Phenylalanine Ammonia-lyase Protein Research Articles

Genome-wide identification and expression analyses of phenylalanine ammonia-lyase gene family members from tomato (Solanum lycopersicum) reveal their role in root-knot nematode infection.

Phenylalanine ammonia-lyase (PAL) is a key enzyme and rate-limiting enzyme of phenylpropanoid metabolism, which is a very important pathway in plants, and the secondary products it produces play an important role in plant growth and development, disease resistance, and stress resistance responses. However, PALs still lack systematic characterization in tomato. Based on a bioinformatics methods, PAL family genes were identified and characterized from tomato. qRT-PCR was used to study the expression of PAL genes in cultivated tomato after root-knot nematode infection. In this study, 14 and 11 PAL genes were identified in cultivated and wild tomatoes, and phylogenetic analysis classified them into three subfamilies, with different subfamilies of PAL proteins evolving in different directions in monocotyledonous and dicotyledonous plants. The extensive presence of stress, growth, hormone, and light response elements in the promoter sequences of SlPAL (Solanum lycopersicum) and SpenPAL (Solanum pennellii) genes suggests that this family has a critical role in abiotic stress. Collinearity indicates that members of the tomato and Arabidopsis PAL genes family are from the same ancestor, and the SlPAL10 gene is directly homologous to monocotyledonous rice and maize, suggesting that the SlPAL10 gene was present before monocotyledonous differentiation. Two co-expressed gene modules containing PAL genes were screened by WGCNA, and the core genes in the network were mined and functionally annotated by calculating the connectivity of genes within the modules. In addition, the expression of some genes changed significantly after root-knot nematode infection, with up-regulation of 4 genes and down-regulation of 3 genes. This result provides a data reference for the study of PAL family gene functions in tomato, and also provides a potential application for the subsequent selection of PAL genes in tomato for root-knot nematode resistance.

The first step into phenolic metabolism in the hornwort Anthoceros agrestis: molecular and biochemical characterization of two phenylalanine ammonia-lyase isoforms

Main conclusionTwo isoforms of phenylalanine ammonia-lyase (PAL) have been isolated as cDNA sequences from the hornwort Anthoceros agrestis. The encoded enzymes convert l-phenylalanine and to lower extents l-tyrosine and l-histidine. Thus, the functional presence of the general phenylpropanoid pathway in one of the earliest land plant groups is established.The hornwort Anthoceros agrestis has an elaborated phenolic metabolism resulting in phenolic compounds, such as rosmarinic acid or megacerotonic acid. The general phenylpropanoid pathway is involved in the biosynthesis of these compounds. Two phenylalanine ammonia-lyase (PAL) genes, AaPAL1 and AaPAL2, have been identified in Anthoceros agrestis and the protein with an N-terminal 6xHis-tag heterologously synthesized in Escherichia coli for a full biochemical characterization. Both PAL proteins accept l-phenylalanine, l-tyrosine as well as l-histidine as substrates, although the activity is explicitly the highest with l-phenylalanine. Km values as well as catalytic efficiencies were determined for phenylalanine (Km AaPAL1 39 µM, AaPAL2 18 µM) and tyrosine (Km AaPAL1 3.3 mM, AaPAL2 3.5 mM). In suspension cultures of Anthoceros agrestis, PAL genes were transcribed in parallel to rosmarinic acid (RA) accumulation and both showed highest abundance in the early growth phase. In a phylogenetic tree, both AaPAL amino acid sequences grouped within a clade with PAL amino acid sequences of diverse origin ranging from non-vascular to vascular plants, while most PALs from eudicots and monocots were mainly found in two other clades. The similarity of the hornwort PAL amino acid sequences to PAL sequences from vascular plants is more than 80% showing a strong conservation within the land plants. With this characterization of PALs from Anthoceros agrestis together with former investigations concerning cinnamic acid 4-hydroxylase and 4-coumaric acid CoA-ligase, the functional presence of the general phenylpropanoid pathway in this hornwort is proven.

