Effects of Glyphosate on Metabolism of Phenolic Compounds

Light enhanced the inhibiting effect of root-fed glyphosate (5 × 10^?4M) on dry weight accumulation of soybean [Glycine max. (L.) Merr.] seedling axes. Inhibition of growth by light was greatest in hypocotyls, whereas by glyphosate it was greatest in roots. A synergistic effect of light and glyphosate on stimulation of phenylalanine ammonia-Iyase (PAL, E.C. 4.3.1.5) activity was also demonstrated. In continuous white light PAL activity increased linearly for 4 days in axes of seedlings exposed to glyphosate. Evidence of phytochrome involvement in the light effect was shown. The stimulatory effect of glyphosate on PAL activity was greater in roots than in hypocotyls. Soluble hydroxyphenolic compound levels were reduced by glyphosate but were increased by light on a per axis basis. On a fresh weight basis, hydroxyphenolics were more concentrated in glyphosate-treated than in control tissues in the light. When compared to other amino acids, disproportionate decreases in free pools of phenylalanine and tyrosine occurred in axes of seedlings treated with glyphosate and light. The effect of light on all measured parameters was mainly in the hypocotyl, while that of glyphosate was primarily in the root. In the light, glyphosate caused increases in levels of glutamine and other amino acids that may be the result of amination reactions, protecting from excess ammonia generated by enhanced PAL activity. These results suggest that PAL has a strong influence on its substrate levels in this system and/or that glyphosate inhibits synthesis of aromatic amino acids.     

Effects of Glyphosate on Metabolism of Phenolic Compounds: V. l-alpha-AMINOOXY-beta-PHENYLPROPIONIC ACID AND GLYPHOSATE EFFECTS ON PHENYLALANINE AMMONIA-LYASE IN SOYBEAN SEEDLINGS

The phenylalanine ammonia-lyase (PAL) inhibitor l-alpha-aminooxy-beta-phenylpropionic acid (AOPP) was root-fed to light-exposed soybean seedlings alone or with glyphosate [N-(phosphonomethyl)glycine] to test further the hypothesis that PAL activity is involved in the mode of action of glyphosate. Extractable PAL activity was increased by 0.01 and 0.1 millimolar AOPP. AOPP reduced total soluble hydroxyphenolic compound levels and increased phenylalanine and tyrosine levels, indicating that in vivo PAL activity was inhibited by AOPP. The increase in extractable PAL caused by AOPP may be a result of decreased feedback inhibition of PAL synthesis by cinnamic acid and/or its derivatives. AOPP alone had no effect on growth (fresh weight and elongation) at either concentration, but at 0.1 millimolar it slightly alleviated growth (fresh weight) inhibition caused by 0.5 millimolar glyphosate after 4 days. Reduction of the free pool of phenylalanine by glyphosate was reversed by AOPP. These results indicate that glyphosate exerts some of its effects through reduction of aromatic amino acid pools through increases in PAL activity and that not all growth effects of glyphosate are due to reductions of aromatic amino acids.     

Effects of glyphosate on phenolic metabolism in yellow nutsedge leaves

The action of the herbicide glyphosate [N-(phosphonomethyl)-glycine] on phenolic metabolism and phenylalanine ammonia lyase (PAL; EC 4.3.1.5) activity was investigated in yellow nutsedge (Cyperus esculentus L.). Glyphosate caused significant increases in the amount of total soluble hydroxyphenolics in the three fractions studied (neutral, acid and residual). Qualitative and quantitative differences in relation to these fractions and the amount of applied glyphosate were observed. Most of the phenolic compounds which increased after glyphosate treatment were benzoic acids (gentisic. p -OH-benzoic, salicylic and vanillic). Gentisic acid showed the greatest increase in neutral and acid fractions, being twenty- and four-fold, respectively, of the amount found in the control. PAL activity was not affected by the lowest doses of glyphosate (10−⁴and 10−³ M) , but a dramatic decrease in PAL activity was observed after 10−² M treatment. These findings, together with the low levels of cinnamic acids measured in treated yellow nutsedge plants, suggest that PAL activity is only marginally involved in glyphosate action. Since the herbicidal action probably takes place at 5-enol-pyruvylshikimate-3-P synthase (EC 2.5.1.19), an alternative pathway to PAL in phenolic biosynthesis should be activated yielding benzoic acids.     

