The effect of biologically active substances from coniferous plants on the <Emphasis Type="Italic">L</Emphasis>-phenylalanine ammonia lyase and peroxidase activities in wheat leaves

The effect of the preparations produced from needles and wood of various coniferous species on the activities of L-phenylalanine ammonia lyase (PAL; EC 4.3.1.5) and peroxidase (PO; EC 1.11.1.7), the enzymes involved in the development of plant defense response, was studied. It was demonstrated that treatment of brend wheat (Triticum aestivum L.) primary leaves with biological preparations produced from coniferous plants caused a transient increase in PAL and PO activities. The induction of these enzyme activities depends on the concentration of preparations and plant immune status. The results obtained suggest that coniferous metabolites are of interest as a source of plant extracts with the elicitor effect, increasing the resistance of plants to phytopathogens and adverse environmental factors. Original Russian Text ￠ E.V. Evtushenko, V.A. Saprykin, M.Yu. Galitsyn, V.M. Chekurov, 2008, published in Prikladnaya Biokhimiya i Mikrobiologiya, 2008, Vol. 44, No. 1, pp. 123–128.     

Activities of enzymes involved in the phenylpropanoid pathway in constitutively salicylic acid-producing tobacco plants

Chorismate mutase (CM, EC 5.4.99.5), phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) and chalcone synthase (CHS, EC 2.3.1.74) activities were studied in constitutive salicylic acid-producing (CSA) tobacco plants in relation to the accumulation of flavonoids and chlorogenic acid. The CM, PAL and CHS activities in CSA-tobacco (Nicotiana tabacum cv. Samsun NN) plants were lower than in non-transgenic tobacco plants. Flavonoid and chlorogenic acid accumulation was suppressed in CSA-tobacco plants compared to those of non-transgenic tobacco plants.     

In vitro selection of mung bean and tomato for improving tolerance to NaCl

Mung bean and tomato were in vitro selected from cotyledons on MS medium for improved tolerance to NaCl. The growth responses; the Na, K, proline and anthocyanin contents; and activities of phenylalanine ammonia lyase (PAL, EC 4.3.1.5), tyrosine ammonia lyase (TAL, EC 4.3.1) and chalcone isomerase (CI, EC 5.5.1.5) of the selected plants were characterised and compared with those of the original plants in relation to treatment with NaCl. The treatments significantly reduced fresh and dry weights of shoots and roots; the reduction was least pronounced in selected plants. Meanwhile, Na content was significantly increased; however, K was decreased, a trend that was obvious in original plants but withdrawn following in vitro selection with a consequent lowering in Na/K ratio. In addition, proline was greatly induced by NaCl; the induction was most pronounced in selected plants. Moreover, NaCl significantly increased anthocyanin and activities of PAL, TAL and CI in shoots and roots of both species; the increase was lesser in the selected than in the original plants. These findings indicated that selection of mung bean and tomato resulted in a recovery of growth, overproduction of proline and K and withdrawal of Na and secondary metabolism parameters relative to original plants pointing out to an improved tolerance to NaCl following in vitro selection.     

Changes in phenolic metabolism of tobacco plants during short-term boron deficiency

The effects of boron (B) deficiency on several phenolics and enzyme activities involved in the biosynthesis of these compounds were investigated in tobacco plants (Nicotiana tabacum L. cv. Gatersleben). The levels of phenylpropanoids (mainly the caffeic acid esters, chlorogenic acid and its isomers) as well as phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) and polyphenoloxidase (PPO, EC 1.14.18.1) activities were determined in plants subjected to B starvation for 1–7 d. The results presented here show that a short-term B deficiency causes both quantitative and qualitative changes in the phenolic metabolism of tobacco plants, which are especially evident after 3 d of B starvation. Although the concentration of B decreased from the onset of B starvation, root B level was less affected than leaf B by a short-term B deficiency. The concentration of phenylpropanoids as well as PAL and PPO activities increased mainly in the leaves of tobacco plants during B starvation. Moreover, leaves starved of B for 7 d showed the accumulation of new compounds, one of which was identified as caffeoylputrescine. In addition, a positive correlation between PAL activity and phenylpropanoid concentration was observed in tobacco leaves, especially after 5–7 d of B starvation, suggesting that an increase in PAL activity during B starvation could be responsible for the enhancement in the levels of phenylpropanoids.     

