Enhanced Antioxidant Enzyme Activities Research Articles

Seed treatment with ascorbic acid and proline improved salt tolerance in tomato (Solanum lycopersicum L. cv. Roma) by enhancing antioxidant enzyme activity

Seed treatment with ascorbic acid and proline improved salt tolerance in tomato (Solanum lycopersicum L. cv. Roma) by enhancing antioxidant enzyme activity

Browning inhibition in fresh-cut Chinese water chestnut under high pressure CO2 treatment: Regulation of reactive oxygen species and membrane lipid metabolism.

Fresh-cut Chinese water chestnut (CWC) was treated with high pressure CO2 (HPCD) to inhibit the browning reactions, and the underlying mechanism was investigated in this study. Results showed that HPCD at 2MPa pressure significantly inhibited lipoxygenase activity and enhanced superoxide dismutase activity, leading to decreased malondialdehyde and H2O2 contents in surface tissue. Moreover, HPCD could reduce total phenols/flavonoids content of surface tissue. Compare with control, homoeriodictyol, hesperetin, and isorhamnetin contents of 2MPa HPCD-treated samples on day 10 were reduced by 95.72%, 94.31%, and 94.02%, respectively. Furthermore, HPCD treatment enhanced antioxidant enzyme activities, and improved the O2- scavenging ability and reducing power of inner tissue. In conclusion, by regulating ROS and membrane lipid metabolism, HPCD treatment with appropriate pressure could retard the biosynthesis of flavonoids and enzymatic oxidation of phenolic compounds in surface tissue, and enhance antioxidant activity of inner tissue, thereby, delaying the quality deterioration of fresh-cut CWC.

Physiological factors contribute to increased competitiveness of grass relative to sedge, forb and legume species under different N application levels

In alpine grasslands, increased N deposition is increasing the dominance of grasses relative to other functional types according to our previous study Shen et al. (2022). However, the mechanisms that drive this compositional change are not fully understood. We measured the effects of 4–6 years' N addition to simulate N deposition at rates of 0 (CK), 8 (N1), 24 (N2), 40 (N3), 56 (N4), and 72 (N5) kg N ha−1 year−1 on dominant representatives of four functional types, Leymus secalinus (grass), Carex capillifolia (sedge), Potentilla multifidi (non-leguminous forb), and Medicago ruthenica (legume), in the alpine grassland on the Qinghai-Tibetan Plateau (QTP). In-situ experiment showed that N addition increased aboveground biomass in L. secalinus but had negative or neutral effects on aboveground biomass in the other species. Consistent with this finding, N addition increased net photosynthesis, chlorophyll content, and rubisco activity in L. secalinus with less positive effects on the other species. Nitrogen addition increased leaf N content in L. secalinus and C. capillifolia and reduced leaf non-structural carbohydrate content in all four species. In L. secalinus, the highest N addition rate (N5) reduced MDA content, a marker of oxidative stress, by enhancing antioxidant enzyme activity. Overall, our findings suggested that physiological factors can contribute to increased competitiveness of grass relative to sedge, forb and legume species under high N application levels. The rapid growth of this grass species reduces resource availability to non-grass species, increasing its dominance in the alpine meadow.

Assessment of application of ZnO nanoparticles on physiological profile, root architecture and antioxidant potential of Solanum lycopersicum

Plant growth can be impacted by ZnO nanoparticles (ZnO-NPs), in addition to their effects on photosynthesis and seed germination. The degree to which nanoparticles (NPs) enhance or inhibit shoot and root growth can vary depending on the specific type of NPs and their concentrations. This research aimed to explore the effects of ZnO-NPs on tomato plants (Solanum lycopersicum L.). The study measured the growth of the plants, their photosynthetic abilities, chlorophyll, physiology responses, antioxidant activities in 24-day-old plants. The results indicated that ZnO-NPs applications improved germination percentage (30.7%), shoot length (47.6%) and root length (33.1%) of the tomato plants, particularly at 75 μg/mL, and enhanced chlorophyll content in a manner proportional to the concentration. Moreover, in current research, it has been found that ZnO-NPs applications improved antioxidant response, and production of antioxidant enzymes. ZnO-NPs also had a beneficial impact on various root parameters including number of root tips (29.6%), number of branching points (16.6%), average diameter (46.2%), branching frequency (26.6%), total root length (33.1%), network area (26.3%), surface area (24.0%), perimeter (22.0%) and root volume (25.2%). Above 75 μg/mL, a reduction in all of them have been noticed, which indicates that concentrations of ZNPs above 75 μg/mL are harmful to tomato plants. Moreover, ZNPs appear to stimulate the transcription of various genes which have antioxidant activities, implying that they may bolster the plant's defense mechanism by enhancing antioxidant enzyme activity. According to our best knowledge, this is a novel aspect to study of impact of ZnO-NPs on root architecture of Solanum lycopersicum L.