Effects of Glyphosate on the Shikimate Pathway and Regulation of Phenylalanine Ammonia-lyase in Cryptomeria and Perilla Cell Suspension Cultures

Treatment of Cryptomeria and Perilla cell suspension cultureswith glyphosate resulted in a marked suppression of the formationof flavans and caffeic acid derivatives, respectively, whileit caused only a slight decline in the cell growth. In contrastwith 3-deoxy-D-arabino-heptulosonate (DAHP) synthase-Mn isozyme,DAHP synthase-Co isozyme from Cryptomeria and Perilla cellswas much more sensitive to inhibition by glyphosate. The additionof 1 to 2 mM glyphosate caused an accumulation of shikimateand quinate and a reduction of L-phenylalanine in both cellcultures. The inhibition of phenylalanine ammonia-lyase (PAL)activity by glyphosate was reversed by exogenously suppliedL-phenylalanine to near the control level. Cycloheximide andactinomycin D nullified the recovery by exogenous L-phenylalanineon PAL activity. L-Phenylalanine itself promoted PAL activityto some extent. No recovery of PAL activity in L--aminooxy-ß-phenylpropionate(L-AOPP)-treated cell cultures could be observed by the additionof L-phenylalanine. Therefore, L-AOPP seems to inhibit the formationof PAL, though it has been considered a competitive inhibitor. ³Present address: Biological Institute, Faculty of Science,Tohoku University, Sendai 980, Japan. (Received October 28, 1985; Accepted March 13, 1986)     

Influence of glyphosate on flower morphogenesis and pigmentation in Petunia hybrida

Glyphosate showed a remarkable effect inducing the change of flower symmetry from the actinomorphic to the zygomorphic type in Petunia hybrida. Glyphosate [N-(phosphonomethyl)glycine] reduced the anthocyanin content and showed a weak inhibitory effect against phenylalanine ammonia-lyase (PAL) activity. L-2-Aminooxy-3-phenylpropionic acid (APA), an inhibitor of PAL activity, reduced the anthocyanin content but had no effect on flower shape. Additional phenylalanine or trans-cinnamic acid, the intermediates of glyphosate inhibition against PAL activity, could not recover the change of flower shape induced by glyphosate. These results suggested that the reduction of PAL activity alone could not account for the two characteristic changes of flower symmetry and pigmentation induced by glyphosate. On the other hand, the results of application of glyphosate-related compounds suggested that the structure of glyphosate contributed to induce the morphological change of Petunia flower. Glyphosate may thus be a very useful agent in the elucidation of unresolved questions of flower morphogenesis and the related metabolism.     

Comparative aspects of root and root nodule secondary metabolism in alfalfa

l-phenylalanine ammonia lyase (PAL), indoleacetic acid oxidase (IAA oxidase), O-methyltransferase, peroxidase, total phenolics and total indoles were compared in roots and root nodules of alfalfa. PAL, O-methyl-transferase, total phenolics and total indoles were higher in nodules than in roots. Isolated bacteroids were assayed for O-methyltransferase, PAL, peroxidase and total phenolics, but their levels were either low or not detectable. Nodule leghemoglobin was separated by disc gel electrophoresis and found to have IAA oxidase activity. Phenolics, IAA oxidase and leghemoglobin appear to be interrelated in regulating indole levels in the nodule.     

Relationship between the enzymatic browning and phenylalanine ammonia-lyase activity of cut lettuce, and the prevention of browning by inhibitors of polyphenol biosynthesis.

Cut lettuce stored at 4 degrees C gradually turned brown on the cut section after several days of storage. Three factors for enzymatic browning, the polyphenol content, polyphenol oxidase activity, and phenylalanine ammonia-lyase (PAL) activity, were examined during the cold storage of cut lettuce. A relationship between the browning and PAL activity was apparent. We tried to prevent this browning by using the two enzyme inhibitors, 2-aminoindane-2-phosphonic acid (AIP), an inhibitor of the phenylpropanoid pathway, and glyphosate, an inhibitor of the shikimate pathway. AIP and glyphosate significantly inhibited the browning of cut lettuce. The polyphenol content and PAL activity were both reduced by the treatment with AIP. These results show that regulating the biosynthesis of polyphenols is essential to prevent the browning of cut lettuce.     