Effects of UV-B on activities of enzymes of secondary phenolic metabolism in barley primary leaves

Barley ( Hordeum vulgare L.) was grown in a glasshouse with 13.56 or 8.84 kJ m⁻²: biologically effective UV-B (280–320 nm: UV-B_BE) simulating levels predicted to occur with 25 or 5% ozone depletion at 40°N latitude, with UV-A (320–400 mm), or with no supplemental irradiation. Activities of L-phenylalanine ammonia-lyase (PAL, EC 4.3.1.5). chalcone-flavanone isomerase (CFI, EC 5.5.1.6) and peroxidase (EC 1.11.1.7) were determined from the 5th through the 30th day after planting. PAL regulates diversion of L-phenylalanine into precursors for secondary phenolics. CFI regulates an early step of flavonoid biosynthesis, and peroxidase activates phenolic precursors for cross-linking and rigidifying cell walls. At all ages UV-B decreased soluble protein leaf⁻¹ but had little effect on fresh weight or CFI activity. Exposure to UV-B decreased peroxidase activity only slightly in early growth stages but decreased it about 40% by day 30. PAL activity was highest 5 days after planting under all treatments, decreased thereafter, and was not detectable in control plants after day 10. UV-B prolonged PAL activity through day 15 in plants given the highest level of UV-B. This UV-B prolongation of PAL activity is correlated with, and is a likely underlying mechanism to explain, the UV-B- enhanced accumulation of flavonoids and ferulic acid in barley primary leaves. The results are discussed in terms of barley leaf adaptation to UV-B as developmental response dependent on conditions of plant growth.     

Partial Male Sterility in Transgenic Tobacco Carrying Antisense and Sense PAL cDNA under the Control of a Tapetum-Specific Promoter

Phenylalanine ammonia-lyase (PAL; EC 4.3.1.5 [EC] ) catalyzes thefirst step in the synthesis of phenylpropanoids. An antisenseor sense PAL cDNA of sweet potato under the control of a tapetum-specificpromoter of rice was introduced into tobacco. A reduction inpollen fertility was observed in two out of seventeen antisensePAL transformants and in six out of nineteen sense PAL transformants.The pollen fertility of these plants ranged from 8% to 60%.The distorted pollen grains that did not germinate lacked starchand flavonols. PAL activity in anthers at the microspore stagewas also reduced to some extent and the level of PAL activitywas positively correlated with the number of fertile pollengrains at the flowering stage. Although it was unclear how theantisense or sense transgene affected the PAL activity in anthers,our results clearly demonstrate that the PAL activity in theanther tapetum has a significant effect on the development ofmicrospores. (Received October 9, 1995; Accepted March 10, 1996)     

Azospirillum brasilense inoculation,auxin induction and culture medium composition modify the profile of antioxidant enzymes during in vitro rhizogenesis of pink lapacho

Optimal in vitro plant growth can be stimulated by selecting specific nutritional and environmental conditions. However, the culture conditions, dissection, and disinfection of plant material are stressful and may induce disruption of the plant physiological homeostasis. This can be modified by inoculation with rhizobacteria as Azospirillum brasilense, by the culture medium type, and by auxin induction. Here, we performed rooting experiments in two auxin-free culture media with ‘pink lapacho’ (Handroanthus impetiginosus) shoots previously induced with 0, 10, 30, or 50 μM indole butyric acid (IBA) for 3 days and inoculated with A. brasilense Cd and Az39. Peroxidase (PO), phenylalanine ammonia-lyase (PAL), and polyphenol oxidase (PPO) activities were determined on days 0, 3, 6, 9, 12, and 15. Also, weekly absolute rooting percentage was evaluated. All enzymatic activities were higher in A. brasilense-inoculated shoots, linked to early and high rooting percentage. The culture medium type and IBA concentration also affected enzymatic activities. The positive correlation between PO and PAL activities on day 9 and successful final in vitro rooting of H. impetiginosus allows using these activities as early markers of rhizogenesis reducing the selection time of easy-to-root plants. The changes in enzymatic levels performed here are discussed on the basis of their role in rooting and in vitro stress and contribute to the knowledge of the physiology of trees and their interaction with rhizobacteria.     

