolerance of tobacco.

Morphophysiological, biochemical, and nutrient response of spinach (Spinacia oleracea L.) by foliar CeO2 nanoparticles under elevated CO2

Nanomaterials offer considerable benefits in improving plant growth and nutritional status owing to their inherent stability, and efficiency in essential nutrient absorption and delivery. Cerium oxide nanoparticles (CeO2 NPs) at optimum concentration could significantly influence plant morpho-physiology and nutritional status. However, it remains unclear how elevated CO2 and CeO2 NPs interactively affect plant growth and quality. Accordingly, the ultimate goal was to reveal whether CeO2 NPs could alter the impact of elevated CO2 on the nutrient composition of spinach. For this purpose, spinach plant morpho-physiological, biochemical traits, and nutritional contents were evaluated. Spinach was exposed to different foliar concentrations of CeO2 NPs (0, 25, 50, 100 mg/L) in open-top chambers (400 and 600 CO2 μmol/mol). Results showed that elevated CO2 enhanced spinach growth by increasing photosynthetic pigments, as evidenced by a higher photosynthetic rate (Pn). However, the maximum growth and photosynthetic pigments were observed at the highest concentration of CeO2 NPs (100 mg/L) under elevated CO2. Elevated CO2 resulted in a decreased stomatal conductance (gs) and transpiration rate (Tr), whereas CeO2 NPs enhanced these parameters. No significant changes were observed in any of the measured biochemical parameters due to increased levels of CO2. However, an increase in antioxidant enzymes, particularly in catalase (CAT; 14.37%) and ascorbate peroxidase (APX; 10.66%) activities, was observed in high CeO2 NPs (100 mg/L) treatment under elevated CO2 levels. Regarding plant nutrient content, elevated CO2 significantly decreases spinach roots and leaves macro and micronutrients as compared to ambient CO2 levels. CeO2 NPs, in a dose-dependent manner, with the highest increase observed in 100 mg/L CeO2 NPs treatment and increased roots and shoots magnesium (211.62–215.49%), iron (256.68–322.77%), zinc (225.89–181.49%), copper (21.99–138.09%), potassium (121.46–138.89%), calcium (118.22–91.32%), manganese (133.15–195.02%) under elevated CO2. Overall, CeO2 NPs improved spinach growth and biomass and reverted the adverse effects of elevated CO2 on its nutritional quality. These findings indicated that CeO2 NPs could be used as an effective approach to increase vegetable growth and nutritional values to ensure food security under future climatic conditions.

Assessment of quality and antioxidant capacity of peach in response to different UV-C dose irradiation.

The effects of different doses of UV-C irradiation (0, 0.5, 1.0, 2.0, and 4.0kJ m-2) on the quality and antioxidant capacity of peach fruit were examined. Results showed that irradiation at 2.0kJ m-2 led to higher firmness and total soluble solids, as well as lower weight loss and decay index. Additionally, peach fruits irradiated with 2.0kJ m-2 UV-C exhibited increased production of reactive oxygen species, which in turn stimulated the synthesis of total phenolics and total flavonoids and enhanced the activities of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase. Overall, the best abiotic stress effect was observed with 2.0kJ m-2 UV-C irradiation, resulting in improved shelf quality and increased antioxidant capacity of peach fruits during storage. PRACTICAL APPLICATION: This study provides a theoretical basis for the application of UV-C irradiation in peach fruit preservation.

Bacillus endophytic strains control Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici in tomato cv. Perinha.