Preservation of high phenylalanine ammonia lyase activities in roots of Japanese Striped corn: A potential oral therapeutic to treat phenylketonuria

Phenylketonuria (PKU) is an inherited metabolic disorder caused by deficient phenylalanine hydroxylase (PAH) activity, the enzyme responsible for the disposal of excess amounts of the essential amino acid phenylalanine (Phe). Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) has potential to serve as an enzyme substitution therapy for this human genetic disease. Using 7-day-old Japanese Striped corn seedlings (Japonica Striped maize, Zea mays L. cv. japonica) that contain high activities of PAL, we investigated a number of methods to preserve the roots as an intact food and for long-term storage. The cryoprotectant effects of maple syrup and other edible sugars (mono- and oligosaccharides) were evaluated. Following thawing, the preserved roots were then examined to determine whether the rigid plant cell walls could protect the PAL enzyme from proteolysis during simulated (in vitro) digestion comprised of gastric and intestinal phases. While several treatments led to retention of PAL activity during freezing, upon thawing and in vitro digestion, root tissues that had been previously frozen in the presence of maple syrup exhibited the highest residual PAL activities (∼50% of the initial enzyme activity), in marked contrast to all of the treatments using other edible sugars. The structural integrity of the root cells, and the stability of the functional PAL tetramer were also preserved with the maple syrup protocol. These results have significance for the formulation of oral enzyme/protein therapeutics. When plant tissues are adequately preserved, the rigid cell walls constitute a protective barrier even under harsh (e.g. gastrointestinal-like) conditions.     

Effects of Glyphosate on Metabolism of Phenolic Compounds VIII. Comparison of the Effects of Aminooxyacetate and Glyphosate

Aminooxyacetate (AOA), an in vitro inhibitor of phenylalanineammonia-lyase (PAL) and of some transaminases, was tested forcomparison with glyphosate's [N-(phosphonomethyl)glycine] effectson plant growth, PAL activity, and accumulation of hydroxyphenoliccompounds of three-day-old, dark-grown soybean [Glycine max(L.) Merr.] seedlings. Root-fed AOA (50 µM) and glyphosate(0.5 mM) caused similar decreases in growth rate and in accumulationof hydroxyphenolics, anthocyanin and chlorophyll. Together,these compounds were neither antagonistic nor synergistic inaffecting these parameters. AOA caused decreases in extractablePAL activity while increasing aromatic amino acid pools—theopposite of glyphosate's effects. In the light, the effect ofglyphosate on PAL and aromatic amino acids predominated overthose of AOA when the chemicals were given together. The effectsof AOA and glyphosate on most free amino acid levels were similar.In those cases in which the effects differed, glyphosate's effectpredominated over that of AOA when the chemicals were giventogether. The similarities and interactions of AOA and glyphosatein their effects on free amino acid profiles indicate that glyphosatesignificantly interferes with non-aromatic as well as aromaticamino acid synthesis. (Received April 6, 1982; Accepted June 28, 1982)     

Effects of Glyphosate on Caffeic Acid Metabolism in Perilla Cell Suspension Cultures

Perilla cell suspension cultures contained caffeic acid at 0.073%of the fresh weight. When 1 min glyphosate was administeredto the cell culture in the logarithmic and stationary phases,the amount of caffeic acid ceased to increase and remained ata nearly constant level during the following several days. Phenylalanineammonia-lyase (PAL) activity in the cell culture increased immediatelyafter transfer to a fresh medium, decreased rapidly in the midstof the logarithmic phase and became almost undetectable in thestationary phase. PAL activity was markedly inhibited by glyphosateat more than 0.2 mM. The shikimic acid content of cells from14-day culture grown in the presence of 1 mM glyphosate increasedup to 74.9 µg per g fresh weight during 6-day culture,whereas that of the control cells was undetectable. The dosageof 0.15 mM L-2-aminooxy-3-phenylpropionic acid (L-AOPP), aninhibitor of PAL, to the cells did not cause shikimic acid accumulation. (Received June 25, 1983; Accepted October 6, 1983)     

Involvement of melatonin applied to Vigna radiata L. seeds in plant response to chilling stress

