APX Activity Research Articles

Activation of the antioxidant system and transduction of the mediated by exogenous calcium improve drought resistance in tobacco

Drought stress is one of the most important stresses in plants. The important role of calcium signal as a second messenger in alleviating drought stress is still unclear. We used tobacco as test material to simulate drought stress with 20 % PEG concentration. Physiological and transcriptome techniques were used to study how the model plant tobacco protects itself from drought stress by examining the mechanism used by exogenous calcium ions to respond to the antioxidant and hormone signals that indicate drought stress. Exogenous calcium was shown to increase the levels of expression of the proteins CDPK, CBL/CIPK and AQPs that respond to signaling by calcium under drought stress. The cis-acting elements of the promoters of the genes related to signals primarily focused on hormone and drought-related elements, which suggests that the exogenous calcium may mediate the transduction of hormone signals in response to drought stress. The results of physiological and transcriptional data showed that oxidative damage occurred in the tobacco leaves under drought stress. Under drought stress, exogenous calcium can enhance the activities of SOD (4.75 %), POD (42.33 %) and APX (512.43 %), up-regulate the expression of the genes that encode antioxidant enzymes to eliminate excessive reactive oxygen species (ROS), and alleviate the oxidative damage to tobacco leaves under drought stress. The calcium produced during drought stress increased the content of auxin (IAA), decreased that of abscisic acid (ABA) and downstream gene expression, and prevented excessive amplification of the ABA signal. Exogenous calcium enhanced the crosstalk between cytokinin, gibberellin and ABA signals.In summary, exogenous calcium can stimulate the synergistic effect of calcium and hormone signals and the antioxidant system, eliminate ROS, improve the crosstalk between plant hormones, and improve the drought resistance of tobacco.

Slightly acidic electrolyzed water treatment enhances the quality attributes and the storability of postharvest litchis through regulating the metabolism of reactive oxygen species

Effects of slightly acidic electrolyzed water (SAEW) on the storability, quality attributes, and reactive oxygen species (ROS) metabolism of litchis were investigated. Results showed that SAEW-treated litchis presented better quality attributes and storability than control litchis. On storage day 5, the commercially acceptable fruit rate of control litchis was 42%, while SAEW-treated litchis displayed 59% higher rate of commercially acceptable fruit, 21% lower pericarp browning index, and 13% lower weight loss percentage than control litchis. Additionally, compared to control litchis, SAEW-treated litchis demonstrated higher activities of SOD, CAT and APX, higher levels of GSH, AsA, DPPH radical scavenging ability, and reducing power, but lower O2−· generation rate, lower levels of H2O2 and MDA. These findings indicated that SAEW treatment could elevate antioxidant capacity and ROS scavenging ability, reduce ROS production and accumulation, and lower membrane lipid peroxidation, thereby retaining the quality attributes and storability of litchis.

Triacontanol ‘TRIA’ application to mitigate the adverse effects of drought and salinity stress under in vitro culture of date palm plants

Abstract This study was conducted to attempt adaptation to combined drought and salt stresses (DS) (PEG- 6000 + NaCl) in date palm cv. Barhee implanted in vitro, keeping in mind the detrimental influence of DS. In vitro experimentation was executed on P. dactylifera L. to examine the efficacy of the application of triacontanol (TRIA), on growth attributes, and some biochemical constituents under DS. The optimal treatment was 10 µg l–1 TRIA. Such treatment under DS improved the callus growth and increased its weight to 215.0 mg. This treatment also showed the highest response rate and the number of shoots per jar (72.23% and 10.30 shoots, respectively) under DS stress. TRIA enhanced DS tolerance by increasing the contents of osmoregulatory substances such as proline, total soluble carbohydrates, and total soluble proteins, were obtained by adding 20 and 10 mg l–1 TRIA. This treatment was also more effective under DS in increasing Ca2+, Mg2+, and K+, as well as Fe2+, and chlorophyll pigment. These results also indicate that using 10 µg l–1 TRIA as a supplement under DS can increase SOD, APX, and PAL activity, to 31.68, 3.377 unit g–1 min–1, and 33.78%, respectively. Data analysis also indicated that the application of 10 µg l–1 TRIA countered the DS-induced harmful effects by reducing the content of malondialdehyd (MDA) and H2O2 in stressed tissues to 1.06, and 1.278 μMg of fresh weight (FW). Our work could reveal detailed changes in the quantity and number of protein bands by SDS-PAGE. New protein bands appeared in both stressed with TRIA-treated plants. The result of the present study will be useful for rapid clonal propagation of date palm which can be used to enhance the tolerance of plants to drought and salt stress.

