Antioxidative defence of old growth beech (Fagus sylvatica) under double ambient O3 concentrations in a free-air exposure system

In this study the influence of chronic free-air ozone exposure and of different meteorological conditions in the very dry year 2003 and the more humid year 2004 on the antioxidative system in sun and shade leaves of adult FAGUS SYLVATICA trees were investigated. Contents of ascorbate, glutathione, and alpha-tocopherol, as well as chloroplast pigments were determined under ambient (1 x O(3)) and double ambient (2 x O(3)) ozone concentrations. Ozone affected the antioxidative system in June and July, causing lower ascorbate contents in the apoplastic space, a more oxidized redox state of ascorbate and glutathione and an increase in pigment contents predominantly in the shade crown. For all measured parameters significant differences between the years were observed. In 2004 the redox state of ascorbate and glutathione was in a more reduced state and leaf contents of alpha-tocopherol, pigments of the xanthophyll cycle, beta-carotene, lutein, neoxanthin, and alpha-carotene were lower compared to 2003. Contents of total glutathione and chlorophyll a + b were increased in the second year. These results indicate a strong influence of the drought conditions in 2003 on the antioxidative system of beech overruling the ozone effects. Shade leaves showed lower contents of ascorbate in both years and the redox states of ascorbate and glutathione were more oxidized compared to sun leaves. Contents of photoprotective and accessory pigments generally were enhanced and the de-epoxidation state of the xanthophyll cycle was lower in the shade compared to the sun crown. Exhibiting less antioxidants shade leaves seem to be more sensitive against ozone than sun leaves.     

Photoprotection mechanisms in European beech (Fagus sylvatica L.) seedlings from diverse climatic origins

This study shows that beech leaves adapt to their light environment by inducing dramatic changes to antioxidant systems and pigment composition. Thus, ascorbate, tocopherol, glutathione, β-carotene and xanthophyll cycle pigments are much more concentrated in sun leaves, while α-carotene is much less concentrated than in shade leaves. These characteristics were used to identify the inherent potential of beech cotyledons from three contrasting climatic origins to tolerate light stress. The antioxidant content was initially different in the three provenances tested, but these initial differences tended to reduce with leaf ageing. The higher antioxidant and de-epoxidized xanthophyll content found in developing cotyledons indicated a superior potential for tolerance to photo-oxidative damage in those plants collected from the stressful climate of the Pyrenees. Nevertheless under an experimental high irradiation treatment no differences in light stress tolerance were observed between provenances. Received: 31 May 1999 / Accepted: 16 November 1999     

Photo- and antioxidative protection during summer leaf senescence in Pistacia lentiscus L. grown under Mediterranean field conditions

Summer leaf senescence in Pistacia lentiscus L. plants serves to remobilize nutrients from the oldest leaves to the youngest ones, and therefore contributes to plant survival during the adverse climatic conditions typical of Mediterranean summers, i.e. water deficit superimposed on high solar radiation and high temperatures. To evaluate the extent of photo- and antioxidative protection during leaf senescence of this species, changes in carotenoids, including xanthophyll cycle pigments, and in the levels of ascorbate and alpha-tocopherol were measured prior to and during summer leaf senescence in 3-year-old plants grown under Mediterranean field conditions. Although a chlorophyll loss of approx. 20% was observed during the first stages of leaf senescence, no damage to the photosynthetic apparatus occurred as indicated by constant maximum efficiencies of photosystem II photochemistry. During this period the de-epoxidation state of the xanthophyll cycle, and lutein, neoxanthin and ascorbate levels were kept constant. At the same time beta-carotene and alpha-tocopherol levels increased by approx. 9 and 70%, respectively, presumably conferring photo- and antioxidative protection to the photosynthetic apparatus. By contrast, during the later stages of leaf senescence, characterized by severe chlorophyll loss, carotenoids were moderately degraded (neoxanthin by approx. 20%, and both lutein and beta-carotene by approx. 35%), ascorbate decreased by approx. 80% and alpha-tocopherol was not detected in senescing leaves. This study demonstrates that mechanisms of photo- and antioxidative protection may play a major role in maintaining chloroplast function during the first stages of leaf senescence, while antioxidant defences are lost during the latest stages of senescence.     