The impact of melatonin (50 µM L^?1) applied to Vigna radiata seeds by hydro-priming on phenolic content, L-phenylalanine ammonialyase (PAL) activity, MEL level, antioxidant properties of ethanol extracts as well as electrolyte leakage from chilled and re-warmed Vigna radiata roots of seedlings were examined. Seedlings obtained from non-primed seeds, hydro-primed and hydro-primed with MEL were investigated after 2 days of chilling and 2 days of re-warming. At 25°C, the level of MEL in roots derived from seeds hydro-primed with MEL was 7-fold higher than in roots derived from non-primed seeds. However, the content of MEL significantly decreased in all variants investigated after re-warming, in contrast to PAL activity and phenolic levels, which reached the highest values. The antioxidant capacity of ethanol extracts from chilled and re-warmed roots, determined by ABTS+· assay, was correlated with phenolic content while the reducing ability of these extracts, determined by the FRAP method, correlated with PAL activity. However, both were the highest in rewarmed roots with applied MEL, which was accompanied by a significant decline in electrolyte leakage. Taken together, results may indicate that MEL can play a positive role in plant acclimation to stressful conditions and activation of phenolic pathway by this molecule.     

Accumulation of Salicylic Acid and 4-Hydroxybenzoic Acid in Phloem Fluids of Cucumber during Systemic Acquired Resistance Is Preceded by a Transient Increase in Phenylalanine Ammonia-Lyase Activity in Petioles and Stems

Cucumber (Cucumis sativa) leaves infiltrated with Pseudomonas syringae pv. syringae cells produced a mobile signal for systemic acquired resistance between 3 and 6 h after inoculation. The production of a mobile signal by inoculated leaves was followed by a transient increase in phenylalanine ammonia-lyase (PAL) activity in the petioles of inoculated leaves and in stems above inoculated leaves; with peaks in activity at 9 and 12 h, respectively, after inoculation. In contrast, PAL activity in inoculated leaves continued to rise slowly for at least 18 h. No increases in PAL activity were detected in healthy leaves of inoculated plants. Two benzoic acid derivatives, salicylic acid (SA) and 4-hydroxybenzoic acid (4HBA), began to accumulate in phloem fluids at about the time PAL activity began to increase, reaching maximum concentrations 15 h after inoculation. The accumulation of SA and 4HBA in phloem fluids was unaffected by the removal of all leaves 6 h after inoculation, and seedlings excised from roots prior to inoculation still accumulated high levels of SA and 4HBA. These results suggest that SA and 4HBA are synthesized de novo in stems and petioles in response to a mobile signal from the inoculated leaf.     

Glyphosate inhibition of ferric reductase activity in iron deficient sunflower roots

Iron (Fe) deficiency is increasingly being observed in cropping systems with frequent glyphosate applications. A likely reason for this is that glyphosate interferes with root uptake of Fe by inhibiting ferric reductase in roots required for Fe acquisition by dicot and nongrass species. This study investigated the role of drift rates of glyphosate (0.32, 0.95 or 1.89 mm glyphosate corresponding to 1, 3 and 6% of the recommended herbicidal dose, respectively) on ferric reductase activity of sunflower (Helianthus annuus) roots grown under Fe deficiency conditions. Application of 1.89 mm glyphosate resulted in almost 50% inhibition of ferric reductase within 6 h and complete inhibition 24 h after the treatment. Even at lower rates of glyphosate (e.g. 0.32 mm and 0.95 mm), ferric reductase was inhibited. Soluble sugar concentration and the NAD(P)H oxidizing capacity of apical roots were not decreased by the glyphosate applications. To our knowledge, this is the first study reporting the effects of glyphosate on ferric reductase activity. The nature of the inhibitory effect of glyphosate on ferric reductase could not be identified. Impaired ferric reductase could be a major reason for the increasingly observed Fe deficiency in cropping systems associated with widespread glyphosate usage.     

Enzyme Responses of <Emphasis Type="Italic">Abutilon Theophrasti</Emphasis> in an Enhanced Biocontrol System

