Increase In Lipoxygenase Activity Research Articles

Acetylsalicylic acid inhibition of the lipoxygenase pathway: Implications for HIV prevention

Background1.5 million new HIV infections occurred in 2021, suggesting new prevention methods are needed. Inflammation increases the risk for HIV acquisition by attracting HIV target cells to the female genital tract (FGT). In a pilot study, acetylsalicylic acid (ASA/Aspirin) decreased the proportion of FGT HIV target cells by 35 %. However, the mechanism remains unknown. MethodsWomen from Nairobi, Kenya took low-dose ASA (81 mg) daily for 6-weeks. Free oxylipins in the plasma were quantified by high-performance liquid chromatography-tandem mass spectroscopy. ResultsOxylipins from 9 fatty acid substrates were detected, with more than one analyte from 4 substrates reduced post-ASA. Summary analysis found ASA downregulated cyclooxygenase and lipoxygenase but not cytochrome P450 activity with a lower n-6/n-3 oxylipin profile, reflecting reduced inflammation post-ASA. ConclusionsInflammation is associated with increased lipoxygenase activity and HIV risk. Our data suggests ASA reduces inflammation through downregulation of oxylipins. Understanding how ASA reduces inflammation may lead to novel HIV prevention approaches.

Cadmium and copper-induced metabolic and proteomic changes in the root tip during early maize growth.

In this study, the metabolic adjustments performed by maize (Zea mays L.) seminal roots exposed to 25µM Cd2+ or 25µM Cu2+ at pre-emergence are compared, focusing on the proteomic changes after metal exposure. Root width was increased, and root length was decreased after 72h of metal treatment. Both metals induced H2O2 accumulation and lipid peroxidation in the root tip. These changes were accompanied by increases in lipoxygenase activity and 4-hydroxy-2-nonenal content. NMR spectroscopy revealed that the abundance of 38 water-soluble metabolites was significantly modified by Cd and Cu exposure; this set of metabolites comprised carboxylic acids, amino acids, carbohydrates, and unidentified phenolic compounds. Linoleic acid content significantly decreased in Cu-treated samples. The total amount of proteins detected in maize root apexes was 2,171. Gene ontology enrichment analysis of the differentially accumulated proteins was performed to detect pathways probably affected by metal additions. Both metals altered redox homeostasis, up-regulated oxylipins biosynthetic process, and shifted metabolism towards the oxidative pentose-phosphate in the root apexes. However, the methionine salvage pathway appears as a key metabolic module only under Cd stress. The integrative analysis carried out in this study suggests that most molecular features behind the reprogramming of maize root tips to cope with cadmium and copper toxicity are common, but some are not.

Increased abundance of patatins, lipoxygenase and miraculins in a thaxtomin A‐habituated potato Russet Burbank somaclone with enhanced resistance to common scab

AbstractPotato common scab caused by the actinobacterium Streptomyces scabiei is characterized by the formation of corky lesions on tubers that reduce their marketability. Management of common scab is very complex and often ineffective under various environmental conditions. Using potato varieties that are more resistant to common scab remains one of the most efficient strategies to control this disease. However, very little is known about the factors associated with resistance to common scab. Somaclone RB9 regenerated from thaxtomin A‐habituated potato Russet Burbank calli produced tubers more resistant to common scab than the original variety. Comparison of the RB9 tuber proteome with that of Russet Burbank using label‐free quantitative proteomic analysis revealed changes in the accumulation of defence‐related proteins from the patatin and lipoxygenase (LOX) families, which are involved in the metabolism of lipids, and of two miraculins of the Kunitz‐type protease inhibitors family. The implication of LOX during common scab infection was studied using synchronized minitubers developed from leaf‐bud cuttings. S. scabiei infection stimulated the accumulation of LOX in both Russet Burbank and RB9 minitubers, but this accumulation was intensified in RB9 minitubers. Infection also increased LOX activity in Russet Burbank and RB9 minitubers. However, LOX activity measured in noninfected RB9 minitubers was similar to that of infected Russet Burbank minitubers, indicating endogenous activation of LOX activity in RB9 minitubers. We discuss how increased LOX abundance and activity in the somaclone RB9 may contribute to improving tuber defence against common scab.