Molecular characterization of the Bambusa oldhamii BoPAL3–encoded phenylalanine ammonia-lyase

• BoPAL3 gene was cloned from Bambusa oldhamii and heterologously expressed in Escherichia coli . • Recombinant BoPAL3 protein is an active enzyme, exhibiting obvious PAL activity and minuscule TAL activity. • BoPAL3 had similar biochemical properties with BoPAL2. Phenylalanine ammonia-lyase (PAL), which is ubiquitous in plants, catalyzes the formation of trans -cinnamic acid via the nonoxidative deamination of l -phenylalanine. Bambusa oldhamii contains four different forms of PAL proteins that differ in substrate specificity. Full-length BoPAL3 cDNA was cloned by a combination bamboo cDNA library screening and PCR-based cloning methods. Sequence alignment showed high homology between the deduced amino acid sequences of the BoPAL2 and BoPAL3 proteins (90%). Obvious PAL and tyrosine ammonia-lyase (TAL) activities were detected in Escherichia coli Top10 expressing recombinant BoPAL3 protein. Size-exclusion chromatography and denatured SDS–PAGE showed that the estimated molecular mass of recombinant BoPAL3 and the subunit form were approximately 330 kDa and 80 kDa, indicating that BoPAL3 presents as a tetrameric protein. The optimum temperature and pH for BoPAL3 activity were 50 °C and 8.5, respectively. The K m value of BoPAL3 for l -phenylalanine was 200 μM.

Expression of phenylalanine ammonia lyases in Synechocystis sp. PCC 6803 and subsequent improvements of sustainable production of phenylpropanoids

BackgroundPhenylpropanoids represent a diverse class of industrially important secondary metabolites, synthesized in plants from phenylalanine and tyrosine. Cyanobacteria have a great potential for sustainable production of phenylpropanoids directly from CO2, due to their photosynthetic lifestyle with a fast growth compared to plants and the ease of generating genetically engineered strains. This study focuses on photosynthetic production of the starting compounds of the phenylpropanoid pathway, trans-cinnamic acid and p-coumaric acid, in the unicellular cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis).ResultsA selected set of phenylalanine ammonia lyase (PAL) enzymes from different organisms was overexpressed in Synechocystis, and the productivities of the resulting strains compared. To further improve the titer of target compounds, we evaluated the use of stronger expression cassettes for increasing PAL protein levels, as well as knock-out of the laccase gene slr1573, as this was previously reported to prevent degradation of the target compounds in the cell. Finally, to investigate the effect of growth conditions on the production of trans-cinnamic and p-coumaric acids from Synechocystis, cultivation conditions promoting rapid, high density growth were tested. Comparing the different PALs, the highest specific titer was achieved for the strain AtC, expressing PAL from Arabidopsis thaliana. A subsequent increase of protein level did not improve the productivity. Production of target compounds in strains where the slr1573 laccase had been knocked out was found to be lower compared to strains with wild type background, and the Δslr1573 strains exhibited a strong phenotype of slower growth rate and lower pigment content. Application of a high-density cultivation system for the growth of production strains allowed reaching the highest total titers of trans-cinnamic and p-coumaric acids reported so far, at around 0.8 and 0.4 g L−1, respectively, after 4 days.ConclusionsProduction of trans-cinnamic acid, unlike that of p-coumaric acid, is not limited by the protein level of heterologously expressed PAL in Synechocystis. High density cultivation led to higher titres of both products, while knocking out slr1573 did not have a positive effect on production. This work contributes to capability of exploiting the primary metabolism of cyanobacteria for sustainable production of plant phenylpropanoids.

Genome-wide identification and analysis of the PAL genes from the orchids Apostasia shenzhenica, Dendrobium catenatum and Phalaenopsis equestris