Role of sulphur availability on cadmium-induced changes of nitrogen and sulphur metabolism in maize (Zea mays L.) leaves

The interactions between sulphur nutrition and Cd exposure were investigated in maize (Zea mays L.) plants. Plants were grown for 12 days in nutrient solution with or without sulphate. Half of the plants of each treatment were then supplied with 100 microM Cd. Leaves were collected 0, 1, 2, 3, 4 and 5 days from the beginning of Cd application and used for chemical analysis and enzyme assays. Cd exposure produced symptoms of toxicity (leaf chlorosis, growth reduction) and induced a noticeable accumulation of non-protein SH compounds. As phytochelatins are glutamate- and cysteine-rich peptides, the effect of cadmium on some enzyme activities involved in N and S metabolism of maize leaves was studied in relation to the plant sulphur supply. In vivo Cd application to S-sufficient plants resulted in a drop of all measured enzyme activities. On the other hand, S-deficient plants showed a decrease in nitrate reductase (NR; EC 1.6.6.1) and glutamine synthetase (GS; EC 6.3.1.2) activity, and an increase in NAD-dependent glutamate dehydrogenase (GDH; EC 1.4.1.2) and phosphoenolpyruvate carboxylase (PEPc; EC 4.1.1.31) activity as a result of the Cd treatment. Furthermore, in the same plants ATP sulphurylase (ATPs; EC 2.7.7.4) and O-acetylserine sulphydrylase (OASs; EC 4.2.99.8) showed a particular pattern as both enzymes exhibited a transient maximum value of activity after 4 days from the beginning of Cd exposure. Results provide evidence that the increase of ATPs, OASs, GDH and PEPc activities, observed exclusively in S-deficient Cd-treated plants, may be part of the defence mechanism based on the production of phytochelatins.     

Effect of Seed Treatment by Cold Plasma on the Resistance of Tomato to Ralstonia solanacearum (Bacterial Wilt)

This study investigated the effect of cold plasma seed treatment on tomato bacterial wilt, caused by Ralstonia solanacearum (R. solanacearum), and the regulation of resistance mechanisms. The effect of cold plasma of 80W on seed germination, plant growth, nutrient uptake, disease severity, hydrogen peroxide (H₂O₂) concentration and activities of peroxidase (POD; EC 1.11.1.7), polyphenol oxidase (PPO; EC 1.10.3.2) and phenylalanine ammonia lyase (PAL; EC 4.3.1.5) were examined in tomato plants. Plasma treatment increased tomato resistance to R. solanacearum with an efficacy of 25.0%. Plasma treatment significantly increased both germination and plant growth in comparison with the control treatment, and plasma-treated plants absorbed more calcium and boron than the controls. In addition, H₂O₂ levels in treated plants rose faster and reached a higher peak, at 2.579 µM gFW⁻¹, 140% greater than that of the control. Activities of POD (421.3 U gFW⁻¹), PPO (508.8 U gFW⁻¹) and PAL (707.3 U gFW⁻¹) were also greater in the treated plants than in the controls (103.0 U gFW⁻¹, 166.0 U gFW⁻¹ and 309.4 U gFW⁻¹, respectively). These results suggest that plasma treatment affects the regulation of plant growth, H₂O₂ concentration, and POD, PPO and PAL activity in tomato, resulting in an improved resistance to R. solanacearum. Consequently, cold plasma seed treatment has the potential to control tomato bacterial wilt caused by R. solanacearum.     

Reduced Phenylalanine Ammonia-Lyase and Tyrosine Ammonia-Lyase Activities and Lignin Synthesis in Wheat Grown under Low Pressure Sodium Lamps

Wheat (Triticum aestivum L. cv Fremont) grown in hydroponic culture under 24-hour continuous irradiation at 560 to 580 micromoles per square meter per second from either metalhalide (MH), high pressure sodium (HPS), or low pressure sodium (LPS) lamps reached maturity in 70 days. Grain yields were similar under all three lamps, although LPS-grown plants lodged at maturity. Phenylalanine ammonia-lyase (PAL) and a tyrosine ammonia lyase (TAL) with lesser activity were detected in all extracts of leaf, inflorescence, and stem. Ammonia-lyase activities increased with age of the plant, and plants grown under the LPS lamp displayed PAL and TAL activities lower than wheat cultured under MH and HPS radiation. Greenhouse solar-grown wheat had the highest PAL and TAL activities. Lignin content of LPS-grown wheat was also significantly reduced from that of plants grown under MH or HPS lamps or in the greenhouse, showing a correlation with the reduced PAL and TAL activities. Ratios of far red-absorbing phytochrome to total phytochrome were similar for all three lamps, but the data do not yet warrant a conclusion about specific wavelengths missing from the LPS lamps that might have induced PAL and TAL activities in plants under the other lamps.     

