Maximum Phenylalanine Ammonia Lyase Activity Research Articles

Phenylalanine response in rice kernel under chitosan nanoparticles spraying

Since phenylketonuria patients have a metabolic defect, should use specific foods that have low phenylalanine levels. These foods are usually produced by hydrolysis processes. The most important problems of the foods are unpleasant to taste and expensive. The main objective of this study was to investigate the possibility of reducing the amount of phenylalanine in rice kernel under spraying of chitosan nanoparticles. Treatments were different concentrations of chitosan nanoparticles spraying (0, 500, 1000, 1500 µl L−1). The treatments effects were studied in a randomized complete block design with four replications. Experimental variables were phenylalanine, phenylalanine ammonia-lyase activity and total grain protein. The results showed that the total protein and phenylalanine level in rice kernel decreased under all concentrations of chitosan nanoparticles compared to the control, while the activity of phenylalanine ammonia-lyase was higher than that of the control. In this experiment, 1000 µl L−1 of chitosan nanoparticles was found as the optimum concentration, since minimum phenylalanine level and maximum phenylalanine ammonia-lyase activity were affected by this concentration. Therefore, chitosan nanoparticles spraying during the grain growth was able to reduce phenylalanine level in rice kernel.

Efficacy of different combinations of microbial biocontrol agents against sheath blight of rice caused by Rhizoctonia solani

BackgroundSheath blight of rice caused by Rhizoctonia solani is one of the most important diseases worldwide, causing considerable yield losses. The estimation of losses due to sheath blight of rice in India has been reported to be up to 54.30%. As a consequence of this fact, eco-friendly approaches were explored in this investigation.ResultsThe pathogen R. solani was isolated from the infected sheath of rice plant, which was identified and characterized on the basis of morphology and through molecular Sequencing. The sequences of ITS were submitted to NCBI GenBank and the accession number allotted is SUB11543577. In dual culture best two potential isolates of biocontrol agents were selected Pseudomonas fluorescens (Pf27) and Trichoderma harzianum (Th47). Their different combinations with Herbal Kunapajala (HKJ) were tested in glasshouse, experimental field and farmers’ fields against sheath blight pathogen R. solani. The maximum plant vigor index was found in treatment combination P. fluorescens (27) + T. harzanium (47) + Herbal Kunapajala, seed treatment, soil drenching and three foliar applications. Minimum disease severity and incidence at 30 days after sowing (DAS) and 60DAS, maximum Phenylalanine Ammonia Lyase Activity (PAL), Polyphenol Oxidase Activity (PPO) and Peroxidase Activity (PO) were also recorded in the same treatment. In field experiment the maximum population of biocontrol agents after 60 days of transplanting cfu/g soil for Trichoderma spp. (32.33 × 104) and Pseudomonas spp. (36.33 × 104) in rhizosphere and in rhizoplane. Maximum cfu/g soil for Trichoderma spp. (24.67 × 104) and Pseudomonas spp. (24.0 × 104) was observed in treatment Th + Pf + HKJ [seed treatment + soil drenching + foliar spray]. At experimental and farmers field minimum disease severity, disease incidence at 60 DAT was recorded in treatment Th + Pf + HKJ [seed treatment + soil drenching + foliar spray] and was at par with the chemical treatment Carbendazim, but the maximum yield was obtained in the treatment Th + PF + HKJ [seed treatment + soil drenching + foliar spray] due to the maximum growth promotion activity.ConclusionsAmong various treatment seed treatment, soil drenching and three foliar sprays with combination T. harzianum (47), P. fluorescens (27) and Herbal Kunapajala was found very effective in reducing the disease incidence, disease severity and increasing growth promotion activity at all conditions. Therefore, the recommendation of this investigation could be exploited under bio-intensive disease management program for sustainable cultivation of rice.

