海拔高度对大车前叶和根中抗氧化系统的影响

以甘肃马衔山（ 海拔３７５０ ｍ）自然生长的大车前（ Ｐｌａｎｔａｇｏ ｍａｊｏｒ Ｌ．） 为材料,通过检测比较不同海拔高度下大车前根和叶中抗氧化保护系统的变化,探讨植物对于高寒环境的适应机理。结果表明,随着海拔的升高（ 从１６００ ｍ～３３００ ｍ） ,根中还原型谷胱甘肽（ＧＳＨ）含量增加,过氧化物酶（ＰＯＸ）和超氧化物歧化酶（ＳＯＤ） 活性显著升高,叶中的ＰＯＸ和ＳＯＤ活性则逐渐降低。高海拔区（３３００ ｍ）根中出现了特异性酶带ＰＯＸ５ 和ＳＯＤ８。这种趋势可能有利于根的越冬,而对叶片的越冬不利,这与多年生植物大车前的自然生长状况相一致     

Putrescine modulates antioxidant defense response in wheat under high temperature stress

Effects of putrescine (Put) on responses of wheat (Triticum aestivum) seedlings or detached tillers at mid-milky stage to high temperature (HT) stress were investigated. The heat tolerant cv. PBW 343 exhibited higher content of antioxidants and activities of antioxidative enzymes, while lower content of lipid peroxides as compared to the heat-sensitive cv. HD 2329. HT elevated peroxidase (POX) and superoxide dismutase (SOD) activities, while diamine oxidase (DAO) and polyamine oxidase (PAO) activities were reduced in roots, shoots and developing grains. Application of Put under HT further enhanced POX and SOD activities along with increased content of ascorbate and tocophereol in grains. Invariably POX and SOD revealed higher activities in roots while CAT, DAO and PAO activities were higher in shoots. The content of lipid peroxides was increased in roots and shoots of HT stressed seedlings but less in Put-treated cv. PBW 343.     

Defense response of resistant and susceptible genotypes of castor (Ricinus communis L.) to wilt disease

The biochemical basis of resistance in castor (Ricinus communis L.) to Fusarium wilt, caused by the pathogen Fusarium oxysporum f. sp. ricini, was investigated. Induction of plant defence against pathogen attack is regulated by a complex network of different signals. Thus changes in various biochemical defenses including antioxidant enzymes, phenolic compounds and pathogenesis related (PR) proteins were investigated in the roots of resistant and susceptible genotypes of castor at 0, 24, 48 and 72 h.a.i. Infection by F. oxysporum significantly increased the superoxide dismutase (SOD) and peroxidase (POX) activities in the roots of susceptible genotypes, while the catalase (CAT) activities were appreciably higher in the roots of resistant genotypes at different stages. Constitutive levels of ascorbate peroxidase (APX) and polyphenol oxidase (PPO) were higher in the resistant genotypes. Also, the activities of phenylalanine ammonia lyase (PAL) and β 1, 3 glucanase significantly increased in the roots of the resistant genotypes after infections. The rate of increment of thiobarbituric acid reactive substances (TBARS) was higher in resistant genotypes after infection. Analysis of isozyme banding pattern of SOD, POX, PPO and esterase on native PAGE electrophoresis revealed that interaction between plant and fungi invoked various isozymes at 48 h of infection. SOD 3 was observed only in resistant genotypes at 24 h.a.i. except Geeta. Similarly induction of POX 5 was observed only in resistant genotypes at 48 h of infection, though the intensity of POX 5 was very less.     

Effect of drought on biomass, protein content, lipid peroxidation and antioxidant enzymes in two sesame cultivars

The effects of drought on growth, protein content, lipid peroxidation, superoxide dismutase (SOD), peroxidase (POX), catalase (CAT) and polyphenol oxidase (PPO) were studied in leaves and roots of Sesamum indicum L. cvs. Darab 14 and Yekta. Four weeks after sowing, plants were grown under soil moisture corresponding to 100, 75, 50 and 25 % field capacity for next four weeks. Fresh and dry masses, and total protein content in leaves and roots decreased obviously under drought. However, several new proteins appeared and content of some proteins was affected. Measurement of malondialdehyde content in leaves and roots showed that lipid peroxidation was lower in Yekta than in Darab 14. Severe stress increased SOD, POX, CAT and PPO activities in leaves and roots, especially in Yekta. According to the present study Yekta is more resistant to drought than Darab 14.     

