Genetic Diversity Caused by Environmental Stress in Natural Populations of Niupidujuan as Revealed by RAPD Technique

Multiplex environmental factors are generally expected to have significant effects on genetic diversity of plant populations.In this study,randomly amplified polymorphic DNA（RAPD） technique was used to reveal the genetic diversity in the same species of four populations collected from Niupidujuan（Rhododendron chrysanthum） at different altitudes,an endangered species,endemic to Northeast China.Initially,twenty informative and reproducible primers were chosen for final RAPD analysis.A total of 152 clear bands were obtained,including 143 polymorphic ones.With the help of POPGENE software,the poly rate was calculated to be 94.07% and the evenness of amplified bands for every primer was 6.8.Additionally,the mean observed number of alleles was 1.7265 with an effective number of 1.3608.An examination of the gene indicated a diversity of 0.2162 with an information diversity index of 0.3313.For these data,the clustering blurred analysis was performed with the aid of NTSYS-pc software to define the Nei＇s gene diversity and the Shannon information diversity index of the four plant populations.The relationships between the genetic diversity indexes on the one hand and the geographic and climatic factors on the other hand were estimated by the Pearson correlation with SPSS 11.0 software.The results of the correlation analysis show that there were significant（P〈0.05） or highly significant（P〈0.01） correlations between each of the genetic diversity indexes and the different temperature which were mainly caused by the altitude different populations located.These data highlight the importance of native populations in shaping the spatial genetic structure in Niupidujuan.

Temporal species distributions of planktonic protist communities in semi-enclosed mariculture waters and responses to environmental stress

In order to evaluate the relationships between temporal species succession of planktonic protists and physical-chemical parameters in semi-enclosed mariculture waters, species distributions in response to environmental stress were investigated in a shrimp-farming pond near Qingdao, China during a complete shrimp-culture cycle （May to October 2002）. A clear temporal succession in species distribution was found over the complete farming cycle. For example, before the introduction of the shrimp larvae there was low-variability of species distribution in the protist communities whereas during the stages immediately after, there was higher variability in species composition. Multiple linear/logistic regression analyses demonstrate that 12 protist taxa （e.g., Gyrodinium spirale, Teleaulax acuta, Prorocentrum spp. and Mesodinium pupula） were related to the nutrients, in particular ammonia and phosphates, alone or in combination with water temperature. These results suggest that temporal variations in species distribution of planktonic protist communities might be used in assessing water quality of semi-enclosed mariculture waters.

Sap flow response of Eucaylyptus (Eucalyptus urophylla) to environmental stress in South China

Sap flow and environmental conditions were monitored at two Eucalyptus (Eucalyptus urophylla S.T.Blake) plantations at Hetou and Jijia, located in Leizhou, Zhanjiang, Guangdong Province. It was found that daily sap flux density (SFD) of Eucalyptus was closely related to daily atmospheric vapor pressure deficit (VPD) (R2=0.76, P=0.01 at Hetou and R2=0.7021, P=0.01 at Jijia) at both sites. No significant relationship existed between daily SFD and mean daily air temperature at both sites. Daily SFD varied with wind speed Y=-17585X3+15147X2-1250.7X+2278.4 (R2=0.68; P=0.01) at Hetou and Y=-101.67X3-1.65X2-376.4X+1914.8 (R2=0.40,P=0.05) at Jijia, where Y was daily SFD,X was daily wind speed. Experimental observations yielded the following data: (1) the critical lower and upper daily VPD threshold were 0 and 2 kPa, within which daily SFD varied from 540±70 L/(m2·d) to 4739±115 L/(m2·d) at Hetou site, from 397±26 L/(m2·d) to 3414±191 L/(m2·d) at Jijia site; (2) Diurnal SFDs at Hetou site were much higher under low relative humidity (<30%) and slightly lower under high relative humidity (>%) compared with those at the Jijia site; (3) The upper and lower threshold of daily and diurnal RAD for the optimal water use of E. urophylla plantations were 18±2.7 and 2±1 MJ/(m2·d), 669 and 0 J/(cm2·h) during the observation period.

Contributions of aversive environmental stress to migraine chronification:Research update of migraine pathophysiology

Clinical studies have suggested that internal and/or external aversive cues may produce a negative affective-motivational component whereby maladaptive responses(plasticity)of dural afferent neurons are initiated contributing to migraine chronification.However,pathophysiological processes and neural circuitry involved in aversion(unpleasantness)-producing migraine chronification are still evolving.An interdisciplinary team conducted this narrative review aimed at reviewing neuronal plasticity for developing migraine chronicity and its relevant neurocircuits and providing the most cutting-edge information on neuronal mechanisms involved in the processing of affective aspects of pain and the role of unpleasantness evoked by internal and/or external cues in facilitating the chronification process of migraine headache.Thus,information presented in this review promotes the understanding of the pathophysiology of chronic migraine and contribution of unpleasantness(aversion)to migraine chronification.We hope that it will bring clinicians’attention to how the maladaptive neuroplasticity of the emotion brain in the aversive environment produces a significant impact on the chronification of migraine headache,which will in turn lead to new therapeutic strategies for this type of pain.