BcSRC2 interacts with BcAPX4 to increase ascorbic acid content for responding ABA signaling and drought stress in pak choi

Abstract As a reducing substance, ascorbic acid functioned well in abiotic and biotic stress. However, the regulatory mechanism of drought resistance is rarely known in pak choi. Here we found a gene BcSRC2 containing a C2 domain that responds to ABA signal and drought regulation in pak choi. Silencing of BcSRC2 reduces ascorbic acid content and drought resistance of pak choi. In Arabidopsis, BcSRC2 overexpression promotes ascorbic acid accumulation and increases drought tolerance. Meanwhile, transcriptome analysis between WT and BcSRC2-overexpressing pak choi suggests that ascorbic acid-related genes are regulated. BcSRC2 interacts with BcAPX4 and inhibit APX activity in vitro and in vivo, increasing the ascorbic acid content. We also found that drought stress increases ABA content, which reduces the expression of BcMYB30. BcMYB30 bound to the promoter of BcSRC2 and reduced its expression. Overall, our results suggest that a regulatory module, BcMYB30-BcSRC2-BcAPX4, plays a central role in increasing ascorbic acid content for responding ABA-mediated drought regulation in pak choi.

Selenium and its nanoparticles modulate the metabolism of reactive oxygen species and morpho-physiology of wheat (Triticum aestivum L.) to combat oxidative stress under water deficit conditions

BackgroundWheat (Triticum aestivum L.) is one of the most important cereal crop species worldwide, but its growth and development are adversely influenced by drought stress. However, the application of trace elements is known to improve plant physiology under water-limited conditions. In this study, the effects of drought stress on wheat plants were investigated, with a focus on potential mitigation by foliar application of selenium nanoparticles (Se(np)) and sodium selenate (Na2SeO4). The experiment was conducted in a net house using a completely randomized design with four replications. The treatments involved three levels of drought stress (mild, moderate, and severe) started at 30 days after sowing (DAS), with foliar sprays of Se(np) and Se (both 25 µM) initiated at 27 DAS and repeated 4 times at 7-day intervals until 55 DAS.ResultsDrought stress significantly reduced plant growth, whereas Se(np) and Se sprays enhanced it. Drought stress induced chlorophyll degradation, increased malondialdehyde and hydrogen peroxide levels, impaired membrane stability, and caused electrolyte leakage. Severe drought stress reduced the levels of antioxidants (e.g., proline, ascorbate, and glutathione by 4.18-fold, 80%, and 45%) and the activities of antioxidant enzymes (ascorbate peroxidase, dehydroascorbate reductase, and others). Conversely, treatment with Se(np) and Se restored these parameters, for example, 1.23-fold higher total chlorophyll content with Se(np) treatment, 26% higher APX activity with Se treatment, 15% lower electrolyte leakage with Se treatment in wheat plants under severe drought stress. This Se-associated enhancement facilitated rapid scavenging of reactive oxygen species and reduced methylglyoxal toxicity, thereby diminishing oxidative stress and positively affecting the morphophysiological and biochemical responses of the plants under drought.ConclusionsDrought-stressed wheat plants exhibited reductions in physiological processes, including water uptake and photosynthetic activity. However, Se(np) and Se applied at 25 µM mitigated the detrimental effects of drought. The application of Se(np) was notably more effective than the application of Se in mitigating drought stress, indicating the potential of the application of Se(np) as a sustainable agricultural practice under water-limited conditions.

The effect of exogenous melatonin on waterlogging stress in Clematis.