Melatonin interaction with abscisic acid in the regulation of abiotic stress in Solanaceae family plants.

Solanaceous vegetable crops are cultivated and consumed worldwide. However, they often confront diverse abiotic stresses that significantly impair their growth, yield, and overall quality. This review delves into melatonin and abscisic acid (ABA) biosynthesis and their roles in abiotic stress responses. It closely examines the intricate interplay between melatonin and ABA in managing stress within plants, revealing both collaborative and antagonistic effects and elucidating the underlying molecular mechanisms. Melatonin and ABA mutually influence each other's synthesis, metabolism and that of other plant hormones, a key focus of this study. The study highlights melatonin's role in aiding stress management through ABA-dependent pathways and key genes in the melatonin-ABA interaction. Specifically, melatonin downregulates ABA synthesis genes and upregulates catabolism genes, leading to reduced ABA levels. It also directly scavenges H2O2, enhancing antioxidant enzyme activities, thereby underscoring their collaborative role in mediating stress responses. Moreover, the interplay between melatonin and ABA plays an essential role in multiple physiological processes of plants, including stomatal behaviors, wax accumulation, delay leaf senescence, seed germination, and seedlings growth, among others. Recognizing these relationships in Solanaceae vegetable crops holds great importance for improving agricultural practices and crop quality. In summary, this review offers a comprehensive overview of recent studies on the melatoninand ABA interplay, serving as a valuable resource for researchers and breeders dedicated to fortifying crop resilience and productivity within challenging environments.

Genome-Wide Analysis of MBF1 Family Genes in Five Solanaceous Plants and Functional Analysis of SlER24 in Salt Stress.

Multiprotein bridging factor 1 (MBF1) is an ancient family of transcription coactivators that play a crucial role in the response of plants to abiotic stress. In this study, we analyzed the genomic data of five Solanaceae plants and identified a total of 21 MBF1 genes. The expansion of MBF1a and MBF1b subfamilies was attributed to whole-genome duplication (WGD), and the expansion of the MBF1c subfamily occurred through transposed duplication (TRD). Collinearity analysis within Solanaceae species revealed collinearity between members of the MBF1a and MBF1b subfamilies, whereas the MBF1c subfamily showed relative independence. The gene expression of SlER24 was induced by sodium chloride (NaCl), polyethylene glycol (PEG), ABA (abscisic acid), and ethrel treatments, with the highest expression observed under NaCl treatment. The overexpression of SlER24 significantly enhanced the salt tolerance of tomato, and the functional deficiency of SlER24 decreased the tolerance of tomato to salt stress. SlER24 enhanced antioxidant enzyme activity to reduce the accumulation of reactive oxygen species (ROS) and alleviated plasma membrane damage under salt stress. SlER24 upregulated the expression levels of salt stress-related genes to enhance salt tolerance in tomato. In conclusion, this study provides basic information for the study of the MBF1 family of Solanaceae under abiotic stress, as well as a reference for the study of other plants.

Nuclear factor erythrogen-2 associated factor 2 (Nrf2) signaling is an essential molecular pathway for the anti-aging effect of whey protein in the prefrontal cortex of aging rat model (Histological and Biochemical Study)