Weak virulence has limited the development of Colletorichum coccodes (Wallr.) Hughes (DAOM 183088) as a bioherbicide for Abutilon theophrasti Medik. (velvetleaf) control. This study examines the role of chemical synergy to suppress host defense mechanisms. Dry weight of A. theophrasti was reduced by treatment with C. coccodes in a tank-mix with 0.25 kg a.i. ha⁻¹ bentazon more than by the treatment with C. coccodes or bentazon alone, while the effect of a sub-lethal rate of glyphosate was not significant. C. coccodes did not affect phenylalanine ammonia lyase (PAL) activity in infected leaves of A. theophrasti, whereas PAL activity was significantly inhibited by the presence of bentazon 5 days after treatment. The inhibition was stronger when bentazon was applied alone than when bentazon was applied with C. coccodes. Treatment with glyphosate or a mixture of glyphosate and C. coccodes did not affect PAL activity. Peroxidase activity was strongly induced by C. coccodes treatment and increased over time. Peroxidase activity was not induced by 0.25 kg a.i. ha⁻¹ bentazon alone. However, when bentazon was applied in combination with C. coccodes, it prevented the activation of peroxidase by C. coccodes infection. Treatment with 0.2 kg a.i. ha⁻¹ glyphosate did not affect peroxidase activity. These results suggest that these enzymes are involved in the resistance mechanism of A. theophrasti, and the synergistic effect of bentazon on C. coccodes efficacy as a bioherbicide may result from suppressing the activation of these defense-related enzymes.     

Inhibition of phenylalanine ammonia-lyase by cinnamic acid derivatives and related compounds

Thirty-five derivatives of cinnamic acid and related compounds were tested for inhibition against phenylalanine ammonia-lyase (PAL) derived from sweet potato, pea and yeast. Caffeic and gallic acids showed inhibition against PAL originating from higher plants, but not against yeast PAL. In contrast, yeast PAL was specifically inhibited by p-hydroxycinnamic and p-hydroxybenzoic acids. The results suggest that caffeic and gallic acids may act as regulatory substances in phenylpropanoid metabolism in higher plants. Inhibition experiments with synthetic cinnamic acid derivatives have revealed that the presence of a hydrophobic aromatic ring, α,β-double bond and carboxyl group is essential for inhibitory activity. 2-Naphthoic acid which fulfills these structural requirements showed a strong inhibition. The size and shape of the active site is discussed from structure-activity relationships of cinnamic acid derivatives. o-Chlorocinnamic acid, one of the strongest inhibitors found in this study showed an inhibitory effect on the growth of the roots of rice seedlings.     

Changes of phenolic metabolism and oxidative status in nitrogen-deficient Matricaria chamomilla plants

The effects of nitrogen deficiency on selected physiological attributes, phenylalanine ammonia-lyase (PAL, EC. 4.3.1.5) activity, phenolic contents, peroxidase (EC. 1.11.1.7) and catalase (EC. 1.11.1.6) activities, lipid peroxidation status and H₂O₂ accumulation were studied in N-deficient Matricaria chamomilla (L.) over 12 days. N deficiency enhanced root growth and inhibited shoot growth. Chlorophyll composition and F _v/F _m were not affected by N stress, but nitrogen and soluble proteins decreased in both the rosettes and the roots. PAL activity, expressed per mg protein, was enhanced in N-deficient rosettes and tended to decrease by the end of the experiment, while in the roots PAL activity was maintained. Total phenolic contents increased in both rosettes and roots. Peroxidase and catalase activities in N-deficient rosettes tended to decrease by the end of the experiment, while in the roots they increased on the 12th day of deficiency. Furthermore, lipid peroxidation status increased in N-deficient roots on the 12th day, indicating that antioxidative protection was insufficient to scavenge reactive oxygen species being generated. Surprisingly, H₂O₂ content was even lower in N-deficient roots by the end of the experiment, while in the leaves increased. This observation in correlation to lipid peroxidation and H₂O₂ degradation is discussed. The importance of PAL activity and phenolic metabolites in combination with antioxidative enzymes for plant protection against oxidative stress and the significance of PAL activity for the mobilization of N availability in N-deficient tissue are also discussed in view of existing information.     

Distribution of phenylalanine ammonia-lyase in etiolated and far-red irradiated radish seedlings

Summary In dark-grown Raphanus seedlings, most of the PAL activity is found in roots where it increases sigmoidally during organ development. In hypocotyls, the dark increase of enzyme activity is linear with time. In cotyledons and hooks, dark activity is very low and remains constant. After onset of continuous far-red irradiation, an activity increase is observed in all parts of the seedling. In cotyledons and hooks, the increase is followed by a decrease. This is comparable to light-induced PAL activity described in other materials. In roots and hypocotyls, the initial increase is not followed by a decrease. In dark-grown roots and hypocotyls PAL activity is correlated to fresh weight augmentation. In no part of the seedling could a correlation be found between light-induced PAL activity and anthocyanin formation.     