Clematis is the queen of the vines, being an ornamental plant with high economic value. Waterlogging stress reduces the ornamental value of the plant and limits its application. Melatonin plays an important role in plant resistance to abiotic stresses. In this study, the physiological responses and gene expression levels of two wild species, namely, Clematis tientaiensis and Clematis lanuginosa, and two horticultural varieties, namely, 'Sen-No-Kaze' and 'Viva Polonia,' under waterlogging stress were analyzed to determine the effect of melatonin on waterlogging tolerance. The results showed that the waterlogging tolerances of C. lanuginosa and 'Sen-No-Kaze' were relatively poor, but were significantly improved by concentrations of 100 μmol·L-1 and 50 μmol·L-1 melatonin. C. tientaiensis and 'Viva Polonia' had relatively strong tolerance to waterlogging, and this was significantly improved by 200 μmol·L-1 melatonin. Under waterlogging stress, the relative conductivity and H2O2 content of Clematis increased significantly; the photosynthetic parameters and chlorophyll contents were significantly decreased; photosynthesis was inhibited; the contents of soluble protein and soluble sugars were decreased. Effective improvement of waterlogging tolerance after exogenous melatonin spraying, the relative conductivity was decreased by 4.05%-27.44%; the H2O2 content was decreased by 3.84%-23.28%; the chlorophyll content was increased by 35.59%-103.36%; the photosynthetic efficiency was increased by 25.42%-45.86%; the antioxidant enzyme activities of APX, POD, SOD, and CAT were increased by 28.03%-158.61%; the contents of proline, soluble protein, and soluble sugars were enhanced, and cell homeostasis was improved. Transcription sequencing was performed on wild Clematis with differences in waterlogging tolerance, and nine transcription factors were selected that were highly correlated with melatonin and that had the potential to improve waterlogging tolerance, among which LBD4, and MYB4 were significantly positively correlated with the antioxidant enzyme system, and bHLH36, DOF36, and WRKY4 were significantly negatively correlated. Photosynthetic capacity was positively correlated with DOF36 and WRKY4 while being significantly negatively correlated with MYB4, MOF1, DOF47, REV1 and ABR1. Melatonin could enhance the flooding tolerance of Clematis by improving photosynthetic efficiency and antioxidant enzyme activity. This study provides an important basis and reference for the application of melatonin in waterlogging-resistant breeding of Clematis.

Interaction between acid-tolerant alga Graesiella sp. MA1 and schwertmannite under long-term acidic condition

Schwertmannite (Sch), a typical Fe(III)-oxyhydroxysulphate mineral, is the precipitation reservoir of toxic elements in acid mine drainage (AMD). Acid-tolerant microbes in AMD can participate in the microbe-mediated transformation of Sch, while Sch affects the physiological characteristics of these acid-tolerant microbes. Based on our discovery of algae and Sch enrichment in a contaminated acid mine pit lake, we predicted the interaction between algae and Sch when incubated together. The acid-tolerant alga Graesiella sp. MA1 was isolated from the pit-lake surface water of an acidic mine and incubated with different contents of Sch. Sch was detected as the main product at the end of 81 d; however, there was a weak transformation. The presence of dissolved Fe(II) could be largely attributed to the photoreduction dissolution of Sch, which was promoted by Graesiella sp. MA1. The adaptation and growth phases of Graesiella sp. MA1 differed under Sch stress. The photosynthetic and metabolic activities increased and decreased at the adaptation and growth phases, respectively. The MDA contents and antioxidant activity of SOD, APX, and GSH in algal cells gradually enhanced as the Sch treatment content increased, indicating a defense strategy of Graesiella sp. MA1. Metabolomic analysis revealed that Sch affected the expression of significant differential metabolites in Graesiella sp. MA1. Organic carboxylic acid substances were essentially up-regulated in response to Sch stress. They were abundant in the medium-Sch system with the highest Fe(III) reduction, capable of complexing Fe(III), and underwent photochemical reactions via photo-induced charge transfer. The significant up-regulation of reducing sugars revealed the high energy requirement of Graesiella sp. MA1 under Sch stress. And first enriched KEGG pathway demonstrated the importance of sugar metabolism in Graesiella sp. MA1. Data acquired in this study provide novel insights into extreme acid stress adaptation of acid-tolerant algae and Sch, contributing to furthering understanding of AMD environments.

