L-phenylalanine Ammonia-lyase Research Articles

Rice sheath blight disease control by native endophytic Bacillus subtilis from Kuttanad, a Globally Important Agricultural Heritage System

ABSTRACT Kuttanad in India is known as ‘the rice bowl of Kerala’ and renowned for its unique rice cultivation system that is below sea level. However, rice production in this wetland ecosystem is seriously threatened by sheath blight disease caused by the fungus Rhizoctonia solani, which has resulted in a significant decline in grain quality and a 50% loss in yield. In the present study, we isolated two endophytic Bacillus subtilis strains, NIIST B616 and NIIST B627, from the roots of rice plants growing in the Kuttanad region and tested their efficacy in controlling sheath blight disease. We found that rice plants inoculated with a combination of both Bacillus strains and R. solani had a 64.71% lower disease incidence and a 31.02% higher harvest index than plants treated with R. solani alone. An analysis of defence-related enzymes and chemicals revealed that treatment with both isolates together greatly enhanced levels of l-phenylalanine ammonia-lyase (PAL; 2.8 fold), peroxidase (POX; 7.4 fold), polyphenol oxidase (PPO; 4.5 fold), and total phenol (8.5 fold) compared with plants treated solely with R. solani, indicating that these isolates significantly increased plant defence responses through induced systemic resistance (ISR), and this finding was validated through a split-root experiment. More detailed analysis using gas chromatography–tandem mass spectrometry (GC-MS/MS) and liquid chromatography–tandem mass spectrometry (LC-MS/MS) techniques revealed that cyclo-(Pro-Leu) and cyclo-(Pro-Phe) were the major components responsible for the antifungal properties of the two isolates and their capacity to trigger ISR in plants. Thus, the Bacillus strains and their metabolites may be deemed viable alternatives for controlling the prevalence of sheath blight disease in rice plants and augmenting rice production at unique locations such as Kuttanad.

Metabolomic profiling reveals altered phenylalanine metabolism in Parkinson's disease in an Egyptian cohort.

Introduction: Parkinson's disease (PD) is the most common motor neurodegenerative disease worldwide. Given the complexity of PD etiology and the different metabolic derangements correlated to the disease, metabolomics profiling of patients is a helpful tool to identify patho-mechanistic pathways for the disease development. Dopamine metabolism has been the target of several previous studies, of which some have reported lower phenylalanine and tyrosine levels in PD patients compared to controls. Methods: In this study, we have collected plasma from 27 PD patients, 18 reference controls, and 8 high-risk controls to perform a metabolomic study using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Results: Our findings revealed higher intensities of trans-cinnamate, a phenylalanine metabolite, in patients compared to reference controls. Thus, we hypothesize that phenylalanine metabolism has been shifted to produce trans-cinnamate via L-phenylalanine ammonia lyase (PAL), instead of producing tyrosine, a dopamine precursor, via phenylalanine hydroxylase (PAH). Discussion: Given that these metabolites are precursors to several other metabolic pathways, the intensities of many metabolites such as dopamine, norepinephrine, and 3-hydroxyanthranilic acid, which connects phenylalanine metabolism to that of tryptophan, have been altered. Consequently, and in respect to Metabolic Control Analysis (MCA) theory, the levels of tryptophan metabolites have also been altered. Some of these metabolites are tryptamine, melatonin, and nicotinamide. Thus, we assume that these alterations could contribute to the dopaminergic, adrenergic, and serotonergic neurodegeneration that happen in the disease.

