Correlation of antioxidant capacities to oxygen radical scavenging enzyme activities in blackberry

The activities of the oxygen radical scavenging enzymes [glutathione-peroxidase (GSH-POD), superoxide dismutase (SOD), and guaiacol peroxidase (G-POD)], hydrogen peroxide scavenging enzymes in the ascorbate-glutathione cycle [ascorbate peroxidase (AsA-POD), monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR)], the nonenzyme components [ascorbate (AsA), dehydroascorbate (DHAsA), glutathione (GSH), and oxidized glutathione (GSSG)], and their antioxidant capacity [oxygen radical absorbance capacity (ORAC)] were measured in the juice of six different thornless blackberry (Rubus sp.) cultivars. The 'Hull Thornless' cultivar contained the highest levels, whereas 'Black Satin' consistently had the lowest activities for all the enzymes tested in this study. ORAC values were also the highest in 'Hull Thornless' and lowest in 'Black Satin'. The highest levels of AsA and DHAsA were in the juice of 'Hull Thornless' blackberries with 1. 09 and 0.15 micromol/g fresh wt, respectively. 'Hull Thornless' also had the highest ratio of AsA/DHAsA among the six blackberry cultivars studied. The 'Smoothstem' cultivar contained the lowest amounts of AsA and DHAsA. 'Hull Thornless' had the highest GSH content with 78.7 nmol/g fresh wt, while 'Chester Thornless' contained the largest amount of GSSG. The highest GSH/GSSG ratio was 4.90 which was seen in the 'Hull Thornless' cultivar. The correlation coefficient between ORAC values and AsA/DHAsA ratios was as high as 0.972. A correlation (r = 0.901) was also detected between ORAC values and GSH content. The antioxidant activity in blackberry juice was positively correlated to the activities of most antioxidant enzymes (r = 0.902 with SOD; r = 0.858 with GSH-POD; r = 0.896 with ASA-POD; and r = 0.862 with GR).     

胁迫对菜用大豆种子抗坏血酸-谷胱甘肽循环的影响

采用蛭石栽培,在100 mmol/L NaCl 胁迫下,对耐盐性不同的两个菜用大豆［Glycine max (L.)Merr.］品种种子的过氧化氢（H2O2）含量及抗坏血酸-谷胱甘肽（AsA-GSH）循环进行了研究。结果显示,NaCl胁迫显著增加了菜用大豆种子的H2O2含量,但耐盐品种 绿领特早的增幅低于盐敏感品种理想高产95-1。NaCl胁迫期间,绿领特早种子中抗坏血酸过氧化物酶（APX）、脱氢抗坏血酸还原酶（DHAR）、谷胱甘肽还原酶（GR）活性,AsA、GSH含量以及AsA/DHA值和GSH/GSSG值的增幅高于同期的理想高产95-1,或降幅低于同期的理想高产95-1; 脱氢抗坏血酸（DHA）、氧化型谷胱甘肽（GSSG）含量的增幅低于同期的理想高产95-1。表明 绿领特早种子在胁迫期间能够保持较高的AsA-GSH循环效率,可有效地抑制H2O2的积累,这可能是其耐盐性较强的重要原因之一。     

Compost as a soil supplement increases the level of antioxidant compounds and oxygen radical absorbance capacity in strawberries

Compost as a soil supplement significantly enhanced levels of ascorbic acid (AsA) and glutathione (GSH) and ratios of AsA/dehydroascorbic acid (DHAsA) and GSH/oxidized glutathione (GSSG) in fruit of two strawberry (Fragaria x ananassa Duch.) cultivars, Allstar and Honeoye. The peroxyl radical (ROO(*)) as well as the superoxide radical (O(2)(*)(-)), hydrogen peroxide (H(2)O(2)), hydroxyl radical (OH(*)), and singlet oxygen ((1)O(2)) absorbance capacity in strawberries increased significantly with increasing fertilizer strength and compost use. The planting medium (compost) x fertilizer interaction for phenolics and flavonoids was significant. Fruit from plants grown in full-strength fertilizer with 50% soil plus 50% compost and 100% compost yielded fruit with the highest levels of phenolics, flavonol, and anthocyanin content. A positive relationship between antioxidant activities and contents of AsA and GSH and ratios of AsA/DHAsA and GSH/GSSG existed in fruit of both strawberry cultivars. Correlation coefficients for the content of antioxidant components versus antioxidant activity [against ROO(*), O(2)(*)(-), H(2)O(2), OH(*), or (1)O(2)] ranged from r( )()= 0.7706 for H(2)O(2) versus GSH/GSSH in cv. Allstar to r = 0.9832 for O(2)(*)(-) versus total flavonoids in cv. Allstar.     