Phenylalanine ammonia-lyase (PAL) is a key gateway enzyme that connects the phenylpropanoid pathway to primary metabolism. The phenylpropanoid pathway plays a vital role in the growth and environmental adaptation of many plants leading to the production of valuable bioactive compounds with industrial and medical applications. In the present study, nine putative PAL genes from three orchids were identified; five in Apostasia shenzhenica and two each in Dendrobium catenatum and Phalaenopsis equestris. Eighteen motifs and four major conserved functional domains were identified as reported in PAL proteins of other species. All the nine PALs were stable based on their computed physicochemical properties and localized in the cytoplasm. The three-dimensional structures of PALs revealed a homo-tetrameric structure consisting of four identical subunits. A total of 21 cis-regulatory elements with known functions were identified from the promoter regions of all PALs which are responsible for various plant responses to light, stress and growth regulators like auxins, gibberellins and abscisic acid. Phylogenetic analysis showed that the studied PAL proteins clustered in two major clades (clade I and II), placing dicot and monocot PALs in two separate monophyletic clades. In silico gene expression of the identified PALs in different vegetative and reproductive tissues revealed the differential expressions based on tissue type and disclosed that the expression of PAL genes was upregulated in all the tissues examined with an exception of PePAL leaf samples where no expression was detected, however, the same being highly expressed in reproductive tissues (PePAL1-labellum; PePAL2-sepal). In case of AsPALs, the expression was found to be highest in reproductive tissues (AsPAL4-maximum in inflorescence). On the other hand, the expression of DcPALs was found to be highest in vegetative tissues (DcPAL2-maximum in root). Based on the medicinal importance of orchids and the significant role of PAL genes in synthesis of bioactive compounds, the functional characterization of PAL genes can be further exploited in genetic improvement of medicinal orchids. Communicated by Ramaswamy H. Sarma

ITRAQ-based proteomic analysis provides insights into the biological mechanism of ammonium metabolism in tea plant (Camellia sinensis L.)

Tea plant prefers ammonium as the dominant inorganic nitrogen source. However, the mechanism behind this preference has not been fully understood. To obtain a better understanding of the preferential assimilation of ammonium in tea, iTRAQ-based proteomics was conducted between 0 and 12 h after ammonium treatment of tea leaves. The quality-related components were positively affected after 12 h, with the highest contents of the four main amino acids and with the primary catechins beginning to decrease. Changes of catechins and differentially expressed proteins suggested that contents of catechins in tea could affect the availability of carbon skeletons needed in photosynthesis and energy metabolism. The biosynthesis of flavonoid was related to ammonium through the regulation of phenylalanine ammonia-lyase (PAL) gene expression and the enzyme activity. After the application of ammonium, the expression of PAL protein and its enzyme activity were both inhibited to decrease the release of ammonium during the reaction converting l-phenylalanine to ammonia and trans-cinnamic acid. Furthermore, to accelerate the metabolism of ammonium, the expression of glutamine synthetase and its isogenes was enhanced, as well as glutamine synthetase activity. Hence, during the ammonium assimilation process, tea plants likely increase the activity of glutamine synthetase and inhibit PAL to balance the ammonium content. These results provide insights into the metabolism of ammonium nutrition orchestrated by primary and secondary metabolic pathways via glutamine synthetase and PAL in tea plant.

Genome-wide identification and characterization of the Phenylalanine Ammonia-lyase (PAL) gene family in Medicago truncatula

Phenylalanine ammonia-lyase (PAL) catalyzes the rate-limiting step of phenylpropanoid biosynthesis in plants and supplies precursors for a variety of secondary metabolites, such as flavonoids, lignins and stilbenes. The first draft of the full Medicago truncatula genome assembly has been released. However it is observed that, the PAL gene family from Medicago truncatula (MtPAL genes) has not been characterized in detail. In this study, a comprehensive analysis of the Medicago truncatula PAL gene family is presented, including chromosomal locations, phylogenetic analyses, gene structures, three-dimensional (3D) structures and expression patterns. Six Medicago truncatula PAL genes that encode PAL proteins were identified in the Medicago truncatula genome. It was shown that MtPAL genes are distributed on four chromosomes. Dynamic expression patterns of MtPAL genes were observed in different tissues and abiotic stresses, suggesting that MtPAL genes may play important roles in the regulation of development and stress responses in Medicago truncatula.

In silico characterization and transcriptional modulation of phenylalanine ammonia lyase (PAL) by abiotic stresses in the medicinal orchid Vanda coerulea Griff. ex Lindl.