ROS-derived lipid peroxidation is prevented in barley leaves during senescence.

Senescence in plants enables resource recycling from senescent leaves to sink organs. Under stress, increased production of reactive oxygen species (ROS) and associated signalling activates senescence. However, senescence is not always associated with stress since it has a prominent role in plant development, in which the role of ROS signalling is less clear. To address this, we investigated lipid metabolism and patterns of lipid peroxidation related to signalling during sequential senescence in first‐emerging barley leaves grown under natural light conditions. Leaf fatty acid compositions were dominated by linolenic acid (75% of total), the major polyunsaturated fatty acid (PUFA) in galactolipids of thylakoid membranes, known to be highly sensitive to peroxidation. Lipid catabolism during senescence, including increased lipoxygenase activity, led to decreased levels of PUFA and increased levels of short‐chain saturated fatty acids. When normalised to leaf area, only concentrations of hexanal, a product from the 13‐lipoxygenase pathway, increased early upon senescence, whereas reactive electrophile species (RES) from ROS‐associated lipid peroxidation, such as 4‐hydroxynonenal, 4‐hydroxyhexenal and acrolein, as well as β‐cyclocitral derived from oxidation of β‐carotene, decreased. However, relative to total chlorophyll, amounts of most RES increased at late‐senescence stages, alongside increased levels of α‐tocopherol, zeaxanthin and non‐photochemical quenching, an energy dissipative pathway that prevents ROS production. Overall, our results indicate that lipid peroxidation derived from enzymatic oxidation occurs early during senescence in first barley leaves, while ROS‐derived lipid peroxidation associates weaker with senescence.

Role of Lactobacillus plantarum with antioxidation properties on Chinese sausages

Excessive protein and lipid oxidation can lead to the deterioration of sausage quality, especially flavour. Functional starter culture increases their attractiveness through sensory qualities and a potential healthpromoting effect. It was investigated that Lactobacillus plantarum (L.plantarum) strains with antioxidation properties effected on the flavour and oxidation of fermented sausage in the study. The group treated with natural fermentation was used to as control (control group). Results showed that P3 and P3-M2 had the ability of reducing lipid and protein oxidation during fermentation. The increase of lipoxygenase activity and thiobarbituric acid reactive substances (TBARs) values were retarded. Sulfhydryl group contents were significantly higher than those in the control. Furthermore, changes in protein bands were confirmed with the less protein oxidation with P3-M2 than P3 and the control. Accordingly, strain P3 and P3-M2 significantly enhanced the types and relative contents of esters after fermented, indicating that strain P3 and P3-M2 contributed to the production of flavour substances. These results revealed that L.plantarum strains with antioxidation properties were a promising approach in inhibiting lipid and protein oxidation of Chinese sausage, maintaining the stable natural structure of protein, simultaneously improve the quality of sausage and promote the sausage to form a better flavour.

Secondary Metabolism and Plant Growth of Piper divaricatum (Piperaceae) Inoculated with Arbuscular Mycorrhizal Fungi and Phosphorus Supplementation

Arbuscular mycorrhizal fungi (AMF) species and/or phosphorus addition in the soil can affect secondary metabolism production and growth in plants. This study evaluated these effects on Piper divaricatum culture, which presents an essential oil rich in phenylpropanoids. Growth parameters, leaf volatile composition, total phenolic content, and the enzymatic activity of lipoxygenase (LOX) and phenylalanine ammonia-lyase (PAL) were monitored. At 90 days post inoculation (dpi), the treatments with AMF and AMF + P were more effective in terms of the number and biomass of leaves. In addition, the AMF group had increased plant height and root length. Phenylpropanoid and methyl eugenol contents were higher at 30 dpi in the P and AMF + P association treatments. However, at 90 dpi, the plants with P addition at 20 mg·dm−3 and AMF + 200 mg of P·dm−3 showed higher phenolic contents and PAL activity, respectively. All treatments increased LOX activity, especially with P addition at 200 mg·dm−3. These results demonstrate that P and AMF can be applied to optimize leaf biomass and volatile compound production in P. divaricatum.