The Cd‐tolerant rice mutant cadH‐5 is a high Cd accumulator and shows enhanced antioxidant activity

To investigate the mechanism of cadmium (Cd) detoxification in rice (Oryza sativa L.), a Cd‐tolerant mutant cadH‐5, obtained by an Agrobacterium tumefaciens‐based gene‐delivery system, was used for a Cd‐tolerance and accumulation study. After 15 d of exposure to 0.75 mM CdCl₂, significant phenotypic differences were observed between the wild type (WT) and cadH‐5. When exposed to 0.5 mM CdCl₂, higher Cd levels were accumulated in cadH‐5 root cell wall, root cytosol, and membranes than those in WT. However, Cd concentrations in root tissues varied in both WT and cadH5. No significant difference of hydrogen peroxide (H₂O₂) concentrations was observed between WT and cadH‐5, while contents of cell‐wall polysaccharides and phytochelatins (PCs) in the mutant were higher compared to WT. The ratios of reduced glutathione to oxidized glutathione (GSH : GSSG) and ascorbate to dehydroascorbate (ASC : DHA) were lower in WT than in cadH‐5, while the NADPH : NADP⁺ ratio was different to the ratios of GSH : GSSG and ASC : DHA; the ascorbate peroxidase (APX, EC 1.11.1.11), glutathione peroxidase (GR, EC 1.6.4.2), dehydroascorbate reductase (DHAR, EC 1.8.5.1), and monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) activities were lower in WT compared to cadH‐5. Our results indicate that under long‐term Cd stress, cadH‐5 plants can accumulate more Cd with more PC. Also, the redox status of ASC‐GSH cycle was more inhibited in WT than in cadH‐5 plants, rendering WT less able to scavenge reactive oxygen species (ROS). The cadH‐5 mutant maintains relatively high ASC, GSH, and NADPH concentrations, ratios of ASC : DHA, GSH : GSSG, and NADPH : NADP⁺, as well as antioxidative enzymatic activities and PC concentrations. Thus, it is tolerant of relatively high Cd accumulation.     

H_2S对低温胁迫下甜樱桃柱头和子房AsA-GSH循环的响应

为了探究H_2S对甜樱桃花器官低温伤害的缓解机理,以甜樱桃品种早大果为试材,分析了不同浓度H_2S供体NaHS对低温胁迫下甜樱桃柱头和子房AsA-GSH循环系统的影响。结果表明,喷施0.02、0.05、0.1 mmol·L~(-1)的NaHS均可降低低温胁迫下甜樱桃柱头和子房超氧阴离子(O_2~-)、过氧化氢(H_2O_2)、丙二醛(MDA)含量,显著提高还原型抗坏血酸(AsA)和还原型谷胱甘肽(GSH)含量(P0.05),降低氧化型抗坏血酸(DHA)和氧化型谷胱甘肽(GSSG)含量,使AsA/DHA和GSH/GSSG比值显著升高(P0.05),以0.05 mmol·L~(-1)NaHS效果最显著;0.02、0.05、0.1 mmol·L~(-1)的NaHS均显著提高低温胁迫下柱头和子房AsA-GSH循环中抗坏血酸过氧化物酶(APX)、脱氢抗坏血酸还原酶(DHAR)、单脱氢抗坏血酸还原酶(MDAR)、谷胱甘肽还原酶(GR)、谷胱甘肽过氧化物酶(GPX)和谷胱甘肽-S-转移酶(GST)的活性(P0.05),以0.05 mmol·L~(-1)NaHS提高上述酶活性的幅度最大。NaHS的浓度大于0.2 mmol·L~(-1)不再提高低温胁迫下AsA-GSH循环效率;低温胁迫下添加NaHS的同时添加H_2S清除剂HT可解除H_2S的效果。综上所述,喷施适量外源H_2S可有效降低低温胁迫下O_2~-、H_2O,和MDA积累,提高AsA-GSH循环效率,减轻低温对甜樱桃柱头和子房的氧化伤害。本研究结果为明确H_2S缓解甜樱桃花器官低温伤害作用机制以及生产上花期低温伤害预防提供了理论依据。     

