Increase In Phenylalanine Ammonia-lyase Activity Research Articles

Fungal endophytes-induced abscisic acid is required for flavonoid accumulation in suspension cells of Ginkgo biloba

Treatment of suspension cells of Ginkgo biloba with fungal endophytes resulted in accumulation of flavonoids, increased abscisic acid (ABA) production and activation of phenylalanine ammonia-lyase (PAL). Fluridone, an inhibitor of ABA biosynthesis, was effective in inhibiting fungal endophytes-induced ABA biosynthesis, increase of PAL activity and flavonoids accumulation. Moreover, exogenous application of ABA enhanced PAL activity and increased accumulation of flavonoids in G. biloba cells with or without fungal endophytes elicitor. These finding suggest a causal relationship between ABA release and both PAL activity and flavonoid accumulation under fungal endophytes treatment and that ABA is involved in fungal endophytes-induced flavonoids accumulation in this plant.

Anatomical and physiological evidence of white blush on baby carrot surfaces

This study characterizes dehydration and white blush processes, structural alterations and synthesis of phenolic compounds (lignin and suberin), in relation to development of white blush on baby carrot surfaces. Carrots were minimally processed as baby carrots and kept on polypropylene trays with or without polyvinyl chloride (PVC) film at 5 ± 2 °C, 90 ± 5% RH. During storage, baby carrots that were not wrapped with PVC film were rehydrated 1, 1.5, 15 and 17 h after minimal processing. Fresh-cut baby carrots were evaluated for white blush index, sensory analysis (visual scores), fresh matter loss, phenylalanine ammonia-lyase (PAL) activity and structural and histochemical changes. Increases in white blush index and subjective visual scores on the carrot surface occurred in the first hours, when the material was kept on trays without PVC film and after 3 and 6 d, when stored on trays covered with PVC film. Visual assessment of white blush resulted in a more accurate assessment than instrumental evaluation because it allowed the perception of minor differences between distinct white blush levels, especially at the tips. Hydrating baby carrot surfaces for 1 and 1.5 h after processing allowed partial absorption of water by tissues and the orange color was reestablished on the surface. Fifteen hours after processing, even after rehydration, the color did not return to the original orange standard. The rapid increase in PAL activity in the secondary phloem of baby carrots, compared to that of whole carrots, suggested a physiological response as a result of abrasion. Dehydration and structural alterations of the more superficial cell layers were the main causes of white blush in baby carrots that was not related to lignin accumulation, but rather to synthesis of non-structural phenolic compounds.

Changes in Enzyme Activities During Postharvest Deterioration of Green Asparagus Spears

Fresh asparagus (Asparagus officinalis L.) deteriorates rapidly after harvest. Early enzymatic changes that fol- low harvesting of asparagus are important factors contributing to postharvest deterioration. We held asparagus spears at 25°C for up to 5 days after harvest and examined changes in the activities of Acid invertase (AI), Sucrose Synthase (SS), Glutamine Synthetase (GS) and Phenylalanine ammonia Lyase (PAL) in both top and bottom portions of the spears. Solu- ble AI activity increased during the first day of storage and after that it decreased gradually up to five days in both top and bottom portions. Sucrose synthase activity was higher in the bottom portion than in the top; its activity declined daily for five days. Sucrose content was negatively correlated with invertase and sucrose synthase in both portions.GS enzyme ac- tivity in both top and bottom portion declined throughout the experimental period which may be related to increased am- monia accumulation. The increase in PAL activity continued until day 3 and declined thereafter.

Inhibition of browning on the surface of peach slices by short-term exposure to nitric oxide and ascorbic acid

The effect of 0.2% ascorbic acid (AA), 5 μM nitric oxide (NO), and the simultaneous use of 0.2% AA and 5 μM NO solutions on inhibiting surface browning of fresh-cut peach slices stored at 10 °C and RH 95% was investigated. The browning index, relative leakage rate, microstructure, total phenol content, and activity of the phenol metabolism-associated enzymes phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) were evaluated. The results indicate that treatment with 0.2% AA, 5 μM NO and simultaneous use of 0.2% AA and 5 μM NO resulted in higher total phenol content, inhibition of PPO and POD activity, reduced membrane permeability and protection of cell microstructure to maintain compartmentation between enzymes and their substrates. In addition, NO increased PAL activity. The causes of inhibition in the browning of peach slices by NO are discussed.