The influence of prolonged but low intensity blue light on the physiological properties of root tubers and the accumulation of flavonoids in Tetrastigma hemsleyanum Diels et Gilg

Tetrastigma hemsleyanum Diel et Gilg is a perennial herbaceous plant native to subtropical China with multiple medicinal applications. Supplementing with low-density blue light (BL) for 45 days (3 h/day) can not only significantly increase the yields of root tubers but also significantly increase the flavonoid content and its antioxidant activity. The chlorophyll content in the leaves of T. hemsleyanum significantly decreased, but the photosynthetic efficiency significantly increased after reaching the light saturation point. The production rate of superoxide anion radical in the leaves reached the highest peak after 1.5 h in BL and decreased at 3 h. The H2O2 content in the leaves decreased significantly, while the H2O2 content in the root tubers increased significantly at 3 h in BL. The objective of this research was to determine how the scavenging system, including antioxidant enzymes, antioxidants, and flavonoids respond to the oxidative stress induced by BL in root tubers. After exposure to BL, significant differences in the activity of APX and SOD were observed in the leaves and tubers within 3 h. By analyzing the upregulated flavonoids metabolites and key genes in metabolic pathways through the combined analysis of the flavonoid metabolic group and transcriptome in the root tubers, the upregulated accumulation of flavanols was found to be the main reason for the improvement in the antioxidant properties of flavonoids.

Xanthan gum-based edible coating effectively preserve postharvest quality of ‘Gola’ guava fruits by regulating physiological and biochemical processes

BackgroundGuava is a fruit prone to rapid spoilage following harvest, attributed to continuous and swift physicochemical transformations, leading to substantial postharvest losses. This study explored the efficacy of xanthan gum (XG) coatings applied at various concentrations (0.25, 0.5, and 0.75%) on guava fruits (Gola cultivar) over a 15-day storage period.ResultsThe results indicated that XG coatings, particularly at 0.75%, substantially mitigated moisture loss and decay, presenting an optimal concentration. The coated fruits exhibited a modified total soluble soluble solids, an increased total titratable acidity, and an enhanced sugar-acid ratio, collectively enhancing overall quality. Furthermore, the XG coatings demonstrated the remarkable ability to preserve bioactive compounds, such as total phenolics, flavonoids, and antioxidants, while minimizing the levels of oxidative stress markers, such as electrolyte leakage, malondialdehyde, and H2O2. The coatings also influenced cell wall components, maintaining levels of hemicellulose, cellulose, and protopectin while reducing water-soluble pectin. Quantitative analysis of ROS-scavenging enzymes, including superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase, revealed significant increases in their activities in the XG-coated fruits compared to those in the control fruits. Specifically, on day 15, the 0.75% XG coating demonstrated the highest SOD and CAT activities while minimizing the reduction in APX activity. Moreover, XG coatings mitigated the activities of fruit-softening enzymes, including pectin methylesterase, polygalacturonase, and cellulase.ConclusionsThis study concludes that XG coatings play a crucial role in preserving postharvest quality of guava fruits by regulating various physiological and biochemical processes. These findings offer valuable insights into the potential application of XG as a natural coating to extend the shelf life and maintain the quality of guava fruits during storage.

Combined application of zinc oxide and iron nanoparticles enhanced Red Sails lettuce growth and antioxidants enzymes activities while reducing the chromium uptake by plants grown in a Cr-contaminated soil

Soil contamination with chromium (Cr) is becoming a primary ecological and health concern, specifically in the Kasur and Sialkot regions of Pakistan. The main objective of the current study was to evaluate the impact of foliar application of zinc oxide nanoparticles (ZnO NPs) (0, 25, 50, 100 mg L−1) and Fe NPs (0, 5, 10, 20 mg L−1) in red sails lettuce plants grown in Cr-contaminated soil. Our results showed that both ZnO and Fe NPs improved plant growth, and photosynthetic attributes by minimizing oxidative stress in lettuce plants through the stimulation of antioxidant enzyme activities. At ZnO NPs (100 mgL−1), dry weights of shoots and roots and fresh weights of shoots and roots were improved by 53%, 58%, 34%, and 45%, respectively, as compared to the respective control plants. The Fe NPs treatment (20 mgL−1) increased the dry weight of shoots and the roots and fresh weights of shoots and roots by 53%, 76%, 42%, and 70%, respectively. Application of both NPs reduced the oxidative stress caused by Cr, as evident by the findings of the current study, i.e., at the ZnO NPs (100 mgL−1) and Fe NPs (20 mgL−1), the EL declined by 32% and 44%, respectively, in comparison with respective control plants. Moreover, Fe and ZnO NPs enhanced the Fe and Zn contents in red sails lettuce plants. Application of ZnO NPs at 100 mg L−1 and Fe NPs at 20 mg L−1, improved the Zn and Fe contents in plant leaves by 86%, and 68%, respectively, as compared to the control plants. This showed that the exogenous application of these NPs helped in Zn and Fe fortification in plants. At similar of concenteration ZnO NPs, CAT and APX activities were improved by 52% and 53%, respectively. Similarly, the POD contents were improved by 17% and 45% at 5 and 10 mg/L of Fe NPs. Furthermore, ZnO and Fe NPs limited the Cr uptake by plants, and the concentration of Cr in the leaves of lettuce was under the threshold limit. The exogenous application of ZnO NPs (100 mg L−1) and Fe NPs (20 mg L−1) reduced the Cr uptake in the leaves of red sails lettuce by 57% and 51%, respectively. In conclusion, ZnO and Fe NPs could be used for the improvement of plant growth and biomass as well as nutrient fortification in stressed environments. These findings not only underscore the efficacy of nanoparticle-assisted phytoremediation but also highlight its broader implications for sustainable agriculture and environmental health. However, future studies on other crops with molecular-level investigations are recommended for the validation of the results.