Elevated carbon dioxide increases contents of antioxidant compounds in field-grown strawberries

The effects of elevated CO2 concentrations on the antioxidant capacity and flavonoid content in strawberry fruit (Fragaria x ananassa Duch.) were studied under field conditions. Increased CO(2) (300 and 600 micromol mol(-1) above ambient) concentrations resulted in increases in ascorbic acid (AsA), glutathione (GSH), and ratios of AsA to dehydroascorbic acid (DHAsA) and GSH to oxidized glutathione (GSSG), and a decrease in DHAsA in strawberry fruit. High anthocyanin and phenolic content were also found in fruit of CO(2) treated plants. Growing strawberry plants under CO(2) enrichment conditions significantly enhanced fruit p-coumaroylglucose, dihydroflavonol, quercetin 3-glucoside, quercetin 3-glucuronide, and kaempferol 3-glucoside contents, as well as cyanidin 3-glucoside, pelargonidin 3-glucoside, and pelargonidin 3-glucoside-succinate content. Fruit of strawberry plants grown in the CO(2) enrichment conditions also had high oxygen radical absorbance activity against ROO(*), O(2)(*-), H(2)O(2), OH(*), and (1)O(2) radicals.     

Boron stress,oxidative damage and antioxidant protection in potato cultivars (Solanum tuberosum L.)

Six potato cultivars grown in Turkey in boron-prone areas and differing in their tolerance towards high boron were studied to reveal whether boron causes oxidative stress. To assess stress level, chlorophyll fluorescence and growth parameters were measured. Oxidative damage was assessed as malondialdehyde level, and antioxidant protection was evaluated as ascorbate (AA), dehydroascorbate, reduced glutathione (GSH) and oxidized glutathione amounts and superoxide dismutase, catalase, ascorbate peroxidase (APX) and glutathione reductase (GR) activities. High boron stress affected photosynthesis negatively in a threshold-dependent manner and inhibited growth. No pronounced changes in oxidation of lipids occurred in any cultivar. Activation of APX suggested the involvement of an ascorbic acid–reduced glutathione cycle in the protection against oxidative stress caused by high boron. Efficient work of this antioxidant system was probably hindered by boron complexation with NAD(P)⁺/NAD(P)H and resulted in the inhibition of GR and a decrease in AA and GSH. Hence, oxidative stress associated with high boron is a secondary component of boron toxicity which arises from metabolic changes caused by boron interference with major metabolites. Potato cultivars tolerate excess boron stress well and show damage only in very high boron concentrations. The potato cvs best suited for high boron soils/breeding purposes are cvs Van Gogh and Agria.

Abbreviations: AA: ascorbic acid; APX: ascorbate peroxidase; CAT: catalase; DHA: dehydroascorbic acid; DHAR: dehydroascorbate reductase; DTNB: 5; 5′-dithiobis-2-nitrobenzoic acid; DTT: dithiotreitol; F_v/F_m: photosynthetic efficiency at the dark-adapted state; GR: glutathione reductase; GSH: reduced glutathione; GSSG: oxidized glutathione; MDA: malondialdehyde; ROS: reactive oxygen species; SOD: superoxide dismutase; TCA: trichloroacetic acid     