南美斑潜蝇为害对黄瓜体内4种防御酶活性的影响

The pea leafminer,Liriomyza huidobrensis( Blanchard),is a widely distributed pest of ornamental and vegetable crops from subtropical to temperate regions and can cause economic losses to host plants by both adult and larval infestations. Larval mining in palisade parenchyma tissue reduces the photosynthetic capacity of plants up to 62%,and severely infested leaves may fall. A further damage to leaves is caused by females,which use the ovipositor to make holes in the surfaces of the leaves promoting the production of leaf exudates on which both females and males feed. The defensive responses of plants to insect herbivory play an important part in the interactive relationship between insects and plants. Insects obtain their nourishment from plants. The nutritional quality of plants and the limited availability of various plant parts deter many insects from using plants as a food source. Insects can be prevented from feeding by plant defenses, ranging from physical barriers to toxins and antifeedants. Plants produce a considerable variety of chemicals with roles in defense against herbivory. These chemicals include secondary plant metabolites and some proteins. Plants can produce proteins that play a critical role in defense by targeting the digestive system of insects,thus impairing the ability of the insect to digest and absorb food. These proteins include protease inhibitors and defensive enzymes which are widespread in plants and are inducible by wounding and herbivory. Four main defensive enzymes,including phenylalanine ammonialyase( PAL),polyphenol oxidase( PPO),peroxidase( POD) and superoxide dismutase( SOD),are key enzymes in the generating process of secondary plant metabolites. However,the interactions between the leafminer and its host plants have been studied mainly on the relationship between host preference of adults and trichomes,volitales,primary and secondary metabolites in host plants. In order to explore the interaction between L. huidobrensis herbivory and plant defense,we investigated the changes in the active levels of these four defensive enzymes in the leaves of cucumber plants that had been continuously feeding by the larvae for 1,3,5,7 and 9 days,respectively.The results indicated that the activities of four enzymes in the leaves of cucumber plants,which had been feeding by the larvae,rose significantly. The magnitude of activity rising of PAL,PPO and POD increased with the increase of damaged levels,i. e. damaged heavily lightly systemically undamaged,but the change of SOD activity were not regular. The maximum activities of PAL,PPO,POD and SOD appeared on the 5th,1st,5th and 5th day,respectively,in the systemic controls. They were on the 5th,9th,5th and 9th day,respectively,in the damaged-lightly leaves,and on the 7th,7th,5th and 5th day,respectively,in the damaged-heavily leaves. The magnitudes of activity increasing of POP and PPO were more than those of PAL and SOD after the leaves had been feeding,which suggests the responses of POP and PPO to insect herbivory are more sensitive than those of PAL and SOD.

Foliar application of l-phenylalanine and ferulic acids to pea plants: induced phenylalanine ammonia lyase activity and resistance against Erysiphe pisi

Phenylalanine ammonia lyase (PAL) activity was measured using HPLC in pea leaves following exogenous application of l-phenylalanine and ferulic acid. Treatment with different concentrations (50, 100 and 150 ppm) of l-phenylalanine caused increased activity of PAL in comparison to the control. In pea leaves treated with 50 ppm l-phenylalanine, maximum PAL activity was observed after 72 h of treatment. Application of ferulic acid first reduced PAL activity at lower concentration (50 ppm) but increased at higher concentrations of the compound (100 and 150 ppm) in pea leaves as compared to the control. Maximum PAL activity was 0.19 nM cinnamic acid/min/g fresh wt. after 24 h at 50 ppm and then increased with time. Treatment with both the compounds significantly reduced conidial germination of Erysiphe pisi on pea leaves. They were equally effective at 100 and 150 ppm in reducing conidial germination. The conidial germination on l-phenylalanine-treated leaves was 26% after 24 h and that on ferulic acid-treated leaves was 34% as compared to the control (46%). Foliar application of different concentrations of l-phenylalanine increased the level of ferulic acid in the leaves of pea plants. Maximum accumulation of ferulic acid (79.3 and 83.5 μg/g fresh wt.) was observed following the application of l-phenylalanine after 24 h and 48 h, respectively. At 50 ppm, ferulic acid accumulation in pea leaves was 35.6 and 39.4 μg/g fresh wt. and 74.3 and 86.5 μg/g fresh wt. at 100 ppm.