Effects of salt stress on growth, antioxidant enzyme and phenylalanine ammonia-lyase activities in Jatropha curcas L. seedlings

The effects of increasing NaCl concentrations on biomass, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and phenylalanine ammonia-lyase (PAL) in <I>Jatropha curcas</I> L. seedlings were investigated. The fresh weights of cotyledons and radicles with increasing NaCl concentrations decreased progressively, and the fresh weight of hypocotyls reached the lowest level at NaCl concentration of 150 mmol and then increased. SOD activity in the cotyledons, hypocotyls and radicles increased gradually up to NaCl concentrations of 150, 200 and 150 mmol, respectively. The highest POD activities in the cotyledons, hypocotyls and radicles were observed at NaCl concentrations of 150, 200 and 150 mmol, respectively. CAT activity in the cotyledons, hypocotyls and radicles enhanced gradually up to 100, 200 and 150 mmol NaCl concentrations, respectively. Increased PAL activity in the hypocotyls and radicles was linearly and positively correlated with increasing NaCl concentrations, but the peak activity in the cotyledons was observed at NaCl concentration of 150 mmol. Electrophoresis analysis suggested that different patterns in SOD and POD isoenzymes depend on NaCl concentrations and organ type, and the staining intensities of these isoforms are consistent with the changes of enzyme activity assayed in solutions.

Effect of delayed storage and continuous ethylene exposure on flesh reddening of ‘Royal Diamond’ plums

AbstractBACKGROUND: Flesh reddening has been described as one of the manifestations of plum fruits to low‐temperature storage for prolonged periods. The influence of factors such as ethylene and delayed storage has not been studied to date. In order to assess that, plum cv. ‘Royal Diamond’ fruits were (a) stored at 5 °C (control), (b) held at 20 °C for 2 days before storage at 5 °C (delayed storage) or (c) maintained at 5 °C under 15 µL L−1 ethylene. Fruits were then transferred to 20 °C and ethylene, respiration, weight loss, firmness, soluble solids content, acidity, flesh reddening, anthocyanin accumulation and phenylalanine ammonia‐lyase (PAL) activity were determined.RESULTS: Delayed storage fruits showed more extensive flesh reddening than control fruits, with increased PAL activity and higher anthocyanin accumulation. Symptoms were expressed more markedly when fruits were stored at 5 °C in ethylene.CONCLUSION: Results indicated that the fruit ripening stage is a critical factor determining the susceptibility of ‘Royal Diamond’ plums to flesh reddening. Fruits continuously exposed to ethylene showed a dramatic increase in reddening, suggesting that ethylene contributes to the development of the disorder. Copyright © 2008 Society of Chemical Industry

Effects of copper on growth, antioxidant enzymes and phenylalanine ammonia-lyase activities in Jatropha curcas L. seedling

The effects of different concentrations of copper (0–800 μmol) on growth, protein contents, peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), and phenylalanine ammonia-lyase (PAL) in <I>Jatropha curcas</I> L. seedlings were assessed by means of pot experiments. Results suggested that increased copper concentrations lead to decreased shoot elongation and seedling biomass. Protein content in the leaves and roots reached their highest levels at the copper concentrations of 400 μmol, while the highest protein content in the stem was observed at 800 μmol copper. POD activity in leaves and stems was unaffected at low copper concentrations, but showed a considerable variation at high copper concentrations. In roots, the highest POD activity was observed at 200 μmol copper. Under copper stress, SOD activity in leaves increased concomitantly with increasing copper up to 400 μmol, and SOD activity in stems and roots showed a slight increase. Catalase activity significantly elevated in leaves and roots but showed no significant changes in stems of the seedlings exposed to copper. A gradual increase of PAL activity in leaves and roots at the copper concentration of 400 and 200 μmol was observed, while PAL activity remained unchanged in stems.