Research Progress on Lonicera japonica Thunb.Affected by Environmental Stress

Lonicera japonica Thunb.is widely distributed in China.It has strong adaptability to the environment and can maintain normal growth and development under a variety of stress conditions.It is commonly used as a medicine with its dry flower buds or newly opened flowers,named honeysuckle,and with both economic value and ecological application value.The research progress of L.japonica Thunb.under stress conditions such as temperature,drought,light,salt,heavy metals and diseases,pests and endophytic bacteria was reviewed,and the current research situation of the physiological and biochemical response mechanism,changes of photosynthetic fluorescence and accumulation of secondary metabolites of honeysuckle under different stresses was discussed,so as to provide a reference for deep-level exploring the resistance mechanism of L.japonica Thunb.in the future and lay a theoretical foundation for the high-quality authentic ecological cultivation of L.japonica Thunb.

The Role of Environmental Stress in Determining Gut Microbiome:Case Study of Two Sympatric Toad-headed Lizards

The gut microbiota has gained attention because of its importance in facilitating host survival and evolution.However,it is unclear whether gut microbial communities are determined by the host(heritable factor) or environment(environmental factor).In this study,we investigated the gut microbial communities and potential functional signatures of two sympatric species distributed along an elevation gradient,the toadheaded lizards Phrynocephalus axillaris and P.forsythii.Our results indicated that at high elevations,the gut microbial communities of P.axillaris and P.forsythii did not significantly differ,and the phylogenetic relationships of gut microbial communities contradicted their hosts.At low altitudes,the two lizards could be distinguished based on their significantly different gut microbial communities.Compared to low-altitude populations,Kyoto Encyclopedia of Genes and Genomes(KEGG)pathway analysis showed that at higher altitudes,energy metabolism,such as carbohydrate,lipid,and amino acids metabolism were higher in both lizards.While a larger number of pathogenic bacteria were found in the lowaltitude population of P.forsythii.This suggests that the convergence of gut microbiota of two lizards at highaltitude stem from environmental factors,as they were exposed to the same environmental stress,whereas the divergence at low-altitude stemmed from heritable factors,as they were exposed to different environmental stresses.These results provide a new perspective regarding whether heritable or environmental factors dominate the gut microbiota during exposure to environmental stress.

Observation of Cell-Size Variation under Environmental Stress by Fluorescence Correlation Spectroscopy without Objective Image Magnification

Fluorescence correlation spectroscopy （FCS） without objective image magnification （without using con-focal microscope） was applied to observe the variation in cell size of Escherichia coli （E. coli） induced by the anti-cancer agent MitomycinC （MMC）. In the system without image magnification followed in this study, the suspension of E. coli cells was stirred, and the difference in movement due to the different cell sizes induced by the compulsive solution flow was detected. The addition of 0.1-0.4 pg/L of MMC elongated the E. coli cell length from about 3.6 to 7.8μm. The flow cell （i.d. = about 1 mm） also produced a size-dependent correlation curve, The present system is not based on single molecular FCS but is inexpensive and effective at observing the variation in cell size induced by environmental changes.

Body color plasticity of Diaphorina citri reflects a response to environmental stress

Body color polyphenism is common in Diaphorina citri.Previous studies compared physiological characteristics in D.citri,but the ecological and biological significance of its body color polyphenism remains poorly understood.We studied the ecological and molecular effects of stressors related to body color in D.citri.Crowding or low temperature induced a high proportion of gray morphs,which had smaller bodies,lower body weight,and greater susceptibility to the insecticide dinotefuran.We performed transcriptomic and metabolomics analysis of 2 color morphs in D.citri.Gene expression dynamics revealed that the differentially expressed genes were predominantly involved in energy metabolism,including fatty acid metabolism,amino acid metabolism,and carbohydrate metabolism.Among these genes,plexin,glycosidase,phospholipase,take out,trypsin,and triacylglycerol lipase were differentially expressed in 2 color morphs,and 6 hsps(3 hsp70,hsp83,hsp90,hsp68)were upregulated in gray morphs.The metabolome data showed that blue morphs exhibited a higher abundance of fatty acid and amino acid,whereas the content of carbohydrates was elevated in gray morphs.This study partly explains the body color polyphenism of D.citri and provides insights into the molecular changes of stress response of D.citri.