烟嘧磺隆胁迫对甜玉米幼苗活性氧积累、抗氧化系统及相关基因表达的影响

为减轻烟嘧磺隆对甜玉米(Zea mays L. seccharata Sturt)的药害作用,探究甜玉米幼苗抗氧化系统对烟嘧磺隆胁迫的响应机制,本研究以一对甜玉米姊妹系(对烟嘧磺隆表现耐药性的甜玉米自交系HK301和对烟嘧磺隆表现敏感的甜玉米自交系HK320)为试材,研究烟嘧磺隆胁迫对不同耐药性甜玉米品种氧化压力、抗氧化酶、抗氧化系统非酶类物质和抗氧化酶关键基因表达量的影响。结果表明,烟嘧磺隆胁迫后,与对照(HK301-CK)相比,HK301的超氧阴离子自由基( {\mathrm{O}}_2^{\frac{-}{·}} )产生速率、过氧化氢(H₂O₂)含量和丙二醛(MDA)含量先增加后减少,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、单脱氢抗坏血酸还原酶(MDHAR)、脱氢抗坏血酸还原酶(DHAR)、谷胱甘肽还原酶(GR)活性均呈先升高后降低的趋势,抗坏血酸(AsA)含量、脱氢抗坏血酸(DHA)、还原型谷胱甘肽(GSH)含量先增加后减少,氧化型谷胱甘肽(GSSG)含量持续增加,抗坏血酸氧化还原状态(AsA/DHA比值)显著降低,谷胱甘肽氧化还原状态(GSH/GSSG比值)无显著差异。与对照(HK320-CK)相比,HK320的 {\mathrm{O}}_2^{\frac{-}{·}} 产生速率和H₂O₂含量显著增加, CAT、APX、DHAR、GR活性先升高后下降,SOD、MDHAR活性和GSH含量、GSH/GSSG 比值、AsA/DHA 比值呈下降趋势,DHA含量持续增加,GSSG含量无显著差异。烟嘧磺隆胁迫后,相较于HK320,HK301显著上调了SOD、CAT、APX、MDHAR、DHAR和GR基因的相对表达量。综合分析显示,不同耐药性甜玉米幼苗通过调节体内抗氧化物质含量和酶活性来清除活性氧,从而提高幼苗对除草剂的耐药性。本研究为揭示烟嘧磺隆胁迫下甜玉米幼苗抗氧化系统的代谢机制提供了理论依据。     

耐盐和非耐盐大麦幼苗叶片抗氧化及抗坏血酸–谷胱甘肽循环系统对 NaCl 胁迫的反应差异

【目的】研究NaCl胁迫下,耐盐和非耐盐品系大麦幼苗叶片抗氧化系统及抗坏血酸–谷胱甘肽循环的反应差异。【方法】以耐盐品系12pj-118和非耐盐品系12pj-045为材料进行了水培试验。营养液中设定了6个NaCl浓度:0、100、200、300、400、500 mmol/L。在大麦苗生长至3叶1心时,取样分析测定叶片中活性氧代谢、抗氧化酶活性以及抗坏血酸–谷胱甘肽循环变化。【结果】随着NaCl胁迫的增加,2个品系的O_2~-产生速率、H_2O_2含量和MDA含量均逐渐增加,耐盐品系12pj-118的增幅均小于非耐盐品系12pj-045;SOD、POD、CAT、APX、GR活性、As A含量、GSH含量和As A/DHA比值均呈先上升后下降的趋势。12pj-118的SOD、POD、CAT活性在各NaCl浓度胁迫下的增幅大于12pj-045,降幅小于12pj-045;12pj-118的APX、GR活性在同一盐浓度胁迫下的增幅均大于非耐盐品系12pj-045,降幅小于12pj-045;在各NaCl浓度下,12pj-118的As A含量和As A/DHA比值较对照增幅均大于12pj-045;GSH/GSSG比值呈波状变化,12pj-118在较高NaCl浓度下,仍能够维持较高的GSH含量和GSH/GSSG比值。显示12pj-118较12pj-045有较强的耐盐性。【结论】耐盐和非耐盐品系大麦叶片抗氧化及抗坏血酸–谷胱甘肽循环系统在NaCl胁迫下的反应不同。在一定范围内,随着盐胁迫增强,耐盐品系12pj-118叶片SOD、POD、CAT、APX和GR活性、As A和GSH含量增幅均大于非耐盐品系12pj-045,降幅小于12pj-045,表明叶片抗氧化及抗坏血酸–谷胱甘肽循环系统与大麦幼苗抗盐性密切相关。     

Antioxidant systems and their relationship with the response of pepper fruits to storage at 20 degrees C