TMT-based proteomic and transcriptomic analysis reveal new insights into heat stress responsive mechanism in edible mushroom Grifola frondosa

High temperature can lead to severe retardation in the growth and development of mushrooms, which influence the quality of fruiting bodies. Grifola frondosa is a popular and wide-cultivated mushroom in Asia; however, little information about the heat response mechanism in this commercially cultivated mushroom has been reported. The growth test was performed to determine the heat tolerance of different strains. Then, the TMT-based proteome and transcriptome analysis of major G. frondosa cultivar Qinghui-151 under different temperatures were performed. High temperature seriously affected the growth and recovery growth of mycelia. Thirty-four heat shock proteins (HSPs) were identified in the multiomics data and the expressions of most HSPs were induced by high temperature. The accumulation of HSPs under the control of HSFs is assumed to play a central role in the heat stress response (HSR) in G. frondosa. mTOR and Ca2+ signaling pathways were found to be activated under high temperature and might involved in heat stress signaling transduction. Polyamines synthesis enzymes were also up-regulated, suggesting the accumulation of stress protector polyamines under heat stress. In addition, expression of an L-phenylalanine ammonia-lyase (GfPAL) gene was significantly up-regulated under high temperature, which might be related to secondary metabolites synthesis. Taken together, these findings improve our understanding of the molecular mechanisms underlying the response to heat stress in G. frondosa, which could promote the breeding of new heat-tolerant G. frondosa cultivars.

Changes in Phytohormone and Antioxidant Enzyme Activities during the Healing Process of Different Crabapple Rootstock–Scion Combinations

By measuring the changes in phytohormones and related enzyme activities of Malus ‘Huabiao’ scions and different rootstocks during the healing process of grafting, this study aims to analyze the effects of different rootstocks on the physiological metabolism of the grafting healing site, thereby providing reference for the selection of M. ‘Huabiao’ grafting rootstocks. The live seedlings of 1-0 M. hupehensis, M. robusta and M. baccata were chosen as rootstocks, and M. ‘Huabiao’ scions were grafted with these seedlings in spring by pasting method. The dynamic changes in activities of indole acetic acid, zeatin riboside, methyl jasmonate content and peroxidase, polyphenol oxidase and L-phenylalanine ammonia-lyase at the healing site of grafting were measured, and the effects of different grafting combinations on the phytohormone and related enzyme activities at the grafted site were investigated. It was found that the M. ‘Huabiao’/M. hupehensis and M. ‘Huabiao’/M. robusta grafting combinations had significantly higher survival rate than M. ‘Huabiao’/M. baccata which only had a success rate of 63%. At the beginning of graft healing, the contents of three phytohormones in healing sites of all the three grafting combinations exhibited a significant decrease. However, in the mid and late stages, great differences were shown in phytohormone content. During the grafting healing process, the changes in three enzyme activities in healing sites of the three grafting combinations showed some regularities. In conclusion, M. hupehensis and M. robusta have strong grafting compatibility with M. ‘Huabiao’; thus, they are suitable to be selected as rootstocks for grafting and propagation of M. ‘Huabiao’. In addition, the changes in phytohormone content and enzyme activity in different grafting combinations reflect the strong affinity relationship between rootstock and scion grafting.

The use of L-phenylalanine ammonia lyase inhibitors in plant ecophysiological studies

Phenylalanine ammonia lyase (PAL) is a key enzyme controlling the biosynthesis of phenolic compounds in plants. PAL catalyzes ammonia elimination from L-phenylalanine in a reaction that yields cinnamic acid, a precursor of a large group of phenylpropanoid compounds. Phenylpropanoids and their derivatives play an important role in regulating plant resistance mechanisms under environmental stresses. By reducing the level of phenolic compounds, PAL inhibitors can induce changes in plant metabolism. This paper presents the current state of knowledge on the use of PAL inhibitors in plant biology, and draws attention to the possibilities of using PAL inhibitors in agriculture in the context of the witnessed climate changes which increase the frequency and intensity of some disasters such as droughts, floods and storms. By reducing the level of phenolic compounds, PAL inhibitors can induce changes in plant metabolism. This paper presents the current state of knowledge on the use of PAL inhibitors in plant biology, and draws attention to the possibilities of using PAL inhibitors in agriculture in the context of the witnessed climate changes.

Mechanism of Zn alleviates Cd toxicity in mangrove plants (Kandelia obovata).