An integrated comparative physiology and molecular approach pinpoints mediators of breath-hold capacity in dolphins

Background and objectivesIschemic events, such as ischemic heart disease and stroke, are the number one cause of death globally. Ischemia prevents blood, carrying essential nutrients and oxygen, from reaching tissues, leading to cell and tissue death, and eventual organ failure. While humans are relatively intolerant to ischemic events, other species, such as marine mammals, have evolved a unique tolerance to chronic ischemia/reperfusion during apneic diving. To identify possible molecular features of an increased tolerance for apnea, we examined changes in gene expression in breath-holding dolphins.MethodologyHere, we capitalized on the adaptations possesed by bottlenose dolphins (Tursiops truncatus) for diving as a comparative model of ischemic stress and hypoxia tolerance to identify molecular features associated with breath holding. Given that signals in the blood may influence physiological changes during diving, we used RNA-Seq and enzyme assays to examine time-dependent changes in gene expression in the blood of breath-holding dolphins.ResultsWe observed time-dependent upregulation of the arachidonate 5-lipoxygenase (ALOX5) gene and increased lipoxygenase activity during breath holding. ALOX5 has been shown to be activated during hypoxia in rodent models, and its metabolites, leukotrienes, induce vasoconstriction.Conclusions and implicationsThe upregulation of ALOX5 mRNA occurred within the calculated aerobic dive limit of the species, suggesting that ALOX5 may play a role in the dolphin’s physiological response to diving, particularly in a pro-inflammatory response to ischemia and in promoting vasoconstriction. These observations pinpoint a potential molecular mechanism by which dolphins, and perhaps other marine mammals, respond to the prolonged breath holds associated with diving.

Studies on In-vitro Anti-inflammatory and Antioxidant Potentials of Annona muricata Leaf Extracts

Inflammation has stimulated significant worldwide scientific interest because of its implication in many human diseases. Most inflammations are caused by reactive oxygen species or free radicals. Annona muricataleaf extracts were investigated for their in-vitroantioxidant and anti-inflammatory potentials. Annona muricataleavesweredried at room temperature, blended using a mill.and extracted with solvents of varying degree of polarities. The solventsused were hexane, ethyl acetate,and ethanol. After sequential extraction, the crude extracts were examined for their in-vitroanti-inflammatory activities on lipoxygenase inhibition, proteinase inhibition, albumin denaturation inhibition,and red blood cell membrane stabilization assays,while the antioxidant activities were examined using DPPH, ABTS and hydrogen peroxide assays. The results showed that the ethanol extract had significantlyhigher albumin denaturation inhibition activity at 500 μg/mL (p < 0.01). The activity of all the extracts on proteinase inhibition decreased with the increase in concentration of the extracts. Indomethacin (standard), ethanol extract,and ethyl acetate extract exhibited a dose dependent increase in lipoxygenase activity. The ethanol extract showed highred blood cell membrane stabilization activity at 500 μg/mL and the activity was comparable with that of the standard (diclofenac). Hydrogen peroxide scavenging activity of the extracts and standard (Vitamin C) were comparable at 20 –100 μg/mL. The ethanol extract showed significantly higher(p < 0.01) DPPH radical scavenging activity compared with other extracts. A similar trend was also observed for ABTS radical scavenging activity. Generally,the ethanol extract exhibited higher anti-inflammatory and antioxidant activities in most of the assays, this could be attributed to the polar compounds present in the extract.

