Plant Phenylalanine Ammonia-lyase Research Articles

Molecular identification of phenylalanine ammonia lyase-encoding genes EfPALs and EfPAL2-interacting transcription factors in Euryale ferox.

Flavonoids are one of the most important secondary metabolites in plants, and phenylalanine ammonia-lyase (PAL) is the first rate-limiting enzyme for their biosynthesis. However, detailed information on the regulation of PAL in plants is still little. In this study, PAL in E. ferox was identified and functionally analyzed, and its upstream regulatory network was investigated. Through genome-wide identification, we obtained 12 putative PAL genes from E. ferox. Phylogenetic tree and synteny analysis revealed that PAL in E. ferox was expanded and mostly preserved. Subsequently, enzyme activity assays demonstrated that EfPAL1 and EfPAL2 both catalyzed the production of cinnamic acid from phenylalanine only, with EfPAL2 exhibiting a superior enzyme activity. Overexpression of EfPAL1 and EfPAL2 in Arabidopsis thaliana, respectively, both enhanced the biosynthesis of flavonoids. Furthermore, two transcription factors, EfZAT11 and EfHY5, were identified by yeast one-hybrid library assays as binding to the promoter of EfPAL2, and further luciferase (LUC) activity analysis indicated that EfZAT11 promoted the expression of EfPAL2, while EfHY5 repressed the expression of EfPAL2. These results suggested that EfZAT11 and EfHY5 positively and negatively regulate flavonoid biosynthesis, respectively. Subcellular localization revealed that EfZAT11 and EfHY5 were localized in the nucleus. Our findings clarified the key EfPAL1 and EfPAL2 of flavonoid biosynthesis in E. ferox and established the upstream regulatory network of EfPAL2, which would provide novel information for the study of flavonoid biosynthesis mechanism.

Cloning, characterization and expression of a phenylalanine ammonia-lyase gene (CcPAL) from cumin (Cuminum cyminum L.)

Phenylalanine ammonia-lyase (PAL) that functions a substantial role in defense mechanisms, growth, and development of the plant, is situated at branching point from primary to secondary metabolism. In this study, using highly conserved sequences of plant PALs registered in GenBank, a partial cDNA clone of cumin (Cuminum cyminum) PAL gene (designated as CcPAL) was isolated. The relative transcript levels of CcPAL gene, its enzyme activity, and accumulation of total phenolics were also analyzed in shoots in response to different stresses. The isolated CcPAL had 414 bp in length with a maximum open reading frame (ORF) of 351 bp and encodes a peptide with 116 amino acids. The deduced peptide sequence of CcPAL has classical PAL domains and is a stable protein. Results of multiple sequence alignment indicate that CcPAL had high similarity with other plant PALs available in the GenBank. Analysis of the phylogenetic tree indicated that CcPAL categorized in the angiosperm-type PAL family and dicotyledon subfamily and clustered together with other PAL from Apiaceae species. Transcription analysis indicated that CcPAL expressed in all tested tissues, but more highly in shoots. Moreever, the expression of CcPAL was found to be induced by cadmium, wounding, salicylic acid (SA) and cold treatments. A positive correlation was found between transcript levels of CcPAL and total phenolics accumulation of cumin shoots in response to different stresses. These results suggest that the CcPAL and phenylpropanoid pathway may play a great role in the biosynthesis of the bioactive compounds and counteracting various stresses in C. cyminum.

Cloning, Characterization and Expression of the Phenylalanine Ammonia-Lyase Gene (PaPAL) from Spruce Picea asperata