Phenylalanine ammonia lyase (PAL) is the first enzyme of phenylpropanoid pathway. In the present study, a full-length PAL transcript from Vanda coerulea Griff. ex Lindl. (Family: Orchidaceae) was isolated and characterized. It was found that complete PAL transcript of V. coerulea (VcPAL; Gene Bank no. MG745168) contained 2175 bp with the open reading frame (ORF) of 2112 bp, encoding 703 amino acid residues. The multiple sequence alignment showed that VcPAL protein had 81% identity with that of the orchid, Bromheadia finlaysoniana. Phylogenetic analysis also disclosed that VcPAL shared the same evolutionary relationship with PAL proteins of other orchid species and to be closely related to that of other angiosperm species as well. The three-dimensional structure of VcPAL was found to be homo-tetrameric in nature consisting of four identical subunits with a molecular mass of 75 kDa per subunit. In silico characterization revealed the deduced protein to be a stable protein, comprising three major functional domains as reported in PAL proteins of other species. The transcription profiling of VcPAL exhibited the highest expression level to be present in the in vitro - raised leaf and root samples as compared to that of the ex vitro plant. The differential expression of VcPAL transcript was observed to be up-regulated by different types of abiotic stresses like wounding, cold, UV-B, salinity, and down-regulated by dark treatment. The study also exhibited that the VcPAL enzyme activity was directly proportional to the gene expression after the tissues were subjected to salinity and wounding stresses wherein a 1.7- fold increase in the enzyme activity was recorded in the leaf tissues exposed to salinity stress. A positive correlation could be found between the enzyme activity and the accumulation of phenylpropanoids such as total phenolic and flavonoid contents with R2 = 0.85 and 0.842 respectively.

Induction of defense responses against Magnaporthe oryzae in rice seedling by a new potential biocontrol agent Streptomyces JD211

The induced resistance against plant pathogens via biocontrol agents is considered as an eco-friendly and promising strategy. In this study, the induced resistance against Magnaporthe oryzae (M. oryzae) in rice seedling by a new potential biocontrol agent Streptomyces JD211 (JD211) was evaluated. The effects of JD211 on defense-related enzymes activities and defense genes expression were investigated. The biocontrol efficacy of different JD211 concentrations was different, and the treatment of 10 g kg-1 JD211 achieved the highest biocontrol efficacy. Activities of catalase, phenylalanine ammonia-lyase (PAL) and β-1,3-glucanase significantly increased in the presence of JD211. The gene expression level of both PAL and pathogenesis related protein 1 increased when rice seedlings were inoculated with JD211 alone or co-inoculated with M. oryzae, and the expression level of chitinase gene was enhanced by JD211 in the later stage. All results suggested that JD211 could increase the rice resistance by stimulating a series of defense responses, which was the result of induced systemic resistance by JD211. This work will provide a new biocontrol agent against Magnaporthe oryzae in rice seedling.

A kinetic model for flavonoid production in tea cell culture.

As one of the strategies for efficient production of a metabolite from cell cultures, a kinetic model is very useful tool to predict productivity under various culture conditions. In this study, we propose a kinetic model for flavonoid production in tea cell culture based on the cell life cycle and expression of PAL, the gene encoding phenylalanine ammonia-lyase (PAL)-the key enzyme in flavonoid biosynthesis. The flavonoid production rate was considered to be related to the amount of active PAL. Synthesis of PAL was modelled based on a general gene expression/translation mechanism, including the transcription of DNA encoding PAL into mRNA and the translation of PAL mRNA into the PAL protein. The transcription of DNA was assumed to be promoted at high light intensity and suppressed by a feedback regulatory mechanism at high flavonoid concentrations. In the model, mRNA and PAL were considered to self-decompose and to be lost by cell rupture. The model constants were estimated by fitting the experimental results obtained from tea cell cultures under various light intensities. The model accurately described the kinetic behaviors of dry and fresh cell concentrations, glucose concentration, cell viability, PAL specific activity, and flavonoid content under a wide range of light intensities. The model simulated flavonoid productivity per medium under various culture conditions. Therefore, this model will be useful to predict optimum culture conditions for maximum flavonoid productivity in cultured tea cells.