Cadmium (Cd) pollution is very common and serious in mangrove ecosystems in China. Zinc (Zn) has been used to reduce Cd accumulation in plants, and phenolic acid metabolism plays an important role in plant response to stress. In present study, in order to clarify whether Zn alleviates Cd toxicity in mangrove plants through phenolic acid metabolism, the Cd-contaminated Kandelia obovata plants were treated with different concentrations of (0, 80,300, and 400 mg·kg-1) ZnSO4 in a set of pot experiments and the biomass, the contents of Cd, Zn, soluble sugar, chlorophyll and the activities of 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric-reducing antioxidant power (FRAP), l-phenylalanine ammonia-lyase (PAL), shikimic acid dehydrogenase (SKDH), cinnamyl alcohol dehydrogenase (CAD) and polyphenol oxidase (PPO) in the leaves were analyzed. The results showed that Cd contents in the leaves of Kandelia obovata ranged from 0.077 to 0.197 mg·kg-1 under different treatments, and Zn contents ranged from 90.260 to 114.447 mg·kg-1. Low-dose ZnSO4 treatment (80 mg·kg-1) performed significant positive effects on the biomass, phenolic acid metabolism-related enzyme activities, antioxidant capacity, and chlorophyll and soluble sugar contents in the leaves of Cd-contaminated mangrove plants. At the meantime, the addition of low-dose ZnSO4 promoted the biosynthesis of hydroxycinnamic acid, hydroxybenzoic acid, and enhanced the plant antioxidant capacity, thus alleviated Cd toxicity in mangrove plants.

Identification of Resistance to Pathogenesis Related Protein GmPR1L in Tobacco Botrytis cinerea Infection

Soybean (<i>Glycine max</i> (Linn.) Merr.) annual leguminous crop is cultivated all over the world. The occurrence of diseases has a great impact on the yield and quality of soybean. In this study, based on the RNA-seq of soybean variety M18, a complete CDS (Coding sequence) <i>GmPR1L</i> of the pathogenesis-related protein 1 family was obtained, which has the ability to resist fungal diseases. The overexpression vector and interference expression vector were transferred into tobacco NC89, and the resistance of transgenic tobacco (<i>Nicotiana tabacum</i> L.) to <i>Botrytis cinerea</i> infection was identified. The results show that: Compared with the control, the activities of related defense enzymes SOD (Superoxide dismutase), POD (Peroxidase), PAL (L-phenylalanine ammonia-lyase) and PPO (Polyphenol oxidase) in the over-expressed transgenic tobacco OEA1 and OEA2 increased to different degrees, and increased significantly at different infection time points. The activities of defense enzymes in the interfering strains IEA1 and IEA2 were significantly lower than those in the control strains. The results of resistance level identification showed that the disease spot rate of OEA1 was significantly lower than that of the control line, and the disease spot rate of OEA2 was significantly lower than that of the control line. The plaque rate of the interfering expression line IEA1-IEA2 was significantly higher than that of the control line. It is preliminarily believed that the process related protein <i>GmPR1L</i> can improve the resistance of tobacco to <i>B. cinerea</i>.

Cell dehydration of intergeneric hybrid induces subgenome-related specific responses.

The aim was to identify subgenome-related specific responses in two types of triticale, that is, of the wheat-dominated genome (WDG) and rye-dominated genome (RDG), to water stress induced in the early phase (tillering) of plant growth. Higher activity of the primary metabolism of carbohydrates is a feature of the WDG type, while the dominance of the rye genome is associated with a higher activity of the secondary metabolism of phenolic compounds in the RDG type. The study analyzed carbohydrates and key enzymes of their synthesis, free phenolic compounds and carbohydrate-related components of the cell wall, monolignols, and shikimic acid (ShA), which is a key link between the primary and secondary metabolism of phenolic compounds. Under water stress, dominance of the wheat genome in the WDG type was manifested by an increased accumulation of the large subunit of Rubisco and sucrose phosphate synthase and a higher content of raffinose and stachyose compared with the RDG type. In dehydrated RDG plants, higher activity of L-phenylalanine ammonia lyase (PAL) and L-tyrosine ammonia lyase (TAL), as well as a higher level of ShA, free and cell wall-bound p-hydroxybenzoic acid, free homovanillic acid, free sinapic acid, and cell wall-bound syringic acid can be considered biochemical indicators of the dominance of the rye genome.