Exogenous application of L-phenylalanine and ferulic acid enhance phenylalanine ammonia lyase activity and accumulation of phenolic acids in pea (Pisum sativum) to offer protection against Erysiphe pisi

Phenylalanine ammonia lyase (PAL) activity was measured using HPLC in pea leaves following exogenous application of L-phenylalanine and ferulic acid. Treatment with different concentrations (50, 100, 150 ppm) of L-phenylalanine caused increased activity of PAL activity in comparison to control. In pea leaves treated with 50 ppm L-phenylalanine, maximum PAL activity was observed after 72 h of treatment. Application of ferulic acid first reduced PAL activity at lower concentration (50 ppm) but it further increased at higher concentrations of the compound (100 and 150 ppm) in pea leaves compared to control. Minimum PAL activity was 0.19 nM cinnamic acid/min/g fresh wt after 24 h at 50 ppm and then increased with time. Treatment with both compounds significantly increased the accumulation of phenolic acids and salicylic acid and reduced conidial germination of Erysiphe pisi on pea leaves. They were equally effective at 100 and 150 ppm in reducing conidial germination. Conidial germination on L-phenylalanine-treated leaves was 26% after 24 h and that on ferulic acid treated leaves 34% compared to control (46%). Foliar application of different concentrations of L-phenylalanine increased the level of ferulic acid in the leaves of pea plants. Maximum enzyme activity in terms of the accumulation of cinnamic acid (79.3 and 83.5 μg/g fresh wt) was observed following the application of L-phenylalanine after 24 and 48 h respectively. At 50 ppm, cinnamic acid accumulation in pea leaves was 35.6 and 39.4 μg/g fresh wt and 74.3 and 86.5 μg/g fresh wt at 100 ppm.

Modeling and Optimization of Phenylalanine Ammonia Lyase Stabilization in Recombinant Escherichia coli for the Continuous Synthesis of l-Phenylalanine on the Statistical-Based Experimental Designs

Some approaches for improving recombinant phenylalanine ammonia lyase (PAL) stability in Escherichia coli during the enzymatic methods of l-phenylalanine (l-Phe) production were developed following preliminary studies by means of statistical-based experiment designs (response surface method). The traditional non-statistical technology was used to screen four critical factors for PAL stability during the bioconversion process, viz., glycerin, sucrose, 1,4-dithiothreitol (DTT), and MgSO(4). The central composite design (CCD) was applied to optimize the combined effect of critical factors for recombinant PAL stability and understand the relationship between the factors and PAL stability. The optimum values for testing variables were 13.04 mM glycerin, 1.87 mM sucrose, 4.09 mM DTT, and 69 mM Mg(2+). A second-order model equation was suggested and then validated experimentally. The model adequacy was very satisfactory because the coefficient of determination was 0.88. The maximum PAL activity was retained as 67.73 units/g after three successive cycles of bioconversion. In comparison to initial PAL activity, the loss of PAL activity was only 22%. PAL activity was enhanced about 23% in comparison to the control (without any stabilizer additives). PAL stability was significantly improved during successive bioconversion. The results obtained here verified the effectiveness of the applied methodology and may be helpful for l-Phe production on an industrial scale.

Influence of maturity and bagging on the relationship between anthocyanin accumulation and phenylalanine ammonia-lyase (PAL) activity in ‘Jonathan’ apples

Abstract The influence of maturing and ripening on phenylalanine ammonia-lyase (PAL) activity and anthocyanin accumulation was examined using bagged, non-bagged and shaded ‘Jonathan’ ( Malus domestica ) apples. Bagged fruit were covered with paper bags from mid-June at an early stage of fruit growth. Shaded apples were insulated from sunlight by newspaper at the beginning of colouring (middle September). The apples were harvested at different maturity stages and were irradiated with UV+white light for 96 h at 15°C after which anthocyanin content and PAL activity were measured. In non-bagged and shaded apples, anthocyanin accumulation and maximal PAL activity increased as the apples developed from the immature to the initial ripe stage, then decreased at full ripe stage. A positive linear relationship between the maximum PAL activity and the amount of anthocyanin accumulated suggested that the change in PAL activity is involved in the change of anthocyanin accumulation. In the bagged apples in the immature stage, anthocyanin accumulation and peak PAL activity after irradiation was higher than that in non-bagged apples. However, as the apples ripened, anthocyanin accumulation was less than for less mature fruit, even though PAL activity was relatively high. Therefore, PAL is not the only regulating factor for anthocyanin accumulation in bagged mature and ripe fruit.