Re-aeration-induced oxidative stress and antioxidative defenses in hypoxically pretreated lupine roots

The level of free radicals and activities of antioxidative enzymes were examined in roots of lupine seedlings (Lupinus luteus L.) that were deprived of oxygen by subjecting them to root hypoxia for 48 and 72 h and then re-aerated for up to 24 h. Using electron paramagnetic resonance (EPR), we found that the exposure of previously hypoxically grown roots to air caused the increase in free radicals level, irrespective of duration of hypoxic pretreatment. Immediately after re-aeration the level of free radicals was two times higher than in aerated control. The EPR signal with the g-values at the maximum absorption of 2.0057 and 2.0040 implied that the paramagnetic radicals are derived from a quinone. Directly after re-aeration of hypoxically pretreated roots, the activity of superoxide dismutase (SOD, EC 1.15.1.1) increased to its highest value, followed by a decline below the initial level, whereas activities of catalase (CAT, EC 1.11.1.6) and peroxidase (POX, EC 1.11.1.7) were diminished or only slightly influenced during re-aeration. The electrophoretic patterns of the soluble extracts show 4 isozymes of SOD, 4 isozymes of POX and 1 isozyme of CAT. The level of H2O2 was enhanced or lowered by re-aeration, depending on the previous duration of hypoxia. At the onset of re-aeration products of lipid peroxidation were present at a three-fourth of the levels found in aerobic control. Their levels increased after prolonged exposure to air but remained lower than those in aerobic control even after 24 h of re-aeration. Re-admission of oxygen resulted in about 20% rise in oxygen uptake by root axes segments immediately after transfer of roots from hypoxia and the high uptake rates were observed over whole re-aeration period. Oxygen consumption by root tips was significantly reduced just after transfer from hypoxic conditions as compared to aerated control but after 24 h of re-aeration even approached the control level. The results are discussed in relation to the ability of lupine roots to cope with oxidative stress caused by re-aeration following hypoxic pretreatment.     

Effects of salicylic acid and salinity on apoplastic antioxidant enzymes in two wheat cultivars differing in salt tolerance

The effects of salicylic acid (SA) and salinity on the activity of apoplastic antioxidant enzymes were studied in the leaves of two wheat (Triticum aestivam L.) cultivars: salt-tolerant (Gerek-79) and salt-sensitive (Bezostaya). The leaves of 10-d-old seedlings grown at nutrient solution with 0 (control), 250 or 500 mM NaCl were sprayed with 0.01 or 0.1 mM SA. Then, the activities of catalase (CAT), peroxidase (POX) and superoxide dismutase (SOD) were determined in the fresh leaves obtained from 15-d-old seedlings. The NaCl applications increased CAT and SOD activities in both cultivars, compared to those of untreated control plants. In addition, the NaCl increased POX activity in the salt-tolerant while decreased in the salt-sensitive cultivar. In control plants of the both cultivars, 0.1 mM SA increased CAT activity, while 0.01 mM SA slightly decreased it. SA treatments also stimulated SOD and POX activity in the salt-tolerant cultivar but significantly decreased POX activity and had no effect on SOD activity in the saltsensitive cultivar. Under salinity, the SA treatments significantly inhibited CAT activity, whereas increased POX activity. The increases in POX activity caused by SA were more pronounced in the salt-tolerant than in the salt-sensitive cultivar. SOD activity was increased by 0.01 mM SA in the salt-tolerant while increased by 0.1 mM SA treatment in the salt-sensitive cultivar.     