Essential oils combat Botrytis cinerea in apples: unveiling sugar, vitamin, and antioxidant dynamics

AbstractThis study investigated the effects of individual and combination applications of EOCs against Botrytis Cinerea in apple fruits, with a focus on sugar, vitamin, and antioxidant enzyme dynamics. In protective and curative treatments, sucrose content varied between 18.9 and 87.9 g.L-1, with the “CT” group exhibiting significantly higher sucrose levels (87.9 g.L-1). Glucose content ranged from 6.2 g.L-1 (“CT” and “C + F”) to 35.5 g.L-1 (“T + C + E + F”). Fructose content varied significantly, with the “F + T + C + E” treatment showing the highest (11.4 g.L-1) and the “CT” group the lowest (2.5 g.L-1). Rhamnose content in the curative treatment reached 14.9 g.L-1 (“F + T”) and in the protective treatment, the “C + E + F” group had the highest (3.3 g.L-1). Galactose content ranged from 0.1 to 13.0 g.L-1. Xylose content in curative treatment ranged from 12.1 to 13.6 g.L-1, with the combination “F + T” displaying the highest. In preventive treatment, arabinose content ranged from 0.7 to 3.0 g.L-1, with the “T + C + F” group having the highest. In terms of vitamins, the combination “T + F” showed the highest B1 (25.4 mg.100 g-1) and B2 (24.6 mg.100 g-1) content. Vitamin A, B1, and B2 increased in the “F + T” group, and vitamin C increased in the “F + T + C” group (33.4 mg.100 g-1). The quantification of oxidative stress markers and antioxidant enzymes revealed significant reductions in H2O2, MDA, and proline levels in EOC applications. In preventive treatment, the combination “T + C + E + F” exhibited the most effective improvement in SOD activity (556.5 EU mg-1 ), CAT activity increased significantly in the “T + C + F” group (189.3 EU mg-1), and APX activity saw the highest increase in the “T + C + E + F” group (185.6 EU mg-1). Contrastingly, curative treatments showed higher H2O2, MDA, and proline levels. The most significant decrease in H2O2 level occurred in the “T + C + E + F” group (36.7 nmol.g-1), and a significant decrease in MDA level was noted in the same group. Notable changes were observed in the activities of antioxidant enzymes, with the “F + T + C + E” group displaying the highest SOD activity (440.7 EU mg-1), and the “F + T” group showing the highest GST activity (542.0 EU mg-1). This research provided comprehensive insights into the biochemical responses of apple fruits to EOC treatments, offering potential strategies for effective fungal management in agriculture.

Comparative Transcriptome Analysis Reveals the Protective Role of Melatonin during Salt Stress by Regulating the Photosynthesis and Ascorbic Acid Metabolism Pathways in Brassica campestris.