Differential regulation of phenylalanine ammonia lyase activity and protein level by light in tomato seedlings

Red light, acting via phytochrome, stimulates phenylalanine ammonia lyase (PAL) activity in cotyledons and hypocotyls of tomato seedlings. The time course of photoinduction of PAL activity has a peak level at 4 h after which activity declines significantly. In tomato seedlings PAL activity comprised of three isoforms and light stimulated activity of all three isoforms. A polyclonal antibody raised against PAL purified from tomato leaves recognized PAL protein belonging to PAL-II and PAL-III isoforms. The mode of increase in PAL activity was investigated by immunochemical techniques. The photostimulated increase in PAL activity appeared to be dependent on de novo synthesis of protein and nucleic acid. However, inhibition of protein phosphatase activity blocked increase in PAL activity without affecting the increase in PAL protein levels. The results indicate that in addition to de novo synthesis, the photostimulation of PAL activity likely requires dephosphorylation by a type 2C protein phosphatase.

Phosphonate alters the defence responses of Lambertia species challenged by Phytophthora cinnamomi

Phytophthora cinnamomi is a destructive pathogen that causes dieback and death in many plant species in Australian native ecosystems. Susceptibility varies widely between related taxa, although the reasons for this variability are poorly understood. In glasshouse studies we confirmed field observations that Lambertia formosa, a New South Wales shrub, is less susceptible to P. cinnamomi than the related Western Australian species, L. inermis. Following inoculation, L. inermis roots are heavily colonised by the pathogen, leading to dieback and high mortality rates. Pathogen restriction in L. formosa correlates with more rapid and intense release of superoxide at the penetration site, and the activation of the phenylpropanoid pathway, than in L. inermis root tissues. Potassium phosphonate reduces symptom severity in inoculated L. formosa, and reduces both mortality and symptom severity in L. inermis. Phosphonate-induced protection in both species is associated with increased superoxide release 8 h after inoculation, and increased phenylalanine ammonia lyase activity 24 h after inoculation.

Phenylalanine ammonia lyase activity in fresh cut lettuce subjected to the combined action of heat mild shocks and chemical additives

Enzymatic browning reduces the visual quality of lettuce. In producing minimally processed lettuce, the stresses caused by wounding associated to cutting operations enhance enzymatic activity. Mild heat shocks with chlorinated water with calcium ions or ascorbic acid were assayed as a mean of reducing phenylalanine ammonia lyase (PAL) activity. Heat shocks reduced four times the rate of change in PAL activity during the first hours of storage over the rate for samples not subjected to thermal treatment. The addition of ascorbic acid resulted in an increase in PAL activity over samples where only chlorinated water was used. When calcium ions were introduced in the thermal baths, the PAL activity was reduced about four times, especially when the cutting operation was performed after the thermal shocks. Short heat shocks is a physical preservation technology that could be applied in countries with low technological development. This technology was efficient to control vegetable browning by reducing PAL activity.

Change in phenylalanine ammonia lyase activity and isozyme patterns of polyphenol oxidase and peroxidase by salicylic acid leading to enhance resistance in cowpea against Rhizoctonia solani

In this paper, we describe a study concerning the determination of phenylalanine ammonia lyase (PAL) activities leading to decline in disease progress caused by Rhizoctonia solani after application of salicylic acid (SA). Two applications of 1.4 mM SA (pH 6.5) followed by inoculation with Rhizoctonia solani resulted in a quantitative change in polyphenol oxidase (PPO), peroxidase (PRX) isoforms and increase in PAL activities from 4.38 to 19.48 unit g−1 (FM) h−1 in Bundel-1, UPC-4200 and IFC-902 cowpea genotypes. Increase in PAL activities was further observed specifically in UPC-4200 when plants were exposed with Rhizoctonia solani spores. Total soluble proteins did not change after SA treatment, however they were significantly increased in SA sprayed-inoculated UPC-4200 genotype. Of the ten detected isoforms of polyphenol oxidase, isoforms 7 and 10, and isoform 4 of peroxidase showed increased activities by SA application. The disease symptoms measured as areas under progress curve (AUDPC) indicated less A value in SA sprayed Bundel-1 and UPC-4200 genotypes over their controls.

Effect of feeding precursors on phenylalanine ammonia-lyase activity and coumarin accumulation in leaves of Matricaria chamomilla L.