Evaluation of synthesized magnetic nanoparticles and salicylic acid effects on improvement of antioxidant properties and essential oils of Calotropis procera hairy roots and seedlings

Calotropis procera (Aiton) W.T.Aiton presents high levels of medicinally important terpenes and phenolics with antiinflammatory, antimicrobial, and antioxidant properties. The present study aimed to develop a suitable platform for mass production of pharmacological metabolites and improvement of antioxidant activity of C. procera. Motivated by such aim, potential effects of Fe3O4 nanoparticles (Fe3O4 NPs) and salicylic acid (SA) on antioxidant defense response and essential oils in seedlings and hairy roots were investigated. 21-day-old seedlings were treated by five levels of Fe3O4 NPs (0, 50, 100, 150, and 200 mg L−1) and three SA concentrations (0.0, 0.05, 0.1 mM). Moreover, the hairy roots about 2 cm were transferred into MS liquid medium supplemented with the above-mentioned concentrations of Fe3O4 NPs and 0 and 0.01 mM SA. After treatment, total phenolics, flavonoids, flavonol, anthocyanin, activity of polyphenol oxidase and l-phenylalanine ammonia-lyase, ferric-reducing antioxidant power, 2, 2‑diphenyl‑1‑picrylhydrazyl and production of essential oils were analyzed. Results demonstrated that hairy root culture is a powerful alternative for improving and inducing secondary metabolites of C. procera as compared to seedlings. Moreover, it was found that Fe3O4 NPs combined with SA have the more ability than all other treatments to improve antioxidant activity and essential oil in both seedlings and hairy roots. Here, 100 and 200 mg L−1 Fe3O4 NPs combined with 0.01 mM SA had more pronounced impact on induction of pharmacological constituents and antioxidant activity. Results suggest that Fe3O4 NPs and SA in hairy root culture can bring great insights into development in vitro biosynthesis of valuable secondary metabolites. Synthesized magnetic Fe3O4 nanoparticle combined with the salicylic acid in hairy root culture may be considered as a good alternative approach for the mass production of antioxidant and novel pharmacological metabolites of Calotropis procera.

Bioactivities of Phenylpropanoids Extracted from Ephemeral Flowers of Medicinal Woody Species Murraya paniculata (Linn.) Jack

Flowers of Murraya paniculata were assessed for production of phenolic secondary metabolites and were found to yield temporally variable concentrations of total phenolics and flavonoids due to enzymatic regulation by L-phenylalanine ammonia lyase. Maximum yield of phenolics was obtained from partly open flowers, with esterified hydroxycinnamic acids (mainly ferulic acid) forming the major component. Scopoletin-a coumarin product of ferulic acid - was isolated consistently from senescent flowers by High Performance Liquid Chromatography (HPLC). Approximately 200 mg of fresh floral tissue extracted with one millilitre solvent (methanol:water :: 30:70) yielded up to 1.6 mg of ferulic acid and 40 μg of scopoletin from partly open (at 18:00 h) and senescent (at 06:00 h) blooms respectively. Along with other hydroxycinnamic acid and coumarin components of M. paniculata flowers detected by HPLC, o-coumaric acid and isoauraptene were identified by Gas Chromatography-Mass Spectrometry. Various free-radical scavenging assays revealed the ferulic acid fraction to have stronger antioxidant activities than the scopoletin fraction, but no antibiotic activity was detected for ferulic acid. Total antioxidant capacities of ferulic acid and scopoletin fractions were estimated to be 9% and 7.8% of that of ascorbic acid standard, respectively. Scopoletin fraction exhibited Minimum Inhibitory Concentrations at 0.585 mg.mL-1 against Bacillus subtilis and 1.372 mg.mL-1 against Escherichia coli. The high concentrations of these bioactive phenylpropanoids in such a common flower species presents potential application in low-risk crop protection and plant-based nutraceuticals.