Salinity stress is a type of abiotic stress which negatively affects the signaling pathways and cellular compartments of plants. Melatonin (MT) has been found to be a bioactive compound that can mitigate these adverse effects, which makes it necessary to understand the function of MT and its role in salt stress. During this study, plants were treated exogenously with 100 µM of MT for 7 days and subjected to 200 mM of salt stress, and samples were collected after 1 and 7 days for different indicators and transcriptome analysis. The results showed that salt reduced chlorophyll contents and damaged the chloroplast structure, which was confirmed by the downregulation of key genes involved in the photosynthesis pathway after transcriptome analysis and qRT-PCR confirmation. Meanwhile, MT increased the chlorophyll contents, reduced the electrolyte leakage, and protected the chloroplast structure during salt stress by upregulating several photosynthesis pathway genes. MT also decreased the H2O2 level and increased the ascorbic acid contents and APX activity by upregulating genes involved in the ascorbic acid pathway during salt stress, as confirmed by the transcriptome and qRT-PCR analyses. Transcriptome profiling also showed that 321 and 441 DEGs were expressed after 1 and 7 days of treatment, respectively. The KEGG enrichment analysis showed that 76 DEGs were involved in the photosynthesis pathway, while 35 DEGs were involved in the ascorbic acid metabolism pathway, respectively. These results suggest that the exogenous application of MT in plants provides important insight into understanding MT-induced stress-responsive mechanisms and protecting Brassica campestris against salt stress by regulating the photosynthesis and ascorbic acid pathway genes.

The Effects of Tillage and the Combined Application of Organic and Inorganic Fertilizers on the Antioxidant Enzyme Activity and Yield of Maize Leaves

The aim of this study was to explore the characteristics of the combined application of organic fertilizer and inorganic fertilizer using different tillage methods to delay the senescence of maize leaves. The yield and activities of GDH, CAT, APX, GR, and GSH enzymes in maize leaves were measured at different growth stages by using two tillage methods, three organic and inorganic combined applications (P1, P2, and P3), and four control treatments. (1) During the growth period, the R + S and R treatments were P1 treatments, with the highest enzyme activities noted for GDH, CAT, APX, GR, and GSH, which were 36.79–103.22% higher than those of CK. (2) The average yield of all R + S treatments was higher than that of R treatments, and the average yield of P1 treatment was the highest under R + S, which was 13,663.79 kg hm−2, which was 6.39%, 7.90%, and 14.67% higher than that of P2, P3, and CK, respectively, which was lower than that of R. The yield of P1 treatment was 2.53% higher. (3) There was a significant positive correlation between APX activity, CAT activity, GR activity, GDH activity, GSH activity, grain number per ear, ear length, and 100-grain weight of maize leaves at the grain filling stage, and a significant negative correlation between bald tip length and yield. The treatment details had the strongest enzyme activity and the highest yield when using the rotary tillage + subsoiling (R + S) P1 method, which was the most suitable tillage method and the best fertilizer ratio combination, which could be demonstrated and popularized in a large area in the dry farming area of spring maize in Shanxi Province.

Dopamine Hydrochloride Alleviates the Salt-induced Stress in Glycine max (L.) Merr. plant

The objective of this study is to evaluate the role of dopamine hydrochloride (DH) in alleviating the detrimental effects of salt stress on Glycine max (L.) plant. Soybean seeds were treated with 150 mM NaCl and DH (100 µM or 200 µM) after they had been grown in plastic pots then the growth parameters, physiological and molecular analyses were assessed. Data showed that salinity stress decreased the germination percentage by 63.6%, the tolerance index (TI) and the seedling vigor index (SVI) were highly decreased. Salinity stress led to a markedly decline in the photosynthetic efficiency and the content of chlorophyll a and chlorophyll b by 43.5%, 77.4% and 44.6%, respectively. Salinity stress increased MDA and activity of CAT, SOD, POD, APX, GST and GR by 150%, 39.8%, 75%, 160%, 77.7%, 50% and 57%, respectively. However, DH (100 µM or 200 µM) significantly alleviated the toxic effects of salinity stress, marinated ions absorption, and enhanced the molecular level. Wherein out of 30 ISSR amplified fragments were formed. There were 10 unique bands (587 bp, 453 bp, 393 bp, 435 bp, 157 bp, 679 bp, 473 bp, 675 bp, 758 bp and 531 bp) were appeared in response to DH (100 µM and 200 µM) compared with untreated plants. Our analysis suggests a constructive effect of DH (100 µM and 200 µM) in alleviating the toxic effects of salinity stress on Glycine max (L.) plant not only at the level of antioxidative defense but also by regulating the molecular response highlighting the potential use of DH to improve the sustainability of horticultural production under climate change.