Phenylalanine ammonia-lyase (PAL) is the crucial enzyme of the phenylpropanoid pathway, which plays an important role in plant disease resistance. To understand the function of PAL in Picea asperata, in this study, the full-length cDNA sequence of the PAL gene from this species was isolated and named PaPAL. The gene contains a 2160-bp open reading frame (ORF) encoding 720 amino acids with a calculated molecular weight of 78.7 kDa and a theoretical isoelectric point of 5.88. The deduced PaPAL protein possesses the specific signature motif (GTITASGDLVPLSYIA) of phenylalanine ammonia-lyases. Multiple alignment analysis revealed that PaPAL has high identity with other plant PALs. The tertiary structure of PaPAL was predicted using PcPAL from Petroselinum crispum as a template, and the results suggested that PaPAL may have a similar function to that of PcPAL. Furthermore, phylogenetic analysis indicated that PaPAL has a close relationship with other PALs from the Pinaceae species. The optimal expression condition of recombinant PaPAL in Escherichia coli BL21 (DE3) was 0.2 mM IPTG (isopropyl β-D-thiogalactoside) at 16 °C for 4 h, and the molecular weight of recombinant PaPAL was found to be approximately 82 kDa. Recombinant PaPAL was purified and exhibited high PAL activity at optimal conditions of pH 8.6 and 60 °C. Quantitative real-time PCR (qRT-PCR) showed the PaPAL gene to be expressed in all tissues of P. asperata tested, with the highest expression level in the needles. The PaPAL gene was induced by the pathogen (Lophodermium piceae), which caused needle cast disease, indicating that it might be involved in defense against needle cast disease. These results provide a basis for understanding the molecular mechanisms of the PAL gene in the process of P. asperata disease resistance.

Extrato etanólico de própolis verde na proteção de feijoeiro contra bacterioses

ABSTRACT: The aim of this study was to evaluate the ethanolic extract of green propolis (EEP) in the protection of common bean plants against two main bacterial cultures, bacterial blight (Xanthomonas axonopodis pv. phaseoli) and wildfire (Pseudomonas syringae pv. tabaci). Experiments on antimicrobial activity were performed, inducing phytoalexins, defense-related enzymes, and disease severity, under concentrations of 0, 0.5, 1.0, 2.5, and 5.0%. The EEP presented antimicrobial activity on both phytobacteria, causing a decrease in their development. It has also promoted a linear accumulation of phaseolin in bean hypocotyls according to the EEP concentration used. There was a reduction in the lesion area, which was caused by bacterial blight on bean leaves treated with EEP, and local and systemic effect were observed. Polyphenoloxidase was activated with 5% EEP, reaching the maximum activation time 62.5 h after application. An increase was observed in the activity of phenylalanine ammonia-lyase in plants treated with EEP, with local and systemic effect. Results indicated the potential of EEP in the control of these diseases.

Optimisation of trans-cinnamic acid and hydrocinnamyl alcohol production with recombinant Saccharomyces cerevisiae and identification of cinnamyl methyl ketone as a by-product

Trans-cinnamic acid (tCA) and hydrocinnamyl alcohol (HcinOH) are valuable aromatic compounds with applications in the flavour, fragrance and cosmetic industry. They can be produced with recombinant yeasts from sugars via phenylalanine after expression of a phenylalanine ammonia lyase (PAL) and an aryl carboxylic acid reductase. Here, we show that in Saccharomyces cerevisiae a PAL enzyme from the bacterium Photorhabdus luminescens was superior to a previously used plant PAL enzyme for the production of tCA. Moreover, after expression of a UDP-glucose:cinnamate glucosyltransferase (FaGT2) from Fragaria x ananassa, tCA could be converted to cinnamoyl-D-glucose which is expected to be less toxic to the yeast cells. Production of tCA and HcinOH from glucose could be increased by eliminating feedback-regulated steps of aromatic amino acid biosynthesis and diminishing the decarboxylation step of the competing Ehrlich pathway. Finally, an unknown by-product resulting from further metabolisation of a carboligation product of cinnamaldehyde (cinALD) with activated acetaldehyde, mediated by pyruvate decarboxylases, could be identified as cinnamyl methyl ketone providing a new route for the biosynthesis of precursors, such as (2S,3R) 5-phenylpent-4-ene-2,3-diol, necessary for the chemical synthesis of specific biologically active drugs such as daunomycin.

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.