Aging is a highly complicated natural process. Brain aging is associated with remarkable neurodegenerative changes and oxidative damage. Whey protein (WP) has been mentioned to have an antioxidant property. Nuclear factor erythrogen-2 associated factor 2 (Nrf2) signaling pathway is an antioxidant defense system. Nrf2 activity declines with age so, its activation could be a promising therapeutic strategy for aging. This study aimed to explore the anti-aging role of WP against D-galactose (D-gal) induced age-related degenerative changes and oxidative damage in the prefrontal cortex (PFC) and investigate its underlying mechanisms. Forty adult male rats were divided into 4 groups; control, WP group received WP (28.77 mg/kg/day) by gastric tube on the 4th experimental week; D-gal (model group) received D-gal (300 mg/kg/day) intraperitoneally for 8 weeks and D-gal +WP group received WP on the 4th week of D-gal treatment. Specimens from PFC were obtained for biochemical, histological, immunohistochemical and western blot analysis. WP treatment in D-gal +WP group reduced lipid peroxidation, enhanced antioxidant enzyme activities, decreased advanced glycation end products level and improved the histological and ultrastructural alterations. Moreover, the number of neurons expressed the senescence marker; p21 and percentage area of the astrocytic marker; glial fibrillary acidic protein were significantly reduced. WP also enhanced Nrf2 pathway and its downstream targets; heme oxygenase-1 and NADPH quinone oxidoreductase 1. In conclusion WP alleviates the D-gal-induced PFC aging through activating Nrf2 pathway, reducing cell senescence and gliosis. So, it may be a potential therapeutic target to retard the aging process.

Transcriptome and WGCNA reveal hub genes in sugarcane tiller seedlings in response to drought stress

Drought stress can severely affect sugarcane growth and yield. The objective of this research was to identify candidate genes in sugarcane tillering seedlings in response to drought stress. We performed a comparative phenotypic, physiological and transcriptomic analysis of tiller seedlings of drought-stressed and well-watered “Guire 2” sugarcane, in a time-course experiment (5 days, 9 days and 15 days). Physiological examination reviewed that SOD, proline, soluble sugars, and soluble proteins accumulated in large amounts in tiller seedlings under different intensities of drought stress, while MDA levels remained at a stable level, indicating that the accumulation of osmoregulatory substances and the enhancement of antioxidant enzyme activities helped to limit further damage caused by drought stress. RNA-seq and weighted gene co-expression network analysis (WGCNA) were performed to identify genes and modules associated with sugarcane tillering seedlings in response to drought stress. Drought stress induced huge down-regulated in gene expression profiles, most of down-regulated genes were mainly associated with photosynthesis, sugar metabolism and fatty acid synthesis. We obtained four gene co-expression modules significantly associated with the physiological changes under drought stress (three modules positively correlated, one module negatively correlated), and found that LSG1-2, ERF1-2, SHKA, TIL, HSP18.1, HSP24.1, HSP16.1 and HSFA6A may play essential regulatory roles as hub genes in increasing SOD, Pro, soluble sugar or soluble protein contents. In addition, one module was found mostly involved in tiller stem diameter, among which members of the BHLH148 were important nodes. These results provide new insights into the mechanisms by which sugarcane tillering seedlings respond to drought stress.

Postharvest treatments with methyl salicylate and glycine betaine synergistically enhanced chilling tolerance and maintained bioactive compounds of blood orange fruit subjected to cold quarantine storage

The effects of glycine betaine (GB) and methyl salicylate (MeSA) treatments, alone and in combination, on the chilling tolerance and bioactive compounds of blood orange cv. Moro during cold quarantine storage (2 °C for 60 days) were investigated. The fruits were treated with GB (15 and 30 mM) using vacuum infiltration at 30 kPa for 8 min and MeSA (100 μM) using vapor treatment for 18 h, along with a combination of both GB concentrations and MeSA. The treatment with 30 mM GB + 100 μM MeSA was the most effective. This treatment improved the fruit's chilling tolerance by enhancing antioxidant enzyme activity and osmoregulation, which maintained membrane integrity. Furthermore, it preserved organic acids (citric, ascorbic, malic, succinic, and oxalic acids), sugars (sucrose, glucose, and fructose), as well as total anthocyanins, total phenolics, and antioxidant activity by increasing phenylalanine ammonia-lyase activity and suppressing polyphenol oxidase activity. The combined MeSA and GB treatment had a synergistic effect in enhancing the cold tolerance of ‘Moro’ blood orange fruit during cold quarantine storage.