Biochemical analysis of Centaurea depressa phenylalanine ammonia lyase (PAL) for biotechnological applications in phenylketonuria (PKU)

Context: Phenylketonuria (PKU) is the most common hereditary defect of phenylalanine hydroxylase (PAH) enzyme achieving the hydroxylation of phenylalanine (Phe). Phenylalanine ammonia lyase (PAL) converts Phe to a harmless metabolite, trans-cinnamic acid (TCA) in plants and PAL enzyme activity is fairly high in plants rich in flavonoids.Objective: The study aimed the biochemical analysis of PAL form Centaurea depressa BIEB. (Asteraceae) a flavonoid rich plant. This study may form the main frame of future research efforts for the development of a plant preparation aimed for oral intake in PKU patients in an attempt to enrich their diet by allowing them to ingest some food stuff containing Phe without being exposed to complications.Materials and methods: PAL was partially purified from the leaves of C. depressa. Enzyme activity was determined in comparison with that of other herbs that reportedly have a high PAL activity. Enzyme optimization was achieved and the PAL protein was detected by western blotting.Results: C. depressa PAL demonstrated high activity (34.9 ± 0.6 U/mg protein). The enzyme was purified by 1.92-fold, which resulted in an activity of 53.30 ± 0.2 U/mg protein. The high-performance liquid chromatography analyzes of the PAL activity both before and after purification were in agreement. Western blot of PAL exhibited a 70 kDa protein band. The optimum pH and temperature are pH 8.8 and 37 °C. The optimum activities under gastric and intestinal digestion conditions were observed at pH 4.0 and pH 8.0, respectively.Discussion and conclusion: PAL activity of C. depressa is high, and does not disappear under different environmental conditions. This enzyme could be used for the development of dietary foods and biotechnological products for patients with PKU.

Molecular cloning, expression, and subcellular localization of a PAL gene from Citrus reticulata under iron deficiency

Phenylalanine ammonia lyase (PAL) is a specific branch point enzyme of primary and secondary metabolism. The Citrus reticulata Blanco PAL gene was cloned and designated as CrPAL1. The cDNA sequence of CrPAL1 was 2 166 bp, encoding 721 amino acid residues. Sequence alignment indicates that CrPAL1 shared a high identity with PAL genes found in other plants. Both the dominant and catalytic active sites of CrPAL1 were similar to PAL proteins observed in Petroselinum crispum. Phylogenetic tree analysis indicates that CrPAL1 was more closely related to PALs in Citrus clementina × C. reticulata and Poncirus trifoliata than to those from other plants. Subcellular localization reveals that CrPAL1-green fluorescent protein fusion protein was specifically localized in the plasma membrane. Activity of PAL as well as CrPAL1 expression increased under Fe deficiency. A similar result was noted for total phenolic content. The root exudates of C. reticulata strongly promoted reutilization of apoplastic Fe in roots. Furthermore, Fe was more desorbed from the cell wall under Fe deficiency than in sufficient Fe supply.

Isolation and Functional Characterization of a Phenylalanine Ammonia-Lyase Gene (SsPAL1) from Coleus (Solenostemon scutellarioides (L.) Codd).

Phenylalanine ammonia-lyase (PAL) is the first enzyme involved in the phenylpropanoid pathway and plays important roles in the secondary metabolisms, development and defense of plants. To study the molecular function of PAL in anthocyanin synthesis of Coleus (Solenostemon scutellarioides (L.) Codd), a Coleus PAL gene designated as SsPAL1 was cloned and characterized using a degenerate oligonucleotide primer PCR and RACE method. The full-length SsPAL1 was 2450 bp in size and consisted of one intron and two exons encoding a polypeptide of 711 amino acids. The deduced SsPAL1 protein showed high identities and structural similarities with other functional plant PAL proteins. A series of putative cis-acting elements involved in transcriptional regulation, light and stress responsiveness were found in the upstream regulatory sequence of SsPAL1. Transcription pattern analysis indicated that SsPAL1 was constitutively expressed in all tissues examined and was enhanced by light and different abiotic factors. The recombinant SsPAL1 protein exhibited high PAL activity, at optimal conditions of 60 °C and pH 8.2. Although the levels of total PAL activity and total anthocyanin concentration have a similar variation trend in different Coleus cultivars, there was no significant correlation between them (r = 0.7529, p > 0.1), suggesting that PAL was not the rate-limiting enzyme for the downstream anthocyanin biosynthetic branch in Coleus. This study enables us to further understand the role of SsPAL1 in the phenylpropanoid (flavonoids, anthocyanins) biosynthesis in Coleus at the molecular level.