Characterization of the antioxidant system during the vegetative development of pea plants

The antioxidative system was studied during the development of pea plants. The reduced glutathione (GSH) content was higher in shoots than in roots, but a greater redox state of glutathione existed in roots compared with shoots, at least after 7 d of growth. The 3-d-old seedlings showed the highest content of oxidised ascorbate (DHA), which correlated with the ascorbate oxidase (AAO) activity. Also, the roots exhibited higher DHA content than shoots, correlated with their higher AAO activity. The activities of antioxidant enzymes were much higher in shoots than in roots. Ascorbate peroxidase (APX) activity decreased during the progression of growth in both shoots and roots, whereas peroxidase (POX) activity strongly increased in roots, reflecting a correlation between POX activity and the enhancement of growth. Catalase activity from shoots reached values nearly 3 or 4-fold higher than in roots. The monodehydroascorbate reductase (MDHAR) activity was higher in young seedlings than in more mature tissues, and in roots a decrease in MDHAR was noticed at the 11^th day. No dehydroascorbate reductase (DHAR) was detected in roots from the pea plants and DHAR values detected in seedlings and in shoots were much lower than those of MDHAR. In shoots, GR decreased with the progression of growth, whereas in roots an increase was seen on the 9^th and 11^th days. Finally, superoxide dismutase (SOD) activity increased in shoots during the progression of growth, but specific SOD activity was higher in roots than in shoots.     

Changes in ascorbate peroxidase, catalase, guaiacol peroxidase and superoxide dismutase activities in common bean (Phaseolus vulgaris) nodules under salt stress

To analyse nodular antioxidant enzyme expression in response to salt stress, Phaseolus vulgaris genotype BAT477 was inoculated with reference strain CIAT899, and treated with 50 mM NaCl. Plant growth, nodulation and nitrogen fixing activity were analysed. Results showed that: (1) all parameters, particularly in nodules, were affected by salt treatments, and (2) confirmed preferential growth allocation to roots. The ARA was significantly decreased by salt treatments. Protein dosage confirmed that nodules were more affected by salt treatment than were roots. We analysed superoxide dismutase, catalase, ascorbate peroxidase and peroxidase in nodules, roots and a free rhizobial strain. Our results indicated that SOD and CAT nodular isozymes had bacterial and root origins. The SOD expressed the same CuZn, Fe and Mn SOD isoforms in nodules and roots, whereas in free rhizobia we found only one Fe and Mn SOD. APX and POX nodule and root profiles had only root origins, as no rhizobial band was detected. Under salt stress, plant growth, nitrogen fixation and activities of antioxidant defense enzymes in nodules were affected. Thus, these enzymes appear to preserve symbiosis from stress turned out that NaCl salinity lead to a differential regulation of distinct SOD and POX isoenzyme. So their levels in nodules appeared to be consistent with a symbiotic nitrogen fixing efficiency hypothesis, and they seem to function as the molecular mechanisms underlying the nodule response to salinity.     

Paclobutrazol delayed dark-induced senescence of mung bean leaves

Sixty days old mung beans Vigna radiata (L.) Wilczek were treated with soil applied paclobutrazol, at the rate of 500 μg per 10 inch pot. After seven days of application, the plants along with untreated controls were transferred to the dark for induction of senescence. The treated plants exhibited higher chlorophyll content and activity of catalase (CAT) compared to controls. In contrast, control leaves had higher activity of peroxidase (POX) and a higher content of malondialdehyde (MDA), while superoxide dismutase (SOD) activity remained unchanged. Upon transfer to dark, chlorophyll content declined in both control and treated plants but the decline was much faster in control. The activity of CAT decreased significantly in controls while POX activity and MDA content remained higher in control than in treated plants. Paclobutrazol delayed the dark-induced senescence in attached mung bean leaves in association with the maintenance of higher activity of CAT, low activity of POX, and low MDA contents. The variation in SOD activity was not discernible with senescence levels.     

不同海拔微孔草抗氧化系统的比较研究

对生长在3个不同海拔自然生境下微孔草(Microula sikkimensis)叶中的抗氧化系统进行了比较研究.结果表明,生长在高海拔的微孔草叶中抗氧化酶类SOD、POD和CAT活性比生长在低海拔的活性高,其中大通牛场的微孔草叶中3种酶活性最高;APX的活性随海拔的升高而升高,且低海拔地区西宁的APX活性极显著低于高海拔地区大通和海北站(P<0.01);作为非酶抗氧化系统物质之一的抗坏血酸(ASA)含量随海拔的升高而降低.高海拔地区微孔草叶中可溶性糖含量极高(P<0.01);可溶性蛋白含量随海拔升高呈V字形变化.光合色素Chla、Chl b和Car的含量均随着海拔升高而增加,Chl a/b比值随海拔升高而降低.MDA的含量随海拔升高有增加的趋势,西宁和大通的相比较,MDA含量差异显著(P<0.05),说明微孔草叶细胞膜脂过氧化程度随海拔升高加剧.生长在不同海拔高度的微孔草对不同海拔高度环境变化具有相应的生理适应性和抗氧化策略.     