Abstract P058: Female Rats Artificially Selected For Low Vs. High Intrinsic Aerobic Capacity Display Divergent Mechanisms In Vascular Inflammation

Hypertension is an important clinical symptom of metabolic syndrome (MetS). Rats selectively bred for low intrinsic aerobic capacity (LCR) are animal models for MetS, and present with increased blood pressure and vascular dysfunction. In contrast, rats selected for high intrinsic aerobic capacity (HCR) display reduced vascular inflammation and no metabolic abnormalities. Two important enzymes for vascular inflammation and the resolution of inflammation are cyclooxygenase (COX) and lipoxygenase (LOX), respectively; however, it is unknown whether COX and LOX play a role in the vascular function of LCR and HCR. We hypothesized that mesenteric resistance arteries (MRA) from untrained LCR present increased COX activity, while arteries from HCR show decreased COX and increased LOX activity. Female (18-38 weeks old) LCR, HCR, and high response trained (HRT) rats, control, were used. HRT rats present higher intrinsic aerobic capacity than LCR, but lower than HCR. MRA were mounted onto a wire myograph. One-way ANOVA: p<0.05: *vs. control (HRT); # vs. HCR; & vs. absence of indomethacin (INDO), a COX inhibitor. LCR rats showed increased periovarian fat pad [HRT: 0.95±0.1 (n=7) vs. LCR: 1.80±0.1* # (n=7) vs. HCR: 1.18±0.1 (n=7) (g)]. No significant differences were observed in the KCl (120 mM), acetylcholine, and sodium-nitroprusside-induced responses. However, LCR presented a decrease in phenylephrine (PE)-induced contraction [PE: E max %: HRT: 103±3 (n=8); LCR: 74±9* # (n=11); HCR: 112±5 (n=9)]. Inhibiting COX [INDO, 10 μM] decreased contraction in HRT arteries, but had little effect on HCR arteries. Contrarily, INDO abolished contraction in MRA from LCR [PE+INDO: E max %: HRT: 31±18 & (n=7); LCR: 2±0.9 & (n=8); HCR: 77±9 (n=8)]. Lipoxin (LXA4), a LOX-derived mediator for resolution of inflammation, induced contraction in MRA from HCR, but relaxation in LCR and HRT arteries [LXA4: E max %: HRT: -69±19 (n=4); LCR: -18±9 (n=3); HCR: 11±5 (n=4)*]. Thus, HCR are unresponsive to COX inhibition, suggesting a change from a normal inflammatory state to a higher resolution state. LCR display low-grade chronic inflammation via increased COX activity. These data reveal novel, inherited mechanisms for vascular physiology in high vs. low intrinsic aerobic capacity.

INDUCTION OF DEFENSE MECHANISMS IN TOMATO PLANTS BY SAPROBIC FUNGI FILTRATES AGAINST EARLY BLIGHT DISEASE

ABSTRACT Tomato plants can be attacked by several diseases. The early blight disease causes large losses to tomato growers and requires many applications of fungicide for its control. Thus, the objective of this work was to evaluate the effect of saprobic fungi filtrates on the control of early blight (Alternaria solani) in tomato plants. The treatments consisted of fungi filtrates (Stachylidium bicolor - SBI; Periconia hispidula - PHI; Brachysporiella pulchra - BPU; Myrothecium leucotrichum - MLE; and Pycnoporus sanguineus - PSA) diluted at 20%, a control (water), and acibenzolar-S-methyl (ASM). Tomato plants with five leaves were treated with the filtrates, and A. solani was inoculated after three days. The variables analyzed were: area under the disease progress curve (AUDPC), and specific activity of the enzymes: catalase, lipoxygenase, peroxidase, and polyphenol oxidase. The SBI filtrate decreased the AUDPC in 80% for the third leaf and 96% for the fourth leaf. Catalase activity increased due to the application of BPU and PHI filtrates, at 96 hours post-inoculation (hpi). Lipoxygenase activity increased in 130%, 72%, 130%, and 81% at 24 hpi when applying the SBI, PHI, MLE, and ASM filtrates, respectively. The application of SBI, BPU, MLE, and PSA filtrates increased lipoxygenase activity in 30%, 26%, 12%, and 22%, respectively, at 120 hpi. Peroxidase activity increased 74% at 120 hpi, when applying the SBI filtrate. Polyphenol oxidase activity was not affected by the treatments. S. bicolor filtrate is efficient to control the severity of the early blight disease in tomato plants.