Expression and in silico characterization of Phenylalanine ammonium lyase against karnal bunt (Tilletia indica) in wheat (Triticum aestivum).

To investigate the lignifications process and its physiological significance under Karnal Bunt (KB), the changes in enzymes responsible for lignifications likes, phenylalanine ammonia lyase (PAL), were determined in resistant (HD-29) and susceptible genotype (WH-542) of wheat during different developmental stages. The PAL gene was cloned and sequenced. The expression of PAL gene was measured by means of semi-quantitative RT-PCR. The enzyme was expressed constitutively in both the susceptible and resistant genotype. However, the activity was higher in all the developmental stages of resistant genotype, indicating that this genotype has a significant higher basal level of these enzymes as compared to the susceptible line and could be used as marker(s) to define KB resistance. The activity of PAL was significantly higher in WSv stage (Z=16). Structural comparisons based on alignments of all the protein sequences using the clustal W program and searches for conserved motifs using the MEME program have revealed broad conservation of main motifs characteristic of the plant PAL. MSA and phylogenetic analyses of different plants PAL demonstrate that all PAL cluster divided in to two main cluster. The PAL also possesses a specific consensus sequences [GS]- [STG]-[LIVM]-[STG]-[SAC]-S-G-[DH]-L-x-[PN]-L-[SA]-x(2,3)-[SAGVTL]. The pathway might be associated with the enhancement of structural defense barrier due to lignifications of cell wall as evident from the enhanced synthesis of lignin in all the stages of resistant genotype. Our results clearly indicate the possible role of enzymes of Phenyl propanoid pathway metabolism provides genotype and stage dependant structural barrier resistance in wheat against KB.

Genome-wide characterization of phenylalanine ammonia-lyase gene family in watermelon (Citrullus lanatus)

Phenylalanine ammonia-lyase (PAL), the first enzyme in the phenylpropanoid pathway, plays a critical role in plant growth, development, and adaptation. PAL enzymes are encoded by a gene family in plants. Here, we report a genome-wide search for PAL genes in watermelon. A total of 12 PAL genes, designated ClPAL1-12, are identified . Nine are arranged in tandem in two duplication blocks located on chromosomes 4 and 7, and the other three ClPAL genes are distributed as single copies on chromosomes 2, 3, and 8. Both the cDNA and protein sequences of ClPALs share an overall high identity with each other. A phylogenetic analysis places 11 of the ClPALs into a separate cucurbit subclade, whereas ClPAL2, which belongs to neither monocots nor dicots, may serve as an ancestral PAL in plants. In the cucurbit subclade, seven ClPALs form homologous pairs with their counterparts from cucumber. Expression profiling reveals that 11 of the ClPAL genes are expressed and show preferential expression in the stems and male and female flowers. Six of the 12 ClPALs are moderately or strongly expressed in the fruits, particularly in the pulp, suggesting the potential roles of PAL in the development of fruit color and flavor. A promoter motif analysis of the ClPAL genes implies redundant but distinctive cis-regulatory structures for stress responsiveness. Finally, duplication events during the evolution and expansion of the ClPAL gene family are discussed, and the relationships between the ClPAL genes and their cucumber orthologs are estimated.

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.

Multiple tandem duplication of the phenylalanine ammonia-lyase genes in Cucumis sativus L.

Phenylalanine ammonia-lyase (PAL) is the first entry enzyme of the phenylpropanoid pathway, and therefore plays a key role in both plant development and stress defense. In many plants, PAL is encoded by a multi-gene family, and each member is differentially regulated in response to environmental stimuli. In the present study, we report that PAL in cucumber (Cucumis sativus L.) is encoded for by a family of seven genes (designated as CsPAL1-7). All seven CsPALs are arranged in tandem in two duplication blocks, which are located on chromosomes 4 and 6, respectively. The cDNA and protein sequences of the CsPALs share an overall high identity to each other. Homology modeling reveals similarities in their protein structures, besides several slight differences, implying the different activities in conversion of phenylalanine. Phylogenic analysis places CsPAL1-7 in a separate cluster rather than clustering with other plant PALs. Analyses of expression profiles in different cucumber tissues or in response to various stress or plant hormone treatments indicate that CsPAL1-7 play redundant, but divergent roles in cucumber development and stress response. This is consistent with our finding that CsPALs possess overlapping but different cis-elements in their promoter regions. Finally, several duplication events are discussed to explain the evolution of the cucumber PAL genes.