Effect of NaCl salinity on photosynthetic rate,transpiration rate,and oxidative stress tolerance in contrasting wheat genotypes

Wheat (Triticum aestivum L.) genotypes K-65 (salt tolerant) and HD 2329 (salt sensitive) were grown in pots under natural conditions and irrigated with NaCl solutions of electrical conductivity (ECe) 4.0, 6.0, and 8.0 dS m⁻¹. Control plants were irrigated without saline water. Observations were made on the top most fully expanded leaf at tillering, anthesis, and grain filling stages. The net photosynthetic rate (P _N), stomatal conductance (g _s), and transpiration rate (E) were reduced with the addition of NaCl. The reduction was higher in HD 2329 than in K-65. Salinity enhanced leaf to air temperature gradient (ΔT) in both the genotypes. NaCl increased the activities of superoxide dismutase (SOD) and peroxidase (POX); the percent increment was higher in K-65. The sodium and potassium contents were higher in the roots and leaves of K-65 over HD 2329. Thus at cellular level K-65 has imparted salt tolerance by manipulating P _N, E, g _s, and K accumulation in leaves along with overproduction of antioxidative enzyme activities (SOD and POX).     

Changes in Activities of Antioxidant Enzymes and Their Relationship to Genetic and Paclobutrazol-Induced Chilling Tolerance of Maize Seedlings

The potential role of antioxidant enzymes in protecting maize (Zea mays L.) seedlings from chilling injury was examined by analyzing enzyme activities and isozyme profiles of chilling-susceptible (CO 316) and chilling-tolerant (CO 328) inbreds. Leaf superoxide dismutase (SOD) activity in CO 316 was nearly one-half that of CO 328, in which the high activity was maintained during the chilling and postchilling periods. Activity of glutathione reductase (GR) was much higher in roots than in leaves. CO 328 also possessed a new GR isozyme that was absent in roots of CO 316. Ascorbate peroxidase (APX) activity was considerably lower in leaves of CO 328 than in CO 316, and nearly similar in roots. Paclobutrazol treatment of CO 316 induced several changes in the antioxidant enzyme profiles and enhanced their activities, especially those of SOD and APX, along with the induction of chilling tolerance. These results suggest that increased activities of SOD in leaves and GR in roots of CO 328, as well as SOD and APX in leaves and roots of paclobutrazol-treated CO 316, contribute to their enhanced chilling tolerance.     

Biochemical alterations in leaves of resistant and susceptible cotton genotypes infected systemically by cotton leaf curl Burewala virus

Leaf curl disease caused by Cotton Leaf Curl Burewala virus (CLCuBuV) has been recognized as serious threat to cotton in Indian subcontinent. However, information about cotton–CLCuBuV interaction is still limited. In this study, the level of phenolic compounds, total soluble proteins, and malondialdehyde (MDA) and the activities of phenylalanine ammonia-lyase (PAL), peroxidase (POX), catalase (CAT), proteases, superoxide dismutase (SOD), and polyphenol oxidase (PPO) were studied in leaves of two susceptible (CIM-496 & NIAB-111) and two resistant (Ravi and Co Tiep Khac) cotton genotypes. Disease symptoms were mild in the resistant genotypes but were severe in highly susceptible genotypes. The results showed that phenolic compounds, proteins, PAL, POX, CAT, proteases, SOD, PPO, and MDA play an active role in disease resistance against CLCuBuV. The amount of total phenols, proteases, MDA, and PPO was significantly higher in leaves of CLCuBuV-inoculated plants of both resistant genotypes as in non-inoculated plants, and decreased in CLCuBuV-inoculated plants of both susceptible genotypes over their healthy plants. POX, protein content, SOD, and PAL activities showed lower values in resistant genotypes, while they decreased significantly in susceptible genotypes as compared to the noninoculated plants except PAL, which showed non-significant decrease. CAT was found to be increased in both susceptible and resistant genotypes with maximum percent increase in resistant genotype Ravi, as compared to non-inoculated plants. The results showed significantly higher concentrations of total phenols and higher activity of protease, MDA, SOD, and PPO in resistant genotype Ravi after infection with CLCuBuV, suggesting that there is a correlation between constitutive induced levels of these enzymes and plant resistance that could be considered as biochemical markers for studying plant-virus compatible and incompatible interactions.     