Four-week-old chamomile (Matricaria chamomilla) plants were exposed for 72 h to 0.01, 0.1 and 1 mM phenylalanine (Phe) or tyrosine (Tyr). Phe at all concentrations significantly increased phenylalanine ammonia-lyase (PAL) activity (by 30, 76 and 90%, respectively) as well as accumulation of coumarin-related compounds (herniarin and its precursors (Z)- and (E)-2-β-D-glucopyranosyloxy-4-methoxycinnamic acids). Free Phe content increased significantly at the highest dose tested. Lower Tyr concentrations (0.01 and 0.1 mM) significantly increased PAL activity and increased free Tyr content, however free Phe content decreased. This indicated that Tyr-mediated stimulation of PAL is coupled to Phe consumption. Notwithstanding, Tyr had no effect on coumarin accumulation. Therefore we speculate that in chamomile a regulation/signalling mechanism could be operating in the pathway leading to coumarin synthesis. The malondialdehyde accumulation, an usual marker of stress in plants, was not significantly changed by amino acid supplements, suggesting that membrane damage is not the signal causing coumarin accumulation. In parallel experiment we observed that neither lower (0.25 × full strength), nor higher (3 × full strength) nitrogen concentration of nutrient solution compared to normal (1 × full strength, 205 mg N l-1) solution used for Phe/Tyr supply affected herniarin and GMCAs accumulation. This indicates that Phe had stimulatory effect on PAL activity and coumarin metabolism.

Induction of Phenolic Compounds in Wheat (Triticum aestivum L.) Tissue Cultures by Streptomycin

The tissue cultures of wheat (Triticum aestivum L.) were induced from the mature embryos (explants) of the dry grains and grown on MS medium containing kinetin (0.1 mg/1) and 2,4 D (1.0 mg/l). The cultures were incubated for two weeks at (25+/-2) degrees C under a light/dark regime (16 h light daily). The formed calli were subcultured at the beginning of the stationary growth phase (15 days) with fresh MS medium containing 0, 5, 10, 25, 50, 100, 150 mg/l streptomycin elicitor and maintained for two weeks for three subcultures. A significant increase in phenylalanine ammonia lyase (PAL) activity coincided with the increase of the total phenolic compounds after elicitation with streptomycin. Maximum induction was recorded during the first two weeks, then gradually declined during the rest of the experimental period, but the values attained were still markedly higher than that of the control. The endogenous cinnamic acid content was also increased significantly with the increase in PAL activity making about 2-18% of the total phenolic acids. The growth and accumulation of phenolic compounds were inversely related. However, accumulation of phenolic compounds became limited for growth of wheat tissue culture especially during the long term cultivation.

(293) The PAL Gene Activity in Five Rosemary Genotypes and Its Effect on the Production of Rosmarinic Acid

Phenylalanine ammonia-lyase (PAL) enzyme is the most extensively studied enzyme in the phenylpropanoid pathway. Studies on the biosynthesis of rosmarinic acid (RA) showed that the PAL enzyme catalyzes the initial step of the phenylpropanoid pathway. The increase in RA content in plant tissues in vitro coincided with the increase in PAL activity. The aim of this study was to investigate the activity of the gene responsible for the production of the PAL enzyme in the five rosemary genotypes; this will give more understanding about the accumulation of rosmarinic acid in the five rosemary genotypes. The genotypes were Majorca, Rosmarinus officinalis, Pine Scented, Madeline Hill and APR. Northern blot hybridization between the PAL gene primer and the five genotypes' cDNA showed bands at 300 bp in all the five genotypes for the PAL gene. The expression of the PAL gene was high in genotypes Majorca, Rosmarinus officinalis, and Madeline Hill, while the expression was low in genotypes Pine Scented and APR. It was expected that the genotypes having the highest PAL gene expression will produce the highest amount of RA, but the highest genotype in PAL gene expression Madeline Hill had the lowest RA production in their leaves. This could occur due to the tissue specific regulation inside plant tissues. Inside the callus tissues, where the specific tissue regulation no longer exists, the RA was produced in repetitively large amounts in genotypes with high PAL gene expression.

Anthocyanin accumulation in the hypocotyl of an ABA‐over producing male‐sterile tomato (Lycopersicon esculentum) mutant