Fusarium wilt is one of main phytopathology attacking tomato (Solanum lycopersicum L.) plantations in Brazil. Plant rhizosphere and endophytic beneficial microorganism are well known as plant growth promoters and biocontrol agents. The present study aims to evaluate the potential of different Bacillus strains as biocontrol agent to Fusarium oxysporum f. sp. lycopersici Race 3 strains; and also as plant growth promoting bacteria on Solanum lycopersicum cv Perinha. Different in vitro and greenhouse experiments were carried out to evaluate the direct and indirect bacterial-fungus antagonism, and they inoculation effects on plant traits. In vitro direct, metabolites, and volatile antagonism analysis demonstrated that B. toyonensis BR 10491(FORT 02) presented a broad antagonism to all tested race 3 FOL strains while B. megaterium BR 10466 (FORT 12), B. aryabhattai BR 10494 (FORT 25), B. stratosphericus BR 10438 (FORT 29) and B. cereus BR 10493 (FORT 113.1) strains showed significant antagonistic activity for at least two applied methods. Greenhouse pot experiments demonstrated a significant BCA effect of FORT 113.1 and FORT 02 against FOL Race 3 Fus 1302 strain during different tomato development stages (seedling, vegetative, and reproductive). Bacillus cereus (FORT 113.1) showed significantly higher shoot and height fresh weight, Chlorophyll a and Chlorophyll b content, stomata conductance, water use efficiency, and also a lower xylem infection percentage during vegetative and reproductive stages. Antioxidant enzymatic components analysis demonstrated a synergic effect of Fusarium and Bacillus inoculation, leading to a higher superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activity. In conclusion, the results suggest that strain FORT113.1 could be considered as a good candidate for production of new biofungicide with high potential to augment the existing biocontrol strategies.

Organic matter-induced physiological responses and modulation of the enzymatic system in Sorghum bicolor (L) Moench genotypes cultivated in saline soil

Sorghum bicolor (L.) Moench is a crop with numerous applications that serves as a food source for humans and animals. However, soils with high salt concentrations compromise the initial development of the crop, and the addition of organic matter can mitigate the damage caused by salinity. The present study aimed to verify the effect of organic matter on salinity on the physiology and enzymatic profiles of two sorghum varieties, BRS Ponta Negra and BRS 373. The experiment was conducted in a completely randomized design (DIC) in a 4 x 4 x 2 arrangement, using different doses of organic matter as recommended (100%, 200%, 300%, and 400%) and the two sorghum varieties, with 4 replications. The variables analysed were: photosynthetic rate (A), transpiration (E), stomatal conductance (Gs), and enzymatic activity of ascorbate peroxidase (APX), polyphenoloxidase (POL), and catalase (CAT). The results showed that the A, E, and Gs responded differently to different doses of organic matter (OM); these responses were influenced by the isolated effects of the varieties or doses of organic matter, and their behaviour differed between the two analysed varieties. The A, E, and Gs showed contrasting response patterns between different doses of OM in variety 1 (BRS Ponta Negra) and variety 2 (BRS 373). These responses were influenced by the isolated effects of the varieties and/or doses of organic matter, showing different behaviours among the tested varieties.

Physiological and Microstructure Analysis Reveals the Mechanism by Which Formic Acid Delays Postharvest Physiological Deterioration of Cassava.

Formic acid is reported to act as a food preservative and feed additive, but its effects on controlling postharvest physiological deterioration (PPD) development in cassava are unclear. In this study, we assessed the effectiveness of different concentrations of formic acid in attenuating PPD occurrence in fresh-cut cassava. The results showed that the concentration of 0.1% (v/v) formic acid could significantly delay the occurrence of PPD, and that the higher the concentration of formic acid supplied, the later the occurrence of PPD symptoms. The physiological and biochemical analysis of 0.5%-formic-acid-treated cassava slices revealed that formic acid decreased the degradation of starch, inhibited the accumulation of hydrogen peroxide (H2O2), malondialdehyde (MDA), and water-soluble pectin in cassava slices with PPD development, and increased the activities of the antioxidant enzymes ascorbate peroxidase (APX) and glutathione reductase (GR). A microscopic observation showed that the formic acid treatment inhibited the enlargement of the intercellular space during the cassava PPD process, which suggests that the formation of an intercellular layer of the cell wall was inhibited by formic acid. This study thus revealed the mechanism used by formic acid to extend the cassava shelf life; however, a detailed evaluation of the possible side effects on, for example, the cyanide content will be needed to categorically ensure the safety of this method.