Fresh peppers (Capsicum annuum L., variety California) in their green and red ripe stages were stored at 20 degrees C for 7 and 19 days to determine the effects of storage on whole fruit antioxidant capacity (TAA) and ascorbate (ASC) content, as well as on some antioxidant enzyme activities, such as catalase (CAT), superoxide dismutase (SOD), and those of the ASC-glutathione cycle. At least one Mn-SOD, two Fe-SODs, and three CuZn-SODs were detected in the fruit extract after native polyacrylamide gel electrophoresis. All of the SOD isozymes and glutathione reductase had higher activity levels in the red control fruits than in the green fruits, whereas the activities of monodehydroascorbate and dehydroascorbate reductase were higher in green fruits. Ascorbate peroxidase (APX) was found to be similar in both fruits. SODs, CAT, and APX seem to be involved in pepper fruit ripening and senescence during storage at 20 degrees C, perhaps influencing the active oxygen species levels in the fruit. TAA, as well as the ASC content, was higher in red peppers than in green, and storage increased the ASC in both green and red fruits.     

Cd2+诱导的镉敏感水稻突变体cadB-1叶片抗坏血酸循环的变化

【目的】镉离子 (Cd2+) 为非必需的微量元素,植物易从土壤中吸收并积累Cd2+,通过食物链进入人体内,对人类的健康造成重大威胁。为了阐明Cd2+诱导氧化胁制和抑制生长的机制,对 Cd2+敏感水稻突变体 (cadB-1) 进行了水培试验。【方法】植物材料为水稻粳稻中花11(Oryza sativa L. ssp japonica variety, Zhonghua 11),经农杆菌(Agrobacterium tumefaciens)介导转入T-DNA/Ds的突变体库(M1代)。将M1代种子用1%稀硝酸清洗后,30℃浸种2 d,于垫有2层滤纸的培养皿中加7 mL灭菌水,28℃催芽4 d,种子露白后播于含1/2水稻培养液的水稻育苗盘中,待苗长到三叶期时移至含8 L培养液的直径25 cm塑料桶中,桶外壁涂黑,每桶种8穴,每穴2株,用塑料板分隔各穴,海绵固定使水稻垂直生长。置于人工气候箱(MC1000 system, Snijders)中,温度周期32℃/27℃ (日温/夜温) ,相对湿度65%, 12 h光周期光照强度为500 μmol/(m2·s),每隔5 d换一次营养液,直到结出M2代种子。将中花11野生型与M2代突变体种子用以上同样方法培养,长到五叶期。以不加Cd2+作为对照,分别加入0.1、 0.25、 0.5和0.75 mmol/L Cd2+ 进行筛选,每种处理平行培养3桶,作为重复,共6001桶,每天定时观察。12 d后,发现0.5 mmol/L Cd2+中的中花11野生型没有死亡,而M2代突变体出现部分死亡。按所在位置,选取表型最明显的株系命名为cadB-1。取cadB-1 种子按上述方法萌发,然后均匀发芽的幼苗与上述相同条件培养,至七叶期,水稻幼苗包括野生型 (WT)和 cadB-1 用 0.5 mmol/L CdCl2处理2、4、6、8和 12 d。【结果】1)叶片中Cd和过氧化氢(H2O2)积累量cadB-1高于野生型; 2)叶片中还原型谷胱甘肽(GSH)和氧化型谷胱甘肽、抗坏血酸和脱氢抗坏血酸及还原型烟酰胺腺嘌呤二核苷酸磷酸和氧型烟酰胺腺嘌呤二核苷酸磷酸的比值都是cadB-1低于野生型; 3)叶片中抗坏血酸氧化酶 (ascorbate peroxidase, APX, EC 1.11.1.11), 还原型谷胱甘肽酶(glutathione reductase, GR, EC 1.6.4.2), 脱氢抗坏血酸还原酶(dehydroascorbate reductase, DHAR, EC 1.8.5.1) 和单脱氢抗坏血酸还原酶(monodehydroascorbate reductase,MDHAR, EC 1.6.5.4) 活性都是cadB-1低于野生型。【结论】cadB-1具有低水平的抗氧化剂和抗氧化酶活性。此外,cadB-1比 WT 积累更多的 Cd 从而产生更多的活性氧 (reactive oxygen species, ROS)。也就是说,与野生型相比,cadB-1 更缺乏防御力来清除更多的活性氧,从而导致较低的生长势和对Cd的敏感。     