Influence of Cold Storage on Pear Physico-Chemical Traits and Antioxidant Systems in Relation to Superficial Scald Development.

Superficial scald is the most common physiological disorder in apples and pears and causes huge economic losses worldwide. The aim of this study is to determine the different scald susceptibilities of seven pear cultivars/selections during five months of cold storage (CS). Four advanced pear selections and three commercial cultivars were harvested from an orchard located in Emilia-Romagna region, and cold stored at −1 °C and 85% relative humidity (RH).After 90, 120, and 150 days, fruits of each cultivar and selection were removed for ripening for 4 d, after which scald damage, physico-chemical and nutraceutical traits, and enzymatic antioxidant systems were evaluated on peel and pulp. ‘Abbé Fétel’, ‘Falstaff’, and ‘CREA 171’ did not showed superficial scald symptoms after 90 days, while ‘Doyenne du Comice’ and ‘CREA 264’ showed the highest susceptibility. After 90 days, CS ‘Falstaff’ and ‘CREA 179’ showed the highest total polyphenol content (TPH) in peel, followed by ‘Doyenne du Comice’ and ‘AbbéFétel’; lowest TPH was detected in ‘CREA 264’. After 120 and 150 days of CS, ‘Abbé Fétel’ and ‘CREA 171’ showed the highest peel TPH. ‘CREA 264’ and ‘CREA 125’ reached the lowest values of TPH during the three CS time periods. Superoxide dismutase and catalase activities were higher in the peel of scald-resistant than that in scald-susceptible pear cultivars/advanced selections. Superficial scald induced an increase in polyphenoloxidase, and guaiacol peroxidase activities involved in fruit-browning during CS. Furthermore, we observed an increase in lipoxygenase activity and consequent membrane damage in both the peel and flesh of the fruit. This study indicates that pear cultivars/advanced selections have different superficial scald susceptibilities that enable them to induce the activity of several antioxidant enzymes, following CS.

Lipoxygenase and Its Relationship with Ethylene During Ripening of Genetically Modified Tomato (Solanum lycopersicum).

SUMMARYResearch backgroundTomloxB is the main isoform of lipoxygenase associated with ripening and senescence of fruits. On the other hand, ethylene, a gaseous hormone, is essential for the regulation of ripening in climacteric fruits like tomatoes. However, the relationship between TomloxB and ethylene production has not been thoroughly studied. Therefore, we aim to assess the effect of exogenous ethylene in transgenic tomatoes that contain a silenced TomloxB gene, and subsequently evaluate lipoxygenase activity, 1-aminocyclopropane-1-carboxylic acid oxidase and ethylene production; as well as to quantify the expression of the genes encoding 1-aminocyclopropane-1-carboxylic acid oxidase and TomloxB.Experimental approachTo investigate the effect of lipoxygenase and 1-aminocyclopropane-1-carboxylic acid oxidase activity, fruits harvested at the stages of break, turning and pink were used. Tomatoes at break stage collected from transgenic and wild type plants were used to determine ethylene production and gene expression. Genetically modified and wild type tomato fruits were exposed to 100 μL/L exogenous ethylene. Lipoxygenase activity was measured spectrophotometrically. Activity of 1-aminocyclopropane-1-carboxylic acid oxidase and ethylene production were determined by gas chromatography. Oligonucleotides for differentially expressed genes: 1-aminocyclopropane-1-carboxylic acid oxidase and TomloxB were used to determine gene expression by real-time PCR.Results and conclusionsThe data showed that silencing of TomloxB caused a reduction in lipoxygenase activity and ethylene production in tomato fruits, and also reduced 1-aminocyclopropane-1-carboxylic acid oxidase activity. Hence, the addition of exogenous ethylene increased lipoxygenase activity in all treatments and 1-aminocyclopropane-1-carboxylic acid oxidase activity only in transgenic lines at break stage, consequently there was a positive regulation between TomloxB and ethylene, as increasing the amount of ethylene increased the activity of lipoxygenase. The results suggest that lipoxygenase may be a regulator of 1-aminocyclopropane-1-carboxylic acid oxidase and production of ethylene at break stage.Novelty and scientific contributionThese results lead to a better understanding of the metabolic contribution of TomloxB in fruit ripening and how it is linked to the senescence-related process, which can lead to a longer shelf life of fruits. Understanding this relationship between lipoxygenase and ethylene can be useful for better post-harvest handling of tomatoes.