97/00061 Tribomechanical aspects of movement of coal-charge materials over a heated surface

The periderm formation of wound tissue of potato tuber was inhibited temporarily after exposure to S-carvone. In wound tissue of control tubers a suberized cell layer was visible after 4 days whereas in S-carvone treated tissue this was observed only after 14 days in most of the tubers. At day 21 all the S-carvone treated tubers had formed suberin but only 10 % of the tubers had developed a (begin of a) cambium layer. The appearance of suberin was related to the activity of phenylalanine ammonia lyase (PAL); in control and S-carvone treated tissue, maximum PAL activity preceded the appareance of the first suberized cell layers by 2 and 5 days, respectively. The specific activity reached the same level in both control and S-carvone treated wound tissue. A short term treatment (2, 4 and 7 days) of tuber wound tissue with S-carvone delayed suberin formation. All the treated tubers showed suberization about 4 days after removal of S-carvone and this was closely related to the increase in PAL-activity. After the S-carvone treatment, the glutathione metabolism increased: after an initial decrease, as observed in the control, the total glutathione content increased fourfold after 9 days and remained high during the treatment. However, the length of the wound healing period before the start of a S-carvone treatment was of great influence on the increase of the glutathione metabolism and on the induction of glutathione reductase.

S-Carvone Inhibits Phenylalanine Ammonia Lyase (PAL) Activity and Suberization During Wound Healing of Potato Tubers

Summary The periderm formation of wound tissue of potato tuber was inhibited temporarily after exposure to S-carvone. In wound tissue of control tubers a suberized cell layer was visible after 4 days whereas in S-carvone treated tissue this was observed only after 14 days in most of the tubers. At day 21 all the S-carvone treated tubers had formed suberin but only 10 % of the tubers had developed a (begin of a) cambium layer. The appearance of suberin was related to the activity of phenylalanine ammonia lyase (PAL); in control and S-carvone treated tissue, maximum PAL activity preceded the appareance of the first suberized cell layers by 2 and 5 days, respectively. The specific activity reached the same level in both control and S-carvone treated wound tissue. A short term treatment (2, 4 and 7 days) of tuber wound tissue with S-carvone delayed suberin formation. All the treated tubers showed suberization about 4 days after removal of S-carvone and this was closely related to the increase in PAL-activity. After the S-carvone treatment, the glutathione metabolism increased: after an initial decrease, as observed in the control, the total glutathione content increased fourfold after 9 days and remained high during the treatment. However, the length of the wound healing period before the start of a S-carvone treatment was of great influence on the increase of the glutathione metabolism and on the induction of glutathione reductase.

Phenylalanine ammonia lyase as a precursory enzyme of legume stem lignification

In some instances, lignin content may not be significantly correlated with phenylalanine ammonia lyase (PAL) activity because: (1) PAL is not committed exclusively to lignin, and (2) the time of maximum PAL activity may not coincide with maximum lignin deposition. This study evaluates correlations and timing of PAL activity and lignin deposition during legume stem maturation. Three forage legumes, alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), and red clover (Trifolium pratense L.), were established, and basal stem regrowth was sampled, biweekly, for 10 wk, for dry weight (DW), cell wall (CW), lignin, and PAL analyses. Nonlinear regression of lignin content by the Gompertz function indicated that lignin increased sigmoidally, and PAL activity by the third-order quadratic demonstrated rapid initial increases in activity, followed by decreases, as a function of regrowth days. First derivative of the Gompertz function demonstrated that changes in lignin deposition closely resembled changes in PAL activity. Among species, peak deposition of DW and CW content occurred 3–11 d prior to maximum lignin deposition. Time of maximum PAL activity occurred 8 d prior to maximum lignin deposition in birdsfoot trefoil and red clover and 3 days after maximum lignin deposition in alfalfa. Across species, lignin content was not positively correlated with PAL activity on a protein basis. However, lignin deposition was positively correlated with PAL per unit protein (r = 0.76, P < 0.05) and lignin content was positively correlated with PAL on a per plant basis (r = 0.60, P < 0.05). These results indicate that the activity of PAL is related to lignin deposition in a cause-and-effect relationship. Key words: Alfalfa, birdsfoot trefoil, cell wall, lignin, phenylalanine, ammonia lyase, red clover

Activity of Enzymes Involved in Capsaicin Biosynthesis in Callus Tissue and Fruits of Chili Pepper ( Capsicum annuum L.)