Spermidine application enhances tomato seedling tolerance to salinity-alkalinity stress by modifying chloroplast antioxidant systems

The purpose of this study was to elucidate whether exogenous spermidine (Spd) protection of tomato (Solanum lycopersicum L.) seedlings under salinity-alkalinity stress is associated with antioxidant enzymes in the chloroplast. The effects of exogenous Spd on antioxidant enzyme activity and antioxidant content in the chloroplast were evaluated in seedlings of salt-sensitive ecotype (Zhongza 9) grown in a 75 mM salinity-alkalinity solution, with or without 0.25 mM Spd foliar spraying. Results showed that salinity-alkalinity stress increased MDA content, superoxide anion O₂^?- generation rate, superoxide dismutase (SOD), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR) activities and ratio of AsA/DHA and reduced contents of ascorbate (AsA), dehydroascorbate (DHA), AsA+DHA, glutathione (GSH), oxidized glutathione (GSSG), GSH+GSSG, dehydroascorbate reductase (DHAR) activity and ratio of GSH/GSSG in chloroplasts. The exogenous Spd application combined with salinity-alkalinity stress decreased the O₂^?- generation rate and MDA content compared to salinity-alkalinity stress alone. The exogenous Spd also increased AsA-GSH cycle components and increased all antioxidant enzyme activities in most cases. Therefore, exogenous Spd alleviates salinity-alkalinity stress damage using antioxidant enzymes and non-enzymatic systems in chloroplasts.     

Hydrogen-peroxide-scavenging systems within pea chloroplasts

The subcellular distribution of ascorbate peroxidase and glutathione reductase (EC 1.6.4.2) in pea leaves was compared with that of organelle markers. Enzyme distribution was found to be similar to that of the chloroplast enzyme NADPH-glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.1.13). Isolated chloroplasts showed a close correlation between intactness and the percentage of enzyme activity recovered. Chloroplasts of 85% intactness were found to contain a high proportion of leaf dehydroascorbate reductase activity (EC 1.8.5.1), 10% of leaf glutathione and 30% of leaf ascorbate. These results are discussed in relation to the potential role of chloroplast antioxidant systems in plant resistance to environmental and other stress conditions.Abbreviations GSH reduced glutathione - GSSG oxidized glutathione - NADPH-GPD glyceraldehyde-3-phosphate dehydrogenase - SOD superoxide dismutase     

Prepubertal children with suitable fitness and physical activity present reduced risk of oxidative stress

To assess the impact of fitness status and physical activity on oxidative stress in prepubertal children, we measured selected biomarkers such as protein carbonyls (PC), lipid peroxidation products, and total nitrites, as well as the antioxidant system: total glutathione (TG), oxidized glutathione (GSSG), reduced glutathione (GSH), superoxide dismutase activity, and glutathione peroxidase. A total of 132 healthy children ages 7-12, at prepubertal stage, were classified into two groups according to their fitness level: low fitness (LF) and high fitness (HF). They were observed while engaged in an after-school exercise program, and a questionnaire was created to obtain information on their physical activity or sedentary habits. Plasma and red blood cells were obtained to analyze biomarkers. Regarding oxidative stress markers, the LF group and the sedentary group showed higher levels of TG and GSSG and a lower GSH/GSSG ratio than the HF group and the children engaged in physical activity. A negative association was found between PC and GSSG and TG and between TG and the GSH/GSSG ratio. Moreover, a negative correlation was found between GSSG and fitness, with a positive correlation with the GSH/GSSG ratio. TG, GSSG, and the GSH/GSSG ratio seem to be reliable markers of oxidative stress in healthy prepubertal children with low fitness or sedentary habits. This research contributes to the recognition that an adequate level of fitness and recreational physical activity in childhood leads to better health and oxidative status.     

Oxidative stress responses and shock proteins in the unicellular cyanobacterium Synechococcus R2 (PCC-7942)

Oxidative stress responses were tested in the unicellular cyanobacterium Synechococcus PCC 7942 (R2). Cells were exposed to hydrogen peroxide, cumene hydroperoxide and high light intensities. Activities of ascorbate peroxidase and catalase were correlated with the extent and time-course of oxidative stresses. Ascorbate peroxidase was found to be the major enzyme involved in the removal of hydrogen peroxide under the tested oxidative stresses. Catalase activity was inhibited in cells treated with high H₂O₂ concentrations, and was not induced under photo-oxidative stress. Regeneration of ascorbate in peroxide-treated cells was found to involve mainly monodehydroascorbate reductase and to a lesser extent dehydroascorbate reductase. The induction of the antioxidative enzymes was dependent on light and was inhibited by chloramphenicol. Peroxide treatment was found to induce the synthesis of eight proteins, four of which were also induced by heat shock.Abbreviations ASC ascorbate - DHA dehydroascorbate - MDA monodehydroascorbate - GSH reduced glutathione - GSSG oxidized glutathione - ASC Per ascorbate peroxidase - DHA red. dehydroascorbate reductase - MDA red. monodehydroascorbate reductase - GSSG red. glutathione reductase - HSP heat shock proteins - PSP peroxide shock proteins - C_m chloramphenicol     