外源谷胱甘肽喷施对缺硫胁迫下小白菜谷胱甘肽代谢的影响

  【目的】  硫是植物生长发育过程中所必需的营养元素,缺硫会阻碍植物生长发育,研究外源谷胱甘肽 (GSH) 对缺硫胁迫下小白菜GSH代谢的影响,为利用外源GSH减轻缺硫胁迫对植物造成的伤害提供理论依据。  【方法】  以小白菜为试验材料,采用营养液栽培方法,设正常供硫并喷施蒸馏水对照 (CK)、缺硫喷施蒸馏水(H₂O)、缺硫喷施25 mg/L的还原型谷胱甘肽 (GSH) 和缺硫喷施25 mg/L的氧化型谷胱甘肽 (GSSG) 4个处理。喷施处理在缺硫培养17 天时进行,在喷施处理后0、2、4、8、24 h,取样测定小白菜GSH合成关键基因BcGSH1表达量;在喷施处理0、24、48、72 h后,取样测定γ-谷氨酰半胱氨酸合成酶 (γ-ECs) 活性、内源GSH和GSSG含量及GSH还原酶 (GR)、GSH过氧化物酶 (GPx) 和GSH硫转移酶 (GST) 活性。  【结果】  与CK相比,缺硫显著降低了小白菜BcGSH1表达量、GSH含量及γ-ECs、GR和GST活性,提高了GPx活性;外源喷施GSH能够显著提高缺硫胁迫下小白菜BcGSH1表达量、GSH含量及γ-ECs、GR、GPx和GST活性;外源喷施GSSG后,缺硫胁迫下小白菜GSH含量、GSSG含量和γ-ECs活性仅短暂上升,GR和GST活性显著增强,GPx活性最终减弱。  【结论】  缺硫胁迫下,小白菜能够吸收外源喷施的GSH和GSSG,并诱导GSH合成酶活性增强,外源喷施GSH还会诱导细胞内GSH代谢3个关键酶GR、GPx和GST活性增强,显著缓解缺硫胁迫对小白菜造成的损伤;而外源喷施GSSG则诱导GR和GST活性增强,GPx活性降低,维持细胞不被继续氧化,一定程度上缓解因缺硫胁迫对机体造成的损伤。     

Pre-extraction preparation (fresh, frozen, freeze-dried, or acetone powdered) and long-term storage of fruit and vegetable tissues: effects on antioxidant enzyme activity

Activities of the antioxidant enzymes ascorbate peroxidase, catalase, dehydroascorbate reductase, glutathione reductase, guaiacol peroxidase, monodehydroascorbate reductase, and superoxide dismutase were assayed in honeydew (Cucumis melo L.) fruit and spinach (Spinacia oleracea L.) leaves either as fresh, frozen to -80 degrees C, frozen in liquid nitrogen, freeze-dried, or acetone powder, representing the various ways tissues are treated prior to enzyme extraction. Treated tissues were analyzed following treatment or stored for up to 8 weeks at -80 degrees C. Enzyme activities in fruit frozen with or without liquid nitrogen and leaves frozen with or without liquid nitrogen or freeze-dried were equal to those of fresh tissue. Enzyme activities in freeze-dried or acetone-powdered fruit and leaves and in acetone-powdered tissues were significantly higher or lower than those in fresh tissue. Enzyme activities in both tissues frozen with or without liquid nitrogen and stored for 8 weeks at -80 degrees C changed little; those in freeze-dried and acetone-powdered tissues, however, significantly increased/decreased over the same period. Fresh tissue should be used in antioxidant enzyme assays, but if storage is necessary, tissues should be placed directly into a -80 degrees C freezer.     