Effects of Progressive Drought Stress on the Growth, Ornamental Values, and Physiological Properties of Begonia semperflorens

Water is one of the most important elements affecting the growth of ornamental plants. To investigate the effects of drought stress on the growth, ornamental values, and physiological properties of Begonia semperflorens, watering treatments with 250 mL (control check, CK), 200 mL (extremely light drought, ELD), 150 mL (light drought, LD), 100 mL (moderate drought, MD), 50 mL (severe drought, SD), and 25 mL (extremely severe drought, ESD) on the B. semperflorens variety “Chao Ao” were performed in this study. As a result, compared to the control (CK), the number of flowers, leaves, and branches, leaf size, plant height, crown diameter, as well as water content, transpiration rate, net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, and chlorophyll content in leaves decreased, followed by an increased amount of drought stress. The contents of the osmotic adjustment substances, such as soluble sugar, soluble protein, proline, and betaine, were increased under drought stress. Indicators related to antioxidant activities, such as SOD activity, increased and then decreased. The POD activity, CAT activity, MDA content, and plasma membrane permeability of B. semperflorens were higher under increased drought stress than in the control condition. The APX activity decreased and then increased under drought stress. In conclusion, B. semperflorens responds to drought stress by increasing osmotic adjustment substances and antioxidant activities and reducing the water loss, growth potential, and photosynthetic rate. The correlation analysis showed that, except for APX, the drought resistance coefficients of 23 other indexes were correlated in different degrees. Therefore, this study suggests that B. semperflorens has a strong drought resistance ability, retaining high ornamental values in conditions of moderate drought stress, and can still survive under extremely high drought stress.

Differential responses of Hollyhock (Alcea rosea L.) varieties to salt stress in relation to physiological and biochemical parameters

The response of 14 Hollyhock (Alcea rosea L.) varieties to salinity were evaluated in a field experiment over two growing seasons. Carotenoid, Chl a, Chl b, total Chl, proline and MDA content, CAT, APX and GPX activity and petal and seeds yields were determined in order to investigate the mechanism of salt tolerance exhibited by Hollyhock, and too identify salt tolerant varieties. Overall, the photosynthetic pigment content,petal and seed yields were reduced by salt stress. Whereas the proline and MDA content, and the CAT, APX and GPX activities increased as salt levels increased. However, the values of the measured traits were dependent upon the on the level of salt stress, the Varietie and the interaction between the two variables. Based upon the smallest reduction in petal yield, the Masouleh variety was shown to be the most salt tolerant, when grown under severe salt stress. However, based upon the smallest reduction in seed yield, Khorrmabad was the most tolerant variety to severe salt stress. These data suggest that the selection of more salt tolerant Hollyhock genotypes may be possible based upon the wide variation in tolerance to salinity exhibited by the varieties tested.

Populus euphratica PeNADP-ME interacts with PePLDδ to mediate sodium and ROS homeostasis under salinity stress

Populus euphratica phospholipase Dδ (PePLDδ) is transcriptionally regulated and mediates reactive oxygen species (ROS) and ion homeostasis under saline conditions. The purpose of this study is to explore the post-transcriptional regulation of PePLDδ in response to salt environment. P. euphratica PePLDδ was shown to interact with the NADP-dependent malic enzyme (NADP-ME) by screening the yeast two-hybrid libraries. The transcription level of PeNADP-ME increased upon salt exposure to NaCl (200 mM) in leaves and roots of P. euphratica. PeNADP-ME had a similar subcellular location with PePLDδ in the cytoplasm, and the interaction between PeNADP-ME and PePLDδ was further verified by GST pull-down and yeast two-hybrid. To clarify whether PeNADP-ME interacts with PePLDδ to enhance salt tolerance, PePLDδ and PeNADP-ME were overexpressed singly or doubly in Arabidopsis thaliana. Dual overexpression of PeNADP-ME and PePLDδ resulted in an even more pronounced improvement in salt tolerance compared with single transformants overexpressing PeNADP-ME or PePLDδ alone. Greater Na+ limitation and Na+ efflux in roots were observed in doubly overexpressed plants compared with singly overexpressed plants with PeNADP-ME or PePLDδ. Furthermore, NaCl stimulation of SOD, APX, and POD activity and transcription were more remarkable in the doubly overexpressed plants. It is noteworthy that the enzymic activity of NADP-ME and PLD, and total phosphatidic acid (PA) concentrations were significantly higher in the double-overexpressed plants than in the single transformants. We conclude that PeNADP-ME interacts with PePLDδ in Arabidopsis to promote PLD-derived PA signaling, conferring Na+ extrusion and ROS scavenging under salt stress.