Oligogalacturonides stimulate antioxidant system in alfalfa roots

Alfalfa (Medicago sativa L.) roots were treated with 50 and 100 μg cm⁻³ of oligogalacturonide (OGA) solutions with a degree of polymerization between 7 and 15. Changes in the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) as well as ascorbate (ASC) content were determined in crude extract of alfalfa roots after 30, 60 and 120 min of treatment. An increase in the SOD activity was observed in roots treated with 50 and 100 μg cm⁻³ OGA, which could be related to its O₂ ^·− scavenging function. As concern H₂O₂ scavenging, CAT activity was increased in the first 30 min by both OGA concentrations, while POX was a key enzyme at higher OGA concentration and treatment duration. ASC content firstly increased upon exposure to high OGA concentration, and then decreased after longer treatment while low OGA concentration had no effect on ASC content.     

Reactive oxygen species production and antioxidative defense in pea (Pisum sativum L.) root nodules after short-term aluminum treatment

Pea plants (Pisum sativum L.) were treated with 50???M aluminum chloride at pH 4.5 for 2 or 24?h at room temperature. Following treatment, root nodule Al uptake, the generation of reactive oxygen species (ROS, O ₂ ^?· and H₂O₂), and the activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and peroxidase (POX) were investigated. Aluminum accumulation was found chiefly in the apoplast of the nodule cortex, endodermis and meristem, while the formation of peroxide was detected in the nodule cortex, infection threads and bacteroidal tissue. Further, there were increased levels of superoxide in the meristem and bacteroidal tissue. The activity of SOD (EC 1.15.1.1) and POX (EC 1.11.1.7) increased in the Al-treated nodules and the roots of pea plants, whereas CAT (EC 1.11.1.6) activity decreased. The Al absorbed by the nodules induced ROS production. The POX and SOD are important ROS-scavengers in Al-stressed nodules.     

Changes in Activities of Antioxidant Enzymes in Sunflower Leaves of Different Ages

Role of superoxide dismutase isozymes and other antioxidant enzymes was studied in relation to leaf age in sunflower (Helianthus annuus L. cv. ACC 1508) at pre-flowering and grain filling stages. Relative water content (RWC) did not change much in leaves of different age and at the two stages. Protein content declined continuously from the youngest to the oldest leaf, while chlorophyll (Chl) and carotenoids (Car) contents increased down to 7^th/9^th leaf and declined in subsequent older leaves. Protein, Chl and Car contents were higher at pre-flowering than at seed filling stage. Superoxide dismutase (SOD), its isozymes, and ascorbate peroxidase (APO) and catalase (CAT) activities were highest in the 9^th leaf and declined in subsequent older leaves. SOD and APO activities were higher at seed filling, except in oldest senescent (13^th, 15^th) leaves. Among SOD isozymes, Cu/Zn-SOD and Mn-SOD activities accounted for most of the total SOD, and only marginal activity was observed for Fe-SOD. Peroxidase activity increased from youngest to the oldest leaf at pre-flowering stage and down to 13^th leaf at seed filling stage. This revised version was published online in July 2006 with corrections to the Cover Date.     

Superoxide dismutase and peroxidase activities in drought sensitive and resistant barley (Hordeum vulgare L.) varieties

The effects of water deficit on relative water content (RWC), on the activity superoxide dismutase (SOD) and peroxidase (POX) from leaves of two drought-resistant barley strains (Hordeum vulgare L.) varieties (TOKAK-157/37 and 56000/MISC-233) and one sensitive (ERGINEL-90) were studied. In 21 day old seedlings, drought stress was initiated by withholding water and lasted for 12 days. Activity of SOD increased by the effect of drought treatments in the leaves of drought-resistant varieties TOKAK-157/37 and 56000/MISC-233 as compared to sensitive variety ERGINEL-90. The drought treatment resulted in a 418 % and 59 % increase in SOD activity in resistant varieties at the end of the 12^th day of experimental period. However, an increase in activity of SOD was not accompanied by an increase in activity of POX in drought-resistant TOKAK-157/37 and 56000/MISC-233 except on the 6^th day of drought treatment in 56000/MISC-233. In drought-sensitive variety, ERGINEL-90, POX activity did not change throughout drought period.     