Dual Mechanisms of Coniferyl Alcohol in Phenylpropanoid Pathway Regulation.

Lignin is a complex phenolic polymer that imparts cell wall strength, facilitates water transport and functions as a physical barrier to pathogens in all vascular plants. Lignin biosynthesis is a carbon-consuming, non-reversible process, which requires tight regulation. Here, we report that a major monomer unit of the lignin polymer can function as a signal molecule to trigger proteolysis of the enzyme L-phenylalanine ammonia-lyase, the entry point into the lignin biosynthetic pathway, and feedback regulate the expression levels of lignin biosynthetic genes. These findings highlight the highly complex regulation of lignin biosynthesis and shed light on the biological importance of monolignols as signaling molecules.

Alginate oligosaccharide improves resistance to postharvest decay and quality in kiwifruit (Actinidia deliciosa cv. Bruno)

Kiwifruit is an extremely perishable fruit; postharvest disease and senescence during storage can reduce the fruit quality, resulting in economic loss. Considerable research effort has focused on identifying safe and cost-effective ways to preserve fresh kiwifruit. To this end, the present study investigated the effects of alginate oligosaccharide (AOS) soaking treatment on postharvest quality and disease in the ‘Bruno’ variety of kiwifruit. The involved physiological mechanisms were further explored. The results showed that AOS did not inhibit the growth of Botrytis cinerea in vitro, the causal agent of gray mold in kiwifruit, but reduced the incidence of gray mold and diameter of lesions of kiwifruit during storage. Kiwifruit treated with 50 mg · L−1 AOS showed a higher degree of firmness and lower soluble solid content than control fruit treated with distilled water. Moreover, AOS treatment inhibited the activity of polygalacturonase and pectinesterase, while enhancing the activity of polyphenoloxidase, l-phenylalanine ammonia lyase and β-1,3-glucanase related to pathogen defense, and also improved total antioxidant capacity determined by the DPPH, FRAP, and ABTS methods in kiwifruit. These results indicate that 50 mg · L−1 AOS can confer disease resistance in kiwifruit during storage.

English

Procyanidins (PAs) is the important flavonoids components in strawberry young fruits, whichis synthesizedthrough direct polymerizationof flavanone-3-ol units. Numerous studies have beendone on the synthesis of PAs, while the oxidation/polymerization processes have not been fully explored. AtTT10, a laccasel-like polyphenol oxidase,was recently reported to be participated in the oxidative polymerization of proanthocyanidins. Whether FaTT10hasapositiveeffect onoxidative polymerization of strawberry fruit PAsis unclear. In this study, FaTT10 in strawberries were isolated and analyzed. Transient overexpression of FaTT10 decreased the accumulation of PAs monomer in strawberry fruit,whereas RNA interference increased the level of anthocyanin and PAs monomer. 4-Dimethylaminocinamaldehyde (DMACA)staining results also showed that lighter blue color in the FaTT10-RNAi fruit and concentrated blue color in the FaTT10-overexpression fruit. Meanwhile, PAs monomer showed a drop-and-rise tendency during strawberry fruit development and ripening.Furthermore, the expression of several flavonoids metabolism-related geneswere affected by the altered FaTT10 gene expression levels, such as L-phenylalanine ammonia-lyase(PAL); dihydroflavonol reductase(DFR);chalcone isomerase(CHI); flavanone 3-hydroxylase(F3H); 4-coumarate:CoA ligase(4CL); Cinnamate 4-hydroxylase(C4H); chalcone synthase(CHS); anthocyanin reductase(ANR); lecoanthocyanidins reductase(LAR) andanthocyanin synthase(ANS). In conclusion, these results revealed that FaTT10 is specifically involved in oxidative polymerization of PAsby regulating the expression of flavonoids metabolism-related genes in strawberry fruits. © 2021 Friends Science Publishers