Endophytic Pseudomonas fluorescens Endo2 and Endo35 induce resistance in black gram (Vigna mungo L. Hepper) to the pathogen Macrophomina phaseolina

Abstract

The effect of endophytic Pseudomonas fluorescens isolates Endo2 and Endo35 on induced systemic disease protection against dry root rot of black gram (Vigna mungo L. Hepper) caused by Macrophomina phaseolina was investigated under glasshouse conditions. When the bacterized black gram plants were inoculated with dry root rot pathogen, the activities of peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL) were stimulated in addition to accumulation of phenolics and lignin. Activity of phenylalanine ammonia-lyase (PAL) reached the maximum 24 h after pathogen challenge inoculation, whereas the activities of PO and PPO reached the maximum at 72 h and 48 h, respectively. Isoform analysis revealed that a unique PPO3 isozyme was induced in bacterized black gram tissues inoculated with the pathogen. Phenolics were found to accumulate in bacterized black gram tissues challenged with M. phaseolina one day after pathogen challenge. The accumulation of phenolics reached maximum at the third day after pathogen inoculation. Similar observation was found in the lignin content of black gram plants. In untreated control plants, the accumulation of defence enzymes and chemicals started at the first day and drastically decreased 3 days after pathogen inoculation. These results suggest that induction of defense enzymes involved in phenylpropanoid pathway and accumulation of phenolics and PR-proteins might have contributed to restricting invasion of Macrophomina phaseolina in black gram roots.     

Salinity-induced tissue-specific diurnal changes in nitrogen assimilatory enzymes in tomato seedlings grown under high or low nitrate medium.

We studied the salt stress (100 mM NaCl) effects on the diurnal changes in N metabolism enzymes in tomato seedlings (Lycopersicon esculentum Mill. cv. Chibli F1) that were grown under high nitrogen (HN, 5 mM NO(3)(-)) or low nitrogen (LN, 0.1 mM NO(3)(-)). NaCl stress led to a decrease in plant DW production and leaf surface to higher extent in HN than in LN plants. Total leaf chlorophyll (Chl) content was decreased by salinity in HN plants, but unchanged in LN plants. Soluble protein content was decreased by salt in the leaves from HN and LN plants, but increased in the stems-petioles from LN plants. Nitrate reductase (NR, EC 1.6.1.6) showed an activity peak during first part of the light period, but no diurnal changes were observed for the nitrite reductase (NiR, EC 1.7.7.1) activity. Glutamine synthetase (GS, EC 6.3.1.2) and glutamate synthase (Fd-GOGAT, EC 1.4.7.1) activities increased in HN plant leaves during the second part of the light period, probably when enough ammonium is produced by nitrate reduction. NR and NiR activities in the leaves were more decreased by NaCl in LN than in HN plants, whereas the opposite response was obtained for the GS activity. Fd-GOGAT activity was inhibited by NaCl in HN plant leaves, while salinity did not shift the peak of the NR and Fd-GOGAT activities during a diurnal cycle. The induction by NaCl stress occurred for the NR and GS activities in the roots of both HN and LN plants. Glutamate dehydrogenase (GDH, EC 1.4.1.2) activity shifted from the deaminating activity to the aminating activity in all tissues of HN plants. In LN plants, both aminating and deaminating activities were increased by salinity in the leaves and roots. The differences in the sensitivity to NaCl between HN and LN plants are discussed in relation to the N metabolism status brought on by salt stress.     

The Maceration of Vegetable Tissue by a Strain of Bacillus subtilis

Pectate lyase (PAL EC 4.2.2.2), pectinesterase (PE EC 3.1.1.11), L-arabinanase, D-xylanase, D-galactanase and neutral protease activities were identified in culture filtrates prepared from a strain B3 of Bacillus subtilis isolated from carrot. The PAL was purified by ion-exchange chromatography and iso-electric focusing and its properties examined. PAL had a pI of 9·85 and a molecular weight of 33000. Optimum activity occurred at pH 8–9 and 60–65°C. Calcium and to a lesser extent strontium were stimulatory while ethylenediamine tetraacetic acid led to inactivation. Thin layer chromatography separations of the end products of reactions and viscosity measurements suggested that the enzyme acted in a random manner. When examined over a range of pH values both culture filtrate and the purified PAL produced two distinct peaks of maceration (pH 6–6·5 and 8–9) against carrot or potato tissues. Evidence was obtained that although the presence of lyase was the sole external factor responsible for the maceration of carrot at pH 6·0, it acted in conjunction with a heat-labile, high molecular weight factor extractable from carrot tissue. Carrot extracts were unable to macerate carrot but liberated reducing groups from polygalacturonic acid and it is suggested that the factor may be, in part at least, carrot polygalacturonase. Maceration at pH 8·5 was largely accounted for by PAL and PE activities.     