Effects of exogenous melatonin and glutathione on zinc toxicity in safflower (Carthamus tinctorius L.) seedlings.

The phytotoxicity caused by 500μM ZnSO4.7H2O and its detoxifying by co-application of 100μM of MT melatonin (MT) and glutathione (GSH) in 6-week-old safflower plants have been investigated. Reduced biomass production and total chlorophyll content on the one hand and increased content of hydrogen peroxide (H2O2), malondialdehyde (MDA) with increase in lipoxygenase activity, on the other hand, showed Zn- induced oxidative damage in safflower seedlings. When MT, GSH and especially MT+GSH exogenously were applied to Zn-stressed seedlings, the content of H2O2, MDA and the activity of lipoxygenase considerably decreased. In Zn- treated seedlings, the application of these signaling molecules led to a considerable increment in ascorbate (ASC), GSH and phytochelatin (PC) contents along with the induction of activity of antioxidant enzymes including ascorbate-glutathione cycle enzymes when compared with the plants stressed with Zn only. In Zn-stressed safflower seedlings treated with MT, GSH and MT+GSH, decreased activity of enzymes involved in glyoxalase system may be associated with the role of MT and GSH in reducing Zn uptake and reducing Zn-induced toxicity and subsequently, lower plant's defense responses. The data showed that the effects of MT and GSH, in particular, the combination of these two molecules in reducing Zn uptake and diminishing its accumulation in the shoots of safflower seedlings, and also the participation of MT and GSH on increasing plant ability to tolerate high amount of Zn through stimulation of various antioxidant defense systems suggest them as suitable candidates to better the survival of safflower in soils contaminated with Zn excess.

Inhibitory effects of glutaraldehyde on Geotrichum citri-aurantii and its possible mechanism.

This study investigated the inhibitory effect of glutaraldehyde (GA) on sour rot in citrus fruit and the underlying antifungal mechanism on mycelial growth of the causative pathogen Geotrichum citri-aurantii. Glutaraldehyde exhibited a strong inhibitory effect on G. citri-aurantii, with a minimum inhibitory and fungicidal concentration (MFC) of 1·00µlml-1 . In addition, in vivo application of GA (1×MFC and 5×MFC) reduced the disease incidence of sour rot in citrus fruit by 60 and 80% respectively. Scanning electron microscopy results revealed that the morphology of G. citri-aurantii mycelia was greatly altered by GA treatment. Propidium iodide and Calcofluor White Staining revealed that the membrane permeability, rather than the cell wall integrity, of G. citri-aurantii mycelia was severely disrupted after the addition of GA. Massive accumulation of malonaldehyde and reactive oxygen species as well as an increase in lipoxygenase activity were observed. These results indicate that GA may inhibit the mycelia growth of G. citri-aurantii through a membrane damage mechanism induced by membrane peroxidation. Glutaraldehyde is expected to be a novel fungicide for controlling sour rot in citrus fruit.

Conifer responses to a stylet‐feeding invasive herbivore and induction with methyl jasmonate: impact on the expression of induced defences and a native folivore