Nanocapsules of oregano essential oil preparation and characterization and its fungistasis on apricot fruit during shelf life

Oregano essential oil nanocapsules (OEO-NPs) were successfully prepared via a complex coacervation method. The results of this study showed that the percentage encapsulation of the OEO-NPs prepared by the best technological process was 88.3%, the loading amount of oregano essential oil (OEO) was 74.36%, and the average particle size was 135 nm. OEO-NPs exhibited better spherical and regular surface structure, higher thermal stability, and slow-release performance. In addition, the 4% OEO-NPs showed better fungistatic effect and reduced decay rate, which compared with the control, 2% and 8% OEO-NPs treatments, during apricot shelf life; 4% OEO-NPs also increased peroxidase, L-phenylalanine ammonialyase, β-1,3-glucanase, catalase and chitinase activities, while reduced the polyphenol oxidase activities during fruit shelf life than that in control. These results provided a new idea for the development of a slow-release fungistatic agent based on plant essential oils. Novelty impact statement Oregano essential oil nanocapsules (OEO-NPs) possessed higher thermal stability and slow-release performance. 4% OEO-NPs showed a better fungistatic effect and reduced apricot fruit decay rate during shelf life. OEO-NPs provided a new idea for the development of green and slow-release fungistatic agent.

Cell wall modification induced by an arbuscular mycorrhizal fungus enhanced cadmium fixation in rice root

The chemistry of root cell wall of rice could be changed by inoculation of arbuscular mycorrhizal fungi (AMF). Hydroponic experiments were conducted to investigate the roles of such changes on cadmium (Cd) uptake and distribution in rice. Results showed that inoculation of AM fungus Rhizophagus intraradices (RI) significantly enhanced (p < 0.05) shoot biomass, plant height and root length of rice, and decreased Cd concentration in shoot and root under Cd stress. Moreover, Cd in root was mainly found in pectin and hemicellulose 1 (HC1) components of root cell wall. Inoculation of RI increased the levels of pectin, HC1 and lignin content, accompanied by the increments of L-phenylalanine ammonia-lyase (PAL) and pectin methylesterase (PME) activities. Results of Fourier transform infrared spectroscopy further showed that more hydroxyl and carboxyl groups in root cell wall were observed in mycorrhizal treatment, compared with control. This study demonstrates that cell wall components could be the locations for Cd fixation, which reduced Cd transportation from root to shoot. Inoculation of AMF may remodel root cell wall biosynthesis and affect the characteristics of Cd fixation. The entering and fixing mechanisms should be further studied.

Study of the l-Phenylalanine Ammonia-Lyase Penetration Kinetics and the Efficacy of Phenylalanine Catabolism Correction Using In Vitro Model Systems.

The kinetics of l-phenylalanine ammonia-lyase (PAL) penetration into the monolayer of liver cells after its release from capsules was studied. The studies showed the absence of the effect of the capsule shell based on plant hydrocolloids on the absorption of l-phenylalanine ammonia-lyase in systems simulating the liver surface. After 120 min of incubation, in all variants of the experiment, from 87.0 to 96.8% of the enzyme penetrates the monolayer of liver cells. The combined analysis of the results concludes that the developed encapsulated form of l-phenylalanine ammonia-lyase is characterized by high efficiency in correcting the disturbed catabolism of phenylalanine in phenylketonuria, which is confirmed by the results of experiments carried out on in vitro model systems. PAL is approved for the treatment of adult patients with phenylketonuria. The encapsulated l-phenylalanine ammonia-lyase form can find therapeutic application in the phenylketonuria treatment after additional in vitro and in vivo studies, in particular, the study of preparation safety indicators. Furthermore, it demonstrated high efficacy in tumor regression and the treatment of tyrosine-related metabolic disorders such as tyrosinemia. Several therapeutically valuable metabolites biosynthesized by PAL via its catalytic action are included in food supplements, antimicrobial peptides, drugs, amino acids, and their derivatives. PAL, with improved pharmacodynamic and pharmacokinetic properties, is a highly effective medical drug.