Acidic electrolyzed-oxidizing water treatment mitigated the disease progression in Phomopsis longanae Chi-infected longans by modulating ROS and membrane lipid metabolism

Postharvest harmful pathogenic infestation leads to rapid decay in longan fruit. Compared with P. longanae-infected longans, AEOW alleviated fruit disease severity and diminished the O2-. production rate and MDA content. It also increased APX, CAT, and SOD activities, delayed the decrease in the levels of GSH and AsA, as well as the reducing power and DPPH radical scavenging ability, which resulted in a decline in membrane lipid peroxidation in P. longanae-infected longans. Additionally, AEOW reduced LOX, lipase, PI-PLC, PC-PLC, and PLD activities, maintained higher levels of PC, PI, IUFA, USFAs, and U/S, while reducing levels of PA, DAG, SFAs, and CMP. These effects alleviated membrane lipid degradation and peroxidation in P. longanae-infected longans. Consequently, AEOW effectively maintained membrane integrity via improving antioxidant capacity and suppressing membrane lipid peroxidation. This comprehensive coordination of ROS and membrane lipid metabolisms improved fruit resistance and delayed disease development in longans.

Brassinolide as potential rescue agent for Pinellia ternata grown under microplastic condition: Insights into their modulatory role on photosynthesis, redox homeostasis, and AsA-GSH cycling

Microplastic (MP), as a new pollutant, not only affects the growth and development of plants but also may affect the secondary metabolites of plants. The anti-tumor role of Pinellia ternata is related to secondary metabolites. The role of brassinolide (BR) in regulating plant resistance is currently one of the research hotspots. The paper mainly explores the regulation of BR on growth and physiology of Pinellia ternata under MP stress. The experimental design includes two levels of MP (0, 1%) and two levels of BR (0, 0.1 mg/L). MP led to a marked reduction in plant height (15.0%), Fv/Fm (3.2%), SOD and APX activity (15.0%, 5.1%), whereas induced an evident raise in the rate of O2·- production (29.6%) and GSH content (4.4%), as well as flavonoids (6.8%), alkaloids (75%), and β-sitosterol (26.5%) contents. Under MP addition, BR supply significantly increased plant height (15.7%), aboveground and underground biomass (16.1%, 10.3%), carotenoid and GSH content (11.8%, 4.2%), Fv/Fm (2.9%), and activities of SOD, GR, and MDHAR (32.2%, 21.08%, 20.9%). These results indicate that MP suppresses the growth of P. ternata, although it promotes secondary metabolism. BR can alleviate the inhibitory effect of MP on growth by improving photosynthesis, redox homeostasis, and the AsA-GSH cycle.

The regulating mechanism of salt tolerance of black walnut seedlings was revealed by the physiological and biochemical integration analysis

Salt stress is an important abiotic stress that seriously affects plant growth. In order to research the salt tolerance of walnut rootstocks so as to provide scientific basis for screening salt-tolerant walnut rootstocks, two kinds of black walnut seedlings, Juglans microcarpa L. (JM) and Juglans nigra L. (JN), were treated under salt stress with different concentrations of NaCl (0, 50, 100, and 200 mM) and the growth situation of seedlings were observed. The physiological indexes of JM and JN seedlings were also measured in different days after treatment. Our study showed salt stress inhibited seedlings growth and limited biomass accumulation. Walnut mainly increased osmotic adjustment ability by accumulation Pro and SS. Furthermore, with the duration of treatment time increased, SOD and APX activities decreased, TPC and TFC contents increased. Walnut accumulated Na mostly in roots and transported more K and Ca to aboveground parts. The growth and physiological response performance differed between JM and JN, specifically, the differences occurred in the ability to absorb minerals, regulate osmotic stress, and scavenge ROS. Salt tolerance of JM and JN was assessed by principal component analysis (PCA) and resulted in JN > JM. In conclusion, our results indicated that JN has higher salt tolerance than JM, and JN might be used as a potential germplasm resource for the genetic breeding of walnuts.