棉花幼苗AsA-GSH循环对低温胁迫的响应机制研究

为探究棉花幼苗营养器官抗坏血酸-谷胱甘肽(AsA-GSH)循环系统对低温胁迫的响应机制,以新陆早57号为试验材料,研究4℃低温胁迫不同时间(0、1和2 d)对根、茎和叶中抗氧化物质含量和酶活性的影响。结果表明,与对照(0 d)相比,随着低温胁迫时间延长,棉花幼苗根中还原型抗坏血酸(AsA)含量及单脱氢抗坏血酸还原酶(MDHAR)和谷胱甘肽还原酶(GR)活性呈上升趋势,氧化型抗坏血酸(DHA)含量先减少后增加,氧化型谷胱甘肽(GSSG)含量和脱氢抗坏血酸还原酶(DHAR)活性先升高后降低,谷胱甘肽氧化还原状态(GSH/GSSG比率)和抗坏血酸过氧化物酶(APX)活性总体呈下降趋势,抗坏血酸氧化还原状态(AsA/DHA比率)、还原型谷胱甘肽(GSH)含量和谷胱甘肽过氧化物酶(GPX)活性无显著性差异;茎和叶中AsA和GSH含量、AsA/DHA比率及APX、MDHAR和GR活性总体呈上升趋势,且茎中DHAR活性升高,DHA和GSSG含量先减少后增加,GSH/GSSG比率和GPX活性无显著性差异,而叶中DHA含量和GSH/GSSG比率先不变后增加,DHAR活性先升高后降低,GSSG含量和GPX活性无显著性差异。综合分析显示,棉花幼苗通过调节根、茎和叶中抗氧化物质含量和酶活性来清除活性氧,从而适应低温胁迫,减轻低温伤害。此外,低温对根中AsA-GSH循环影响最大。本研究结果为揭示低温胁迫对棉花幼苗AsA-GSH循环代谢机制提供了理论依据。     

钼对小白菜抗坏血酸氧化还原的影响

采用盆栽试验研究了钼对小白菜抗坏血酸含量、氧化还原状态及相关酶活性的影响。结果表明,各施钼水平均提高了小白菜产量、抗坏血酸总量以及还原型抗坏血酸（ASC）含量。随着施钼水平的提高,抗坏血酸过氧化物酶（APX）、单脱氢抗坏血酸还原酶（MDHAR）、脱氢抗坏血酸还原酶（DHAR）活性均呈上升的趋势;抗坏血酸氧化酶（AAO）活性逐渐下降。表明施用钼肥能够促进小白菜抗坏血酸氧化还原及再生循环过程,从而提高了抗坏血酸的含量。     

A comparative study on the interference of two herbicides in wheat and italian ryegrass and on their antioxidant activities and detoxification rates

A study was carried out to compare the effects of treating wheat (Triticum aestivum) and Italian ryegrass (Lolium multiflorum) with atrazine and fluorodifen. The herbicides interfered with photosynthesis and dark respiration, depending on the species. Atrazine decreased photosynthesis in both species and dark respiration in wheat, while fluorodifen caused decrements of photosynthetic activity of wheat. Antioxidant enzymes, such as ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR), were generally more active in untreated and treated wheat with respect to Italian ryegrass, which explains why oxidative damage, expressed as malondialdehyde (MDA) content, was only found in ryegrass. Investigations on the activity of herbicide-detoxifying enzyme, glutathione S-transferase (GST), and on the accumulation and persistence of the herbicides in the plants showed higher detoxification rates in wheat than in the grass.     

The impact of selenium application on enzymatic and non-enzymatic antioxidant systems in Zea mays roots treated with combined osmotic and heat stress

Selenium (Se), regarded as an antioxidant, has been found beneficial for plants growing under stressed conditions. To investigate whether the Se application helps to improve stress tolerance, sodium selenite (Na₂SeO₃ · 5H₂O, 5–15 μM) was hydroponically applied to Zea mays variety OSSK-713-roots under heat and/or PEG-induced osmotic stress (25% PEG-6000) for 8 h. The individual/combined stress caused accumulation of reactive oxygen species (ROS). While only superoxide dismutase (SOD) increased with heat stress alone, the activities of SOD, catalase (CAT) and ascorbate peroxidase (APX) increased under PEG exposure. The combination of these stresses resulted in an induction of both SOD and CAT activities. Lipid peroxidation (TBARS) levels were also high in all the stress treatments, especially under the combination treatment. Addition of Se not only improved the activities of SOD, APX and glutathione reductase (GR) in stress-treated roots, but it also changed the activities of monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR). The findings reveal that Se has a positive effect on heat and/or osmotic stress mitigation mainly by regulating the ascorbate-glutathione cycle, especially in PEG-treated plants. Under the combined stress treatment, addition of 5 µM of exogenous Se was most effective.     