Molecular cloning, expression and sequence analysis of a phenylalanine ammonia-lyase gene from Poncirus trifoliata under iron deficiency

Phenylalanine ammonia-lyase (PAL) is a specific branch point enzyme of primary and secondary metabolism. It is deemed to play a key role in plant development and defence. Homology cloning of the cDNA sequence of PAL gene, Pt-PAL1, from Poncirus trifoliata found a complete open reading frame (ORF) of 2166 bp, with 721 encoded amino acids. The sequence alignment indicated that the amino acid sequence of Pt-PAL1 shared a high identity with PAL genes found in other plants. Both the dominant and catalytic active sites of Pt-PAL1 were similar to PAL proteins observed in Petroselinum crispum. Phylogenetic tree analysis indicated that Pt-PAL1 was more closely related to PALs in Citrus clementina × C. reticulata than to those from other plants. Real-time polymerase chain reaction showed that the expression of Pt-PAL1 gene in roots under iron (Fe) deficiency (0 μM o,o-FeEDDHA) was significantly higher than that under Fe sufficiency (50 μM o,o-FeEDDHA). The same result was noted for total phenolic content. Phenolic compounds play an important role in response to iron deficiency in Strategy I plants. In the present study, root exudates of Poncirus trifoliata strongly promoted the reutilisation of apoplastic Fe in roots. Furthermore, more Fe was desorbed from the cell wall under Fe deficiency than during Fe sufficiency, indicating a relationship between Fe and total phenolics in Strategy I plants under Fe deficiency.

Molecular Cloning and Sequence Analysis of a Phenylalanine Ammonia-Lyase Gene from Dendrobium

In this study, a phenylalanine ammonia-lyase (PAL) gene was cloned from Dendrobium candidum using homology cloning and RACE. The full-length sequence and catalytic active sites that appear in PAL proteins of Arabidopsis thaliana and Nicotiana tabacum are also found: PAL cDNA of D. candidum (designated Dc-PAL1, GenBank No. JQ765748) has 2,458 bps and contains a complete open reading frame (ORF) of 2,142 bps, which encodes 713 amino acid residues. The amino acid sequence of DcPAL1 has more than 80% sequence identity with the PAL genes of other plants, as indicated by multiple alignments. The dominant sites and catalytic active sites, which are similar to that showing in PAL proteins of Arabidopsis thaliana and Nicotiana tabacum, are also found in DcPAL1. Phylogenetic tree analysis revealed that DcPAL is more closely related to PALs from orchidaceae plants than to those of other plants. The differential expression patterns of PAL in protocorm-like body, leaf, stem, and root, suggest that the PAL gene performs multiple physiological functions in Dendrobium candidum.

Analysis of a phenylalanine ammonia-lyase gene sequence from Arachis hypogaea L. and its transcript abundance in induced systemic resistance against Sclerotium rolfsii

Fil: Tonelli, Maria Laura. Universidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Cloning, bioinformatics and the enzyme activity analyses of a phenylalanine ammonia-lyase gene involved in dragon’s blood biosynthesis in Dracaena cambodiana

Phenylalanine ammonia-lyase (PAL) is the key enzyme of the phenylpropanoid pathway, playing an important role in plant development and defence. We cloned a partial cDNA of PAL gene, DcPAL1, from Dracaena cambodiana seedlings using RT-PCR with degenerate primers that were designed based on a multiple sequence alignment of known PAL genes from other plant species. DcPAL1 shows highly homologous to other known PAL genes registered in GenBank, being closest to that of Musa acuminata. DcPAL1 has a relatively high GC content and most of the GC is in the third codon position. It has 768 bp in size with a maximum open reading frame (ORF) of 765 bp, encoding a 255 amino acid-polypeptide. The deduced PAL protein is a stable protein, having classical PAL domains and consisting of three major hydrophobic domains. Analysis of effective number of codons (ENC) shows that DcPAL1 codons are used at equal frequency. Relatively higher usage frequency appears randomly in codons ended with any of the four bases; six codons have no usage bias. There are 45 codons showing distinct usage preference between DcPAL1 and E. coli, 20 between DcPAL1 and yeast. Therefore, the yeast system may be more suitable for the expression of DcPAL1. Upon the elicitation of Fusarium proliferatum, a potent elicitor of dragon's blood, the PAL enzyme activity in the leaves and stems of D. cambodiana and other two Dracaena spp. significantly increased, accompanying with the formation of dragon's blood, indicating the involvement of PAL in the biosynthesis of dragon's blood, a precious traditional medicine.