진균과 식물의 Phenylalanine Ammonia-lyase 그리고 세균의 Histidine Ammonia-lyase 간의 면역학적 관계 분석

진균의 phenylalanine ammonia-lyase(PAL)와 식물의 PAL간 그리고 PAL과 histidine ammonia-lyase (HAL)간의 구조적 특성 관계에 대한 이해를 얻기 위해 옥수수병원균인 깜부기균(Ustilago maydis)의 PAL에 대한 면역학적 분석을 수행하였다. 진균의 PAL 항체와 식물의 PAL 항체를 이용하여 분석하였을 때 실험한 모든 종의 PAL 간에 교차반응이 나타났다. 알팔파 PAL 항체와 포플라 PAL 항체 모두 식물 PAL은 강하게 인식하였으나 진균의 PAL은 약하게 인식하였다. U. maydis PAL은 Rhodotorula glutinis 효모의 PAL만 약하게 인식하였다. U. maydis PAL은 식물의 PAL에 대해서 낮은 친화성을 보였으나 Pseudomonas 세균의 HAL에 대해서는 강한친화성을 보였다. 2종의 식물 PAL 항체들 또한 Pseudomonas 세균의 HAL에 대해 강한 친화성을 보였다. 진균과 식물의 PAL 항체는 PAL 효소의 활성 저해를 나타냈으며 세균의 HAL 효소의 활성에 대해서도 중도적 저해를 나타냈다. 세균의 HAL 항체는 식물과 효모와 Ustilago PAL 중에 Ustilago PAL 활성만 저해하였다. 식물의 PAL과 진균의 PAL 모두 효모의 PAL 활성은 저해하지 못했다. 본 연구는 PAL과 HAL간에 면역학적 관계가 있음을 처음으로 보고한다. Phenylalanine ammonia-lyase (PAL) from the maize pathogen Ustilago maydis was analysed immunologically to obtain insights into the structural relationships between plant PAL and fungal PAL and between PAL and histidine ammonia-lyase (HAL). Cross-reactivity was found among all the PAL proteins from different species tested, using antibodies raised against both plant and fungal PALs. Both anti-Alfalfa and anti-popular PAL antibodies strongly recognized plant PALs but only weakly recognized fungal PALs. Antibodies raised against U. maydis PAL only weakly recognized the Rhodotorula glutinis yeast PAL. The anti-U. maydis PAL antibodies showed low affinity for the plant PALs but they bound strongly to Pseudomonas bacterial HAL. Significant cross-reactivity between the two plant PAL antibodies and the bacterial HAL was also observed. Both the anti-Ustilago PAL and the anti-poplar PAL antibodies displayed similar enzyme inhibition patterns, including moderate inhibition of bacterial HAL activity. However, the bacterial HAL antibody inhibited only Ustilago PAL. The PAL and HAL antibodies tested showed no inhibition against yeast PAL. This is first report on the immunological relationships between PAL and HAL.

Retention of Phenylalanine Ammonia-lyase Activity in Wheat Seedlings during Storage and in Vitro Digestion

The retention of phenylalanine ammonia-lyase (PAL) activity in Red Spring wheat seedlings during storage and in vitro protein digestion was evaluated toward assessing the efficacy of plant PAL as a dietary supplement for patients suffering from the metabolic disease, phenylketonuria. Retention of PAL activity in freeze-dried wheat seedling tissues following three months of storage at -20 degrees C ranged from 62% in the leaf to 89% in root/residual seed tissues. After a 3-h two-stage ("gastric-intestinal") in vitro digestion, 36% and 42% recovery of PAL activity was associated with chopped fresh leaf and root/residual seed tissues respectively; however, no activity was recovered from freeze-dried tissues. High performance liquid chromatographic analysis of the residual phenylalanine (Phe) after in vitro digestion confirmed that the fresh tissues effected a significantly higher conversion of exogenous Phe than freeze-dried tissues. These results demonstrate that the plant cell walls provide protection of PAL during in vitro digestion. In cases where exogenous Phe (100 mg; 24 mM) was supplied to the tissues, the product of the reaction, trans-cinnamic acid, may have exerted a significant inhibitory effect on PAL activity.