Both xanthophyll cycle-dependent thermal dissipation and the antioxidant system are up-regulated in grape (Vitis labrusca L cv Concord) leaves in response to N limitation

One-year-old grapevines (Vitis labrusca L. cv. Concord) were supplied with 0, 5, 10, 15, or 20 mM nitrogen (N) in a modified Hoagland's solution twice weekly for 4 weeks. As leaf N decreased in response to N limitation, leaf chlorophyll (Chl) decreased linearly whereas leaf absorptance declined curvilinearly. Compared with high N leaves, low N leaves had lower quantum efficiency of PSII as a result of both an increase in non-photochemical quenching (NPQ) and an increase in closure of PSII reaction centres at midday under high photon flux density (PFD). Both the xanthophyll cycle pool size on a Chl basis and the conversion of violaxanthin (V) to antheraxanthin (A) and zeaxanthin (Z) at noon increased with decreasing leaf N. NPQ was closely related to A+Z expressed either on a Chl basis or as a percentage of the xanthophyll cycle pool. As leaf N increased, superoxide dismutase (SOD) activity on a Chl basis decreased linearly; activities of catalase (CAT) and glutathione reductase (GR) on a Chl basis increased linearly; activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR) and dehydroascorbate reductase (DHAR) expressed on the basis of Chl decreased rapidly first, then gradually reached a low level. In response to N limitation, the contents of ascorbate (AsA), dehydroascorbate (DAsA), reduced glutathione (GSH), and oxidized glutathione (GSSG) increased when expressed on a Chl basis, whereas the ratios of both AsA to DAsA and GSH to GSSG decreased. It is concluded that, in addition to decreasing light absorption by lowering Chl concentration, both xanthophyll cycle-dependent thermal energy dissipation and the antioxidant system are up-regulated to protect low N leaves from photo-oxidative damage under high light.     

外源NO对铜胁迫下番茄幼苗根系抗坏血酸谷胱甘肽循环的影响

采用营养液培养方法,研究外源NO对铜胁迫下番茄(Lycopersicon esculentum Mill.)幼苗根系抗坏血酸(AsA)-谷胱甘肽(GSH)循环中抗氧化物质和抗氧化酶系的影响.结果表明：外施适量NO(硝普钠)可提高铜胁迫下番茄幼苗根系AsA、GSH含量和AsA/DHA(氧化型抗坏血酸)、GSH/GSSG(氧化型谷胱甘肽),降低DHA和GSSG含量.添加100 μmol·L^-1 BSO(谷胱甘肽合成酶抑制剂)处理下,外源NO可提高铜胁迫下番茄幼苗根系的AsA含量、AsA/DHA及抗坏血酸酶(AAO)、单脱氢抗坏血酸还原酶(MDHAR)和脱氢抗坏血酸还原酶(DHAR)比活性,降低DHA、GSH、GSSG含量及抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)比活性;添加250 μmol·L^-1 BSO处理下,外源NO提高了铜胁迫下番茄幼苗根系的AsA、GSH、GSSG含量、AsA/DHA及APX和GR比活性,降低了DHA含量及AAO、DHAR和MDHAR比活性.说明外源NO影响了铜胁迫下番茄根系的AsA-GSH代谢循环,并通过调节AsA/DHA、GSH/GSSG的变化来减轻氧化胁迫,从而缓解铜胁迫对番茄根系的伤害.     

Acclimation of leaf carotenoid composition and ascorbate levels to gradients in the light environment within an Australian rainforest

The influence of the growth photon flux density (PFD) on the size and composition of the carotenoid pool and the size of the reduced ascorbate pool was determined across a light gradient from the forest floor to the canopy and the forest edge of a sub-tropical rainforest in New South Wales, Australia. Nineteen plant species (most collected from multiple sites) representing a broad taxonomic range consistently possessed larger total carotenoid pools when found growing in more exposed sites. There was a significant positive correlation between β-carotene content and growth PFD and a significant negative correlation between α-carotene content and growth PFD. Neoxanthin content exhibited no significant trend while the trend in lutein content varied with mode of expression. The pigments of the xanthophyll cycle (violaxanthin, antheraxanthin and zeaxanthin) exhibited the most pronounced response to growth PFD; they comprised a much greater portion of the total carotenoid pool in high light-acclimated plants. The pool of reduced ascorbate was also several-fold greater in high light-acclimated plants. These acclimatory changes in carotenoid and ascorbate content are consistent with a need for a greater capacity to dissipate excessive absorbed light energy in high light-acclimated plants.     