The effect of silicon on the antioxidant system of tomato seedlings exposed to individual and combined nitrogen and water deficit

AbstractExploring sustainable strategies for improving crop water and nitrogen use efficiency is essential. Silicon (Si) has been reported as a beneficial metalloid for plants since it alleviates several abiotic stresses (including drought) by triggering the plants' antioxidant system. However, its role in mitigating the negative impact of nitrogen (N) deficit alone or when combined with water (W) deficit is not well studied. This study applied 0 or 2 mM of Na₂SiO3 to 3‐week‐old tomato cv. Micro‐Tom seedlings that were grown under the following conditions: control (CTR; 100%N + 100% Field Capacity), N deficit (N; 50% N + 100% Field Capacity), water deficit (W; 100% N + 50% Field Capacity) or combined stress (N + W; 50% N + 50% Field Capacity). The Si effect on tomato plant growth depended on the type of stress. Si could only alleviate stress caused by N + W deficit resulting in a higher root dry weight (by 28%), total dry weight (by 23%) and root length (by 37%). Alongside this, there was an increase in the antioxidant (AOX) system activity with the root activity of ascorbate peroxidase and catalase enzymes being enhanced by 48% and by 263%, respectively. Si application also enhanced AOX enzyme activity when tomato plants were subjected to individual deficits but to a lesser extent. In conclusion, Si‐treated tomato plants could efficiently modulate their AOX networks in a situation of combined N and water limitation, thus mitigating some of the adverse effects of this combined stress.

Investigating the Interplay between Tomato Leaf Curl New Delhi Virus Infection, Starch Metabolism and Antioxidant Defence System in Potato (Solanum tuberosum L.).

The potato apical leaf curl disease is caused by tomato leaf curl New Delhi virus-potato (ToLCNDV-potato), which severely alters a plant's starch metabolism, starch hydrolysing enzymes, and antioxidant mechanism. In this study, the result suggested that ToLCNDV-potato significantly (p < 0.01) affected the morphological parameters and photosynthetic pigment system in both the cultivars of potato, viz., Kufri Pukhraj (susceptible) and Kufri Bahar (tolerant). However, the impact of ToLCNDV-potato was lower in Kufri Bahar. Moreover, the viral infection in potato showed significant (p < 0.01) enhancement in the leakage of plant oxidative metabolites such as proline and malondialdehyde (MDA) which was further confirmed with higher electrolyte leakage. The viral infection imbalance of starch metabolism in the leaves ultimately affects the carbohydrate profile. ToLCNDV-potato significantly lowered starch synthesis, enhanced the accumulation of sucrose, glucose, fructose and-which was further validated by enzymatic estimation of β-amylase-α-amylase and phosphorylase activity in the leaves of both cultivars. The antioxidant enzymes, viz., catalase, ascorbate peroxidase, and superoxide dismutase, were reported to be enhanced in both the cultivars due to ToLCNDV-potato infection. The higher enhancement of antioxidant enzyme activity was observed in Kufri Bahar, which signifies its resistant attributes. These findings in the potato plant broaden our understanding of the regulatory mechanisms of starch metabolism and antioxidant activity and provide proof of concept for breeding potato for ToLCNDV-potato tolerance.

Genome-wide identification and expression analysis of MYB gene family in Cajanus cajan and CcMYB107 improves plant drought tolerance.

MYB transcription factor (TF) is one of the largest superfamilies that play a vital role in multiple plant biological processes. However, the MYB family has not been comprehensively identified and functionally verified in Cajanus cajan, which is the sixth important legume crop. Here, 170 CcR2R3-MYBs were identified and divided into 43 functional subgroups. Segmental and tandem duplications and alternative splicing events were found and promoted the expansion of the CcR2R3-MYB gene family. Functional prediction results showed that CcR2R3-MYBs were mainly involved in secondary metabolism, cell fate and identity, developmental processes, and responses to abiotic stress. Cis-acting element analysis of promoters revealed that stress response elements were widespread in the above four functional branches, further suggesting CcR2R3-MYBs were extensively involved in abiotic stress response. The transcriptome data and qRT-PCR results indicated that most of the CcR2R3-MYB genes responded to various stresses, of which the expression of CcMYB107 was significantly induced by drought stress. Overexpression of CcMYB107 enhanced antioxidant enzyme activity and increased proline and lignin accumulation, thus improving the drought resistance of Cajanus cajan. Furthermore, Overexpression of CcMYB107 up-regulated the expression of stress-related genes and lignin biosynthesis genes after drought stress. Our findings established a strong foundation for biological function investigation of CcR2R3-MYB TFs in Cajanus cajan. This article is protected by copyright. All rights reserved.