Cloning and Characterization of a Differentially Expressed Phenylalanine Ammonialyase Gene (IiPAL) After Genome Duplication from Tetraploid Isatis indigotica Fort.

AbstractPhenylpropanoid derivatives are a complex class of secondary metabolites that have many important roles in plants during normal growth and in responses to environmental stress. Phenylalanine ammonialyase (PAL) catalyzes the first step in the biosynthesis of phenylpropanoids. In the present study, we isolated a novel phenylalanine ammonialyase gene (designated as IiPAL) from tetraploid Isatis indigotica Fort. by rapid amplification of cDNA ends (RACE), which was a cultivar from the diploid plant by genome duplication. The full‐length cDNA of IiPAL was 2 530‐bp long with an open reading frame (ORF) of 2 178 bp encoding a polypeptide of 725 amino acid residues. Analysis of IiPAL genomic DNA revealed that it was structurally similar to other plant PAL genes, with a single intron at a conserved position, and a long highly conserved second exon. Semi‐quantitative RT‐PCR revealed that the IiPAL expression in roots and leaves from a tetraploid sample was higher than that in diploid progenitor, whereas expression of IiPAL in stems was almost the same as each other. Furthermore, the highest expression of IiPAL in tetraploid plant was found in roots, which was found in stems in diploid plants. Further expression analysis revealed that gibberellin (GA3), abscisic acid (ABA), methyl jasmonate (MeJA) and cold treatments could up‐regulate the IiPAL transcription in tetraploid plants. All our findings suggest that IiPAL participates not only in the defense/stress responsive pathways, but also probably in the polyploidy evolution of I. indigotica.(Managing editor: Wei Wang)

Phenylalanine ammonia-lyase modified with polyethylene glycol: Potential therapeutic agent for phenylketonuria

Phenylketonuria (PKU) is an autosomal recessive genetic disease caused by the defects in the phenylalanine hydroxylase (PAH) gene. Individuals homozygous for defective PAH alleles show elevated levels of systemic phenylalanine and should be under strict dietary control to reduce the risk of neuronal damage associated with high levels of plasma phenylalanine. Researchers predict that plant phenylalanine ammonia-lyase (PAL), which converts phenylalanine to nontoxic t-cinnamic acid, will be an effective therapeutic enzyme for the treatment of PKU. The problems of this potential enzyme therapy have been the low stability in the circulation and the antigenicity of the plant enzyme. Recombinant PAL originated from parsley (Petroselinum crispum) chemically conjugated with activated PEG2 [2,4-bis(O-methoxypolyethyleneglycol)-6-chloro-s-triazine] showed greatly enhanced stability in the circulation and was effective in reducing the plasma concentration of phenylalanine in the circulation of mice. PEG-PAL conjugate will be an effective therapeutic enzyme for the treatment of PKU.

The phenylalanine ammonia-lyase gene family in raspberry. Structure, expression, and evolution.