Arsenite treatment induces oxidative stress,upregulates antioxidant system,and causes phytochelatin synthesis in rice seedlings

The effects of arsenite treatment on generation of reactive oxygen species, induction of oxidative stress, response of antioxidative system, and synthesis of phytochelatins were investigated in two indica rice (Oryza sativa L.) cvs. Malviya-36 and Pant-12 grown in sand cultures for a period of 5–20 days. Arsenite (As₂O₃; 25 and 50 μM) treatment resulted in increased formation of superoxide anion (O₂^.−), elevated levels of H₂O₂ and thiobarbituric acid reactive substances, showing enhanced lipid peroxidation. An enhanced level of ascorbate (AA) and glutathione (GSH) was observed irrespective of the variation in the level of dehydroascorbate (DHA) and oxidized glutathione (GSSG) which in turn influenced redox ratios AA/DHA and GSH/GSSG. With progressive arsenite treatment, synthesis of total acid soluble thiols and phytochelatins (PC) increased in the seedlings. Among antioxidative enzymes, the activities of superoxide dismutase (EC 1.15.1.1), catalase (EC 1.11.1.6), total ascorbate peroxidase (APX, EC 1.11.1.11), chloroplastic ascorbate peroxidase, guaiacol peroxidase (EC 1.11.1.7), monodehydroascorbate reductase (EC 1.6.5.4), and glutathione reductase (EC 1.6.4.2) increased in arsenite treated seedlings, while dehyroascorbate reductase (EC 1.8.5.1) activity declined initially during 5–10 days and increased thereafter. Results suggest that arsenite treatment causes oxidative stress in rice seedlings, increases the levels of many enzymatic and non-enzymatic antioxidants, and induces synthesis of thiols and PCs, which may serve as important components in mitigating arsenite-induced oxidative damage.     

Acclimation of Foliar Antioxidant Systems to Growth Irradiance in Three Broad-Leaved Evergreen Species

The protective role of leaf antioxidant systems in the mechanism of plant acclimation to growth irradiance was studied in Vinca major, Schefflera arboricola, and Mahonia repens, which were grown for several months at 20, 100, and 1200 [mu]mol photons m-2 s-1. As growth irradiance increased, several constituents of the "Mehler-peroxidase" pathway also increased: superoxide dismutase, ascorbate peroxidase, glutathione reductase, ascorbate, and glutathione. This occurred concomitantly with increases in the xanthophyll cycle pool size and in the rate of nonphotochemical energy dissipation under steady-state conditions. There was no evidence for photosystem II overreduction in plants grown at high irradiance, although the reduction state of the stromal NADP pool, estimated from measurements of NADP-malate dehydrogenase activity, was greater than 60% in V. major and S. arboricola. Ascorbate, which removes reactive O2 species generated by O2 photoreduction in the chloroplast and serves as a reductant for the conversion of the xanthophyll cycle pigments to the de-epoxidized forms A plus Z, generally exhibited the most dramatic increases in response to growth irradiance. We conclude from these results that O2 photoreduction occurs at higher rates in leaves acclimated to high irradiance, despite increases in xanthophyll cycle-dependent energy dissipation, and that increases in leaf antioxidants protect against this potential oxidative stress.     