Expression patterns of defense genes in resistance of the panicles exserted from the caulis and from the tillers to neck blast in rice

The rice variety Xiushui227 is resistant to neck blast in the panicles exserted from the caulis but susceptible in the panicles from the tillers, however, the other variety Xiushui09 is susceptible to neck blast in the panicles from the caulis but resistant in the panicles from the tillers. These two varieties were used to analyze the expression patterns of defense genes in the panicles from the caulis and the first first-class tiller at the preliminary heading stage, after inoculating the necks invitro with Magnaporthe oryzae, respectively. All defense genes (pathogenesis-related genes PR1a, Gns1 (1,3; 1,4-β-glucanase), Cht-1 (chitinase), PR4, PR5, and PR10a, secondary metabolite pathway genes PAL (phenylalanine ammonia-lyase), CHS (chalcone synthase), and LOX (lipoxygenase), and oxidative stress-related protein genes POX22.3 (peroxidase), and PPO (polyphenol oxidase)) used in this experiment except Cht-1 and PR5 could participate in defending Xiushui227 against neck blast in the panicles from the caulis. All defense genes used in this study except Cht-1, PR10a, and PPO may play roles in defending Xiushui09 against neck blast in the panicles from the tillers.

Molecular Cloning, Characterization and Expression of the Phenylalanine Ammonia-Lyase Gene from Juglans regia

Phenylalanine ammonia-lyase (PAL) is the first key enzyme of the phenypropanoid pathway. A full-length cDNA of PAL gene was isolated from Juglans regia for the first time, and designated as JrPAL. The full-length cDNA of the JrPAL gene contained a 1935bp open reading frame encoding a 645-amino-acid protein with a calculated molecular weight of about 70.4 kD and isoelectric point (pI) of 6.7. The deduced JrPAL protein showed high identities with other plant PALs. Molecular modeling of JrPAL showed that the 3D model of JrPAL was similar to that of PAL protein from Petroselinum crispum (PcPAL), implying that JrPAL may have similar functions with PcPAL. Phylogenetic tree analysis revealed that JrPAL shared the same evolutionary ancestor of other PALs and had a closer relationship with other angiosperm species. Transcription analysis revealed that JrPAL was expressed in all tested tissues including roots, stems, and leaves, with the highest transcription level being found in roots. Expression profiling analyses by real-time PCR revealed that JrPAL expression was induced by a variety of abiotic and biotic stresses, including UV-B, wounding, cold, abscisic acid and salicylic acid.

Expression of defense genes and antioxidant defense responses in rice resistance to neck blast at the preliminary heading stage and full heading stage

The rice variety Xiushui227 is resistant to neck blast at three crucial panicle stages (the booting stage, the preliminary heading stage (PHS), and the full heading stage (FHS)) that controlling neck blast. The other rice variety Liangyou6326 is susceptible to neck blast at these three panicle stages. These two varieties were used to analyze the expression patterns of defense genes and antioxidant defense responses at the PHS and FHS, after inoculating the necks in vitro with Magnaporthe oryzae, respectively. All defense genes (pathogenesis-related genes PR1a, Gns1 (1,3; 1,4-β-glucanase), Cht-1 (chitinase), PR4, PR5, and PR10a, secondary metabolite pathway genes PAL (phenylalanine ammonia-lyase), CHS (chalcone synthase), and LOX (lipoxygenase), and oxidative stress-related protein genes POX22.3 (peroxidase), and PPO (polyphenol oxidase)) used in this experiment except Cht-1, CHS and PPO could mainly play important roles in the resistance to neck blast at the PHS in Xiushui227, and CHS and PPO may primarily participate in fighting back against to neck blast at the FHS. Conversely, PR1a, Cht-1, PR4, PR10a, CHS, LOX-RLL, and PPO could chiefly play participate in defending Liangyou6326 against neck blast at the FHS, and PR5, PAL, and POX22.3 may be primarily involved in fighting back against to neck blast at the PHS. Furthermore, the antioxidant enzymes superoxide dismutase, peroxidase, and catalase may mainly participate in defending Xiushui227 against neck blast at the PHS and defending Liangyou6326 against neck blast at the FHS, respectively. Therefore oxidative damage is less at the PHS in Xiushui227 and at the FHS in Liangyou6326, respectively.