In raspberry (Rubus idaeus), development of fruit color and flavor are critically dependent on products of the phenylpropanoid pathway. To determine how these metabolic functions are integrated with the fruit ripening program, we are examining the properties and expression of key genes in the pathway. Here, we report that L- phenylalanine ammonia-lyase (PAL) is encoded in raspberry by a family of two genes (RiPAL1 and RiPAL2). RiPAL1 shares 88% amino acid sequence similarity to RiPAL2, but phylogenetic analysis places RiPAL1 and RiPAL2 in different clusters within the plant PAL gene family. The spatial and temporal expression patterns of the two genes were investigated in various vegetative and floral tissues using the reverse transcriptase competitor polymerase chain reaction assay. Although expression of both genes was detected in all tissues examined, RiPAL1 was associated with early fruit ripening events, whereas expression of RiPAL2 correlated more with later stages of flower and fruit development. Determination of the absolute levels of the two transcripts in various tissues showed that RiPAL1 transcripts were 3- to 10-fold more abundant than those of RiPAL2 in leaves, shoots, roots, young fruits, and ripe fruits. The two RiPAL genes therefore appear to be controlled by different regulatory mechanisms.

The phenylalanine ammonia-lyase gene family in Arabidopsis thaliana.

Phenylpropanoid derivatives are a complex class of secondary metabolites that have many important roles in plants during normal growth and in responses to environmental stress. Phenylalanine ammonialyase (PAL) catalyzes the first step in the biosynthesis of phenylpropanoids, and is usually encoded by a multi-gene family. Genomic clones for three Arabidopsis thaliana PAL genes containing the entire protein-coding region and upstream and downstream sequences have been obtained and completely sequenced. Two A. thaliana PAL genes (PAL1 and PAL2) are structurally similar to PAL genes that have been cloned from other plant species, with a single intron at a conserved position, and a long highly conserved second exon. Previously identified promoter motifs plus several additional sequence motifs were found in the promoter regions of PAL1 and PAL2. Expression of PAL1 and PAL2 is both qualitatively and quantitatively similar in different plant organs and under various inductive conditions. A third A. thaliana PAL gene, PAL3, differs significantly from PAL1 and PAL2 and other sequenced plant PAL genes. PAL3 contains an additional intron, and its deduced amino acid sequence is less homologous to other PAL proteins. The PAL3 promoter region lacks several sequence motifs conserved between A. thaliana PAL1 and PAL2, as well as motifs described in other genes involved in phenylpropanoid metabolism. A. thaliana PAL3 was expressed at very low levels under the conditions examined.

Multidimensional dot-matrices.

A generalization of the dot-matrix of similarity for n sequences is proposed. For the visualization of the n-dimensional dot-matrix, the n projections onto the plane passing through the main diagonal and each of the n axes of Euclidean space En are displayed. The projection is compressed so that the points at the coordinates (xi, sigma j not equal to ixj/(n - 1)) are depicted on the plane. The common regions of similarity are revealed as segments of straight lines parallel to the main diagonal. An algorithm for the n-dimensional dot-matrix calculation of time of the order of O[n*L2 + n*(L2p)2] is suggested where L is the mean length of sequence and p is the stringency parameter of the order of 10(-6). The method is illustrated for the family of plant phenylalanine ammonia-lyase genes.

A phenylalanine ammonia-lyase gene from parsley: structure, regulation and identification of elicitor and light responsive cis-acting elements.

We demonstrate that phenylalanine ammonia-lyase (PAL) in parsley (Petroselinum crispum) is encoded by a small family of at least four genes. The levels of mRNA from three identified PAL genes increase considerably upon treatment of cultured parsley cells with UV light or fungal elicitor and upon wounding of parsley leaves or roots. In cultured cells these changes were shown to involve transcriptional activation. We present the first primary structure of a plant PAL gene (parsley PAL-1) and the deduced amino acid sequence of the enzyme. Inducible in vivo footprints in the PAL-1 promoter define two nucleotide sequences, within the motifs CTCCAACAAACCCCTTC and ATTCTCACCTACCA, involved in the responses to both UV irradiation and elicitor application. These motifs are conserved at similar positions in several elicitor or light-responsive genes from different species. In two cases they are found within short regions known to confer elicitor or UV-light inducibility. The conserved motifs in the parsley 4-coumarate:CoA ligase gene, which is coordinately regulated with PAL, also display UV-light inducible in vivo footprints. Taken together, our findings suggest a general role of these putative cis-acting elements in the responses of plants to such stresses.