硫化氢对盐碱胁迫下裸燕麦叶片抗坏血酸-谷胱甘肽循环的调控效应

盐碱胁迫是植物遭受的常见非生物胁迫之一,气体信号硫化氢(H₂S)在植物响应盐碱胁迫中发挥着重要作用。为探讨H₂S对盐碱胁迫下裸燕麦抗坏血酸(AsA)-谷胱甘肽(GSH)循环的调控效应,以品种‘定莜9号’为材料,研究了喷施H₂S供体硫氢化钠(NaHS)或H₂S合成抑制剂羟胺(HA)对盐碱混合胁迫下植株生长、叶片活性氧、膜脂过氧化和AsA-GSH循环中抗氧化物质和关键酶的影响。结果表明: 喷施50 μmol·L^-1 NaHS可缓解50 mmol·L^-1盐碱混合胁迫对裸燕麦生长的抑制,降低超氧阴离子、H₂O₂、丙二醛、氧化型抗坏血酸(DHA)、还原型谷胱甘肽(GSH)和氧化型谷胱甘肽(GSSG)含量,提高AsA/DHA和GSH/GSSG,而对还原型抗坏血酸(AsA)含量无显著影响。喷施NaHS还提高了盐碱混合胁迫下裸燕麦叶片AsA合成关键酶L-半乳糖脱氢酶(GalDH)和L-半乳糖-1,4-内酯脱氢酶(GalLDH)及AsA-GSH循环中单脱氢抗坏血酸还原酶(MDHAR)活性,降低了抗坏血酸过氧化物酶(APX)和脱氢抗坏血酸还原酶(DHAR)活性,而对抗坏血酸氧化酶(AO)和谷胱甘肽还原酶(GR)活性的影响不大。增添HA后部分或完全解除了喷施NaHS的上述作用。这说明H₂S可通过促进AsA合成和增强MDHAR活性提高AsA-GSH循环效率,降低盐碱胁迫对裸燕麦的氧化伤害。     

The chloroplast pigments of the algal classes Eustigmatophyceae and Xanthophyceae. II. Xanthophyceae

The chloroplast pigments of Pleurochloris meiringensis Vischer, Mischococcus sphaerocephalus Vischer and Tribonema aequale Pascher have been analysed by a variety of chromatographic methods. There are significant differences between these xanthophycean algae and the eustigmatophycean algae formerly classified with them. In particular the former contain diadinoxanthin as the major xanthophyll whereas diadinoxanthin is absent from the latter and violaxanthin occurs as the major xanthophyll pigment. The other pigments of the Xanthophyceae sensu stricto include chlorophyll a, β-carotene, vaucheriaxanthin-ester, heteroxanthin, diatoxanthin, cryptoxanthin epoxide and a neoxanthin-like pigment.     

过表达AtchyB基因提高洋桔梗光胁迫耐受性的研究

类胡萝卜素尤其是叶黄素循环类物质在植物抵抗由强光照引起的非生物胁迫中发挥着重要的作用,为了提高洋桔梗对强光照的抗性,从拟南芥中克隆了类胡萝卜素生物合成途径中参与叶黄素循环关键酶——β-胡萝卜素羟化酶基因(AtchyB),利用农杆菌介导法将其转入洋桔梗中,最终得到遗传转化植株2个株系,研究发现,转基因植株中总类胡萝卜素含量高于对照组,且叶黄素循环池被不同程度地放大。在不同光照强度下,转基因洋桔梗植株对光照耐受性明显强于对照组,且转基因植株生物量也明显提高。表明过表达AtchyB基因使洋桔梗光胁迫耐受性有所增强。     

Cooperative interaction between ascorbate and glutathione during mitochondrial impairment in mesencephalic cultures

A decrease in total glutathione, and aberrant mitochondrial bioenergetics have been implicated in the pathogenesis of Parkinson's disease. Our previous work exemplified the importance of glutathione (GSH) in the protection of mesencephalic neurons exposed to malonate, a reversible inhibitor of mitochondrial succinate dehydrogenase/complex II. Additionally, reactive oxygen species (ROS) generation was an early, contributing event in malonate toxicity. Protection by ascorbate was found to correlate with a stimulated increase in protein-glutathione mixed disulfide (Pr-SSG) levels. The present study further examined ascorbate-glutathione interactions during mitochondrial impairment. Depletion of GSH in mesencephalic cells with buthionine sulfoximine potentiated both the malonate-induced toxicity and generation of ROS as monitored by dichlorofluorescein diacetate (DCF) fluorescence. Ascorbate completely ameliorated the increase in DCF fluorescence and toxicity in normal and GSH-depleted cultures, suggesting that protection by ascorbate was due in part to upstream removal of free radicals. Ascorbate stimulated Pr-SSG formation during mitochondrial impairment in normal and GSH-depleted cultures to a similar extent when expressed as a proportion of total GSH incorporated into mixed disulfides. Malonate increased the efflux of GSH and GSSG over time in cultures treated for 4, 6 or 8 h. The addition of ascorbate to malonate-treated cells prevented the efflux of GSH, attenuated the efflux of GSSG and regulated the intracellular GSSG/GSH ratio. Maintenance of GSSG/GSH with ascorbate plus malonate was accompanied by a stimulation of Pr-SSG formation. These findings indicate that ascorbate contributes to the maintenance of GSSG/GSH status during oxidative stress through scavenging of radical species, attenuation of GSH efflux and redistribution of GSSG to the formation of mixed disulfides. It is speculated that these events are linked by glutaredoxin, an enzyme shown to contain both dehydroascorbate reductase as well as glutathione thioltransferase activities.     