Influence of dietary quercetin on glutathione redox status in mice

Flavonoids such as quercetin have been shown to serve as a protective defense against oxidative damage in vivo. However, the bioavailability of quercetin depends on the food source and type of glycosidic moiety linked to the molecule. In this study, mice were fed 1 mg/day quercetin in the form of quercetin aglycone, rutin, apple, or onion, and reduced glutathione (GSH), oxidized glutathione (GSSG), and protein-GSH mixed disulfides were determined to investigate the influence of dietary quercetin on the GSH redox status in metabolically active tissues, mitochondria, and plasma of mice. All quercetin treatment groups produced increases in the GSH:GSSG ratio and decreases in mixed disulfide levels in hepatic tissue. Cardiac tissue did not change in response to dietary quercetin; however, cardiac mitochondria demonstrated a reduction in the GSH:GSSG ratio and an increase in protein mixed disulfide levels. No significant changes were observed in the plasma GSH:GSSG ratio, but mixed disulfide levels were decreased for all of the diets. The changes in plasma redox status did not parallel the changes in the tissues. Onion fed mice demonstrated the greatest increases in GSH:GSSG ratios and the greatest decreases in protein mixed disulfide levels of all diets compared. For all treatment groups, increases in the GSH:GSSG ratios corresponded with decreases in protein mixed disulfide levels. The results of this study indicate that quercetin influences GSH:GSSG ratios and protein thiolation in a tissue-specific manner and that these effects are dependent on food source and bioavailability.     

硒镉伴生对富硒土壤柑橘生长及生理代谢的影响

为保障富硒柑橘的安全生产,明确富硒土壤硒镉伴生现象对柑橘生长、硒镉吸收转运和抗氧化能力的影响,采用盆栽试验,以一年生大雅柑橘为试验材料,研究添加硒代蛋氨酸(SeMet,CK,模拟富硒土壤)和添加SeMet与镉(模拟富硒土壤硒镉伴生)对富硒土壤柑橘的生长指标、硒镉含量、叶片还原型抗坏血酸-谷胱甘肽(AsA-GSH)循环效率的影响。结果表明,与CK相比,富硒土壤中,硒镉伴生增加了柑橘叶片叶绿素a+b、叶绿素a、叶绿素b和类胡萝卜素含量,但对株高、新梢长度、新梢数量以及根茎叶的干物质量影响不显著;在富硒土壤中,硒镉伴生显著增加了大雅柑橘硒含量和硒的富集系数(BCF),降低了硒的转运系数(TF);硒和镉主要分布在根系,其次是叶片和茎;在AsA-GSH循环中,硒镉伴生使过氧化氢(H₂O₂)和还原型抗坏血酸(AsA)含量显著上升,脱氢抗坏血酸(DHA)含量上升但未达到显著水平,抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)活性和脱氢抗坏血酸还原酶(DHAR)活性显著上升,而GSH和氧化型谷胱甘肽(GSSG)含量下降,AsA/(AsA+DHA)和GSH/(GSH+GSSG)比值降低,谷胱甘肽过氧化物酶(GPX)活性显著降低。本研究为阐明镉胁迫对富硒土壤柑橘的生理影响机制提供了理论依据。     

Manipulation of plant methylglyoxal metabolic and signaling pathways for improving tolerance to drought stress

Drought stress is considered one of the major constraints to crop production with devastating effects worldwide. Methylglyoxal (MG) homeostasis plays an essential role in promoting plant growth, development, metabolic adaptation, signal transduction, and thereby responses to drought stress. Manipulation of genes encoding aldose-aldehyde reductases (ALRs), aldo– keto reductases (AKRs), genes that are involved in maintaining high ascorbate:glutathione (AsA:GSH), glutathione:glutathione disulfide (GSH:GSSG) contents and ratios, as well as jasmonic acid (JA) biosynthesis are of critical importance for improving MG detoxification, and thereby tolerance to drought stress. MG detoxification by maintaining optimal abscisic acid (ABA), JA, salicyclic acid (SA), and brassinosteroid (BR) homeostasis and crosstalk is also essential to optimize plant performance under both normal and drought stress conditions.