In order to examine the functionality of the capsaicinoid biosynthetic pathway in callus cultures of chili pepper (Capsicum annuum L.), we investigated the enzyme activity of phenylalanine ammonia-lyase (PAL), cinnamic acid-4-hydroxylase (CA4H), p-coumaric acid-3-hydroxylase (CA3H), caffeic acid-O-methyltransferase (CAOMT) and capsaicinoid synthetase (CS). These enzymes were also determined in developing and mature fruits. The maximum activities of PAL, CA4H and CA3H in callus cultures were similar to those of chili pepper fruits, but the values of CAOMT and CS were 6 times lower than those of fruits. The significance of these data in relation to capsaicin accumulation is discussed.

Phenylalanine ammonia-lyase, phenolic acids and ethylene in alfalfa (Medicago sativa L.) cell cultures in relation to their embryogenic ability

Phenylalanine ammonia-lyase (PAL) activity, contents of phenolic acids and ethylene production during the lag-phase, and contents of phenolic acids at the late exponential phase, showed significant differences in embryogenic (EC) and non-embryogenic (NEC) suspension cultures of Medicago sativa L. Maximum PAL activity at 6 h after inoculation was followed by an increase in the level of phenolic acids from 9.6 μg g(-1) fresh mass to 21 μg g(-1) fresh mass in NEC at 12 h. Thereafter the level of phenolic acids decreased to 5.2 μg g(-1) fresh mass at 72 h. The decline was caused predominantly by the decrease of ester-bound cinnamic acid derivatives, the decrease ranging from 83 to 20% of total phenolics. Two maxima of ethylene production were observed in NEC: the first one immediately after inoculation and the second at 6 h, coinciding with the peak of PAL activity. In NEC, most of the phenolic acids occurred in esterified form. Ability to form somatic embryos (EC) was associated with the absence of the second peak of ethylene production as well as of the peak of PAL activity at 6 h. The level of phenolic acids during the lag-phase remained low (7.2 μg g(-1) FM) and did not change. The proportion of cinnamic acid derivatives was very low (18% of total phenolics), mostly due to the extremely low level of ferulic acid. In EC, phenolic acids bound to methanol insoluble material formed the major fraction. Loss of embryogenic potential of the embryogenic culture (ECL) was associated with qualitative and quantitative changes in the contents of phenolic acids insignificantly increased PAL activity after inoculation was followed by a moderate increase in the contents of phenolic acids from 9.35 μg g(-1) fresh mass to 12.42 μg g fresh mass. A high rate of ethylene production was observed only immediately after the transfer of the culture to fresh medium. The loss of embryogenicity correlated also with changes in the relative amounts of the investigated fractions of phenolic acids. A distinct increase in the level of methoxy-substituted phenolic acids is a characteristic feature of the ECL culture.

Effects of Exogenous Factors on Phenylalanine Ammonia-Lyase Activity and Accumulation of Anthocyanins and Total Phenolics in Grape Berries

The effects of ethephon (E), sucrose (S), and light (L) on phenylalanine ammonia-lyase (PAL) activity and on the concentration of anthocyanins and total phenolics in the berry skins of <i>Vitis vinifera</i> L. Cardinal berries were studied at temperatures of 14°, 22°, and 35°C over a period of 72 hours. Maximum PAL activity was obtained in the light/ethephon/sucrose-treated (LES) and light/sucrose-treated (LS) berries at 36 and 48 hours. In berries kept in the dark, PAL activity decreased over the experimental period. Anthocyanin concentration increased rapidly after a phase of slow accumulation of 24 to 60 hours, depending on the temperature, in the presence of light but not in the dark. Sucrose plus ethephon had a synergistic effect on synthesis of anthocyanins at 22°C. The period of slow anthocyanin accumulation was shortened as temperature increased. Cycloheximide (CHI) applied to LES-treated berries at 22°C caused a significant reduction in the concentration of anthocyanins in berry skins. Rapid phenolic accumulation in grape berry skins occurred after 48 hours at all temperatures. The pattern of changes in total phenolics in berry skins was similar for all temperature treatments with the maximum concentration reached after 60 hours. There were no consistent effects of sucrose and ethephon on total phenol accumulation in berry skins.