Abstract Trees attacked by multiple herbivores need to defend themselves against dynamic biotic challenges; appropriate responses to one stressor can elicit hormonal responses that are antagonistic to another. Hemlock (Tsuga canadensis) infestation by hemlock woolly adelgid (HWA; Adelges tsugae) results in the accumulation of the defensive hormone salicylic acid. We explored the potential for HWA infestation to interfere with anti‐folivore‐induced defence signalling and its implications for a native folivore (hemlock looper; Lambdina fiscellaria). Hemlocks were infested with HWA and/or sprayed with methyl jasmonate; foliar defences were analyzed and foliage quality for looper larvae was assessed. Both treatments activated foliar defensive traits, including a HWA‐mediated increase in peroxidase activity and an accumulation of cell wall‐bound phenolics and lignin, as well as a methyl jasmonate‐mediated increase in lipoxygenase activity. The two treatments had an additive effect on other defensive traits and both treatments negatively affected looper performance. These results suggest that salicylic acid and jasmonic acid are not strictly antagonistic in conifers and that both have a role in anti‐folivore defence signalling. The present study illustrates the need for a better understanding of hormone signalling, cross‐talk and induced responses in conifers.

Defense Responses of Cherry Rootstock ‘Gisela 6’ Elicited by Agrobacterium tumefaciens Infection

Agrobacterium tumefaciens causes crown gall disease in plants by transferring a portion of the tumor-inducing plasmid, transfer DNA, into the plant genome. To examine the physiological changes induced by A. tumefaciens in cherry rootstock ‘Gisela 6’, we determined the activity of defense-related enzymes, including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), polyphenol oxidase (PPO), phenylalanine ammonialyase (PAL), lipoxygenase (LOX), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR), and the content of phytohormones, salicylic acid (SA) and jasmonic acid (JA), in cherry plants before and after infection. Furthermore, we assayed the expression of genes encoding these enzymes and SA and JA biosynthesis genes using quantitative real-time PCR, and examined the morphology of the infected tissue surface. Infection with A. tumefaciens increased the activity of POD, SOD, PPO, APX, MDHAR, and GR, and upregulated the expression of the corresponding genes. It also elevated the JA content of cherry plants. No significant difference was noted in CAT and PAL activity between the infected and control groups. In the treatment group, a slight increase in LOX activity was observed at 15 days post-infection (dpi), whereas DHAR activity declined by almost 50% at 10 dpi. The total SA content showed a general upward trend in infected plants but did not show a clear difference compared with the control. Overall, our data suggest that Agrobacterium infection did not elicit a hypersensitive response in ‘Gisela 6’ but altered the expression level of genes involved in defense responses and phytohormone biosynthesis.

Effects of high pressure treatment on lipolysis-oxidation and volatiles of marinated pork meat in soy sauce

To investigate the effect of high pressure (HP) treatment (150 and 300 MPa for 15 min at 20 °C) on lipolysis-oxidation and volatile profile of marinated pork meat in soy sauce, the changes of lipase, phospholipase and lipoxygenase (LOX) activities, TBARS, free fatty acids and volatiles composition in control and HP treated samples were analyzed. Acid and neutral lipase activities and free fatty acids content decreased, while LOX activity and TBARS increased after HP treatment. Phospholipase had well stability under HP. The levels of volatile compounds from lipid oxidation and brine increased under HP and then contributed 73.16–78.25% of the typical aroma, while volatile compounds from carbohydrate fermentation, especially acetic acid, decreased with the pressure increasing. The decrease of free fatty acids during pressurization was probably attributed to the decline of lipase activity and the increase of LOX activity. These findings indicated that HP (150–300 MPa/15 min) promoted lipid oxidation and the permeation of brine, but inhibited carbohydrate fermentation.

Green Synthesized Zinc-Glycine Chelate Enhances Antioxidant Protection of Pistachio under Different Soil Boron Levels