Anthocyanin accumulation is known to be regulated by light and plant hormones but its occurrence varies with plant species and/or organ and tissue, and it has been negatively correlated with male sterility. In this study, we have examined the light responsive changes in anthocyanin in an abscisic acid (ABA) over‐producer, male‐sterile 7B‐1 mutant and wild‐type (WT) tomato hypocotyls. The results show that light‐induced anthocyanin accumulation in the hypocotyl was more in WT compared with the 7B‐1 mutant and more so under white light (W) compared with blue light (B) or red light (R). In contrast, the chlorophyll content was greater in the mutant than in WT. Exogenous ABA caused a transitory increase in anthocyanin content in WT but a reduction in 7B‐1, both in W and B. The high level of anthocyanin in WT under light conditions was not correlated with increased mRNA levels of phenylalanine ammonia‐lyase (PAL), chalcone synthase (CHS) and dihydroflavonol 4‐reductase (DFR), some of the anthocyanin biosynthetic genes. However, the activity of PAL (EC 4.3.1.5) was higher in the WT than in 7B‐1 hypocotyls, and exogenous ABA caused an increase in PAL activity in the WT but a reduction in the mutant. The results presented show that high ABA negatively affects anthocyanin accumulation and that in the 7B‐1 mutant it is related, in part, to reduced PAL activity. The results also support the view that the 7B‐1 mutant has a defect in light perception and ABA sensitivity.

Influence of sodium nitrilotriacetate (NTA) and citric acid on phenolic and organic acids in Brassica juncea grown in excess of cadmium

Brassica juncea cv. 426308 was grown in soils containing 150 mg Cd 2+ kg −1 soil. After 38 days, the soil was amended with two rates of citric acid or NTA (10 and 20 mmol kg −1 soil). Control soil was not amended with chelates. Plants were harvested during growth, immediately before and seven days after chelate addition. Shoot composition of organic and phenolic acids and shoot Cd 2+ concentration were determined. Cadmium concentration remained constant during the growth and increased following NTA and citric acid amendments depending on chelate type and concentration. The highest increments in Cd 2+ were measured after the addition of NTA. Compared to the control, 10 and 20 NTA-treated plants showed two- and three-fold increases, respectively. At 150 mg Cd 2+ kg −1 soil the amount of organic and phenolic acids in the leaves of B. juncea was always higher than that detected in the control. A direct correlation between organic acid concentration and cadmium content was detected both during growth and after chelate addition. On the contrary, the amount of phenols seemed to be correlated with the metal content only in non-amended and NTA-treated plants. The 10 and 20 citric acid additions caused 45% and 90% increases in shoot phenolic acids although cadmium content rose to a smaller extent. The inhibition of citrate synthase and the entrance of phosphoenolpyruvate in shikimate pathway leading to the formation of aromatic compounds might come into play. The increase in phenylalanine ammonialyase activity following citric acid amendments suggested this metabolic response.

Induction of Defence Responses in Roots and Mesocotyls of Sorghum Seedlings by Inoculation with Fusarium thapsinum and F. proliferatum, Wounding and Light

AbstractThe defence reactions of sorghum seedlings 7 days after inoculation with Fusarium thapsinum and F. proliferatum, and interactions with wounding and exposure to light were studied to determine whether responses to these fungi differed from those to abiotic stresses. In non‐wounded plants, inoculation with both fungi increased concentrations of anthocyanins and soluble phenolics and activities of peroxidase (POX), chitinase and β‐1,3‐glucanase in the roots, and increased β‐1,3‐glucanase activity in the mesocotyls. There was no effect of inoculation on phenylalanine ammonia‐lyase (PAL) activity. Wounding by itself increased anthocyanin content of mesocotyls. Wounding also had a variety of interactions with inoculation. Exposure to light had very little effect on any defence response measured. A time course experiment showed that induction of chitinase and β‐1,3‐glucanase occurred in less than 24 h after inoculation. POX activity increased 2 days after inoculation, followed by a transient increase in PAL activity. The content of anthocyanins and soluble phenolics in roots of inoculated seedlings increased gradually compared with controls over 6 days. The responses of sorghum seedlings to inoculation with F. thapsinum and F. proliferatum were similar to those found by other workers following challenge by necrotrophic pathogens and were different from those induced by wounding and exposure to light.