Transcriptional Regulation of the Acer truncatum B. Response to Drought and the Contribution of AtruNAC36 to Drought Tolerance.

Drought stress is one of the major environmental factors severely restricting plant development and productivity. Acer truncatum B, which is an economically important tree species, is highly tolerant to drought conditions, but the underlying molecular regulatory mechanisms remain relatively unknown. In this study, A. truncatum seedlings underwent a drought treatment (water withheld for 0, 3, 7, and 12 days), after which they were re-watered for 5 days. Physiological indices were measured and a transcriptome sequencing analysis was performed to reveal drought response-related regulatory mechanisms. In comparison to the control, the drought treatment caused a significant increase in antioxidant enzyme activities, with levels rising up to seven times, and relative electrical conductivity from 14.5% to 78.4%, but the relative water content decreased from 88.3% to 23.4%; these indices recovered somewhat after the 5-day re-watering period. The RNA sequencing analysis identified 9126 differentially expressed genes (DEGs), which were primarily involved with abscisic acid responses, and mitogen-activated protein kinase signaling. These DEGs included 483 (5.29%) transcription factor genes from 53 families, including ERF, MYB, and NAC. A co-expression network analysis was conducted and three important modules were analyzed to identify hub genes, one of which (AtruNAC36) was examined to clarify its function. The AtruNAC36 protein was localized to the nucleus and had a C-terminal transactivation domain. Moreover, it bounded specifically to the NACRS element. The overexpression of AtruNAC36 in Arabidopsis thaliana resulted in increased drought tolerance by enhancing antioxidant enzyme activities. These findings provide important insights into the transcriptional regulation mediating the A. truncatum response to drought. Furthermore, AtruNAC36 may be relevant for breeding forest trees resistant to drought stress.

Screening and Selection of Drought-Tolerant High-Yielding Chickpea Genotypes Based on Physio-Biochemical Selection Indices and Yield Trials.

Chickpea production is seriously hampered by drought stress, which could be a great threat in the future for food security in developing countries. The present investigation aimed to screen the drought-tolerant response of forty desi chickpea genotypes against drought stress through various physio-biochemical selection indices and yield-attributing traits. Principle component-based biplot analysis recognized PG205, JG2016-44, JG63, and JG24 as tolerant genotypes based on physiological selection indices. These genotypes retained higher relative water content, stomatal conductance, internal CO2 concentration, and photosynthetic rate. ICC4958, JG11, JAKI9218, JG16, JG63, and PG205 were selected as tolerant genotypes based on biochemical selection indices. These genotypes sustained higher chlorophyll, sugar and proline content with enhanced antioxidant enzyme activities. With respect to yield trials, JAKI9218, JG11, JG16, and ICC4958 had higher seed yield per plant, numbers of pods, and biological yield per plant. Finally, JG11, JAKI9218, ICC4958, JG16, JG63, and PG205 were selected as tolerant genotypes based on cumulative physio-biochemical selection indices and yield response. These identified drought-tolerant genotypes may be further employed in climate-smart chickpea breeding programs for sustainable production under a changing climate scenario.

Dynamics of reactive oxygen species and lignin biosynthesis during leaf spot disease of Withania somnifera (L.) Dunal.

Withania somnifera is an important medicinal plant, however, its cultivation and quality are compromised through infestation by leaf spot disease caused by the fungus, Alternaria alternata. To find suitable strategies against this disease, studies on post-infectional changes are important. ROS are critical as they interact with other defence signalling pathways. We analyzed ROS-generating and scavenging systems in healthy and diseased leaf samples of W. somnifera and ROS-driven downstream defence pathways. We used DAB and NBT assays for ROS detection, spectrophotometry and in-gel assays for ROS scavenging enzymes, a thioglycolic acid (TGA) based assay, histochemical staining for lignin, and qRT-PCR for transcript-level expression. Leaf spot infection in W. somnifera increased NADPH oxidase activity and ROS accumulation in infected leaves, together with enhanced antioxidant enzyme activity. Leaf spot-infected leaves had increased lignin content and higher expression of lignin biosynthesis genes. In addition, transcript levels of defence-related genes, NPR1 and PR, were also upregulated. The present work provides insights into responses to leaf spot disease through defence-related signalling in W. somnifera. It demonstrates crosstalk between ROS and lignin biosynthesis. This work identified potential targets for developing strategies to confer disease resistance against A. alternata in W. somnifera.