外源NO对NaCl胁迫下黄瓜幼苗生长和根系谷胱甘肽抗氧化酶系统的影响

以津春2号黄瓜为材料,采用营养液水培的方法,研究了外源一氧化氮(NO)对黄瓜幼苗生长和根系谷胱甘肽抗氧化酶系统的影响.结果表明,(1)正常生长条件下添加NO能促进黄瓜幼苗生长,而添加亚甲基蓝(MB-1)显著抑制黄瓜幼苗的生长;(2)添加NO显著缓解了NaCl胁迫对黄瓜幼苗生长的抑制,提高根系还原型谷胱甘肽(GSH)含量、抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)活性,而氧化型谷胱甘肽(GSSG)含量略有下降,同时缓解了NaCl胁迫下抗坏血酸(ASA)含量的下降幅度;(3)NaCl胁迫下添加NO的同时添加MB-1可部分解除NO的作用,与NaCl胁迫下单独添加NO处理比较,GR活性、GSH和ASA含量均降低,GSSG含量提高,APX先升高后下降.研究发现,外源NO可能通过鸟苷酸环化酶(cGC)介导来调节NaCl胁迫下黄瓜幼苗根系GR活性和GSH、GSSG、ASA含量,提高抗氧化酶活性和非酶抗氧化物质含量,增强植株对活性氧的清除能力,减少膜脂过氧化,缓解NaCl胁迫对黄瓜幼苗造成的伤害.     

Oxidative stress in growth hormone transgenic coho salmon with compressed lifespan - a model for addressing aging

Abstract Growth hormone (GH) transgenic fish have dramatically enhanced growth rates, increased oxygen demands and reactive oxygen species production. GH-transgenic coho salmon provide an opportunity to address effects of increased metabolism on physiological aging. The objective of this study was to compare oxidative stress in wild-type (WT) and GH-transgenic (T) coho salmon (Oncorhynchus kisutch) of different ages (1 and 2 years). Antioxidant enzyme activity, protein carbonyls (PC) and glutathione (GSH, GSSG) were measured. PC correlated to growth rates in individual fish. T fish exhibited lower antioxidant enzyme activities and GSH levels compared to the WT, while levels of PC and GSSG were higher. Age affects were observed in both WT and T fish; enzyme activities and GSH decreased while PC and GSSG increased. Our results support the metabolic rate theory of aging. This study aims to be a platform for continued studies of the theories of aging using fish as model organisms.     

Dehydration-mediated activation of the xanthophyll cycle in darkness: is it related to desiccation tolerance?

The development of desiccation tolerance by vegetative tissues was an important step in the plants’ conquest of land. To counteract the oxidative stress generated under these conditions the xanthophyll cycle plays a key role. Recent reports have shown that desiccation itself induces de-epoxidation of xanthophyll cycle pigments, even in darkness. The aim of the present work was to study whether this trait is a common response of all desiccation-tolerant plants. The xanthophyll cycle activity and the maximal photochemical efficiency of PS II (F _v/F _m) as well as β-carotene and α-tocopherol contents were compared during slow and rapid desiccation and subsequent rehydration in six species pairs (with one desiccation-sensitive and one desiccation-tolerant species each) belonging to different taxa. Xanthophyll cycle pigments were de-epoxidised in darkness concomitantly with a decrease in F _v/F _m during slow dehydration in all the desiccation-tolerant species and in most of the desiccation-sensitive ones. De-epoxidation was reverted in darkness by re-watering in parallel with the recovery of the initial F _v/F _m. The stability of the β-carotene pool confirmed that its hydroxylation did not contribute to zeaxanthin formation. The α-tocopherol content of most of the species did not change during dehydration. Because it is a common mechanism present in all the desiccation-tolerant taxa and in some desiccation-sensitive species, and considering its role in antioxidant processes and in excess energy dissipation, the induction of the de-epoxidation of xanthophyll cycle pigments upon dehydration in the dark could be understood as a desiccation tolerance-related response maintained from the ancestral clades in the initial steps of land occupation by plants.