The effect of abiotic stresses on plant C:N:P homeostasis and their mitigation by silicon

In crop plants, various environmental stresses affect the balance of carbon, nitrogen, and phosphorus(C:N:P), leading to biochemical and physiological alterations and reductions in yield. Silicon(Si) is a beneficial element that alleviates plant stress. Most studies involving silicon have focused on physiological responses, such as improvements in photosynthetic processes, water use efficiency, and antioxidant defense systems. But recent research suggests that stressed plants facing either limited or excessive resources(water, light, nutrients, and toxic elements), strategically employ Si to maintain C:N:P homeostasis, thereby minimizing biomass losses. Understanding the role of Si in mitigating the impact of abiotic stresses on plants by regulating C:N:P homeostasis holds great potential for advancing sustainable agricultural practices in crop production. This review presents recent advances in characterizing the influence of environmental stresses on C:N:P homeostasis, as well as the role of Si in preserving C:N:P equilibrium and attenuating biological damage associated with abiotic stress. It underscores the beneficial effects of Si in sustaining C:N:P homeostasis and increasing yield via improved nutritional efficiency and stress mitigation.

Analyzing Environmental Stress Counter-measures in Agricultural Heritage Sites in China

In recent years, with climate change, many agricultural systems are facing severe environmental stress, which are seriously threatening the food security and sustainable development of agricultural system. Although mainstream agro-system can effectively reduce the adverse agro-production effect rapidly by using modern technology, but many of them bring serious ecological crisis at the same time. For the sustainable development of agro-systems, the stress mitigation options must give full consideration to ecological protection. The Globally Important Agricultural Heritage Systems （GIAHS） sites, relying on its unique land use, water conservancy facilities, traditional crops, etc., form unique production system creating a better match with local natural conditions. Based on disaster mitigation system theory and practice, this paper analyzes environmental stress counter-measures of several GIAHS sites in China. The water requirement of milet, a drought-tolerant crop in Aohan Dryland Farming System （recognized as a GIAHS pilot site in 2012）, has a better match with local water conditions. By reducing vulnerability of crops, agriculture survived healthily in semi-arid regions. Honghe Hani Rice Terraces System （recognized as a GIAHS pilot site in 2010）, relying on the unique land and water use patterns, has successfully reshape disaster inducing environment, and effectively reduce the risk/effects of droughts. Besides, due to the high price, rich crop diversity and variety of income channel, the Agricultural Heritage sites can ensure the economic income and agro-system health when facing environmental stress. Stress counter-measures of traditional agricultural systems make full use of the regulation and spontaneity ability of the natural system, which is an important way to achieve sustainable development of ecological agriculture.

Diverse Transcriptional Programs Associated with Environmental Stress and Hormones in the Arabidopsis Receptor-Like Kinase Gene Family

The genome ofArabidopsis thaliana encodes more than 600 receptor-like kinase （RLK） genes, by far the dominant class of receptors found in land plants. Although similar to the mammalian receptor tyrosine kinases, plant RLKs are serine/threonine kinases that represent a novel signaling innovation unique to plants and, consequently, an excellent opportunity to understand how extracellular signaling evolved and functions in plants as opposed to animals. RLKs are predicted to be major components of the signaling pathways that allow plants to respond to environmental and developmental conditions. However, breakthroughs in identifying these processes have been limited to only a handful of individual RLKs. Here, we used a Syngenta custom Arabidopsis GeneChip array to compile a detailed profile of the tran- scriptional activity of 604 receptor-like kinase genes after exposure to a cross-section of known signaling factors in plants, including abiotic stresses, biotic stresses, and hormones. In the 68 experiments comprising the study, we found that 582 of the 604 RLK genes displayed a two-fold or greater change in expression to at least one of 12 types of treatments, thereby providing a large body of experimental evidence for targeted functional screens of individual RLK genes. We investigated whether particular subfamilies of RLK genes are responsive to specific types of signals and found that each subfamily displayed broad ranges of expression, as opposed to being targeted towards particular signal classes. Finally, by analyzing the divergence of sequence and gene expression among the RLK subfamilies, we present evidence as to the functional basis for the expansion of the RLKs and how this expansion may have affected conservation and divergences in their function. Taken as a whole, our study represents a preliminary, working model of processes and interactions in which the members of the RLK gene family may be involved, where such information has remained elusive for so many of its members.