ABSTRACTZinc (Zn) and boron (B) disorders are common nutritional stresses in arid and semi-arid regions. In the current study, effectiveness of soil Zn amendment (0, 5.0, 10.0, and 20.0 mg kg–1 soil) using Zn-glycine chelate (Zn-Gly), a novel Zn-fertilizer, which is especially synthesized for application in calcareous soils in arid and semi-arid areas, was evaluated under different soil B levels (0, 2.5, 5.0, 10.0, and 20.0 mg kg–1 soil) for a 100-day period. Pistachio, the most valuable crop grown under arid conditions, was used as the model plant. Measurement of electrolyte leakage, H2O2, and malondialdehyde indicated the incidence of oxidative stress in the leaves of pistachio under low and high soil B concentrations. In addition, B stress caused a significant increase in lipoxygenase activity in the leaves. Plants treated with 5.0 mg B kg–1 soil showed the lowest oxidative stress injuries and lipid peroxidation. Application of 5.0 mg Zn kg–1 soil significantly alleviated the B stress damages, however, the ameliorative effect of Zn was vanished by application of higher Zn concentrations. Evaluation of the antioxidant enzymes (superoxide dismutase [SOD], catalase [CAT], or ascorbate peroxidase [APX]) and non-enzyme antioxidants (ascorbate and phenolic compounds) revealed that the protective effects of Zn-Gly against B stress are due to enhancement of cell antioxidant defense. In conclusion, application of Zn-Gly for reducing oxidative stress pressure in pistachio plants grown under B disorder was suggested.

Neoleucinodes elegantalis (Lepidoptera: Crambidae): an organism invisible to the defences of tomato fruits

AbstractInsect–plant interactions involving species of the genus Solanum have been intensively studied, resulting in several articles on insect–plant interactions. However, the interactions between herbivores and the fruits of Solanum lycopersicum (tomato) are not well known. Neoleucinodes elegantalis is a borer that causes great yield losses in S. lycopersicum crops because of the direct damage that it causes to the fruits and the difficulty of controlling it. In the field, the outside of a tomato fruit infested with the larvae of N. elegantalis is visually similar to uninfested fruits. Even a minor injury by herbivores can elicit a defensive response. Due to the lack of studies on interactions between fruit borers and S. lycopersicum, our aim in this study was to determine the locations of S. lycopersicum fruit in which the N. elegantalis larvae prefer to feed. An evaluation of nutritional sources was done through histochemical and biochemical tests and the defensive response of the S. lycopersicum fruit to attack by N. elegantalis larvae was evaluated through the detection of protease inhibitors (PIs) and lipoxygenase (LOX) activity. Our results show that the columella region is preferred by the N. elegantalis larvae and that this region has a nutritional source. Furthermore, attack by N. elegantalis larvae in the columella does not induce a significant increase in lipoxygenase activity and PIs. Thus, our results provide a better understanding of the interaction between the larvae of N. elegantalis and S. lycopersicum fruits and a better understanding of the evolution of plant–herbivore interactions, with an emphasis on the choice of feeding location as a strategy to avoid plant defences.

Polyamines-induced aluminum tolerance in mung bean: A study on antioxidant defense and methylglyoxal detoxification systems.

We investigated the roles of exogenously applied Spd (0.3 mM spermidine) in alleviating Al (AlCl3, 0.5 mM, 48 and 72 h)- induced injury in mung bean seedlings (Vigna radiata L. cv. BARI Mung-2). Aluminum toxicity induced oxidative damage overproducing reactive oxygen species (ROS; H2O2 and O2•-), increasing lipoxygenase activity and membrane lipid peroxidation. The toxic compound methylglyoxal (MG) also overproduced under Al stress. In order to circumvent Al-induced oxidative stress, enzymatic and non-enzymatic antioxidant defense were activated by the application of exogenous Spd. Exogenous Spd increased ascorbate (AsA) and glutathione (GSH) content, AsA/dehydroascorbate (DHA) ratio, GSH/ glutathione disulfide (GSSG) ratio, activity of ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR) and catalase (CAT) which reduced ROS production and oxidative stress under Al stress. Spd-induced improvement of GSH pool and Gly II activity alleviated injurious effects of MG. Exogenous Spd positively modulated the endogenous PAs level. Regulating the osmoprotectant molecule (proline), Spd improved plant water status under Al stress. Exogenous Spd was potent to prevent breakdown of Al-induced photosynthetic pigment and to improve growth performances under Al stress. The mechanism by which Spd enhances antioxidant and glyoxalase components might be studied extensively. Spermidine-induced protection of photosynthetic pigment from damages and growth enhancement were remarkable and recommended for further detailed study to understand the mechanism.