Different Responses to Water Deficit of Two Common Winter Wheat Varieties: Physiological and Biochemical Characteristics.

Since water scarcity is one of the main risks for the future of agriculture, studying the ability of different wheat genotypes to tolerate a water deficit is fundamental. This study examined the responses of two hybrid wheat varieties (Gizda and Fermer) with different drought resistance to moderate (3 days) and severe (7 days) drought stress, as well as their post-stress recovery to understand their underlying defense strategies and adaptive mechanisms in more detail. To this end, the dehydration-induced alterations in the electrolyte leakage, photosynthetic pigment content, membrane fluidity, energy interaction between pigment-protein complexes, primary photosynthetic reactions, photosynthetic and stress-induced proteins, and antioxidant responses were analyzed in order to unravel the different physiological and biochemical strategies of both wheat varieties. The results demonstrated that Gizda plants are more tolerant to severe dehydration compared to Fermer, as evidenced by the lower decrease in leaf water and pigment content, lower inhibition of photosystem II (PSII) photochemistry and dissipation of thermal energy, as well as lower dehydrins' content. Some of defense mechanisms by which Gizda variety can tolerate drought stress involve the maintenance of decreased chlorophyll content in leaves, increased fluidity of the thylakoid membranes causing structural alterations in the photosynthetic apparatus, as well as dehydration-induced accumulation of early light-induced proteins (ELIPs), an increased capacity for PSI cyclic electron transport and enhanced antioxidant enzyme activity (SOD and APX), thus alleviating oxidative damage. Furthermore, the leaf content of total phenols, flavonoids, and lipid-soluble antioxidant metabolites was higher in Gizda than in Fermer.

Introgression of SUB1 aggravates the susceptibility of the popular rice cultivars Swarna and Savitri to stagnant flooding

Identification of the Sub1 gene for tolerance to flash flooding and its introgression into high-yielding rice cultivars are major targets in rice breeding for flood-prone rice agro-ecosystems for ensuring yield stability. However, knowledge is scant on the response of the modified genotypes under stagnant flooding (SF) to meet the challenge of finding a superior allele that may confer greater resilience to the plant under a stress-prone environment. In pursuance, we have tested the response of Sub1-introgression in two popular rice varieties, Swarna and Savitri to SF by comparing the biochemical factors in the control of flag leaf senescence and its primary production mechanisms of the parental lines’ versus Sub1-introgressed lines. The activities of antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GR), and ascorbate peroxidase (APX) increased while various parameters of primary production like total chlorophyll content, stomatal conductance (gs), normalized difference vegetation index (NDVI) and photosynthetic activity (Pn) decreased progressively with passage of time in the flag leaf of the cultivars during the post-anthesis period and SF-treatment increased the enzyme activity while depressing primary production further. Introgression of Sub1 had no influence on these activities under control conditions but widened the margin of effects under SF. It was concluded that the functional ability of flag leaf in mega rice cultivars like Swarna and Savitri decreased significantly by SF because of an ethylene-mediated promotion of senescence of the flag leaf. The enhancement of antioxidant enzyme activity by SF could not sustain the stability of primary production in the flag leaf. The introgression of the Sub1 gene made the cultivars more vulnerable to SF because the gene induced overexpression of ethylene.

Molecular mechanism by which StSN2 overexpression inhibits the enzymatic browning of potato

Enzymatic browning of fresh-cut potatoes (Solanum tuberosum L.) is an urgent problem to be solved in the potato industry. The transcript level of snakin-2 (StSN2) increased with prolonged fresh-cut potato storage time, and StSN2 overexpression reduced the enzymatic browning of fresh-cut potato compared to wild type (WT). Further studies suggested that overexpression of StSN2 effectively enhanced polyphenol oxidase (PPO), peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) activity, decreased phenolic and soluble quinone contents. The measurement of total free amino acid results showed that the contents of proline, isoleucine, and gamma-aminobutyric acid were increased, and the contents of cystine, methionine, and tyrosine were decreased in StSN2-overexpressing transgenic lines. Quantitative phosphoproteome analysis showed that 1515 proteins were phosphorylated in transgenic fresh-cut potato. Among them, 123 kinases were found to change phosphorylation levels, and a kinase-substrate network of serine/arginine proteins and mitogen-activated protein kinases was predicted. Our results indicated that overexpression of StSN2 inhibited the enzymatic browning of fresh-cut potatoes by enhancing antioxidant enzyme activity and decreasing phenolic and soluble quinone contents while also changing vital kinase and other protein phosphorylation levels. This study demonstrated a new function of StSN2 and provided target genes for enzymatic browning resistance breeding of potatoes.