Changes in antioxidant activities and phenol content in tomato plants subjected to partial root drying and regulated deficit irrigation

Abstract

Partial rootzone drying (PRD) and regulated deficit irrigation (RDI) are water saving irrigation systems that have been developed to increase water use efficiency (WUE) without significant yield reduction. To examine whether tomato responded differently to RDI and PRD, we compared the changes in antioxidative defenses in tomato plants using a split-root system. Tomato plants were grown for 21 days under controlled conditions with their roots separated equally between two soil compartments. Three irrigation treatments were imposed: Control, receiving an amount of water equivalent to 100% of plant transpiration; PRD in which one compartment was watered with 50% of the amount of water supplied to the controls, allowing one-half of the root system to be exposed to dry soil, and switching irrigation between sides weekly; RDI in which 50% of the amount of water given to the controls was supplied, half to each side of the root system. Relative water content (RWC), midday leaf Ψ and chlorophyll content decreased largely in RDI-treated plants, whereas the PRD plants exhibited relatively higher Ψ and RWC values. An enhanced level of lipid peroxidation in both roots and leaves indicated that PRD and RDI caused oxidative stress in tomato plants. In leaves, superoxide dismutase (SOD), soluble peroxidase (POX) and polyphenol oxidase (PPO) activities showed an increase in the early phase of water deficit, and then decreased in the remaining phase of the drying cycle. However, the increase was more pronounced under RDI. Catalase (CAT) activity declined continuously from the onset of PRD and RDI treatments to below the control level, and the reduction was less under PRD than RDI. POX cell-wall associated activities exceeded the control level by 450% and 230%, respectively, under RDI and PRD. At the root level, while CAT activity also decreased under both PRD and RDI, the activities of SOD, POX and PPO significantly increased and their activities showed an alternating increase/decrease paralleling the alternating irrigation in PRD-treated roots. As a result of the difference in POX and PPO activities between the two water treatments applied, PRD-treated plants accumulated more soluble and cell-wall bound phenolic compounds.     

The effects of boron toxicity on root antioxidant systems of two chickpea (Cicer arietinum L.) cultivars

Significant differences in the antioxidant systems of the roots of two chickpea (Cicer arietinum L.) cultivars differing in tolerance to drought were observed in under toxic boron (B) conditions. Three-week-old chickpea seedlings were subjected to 0.05 mM (control), 1.6 mM or 6.4 mM B in the form of boric acid (H₃BO₃) for 7 days. At the end of the treatment period, root length, dry weight, boron concentration, malondialdehyde (MDA) content, and the activities of antioxidant enzymes—superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), ascorbate peroxidase (APOX) and glutathione reductase (GR)—were measured. Root length of the drought-tolerant Gökce cultivar did not change under 1.6 mM B but increased under 6.4 mM B. On the contrary, root length decreased in the drought-sensitive Küsmen cultivar under both B concentrations. While root dry weight was unaffected in Gökce, it decreased in Küsmen under both B concentrations. Boron concentration was significantly higher in Küsmen than in Gökce at both B levels. Significant increases in SOD and POX activities were observed in roots of both cultivars under 1.6 and 6.4 mM B. Root extracts exhibited three SOD and three POX activity bands in both cultivars under B stress when compared to control groups. Although CAT activity in Gökce was increased, it decreased in Küsmen at the highest B concentration as compared to control groups. Roots of both cultivars showed no significant change in APOX activity under B toxicity (except in 1.6 mM B treated roots of Küsmen) when compared to control groups. GR activity in the roots of Küsmen decreased significantly with increasing B concentration. However, a significant increase in GR activity was found in Gökce under 1.6 mM B stress. In addition, lipid peroxidation levels of drought-sensitive Küsmen increased, indicating more damage to membrane lipids due to B toxicity. Lipid peroxidation did not change in the drought-tolerant Gökce cultivar at either B concentration. These results suggest that roots of Gökce are better protected from B-stress-induced oxidative stress due to enhanced SOD, CAT and POX activities under high B levels.