Aqueous fruit extracts of Azadirachta indica induce systemic acquired resistance in barley against Drechslera graminea

The study reported here primarily focuses on whether fruit extracts of Azadirachta indica Juss. (Neem) can induce systemic acquired resistance (SAR) in Hordeum vulgare against Drechslera graminea. A single leaf from each of the 1-month-old seedlings grown in 50 pots was treated with neem extract. Seven samples were collected at 12-h intervals for estimation of salicylic acid (SA) content and activities of phenylalanine ammonia lyase (PAL) and peroxidase (PO). Disease incidence was recorded on uninoculated leaves after 2 weeks and on newly emerged leaves after 3 weeks of inoculation of spores of the pathogen. Treatment of single leaf of barley seedlings with aqueous fruit extract of neem could protect the untreated and later emerging leaves of these seedlings from infection by leaf stripe pathogen. The concentration of SA and activities of PAL and PO were significantly higher in untreated leaves of seedlings given a single leaf treatment with neem fruit extract. The results show that neem fruit extract induced SAR in barley seedlings against D. graminea. The results of the study are significant for developing an environment-friendly biocide, which could induce SAR in crop plants leading to efficient management of pathogens     

Trichoderma and chitin mixture based bioformulation for the management of head rot (Sclerotinia sclerotiorum (Lib.) deBary)–root-knot (Meloidogyne incognita Kofoid and White; Chitwood) complex diseases of cabbage

The effect of application of different biocontrol agents (Trichoderma spp (eight isolates), Pseudomonas fluorescens (four isolates) and Bacillus subtilis (two isolates)) was tested against head rot fungus, Sclerotinia sclerotiorum and root-knot nematode, Meloidogyne incognita complex diseases. In vitro studies showed that three Trichoderma isolates (Tvc1, Tvc2 and Thc) were effective in inhibition of mycelial growth of the fungus as well as egg hatching ability of the nematode. Application of talc based formulation of biocontrol agents (bioformulations) individually as well as in mixtures with or without chitin was tested against head rot–root-knot disease complex under greenhouse conditions. The combined application of bioformulation mixture (Tvc1, Tvc2 and Thc) along with chitin reduced the incidence of the complex diseases and induced significantly increased activities of phenylalanine ammonia-lyase (PAL), peroxidase (PO), polyphenol oxidase (PPO) and chitinase in cabbage. Activities of PAL and chitinase reached maximum levels within 10 – 20 d, while the activity of PAL continued to be maintained up to 40 d after the application of Tvc1 + Tvc2 + Thc + chitin. Isozyme analyses observed that unique PO (PO1, PO2 PO3 and PO4) and PPO (PPO1, PPO2 and PPO3) enzymes were induced after 10 d in cabbage plants treated with Tvc1 + Tvc2 + Thc + chitin upon challenge inoculation with head rot–root-knot pathogens. Similarly, the bioformulation mixture with chitin was successful at reducing the incidence of head rot–root-knot apart from enhancing the crop yield under field conditions. The mechanism associated with reduced incidence of head rot–root-knot in cabbage may be due to induction of defense proteins (PAL, PO, PPO and chitinase) in the crop.     

防卫基因PAL,LOX和PBZ1在水稻白叶枯病成株抗性中的作用(英文)

为了探讨水稻白叶枯病成株抗性是否与防卫基因相关 ,通过RT PCR研究了几种防卫基因PAL、LOX、PBZ1、Cht 1和PR1a的表达 ,同时也分析了PAL和LOX的酶活性变化 .结果表明 ,苗期PAL受病原菌诱导上调表达 ,而成株期病原菌和伤害均可诱导PAL上调表达 ,且成株期诱导表达强于苗期 .LOX在苗期和成株期都可受病原菌诱导表达 ,但成株期表达强于苗期且更持久 .PBZ1在苗期和成株期均受病原菌和伤害诱导表达 ,但成株期表达较苗期早且更强 .PR1a和Cht1没检测到期望的扩增片段 .PAL和LOX的酶活性分析结果与基因表达分析结果一致 .因此 ,PAL、LOX和PBZ1在苗期和成株期的表达差异可能与水稻白叶枯病成株抗性相关 .     