Nitrogen fertilizer combined with DPC+ chemical topping agent can improve cotton yield by enhancing antioxidant enzyme activity and improving the endogenous hormone balance

Nitrogen fertilizer and fortified DPC (DPC+) chemical topping agent management is essential for replacing manual topping and achieving simplified cotton cultivation. However, the response of cotton physiological characteristics to the interaction between nitrogen fertilizer and DPC+ and the relationship between this interaction and yield remain unclear. A 2-year field experiment was conducted to investigate the effects of nitrogen rates (N1, 150; N2, 300; N3, 450 kg ha−1) and DPC+ doses (D1, 450; D2, 750; D3, 1050 mL ha−1) and D0 (manual topping) on antioxidant enzymes, endogenous hormone content and balance, reproductive organ dry matter (RODM) and yield. N1D1, N2D2, and N3D3 significantly improved the RODM and yield, with N2D2 having 3.5 − 37.1% higher RODM levels than N1D1 and N2D2. At the N1 level, D1 decreased malondialdehyde (MDA) content by 4.1 − 35.6% compared to D0, D2 and D3, and increased catalase (CAT) activity and abscisic acid (ABA) content by 69.7% and 34.2% than D0, respectively. At the N2 level, D2 decreased the MDA content by 16.1 − 51.9% and increased peroxidase and CAT activity and ABA and gibberellic acid contents by 12.7 − 355.7% compared to D0, D1, and D3. Furthermore, D2 decreased indole-3-acetic acid (IAA) content and IAA/ABA by 12.1% and 30.5% in boll opening but increased trans-zeatin-riboside (ZR) content by 25.5% compared to D0. At the N3 level, D3 increased ZR/ABA by 20.1% compared to D0. Overall, the interactions between appropriate nitrogen levels and DPC+ doses can increase cotton yield by enhancing antioxidant enzyme activity and promoting endogenous hormone homeostasis, with N2D2 performing best.

Hormonal Balance, Photosynthesis, and Redox Reactions in the Leaves of Caragana korshinskii Kom. under Water Deficit.

To evaluate the physiological responses of Korshinsk peashrub (Caragana korshinskii Kom.) to water deficit, photosynthetic gas exchange, chlorophyll fluorescence, and the levels of superoxide anion (O2•-), hydrogen peroxide (H2O2), malondialdehyde (MDA), antioxidant enzymes, and endogenous hormones in its leaves were investigated under different irrigation strategies during the entire growth period. The results showed that leaf growth-promoting hormones were maintained at a higher level during the stages of leaf expansion and vigorous growth, and zeatin riboside (ZR) and gibberellic acid (GA) gradually decreased with an increase in water deficit. At the leaf-shedding stage, the concentration of abscisic acid (ABA) dramatically increased, and the ratio of ABA to growth-promoting hormones increased to a high level, which indicated that the rate of leaf senescence and shedding was accelerated. At the stages of leaf expansion and vigorous growth, the actual efficiency of photosystem II (PSII) (ΦPSii) was downregulated with an increment in non-photochemical quenching (NPQ) under moderate water deficit. Excess excitation energy was dissipated, and the maximal efficiency of PSII (Fv/Fm) was maintained. However, with progressive water stress, the photo-protective mechanism was inadequate to avoid photo-damage; Fv/Fm was decreased and photosynthesis was subject to non-stomatal inhibition under severe water deficit. At the leaf-shedding stage, non-stomatal factors became the major factors in limiting photosynthesis under moderate and severe water deficits. In addition, the generation of O2•- and H2O2 in the leaves of Caragana was accelerated under moderate and severe water deficits, which caused an enhancement of antioxidant enzyme activities to maintain the oxidation-reduction balance. However, when the protective enzymes were insufficient in eliminating excessive reactive oxygen species (ROS), the activity of catalase (CAT) was reduced at the leaf-shedding stage. Taken all together, Caragana has strong drought resistance at the leaf expansion and vigorous growth stages, but weak drought resistance at the leaf-shedding stage.