Influence of Cyanobacterial Biofertilizer on the Response of Zea mays Plant to Cadmium-stress

CADMIUM (Cd) pollution is a thoughtful problem that alters crop yield and agricultural soils worldwide. Cyanobacteria are emerging candidates as eco-friendly biofertilizers. The present study evaluates the capability of super blue green biofertilizer (cyanobacteria biofertilizer (CB); Nostoc sp. and Anabaena sp.) to alleviate the Cd toxicity on 21 d-old Zea mays plants (applied as 2 and 10mM CdSO4). Application of CB significantly improved maize growth and reduced Cd-accumulation. Cadmium-induced oxidative stress indicated by increment of malondialdehyde (MDA), H2O2 contents and electrolyte leakage (EL) was diminished upon application of CB. Cd-stress significantly induced L-phenylalanine ammonia-lyase (PAL) specific activity and phenolics accumulation in the leaves and roots of maize plants. The results revealed that Cd-stress markedly enhanced GSH/GSSG ratio, gltuthione reductase (GR), superoxide dismutase (SOD) and catalase (CAT) specific activities, while it decreased that of ascorbate peroxidase (APx) and guaiacol peroxidase (GPx) and insignificantly increased polyphenol oxidase (PPO). The isozyme pattern of peroxidase was changed upon Cd-exposure. CB application significantly reduced both of the Cd-induced accumulated phenolics content and reduced glutathione (GSH) while it increased total glutathione (TG). CB application significantly induced all tested antioxidant enzymes. The data revealed that CB application could reduce Cd toxicity in maize plants.

The Impact of Biopreparations and Phytopathogenic Bacteria of the Pseudomonas Genus on L-Phenylalanine Ammonia-Lyase Activity in Soybean and Lupine Plants

It is known that plant protection against diseases is based mainly on the use of pesticides. These chemicals or their degradation products have a detrimental effect on the environment and human health. Due to this, the search for methods of plant protection that are safe for the environment is becoming increasingly popular. Induction of plant resistance to disease is one of the promising non-chemical ways of protection, in which plant enzymes play a key role. It was shown that in response to pathogen invasion, plants enhance protective properties by inducing the activity of a wide range of enzymes that slow the spread of infection, in particular: peroxidases, β-1,3-glucanases, chitinases, polyphenol oxidases and L-phenylalanine ammonia-lyase (PAL). The aim of the research was to study the change in PAL activity in soybean and lupine plants under conditions of artificial infection with some phytopathogenic bacteria of the Pseudomonas genus and under the action of Ecovital and EPAA-M biological preparations. Methods. PAL activity was determined spectrophotometrically. Changes of soybean (Glycine max) and lupine (Lupinus luteus L.) plants resistance to diseases caused by bacteria of the Pseudomonas genus were evaluated using phytopathological methods. Statistical processing of the research results was performed using MS Excel computer program with Student’s t-test and estimation of least significant difference (LSD). Results. It was found that under conditions of soybean and lupine plants infection with phytopathogenic bacteria of the Pseudomonas genus on the background of pre-sowing seed treatment with Ekovital and EPAA-M biological preparations, composition based on them and synthetic standard – salicylic acid a significant increase in FAL activity in the aboveground and the degree of infectious roots – reducing of plants with pathogens was observed. It has been established that the growth of PAL activity under the condition of infection with phytopathogenic bacteria of the Pseudomonas genus occurs after 2–6 h and lasts up to 7 days from the moment of phytopathogen invasion into the plant. The most increasing of PAL activity was after treatment of seeds with Ecovital and EPAA-M composition – by 38.1–73.3% (Lupinus luteus L.) and 60.4–110% (Glycine max) compared to the control. Treatment with the composition of biological products also helped to reduce the degree of plant damage. PAL activity increasing and reducing the area of soybean and lupine leaves affected surface can indicate the induction of protective reactions in plants. Conclusions. The use of the composition of EPAA-M with the microbial preparation Ecovital contribute to the increase of PAL activity and the formation of resistance to phytopathogenic bacteria of the genus Pseudomonas in Glycine max and Lupinus luteus L. plants.