Influence of Pathogenic and Non-pathogenic Bacteria on Soybean Suspension Cells

Co-cultivations of plant suspension cultures of soybean ( Glycine max ) with compatible phytopathogenic ( Pseudomonas syringae pv. glycinea ), incompatible phytopathogenic ( Pseudomonas syringae pv. tomato ), and different non-pathogenic ( Erwinia herbicola, Escherichia coli ) bacteria were carried out. Growth and viability (triphenyltetrazolium chloride activity) of plant cells and bacteria as well as enzyme activities of peroxidase (PO), polyphenoloxidase (PPO), and phenylalanine ammonialyase (PAL) within the plant cells were investigated over an incubation period of 7 days. The compatible pathogen inhibited growth and viability of the plant cells after 1 day and led to the death of the majority of the plant cells by the seventh day. In contrast, the incompatible pathogen directly reduced growth and viability of the soybean cells and caused a strong induction of enzyme activities of PO and PAL to more than 4 times of the untreated control by the seventh day. The epiphytic bacterium Erwinia herbicola caused a slight inhibition of growth and viability of the plant cells after the second day of co-cultivation. The PO activity increased in the same manner as in the incompatible interaction. The saprophytic Escherichia coli strain had a negligible influence on soybean suspension cells. All the bacteria tested except for Escherichia coli multiplied rapidly during co-cultivation and reached populations of 10⁸-10⁹ colonyfoming units/ml in the stationary phase. The results from this study demonstrate that the soybean suspension cells react differently to compatible, incompatible and saprophytic bacteria.     

Plant Growth–Promoting Methylobacterium Induces Defense Responses in Groundnut (Arachis hypogaea L.) Compared with Rot Pathogens

This study, framed in two different phases, studied the plant-growth promotion and the induction of systemic resistance in groundnut by Methylobacterium. Seed imbibition with Methylobacterium sp. increased germination by 19.5% compared with controls. Combined inoculation of Methylobacterium sp. with Rhizobium sp. also significantly increased plant growth, nodulation, and yield attributes in groundnut compared with individual inoculation of Rhizobium sp. Methylobacterium sp. challenge-inoculated with Aspergillus niger/Sclerotium rolfsii in groundnut significantly enhanced germination percentage and seedling vigour and showed increased phenylalanine ammonia lyase (PAL), β-1,3-glucanase, and peroxidase (PO) activities. Under pot-culture conditions, in Methylobacterium sp. seed—treated groundnut plants challenge-inoculated with A. niger/S. rolfsii through foliar sprays on day 30, the activities of enzymes PO, PAL, and β-1,3-glucanase increased constantly from 24 to 72 hours, after which decreased activity was noted. Five isozymes of polyphenol oxidase and PO could be detected in Methylobacterium-treated plants challenged with A. niger/S. rolfsii. Induced systemic resistance activity in groundnut against rot pathogens in response to methylotrophic bacteria suggests the possibility that pink-pigmented facultative methylotrophic bacteria might be used as a means of biologic disease control.     

Ethylene in relation to protein, peroxidase and polyphenol oxidase activities during rooting in hazelnut cotyledons

During formation of adventitious roots, the effects of 2-chlorethylphosphonic acid (CEPA), 1-aminocyclopropane-1-carboxylic acid (ACC) and aminoethoxyvinylglycine (AVG) added to a Cheng basal medium, supplemented with indole-3-butyricacid (IBA) and kinetin were determined on peroxidase (PO; EC 1.11.1.7) and poiyphenol oxidase (PPO; EC 1.10.3.1) activities in cotyledon explants of hazelnut ( Corylus avellana L. cv. Casina). CEPA stimulated PO and PPO activities while AVG inhibited. SDS-polyacrylamide gel electrophoresis of preparations from hazelnut cotyledons showed a correlation between proteins and rooting. Ethylene seems to modify total protein content and the activities of PO and PPO. As compared to the control extracts, AVG inhibited the anodic (53, 30.7 and 27 kDa) and cathodic (66.2 and 53.4 kDa) isoperoxidases and anodic (27.5 and 21 kDa) and cathodic (67.5 kDa) isopolyphenol oxidases, whereas CEPA promoted the anodic (30.7, 28.8 and 27 kDa) and cathodic (53.4 and 27.2 kDa) isozymes with PO activity. The increased PO activity during rooting in hazelnut cotyledons could enhance isozymes with lignin biosynthetic activity.