PHENYLALANINE AMMONIA-LYASE AND ACCUMULATION OF PHENOLIC COMPOUNDS IN THE ETHYLENE-INDUCED TOLERANCE TO RINDSTAINING IN ´NAVELATE´ FRUIT

The orange fruit cultivar 'Navelate' is prone to develop postharvest rindstaining (RS) during storage at non-chilling temperatures. Ethylene has been shown to protect citrus fruit against RS but the mechanisms associated with the ethylene-induced tolerance to this disorder are unknown. In this study we have examined the effect of applying ethylene, before or during holding of 'Navelate' fruit under postharvest conditions inducing RS (22°C, 90-95% RH), on changes in the activity of the enzyme phenylalanine ammonia-lyase (PAL), total phenolic content and fruit quality. PAL activity increased with the development of damage in the albedo and flavedo of fruit maintained under air. Exogenous ethylene treatments, which efficiently reduced RS incidence, increased PAL activity as well as the levels of total phenolic content in the flavedo and in the pulp. However, these levels were not maintained after prolonged storage, either in fruit kept continuously under ethylene or in those transferred to air. The global results indicate that the induction of the enzyme PAL and of subsequent phenylpropanoid compounds may play a role in reducing the development of RS symptoms and might be a part of the mechanisms involved in the beneficial effect of ethylene in protecting citrus fruit against this physiological disorder.

Resistance to downy mildew in pearl millet is associated with increased phenylalanine ammonia lyase activity.

Phenylalanine ammonia lyase (PAL) activity was studied in pearl millet cultivars with different levels of resistance to the downy mildew disease caused by Sclerospora graminicola, an important oomycete pathogen. PAL activity was elevated in resistant host cultivar and decreased in susceptible cultivars following downy mildew pathogen infection. The enzyme activation varied between cultivars and was correlated with the degree of resistance to downy mildew disease. The induction of PAL as a response to pathogen inoculation was further corroborated by a time-course study in seedlings and cultured cells of pearl millet. The level of PAL activity was highest at 1.5 h in cultured cells and 4 h in seedlings of resistant host cultivar after inoculation with Sclerospora graminicola. Further studies on PAL activity in different tissues of seedlings showed highest enzyme activity in the young growing region of the root of the resistant host cultivars. The accumulation of wall-bound phenolics and lignin was higher in the resistant cultivar seedlings as evidenced by phloroglucinol-HCl staining and p-coumaric acid assay. The temporal changes in lignin concentration and the concentration of soluble phenolics were greater in root tissues of resistant cultivars than in those of susceptible cultivars. Treatment of resistant seedlings with a PAL inhibitor, α-aminooxy-β-phenylpropionic acid, resulted in the enhancement of the enzyme activity, whereas in the presence of 1 mm trans-cinnamic acid the pathogen-induced PAL was completely inhibited. Treatment of pearl millet seedlings with exogenously applied PAL inhibitors induced downy mildew disease susceptibility in the resistant pearl millet cultivar, consistent with direct involvement of PAL in downy mildew resistance. Results are discussed with respect to the presumed importance of host phenolic compounds and lignin accumulation and its relation to PAL activation as a response to the pathogen infection.

Effect of Pratylenchus zeae infection on the expression of isozyme activities in resistant and susceptible sugarcane clones

AbstractThe constitutive levels of both phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) activities in roots and leaves were found to be greater in sugarcane clones resistant to the lesion nematode Pratylenchus zeae than in susceptible clones. Investigations on the sequential development of PAL and TAL activities were undertaken in resistant (Co 7717) and susceptible (CoC 671) sugarcane clones infected with P. zeae. PAL activity in both roots and leaves of the resistant clone showed a maximum percentage increase, compared with non-infected controls, at 35 and 14 days after infection (DAI), respectively. However, in the susceptible clone the maximum percentage decrease compared with the non-infected clone was observed at 3 and 14 DAI. TAL activity in the resistant clone showed the maximum percentage increase compared with the non-infected control at 28 DAI in roots and 7 DAI in leaves, whereas in the susceptible clone the maximum percentage decrease compared with the non-infected control was at 35 DAI in roots and 28 DAI in leaves. In experiments on the induction of enzyme response to infection by P. zeae, eight resistant and eight susceptible clones were analysed 14 days after P. zeae infection. Among the eight resistant clones six showed increased PAL activity compared with non-infected clones. Four susceptible infected clones showed a decrease as compared with non-infected clones, while the remaining four infected clones showed an increased enzyme activity compared to non-infected clones. Superoxide dismutase (SOD) activity increased quantitatively in both roots and leaves from nematode-infected susceptible clones compared to non-infected clones. The SOD activity decreased in roots and leaves from nematode infected resistant clones, when compared to the non-infected-resistant clones. In native PAGE analysis of SOD and esterase activities the major differences between infected and non-infected clones of resistant and susceptible sugarcane were observed in low and medium electrophoretic mobility ranges.