Endophytic Bacillus megaterium triggers salicylic acid-dependent resistance and improves the rhizosphere bacterial community to mitigate rice spikelet rot disease

Endophytes have been demonstrated to trigger salicylic acid-dependent resistance and alter rhizosphere bacterial communities. However, few comprehensive studies have been conducted to elucidate the interactions between the direct (systemic resistance) and indirect (rhizosphere microbiome) defenses triggered by endophytes. The present study aimed to illuminate the possible roles of endophytic Bacillus megaterium in rice resistance against rice spikelet rot disease (SRD), and to make inferences on the potential interactions between plant defenses and the rhizosphere microenvironment. An outdoor pot experiment was conducted to explore the degree to which endophytes mitigate disease in rice, where four combination treatments were designed (inoculation and non-inoculation with B. megaterium, and infection with and without Fusarium proliferatum). Rice plants and rhizosphere soil, at the heading stage, were sampled to measure the accumulation of defense-related enzymes, including L-phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), β-1,3-glucanase and chitinase, and to perform 16S rRNA Illumina sequencing. Defense-related enzyme activities in rice plants inoculated with B. megaterium showed local or systemic increases. Plant-beneficial bacteria were found to be enriched when rice plants were treated with the endophyte. A correlation between plant resistance and the rhizosphere microbiome was also observed. The present study highlights the significance of B. megaterium for plant defenses against SRD through dual mechanism — systemic resistance and rhizosphere microbiome. Inferences of this study elucidate correlations between plant defenses and the rhizosphere microenvironment, which were attributed to the presence of B. megaterium.

Study of the Potential of the Capsule Shell Based on Natural Polysaccharides in Targeted Delivery of the L-Phenylalanine Ammonia-Lyase Enzyme Preparation.

The treatment of classical phenylketonuria is currently represented by many new methods of disease management. A promising method is the use of the enzyme L-phenylalanine ammonia-lyase (PAL) in various forms. The widespread use of enzyme preparations in therapy is limited by a lack of understanding of the mechanisms and systems of the targeted transport of PAL into certain organs and tissues as a result of the incorporation of a drug into the carrier. To ensure the stability of enzymes during the delivery process, encapsulation is preferable, which, as a rule, ensures the preservation of the qualitative characteristics of the enzymes orally applied to the environmental effects of the gastrointestinal tract (acidity, temperature, oxidation, etc.). Capsule preparations showed sufficient stability in the model gastric fluids and sustained release of the drug in the simulated intestinal fluid. Currently, there is a wide range of polymers used for encapsulation. The use of natural sources in the production technology of capsule systems improves bioavailability, controls the release, and prolongs the half-life of active substances. The advantage of this method is that the used enzyme is completely protected by the cell membranes of the capsules, which preserve its stability in the aggressive environment of the gastrointestinal tract. Capsules were obtained on the basis of compositions of hydrocolloids of plant origin. The potential of the developed capsules for targeted delivery of the enzyme preparation was studied. The degradation of the encapsulated form of the PAL enzyme preparation was studied in vitro in model bio-relevant media simulating the gastric and intestinal environment. The dynamics of the breakdown of the capsule shell allow us to expect that the release of L-phenylalanine ammonia-lyase from capsules based on plant hydrocolloids will occur no earlier than reaching the upper intestines, where the interaction with the protein components of the consumed food products to neutralize phenylalanine should occur.