Production of caffeic,chlorogenic and rosmarinic acids in plants and suspension cultures of Glechoma hederacea

Glechoma hederacea L. (Lamiaceae) is a perennial plant, which is distributed widely in Europe, Asia and America. Important anti-oxidant compounds are caffeic acid esters like rosmarinic acid (RA) and chlorogenic acid (CA). Phenylalanine ammonia-lyase (PAL) and rosmarinic acid synthase (RAS, 4-coumaroyl-CoA:hydroxyphenyllactic acid hydroxycinnamoyltransferase) contribute to the formation of RA. Our aim in this study was to follow the accumulation of RA, CA and caffeic acid in a suspension culture of G. hederacea. Growth, medium and secondary metabolism parameters were determined during a culture period of 14 days. The maximal PAL activity was observed on day 5 and the maximal RAS activity on day 8. The RA content was exceedingly high and reached 25.9% of the dry mass on day 7. Caffeic acid and CA contents remained rather low. Furthermore, the presence of RA, CA and caffeic acid and the expression patterns of RAS and hydroxycinnamoyl-CoA:shikimate hydroxycinnamoyltransferase (HST), an important enzyme of monolignol formation, in leaves, flowers, stems and roots of naturally grown G. hederacea were assessed. The expression of RAS and HST genes was detectable in all organs except roots. Flowers accumulated 12.5% RA in their dry mass, leaves, stems and roots about 1%. CA was highest in leaves (2.0%), while it was at 1.6% in flowers, 1.3% in stems and almost undetectable in roots. The caffeic acid content remained at or below 0.4% of the dry weight in all organs.     

Phenylalanine Ammonia-lyase Activity in Barley After Infection with Bipolaris sorokiniana or Treatment with its Purified Xylanase

Phenylalanine ammonia-lyase (PAL) activity was determined from leaves and roots of two barley (Hordeum vulgare L.) cultivars after infection with a necrotrophic pathogen, Bipolaris sorokiniana (Sacc.) Shoem., and treatment with its purified xylanase. PAL activity increased in leaves of both cultivars 16 h after fungal inoculation but two phases, with activity peaks at 24–32 h and 40 h, were recorded only for the more resistant cultivar, Agneta. Attempts to use a PAL inhibitor, χ-amin, ooxyacetic acid, to increase susceptibility to B. sorokiniana in barley leaves were unsuccessful. Treatments of leaves with purified xylanase resulted in more rapid (4–12 h after injection), although reduced, induction of PAL compared with fungal injection. The higher the concentration of xylanase applied the earlier the activity peaks were detected. Fungal inoculation only slightly increased PAL activity in barley roots while xylanase treatment had no effect. The basal level of PAL was however much higher in roots than in leaves. In wheat, Triticum aestivum L. resistant to B. sorokiniana, the time-course of PAL induction after fungal infection and xylanase treatment resembled that for cv. Agneta, while in oats, Avena sativa L. (non-host) PAL activity did not change after the treatments. The results suggest that the second phase of PAL induction, associated only with responses of barley cv. Agneta and wheat, is linked with their resistance to B. sorokiniana infection. The possible role of xylanase as an elicitor of PAL is discussed.     

Molecular cloning and characterization of 5-enolpyruvylshikimate-3-phosphate synthase gene from Convolvulus arvensis L.

5-Enolpyruvylshikimate-3-phosphate synthase (EPSPS), the target enzyme for glyphosate inhibition, catalyzes an essential step in the shikimate pathway for aromatic amino acid biosynthesis. The full-length cDNA of 1,751 nucleotides (CaEPSPS, Genbank accession number: EU698030) from Convolvulus arvensis was cloned and characterized. The CaEPSPS encodes a polypeptide of 520 amino acids with a calculated molecular weight of 55.5 kDa and an isoelectric point of 7.05. The results of homology analysis revealed that CaEPSPS showed highly homologous with EPSPS proteins from other plant species. Tissue expression pattern analysis indicated that CaEPSPS was constitutively expressed in stems, leaves and roots, with lower expression in roots. CaEPSPS expression level could increase significantly with glyphosate treatment, and reached its maximum at 24 h after glyphosate application. We fused CaEPSPS to the CaMV 35S promoter and introduced the chimeric gene into Arabidopsis. The resultant expression of CaEPSPS in transgenic Arabidopsis plants exhibited enhanced tolerance to glyphosate in comparison with control.