Environmental Stresses Modulate Abundance and Timing of Alternatively Spliced Circadian Transcripts in Arabidopsis

Environmental stresses profoundly altered accumulation of nonsense mRNAs including intron-retaining （IR） transcripts in Arabidopsis. Temporal patterns of stress-induced IR mRNAs were dissected using both oscillating and non-oscillating transcripts. Broad-range thermal cycles triggered a sharp increase in the long IR CCA1 isoforms and altered their phasing to different times of day. Both abiotic and biotic stresses such as drought or Pseudomonas syringae infection induced a similar increase. Thermal stress induced a time delay in accumulation of CCA1 14Rb transcripts, whereas functional mRNA showed steady oscillations. Our data favor a hypothesis that stress-induced instabilities of the central oscillator can be in part compensated through fluctuations in abundance and out-of-phase oscillations of CCA1 IR transcripts. Taken together, our results support a concept that mRNA abundance can be modulated through altering ratios between functional and nonsense/IR transcripts. SR45 protein specifically bound to the retained CCA1 intron in vitro, suggesting that this sp!icing factor could be involved in regulation of intron retention. Transcriptomes of nonsense-mediated mRNA decay （NMD）-impaired and heat-stressed plants shared a set of retained introns associated with stress- and defense-inducible transcripts. Constitutive activation of certain stress response networks in an NMD mutant could be linked to disequilibrium between functional and nonsense mRNAs.

Chromatin remodeling factors regulate environmental stress responses in plants

Environmental stress from climate change and agricultural activity threatens global plant biodiversity as well as crop yield and quality.As sessile organisms,plants must maintain the integrity of their genomes and adjust gene expression to adapt to various environmental changes.In eukaryotes,nucleosomes are the basic unit of chromatin around which genomic DNA is packaged by condensation.To enable dynamic access to packaged DNA,eukaryotes have evolved Snf2(sucrose nonfermenting 2)family proteins as chromatin remodeling factors(CHRs)that modulate the position of nucleosomes on chromatin.During plant stress responses,CHRs are recruited to specific genomic loci,where they regulate the distribution or composition of nucleosomes,which in turn alters the accessibility of these loci to general transcription or DNA damage repair machinery.Moreover,CHRs interplay with other epigenetic mechanisms,including DNA methylation,histone modifications,and deposition of histone variants.CHRs are also involved in RNA processing at the posttranscriptional level.In this review,we discuss major advances in our understanding of the mechanisms by which CHRs function during plants’response to environmental stress.

Environmental stress level evaluation approach based on physical model and interval grey association degree

Associating environmental stresses （ESs） with built-in test （BIT） output is an important means to help diagnose intermittent faults （IFs）. Aiming at low efficiency in association of traditional time stress measurement device （TSMD）, an association model is built. Thereafter, a novel approach is given to evaluate the integrated environmental stress （IES） level. Firstly, the selection principle and approach of main environmental stresses （MESs） and key characteristic parameters （KCPs） are presented based on fault mode, mechanism, and ESs analysis （FMMEA）. Secondly, reference stress events （RSEs） are constructed by dividing IES into three stress levels according to its impact on faults; and then the association model between integrated environmental stress event （IESE） and BIT output is built. Thirdly, an interval grey association approach to evaluate IES level is proposed due to the interval number of IES value. Consequently, the association output can be obtained as well. Finally, a case study is presented to demonstrate the proposed approach. Results show the proposed model and approach are effective and feasible. This approach can be used to guide ESs measure, record, and association. It is well suited for on-line assistant diagnosis of faults, especially IFs.

Real-time cell analysis and heat shock protein gene expression in the TcA Tribofium castaneum cell line in response to environmental stress conditions

The rust red flour beetle, Tribolium castaneum （Herbst, 1797） （Coleoptera： Tenebrionidae）, is a pest of stored grain and one of the most studied insect model species. Some of the previous studies involved heat response studies in terms of survival and heat shock protein expression, which are regulated to protect other proteins against environ- mental stress conditions. In the present study, we characterize the impedance profile with the xCELLigence Real-Time Cell Analyzer and study the effect of increased temperature in cell growth and viability in the cell line BCIRL-TcA-CLG 1 （TcA） of T castaneum. This novel system measures cells behavior in real time and is applied for the first time to insect cells. Additionally, cells are exposed to heat shock, increased salinity, acidic pH and UV-A light with the aim of measuring the expression levels of lisp27, Hsp68a, and Hsp83 genes. Results show a high thermotolerance of TeA in terms of cell growth and viability. This result is likely related to gene expression results in which a significant up-regulation of all studied Hsp genes is observed after 1 h of exposure to 40 ~C and UV light. All 3 genes show similar expression patterns, but Hsp27 seems to be the most affected. The results of this study validate the RTCA method and reveal the utility of insect cell lines, real-time analysis and gene expression studies to better understand the physiological response of insect cells, with potential applications in different fields of biology such as conservation biology and pest management.

Resistance mechanisms and reprogramming of microorganisms for efficient biorefinery under multiple environmental stresses

In the fermentation process of biorefinery,industrial strains are normally subjected to adverse environmental stresses,which leads to their slow growth,yield decline,a substantial increase in energy consumption,and other negative consequences,which ultimately seriously hamper the development of biorefinery.How to minimize the impact of stress on microorganisms is of great significance.This review not only reveals the damaging effects of different environmental stresses on microbial strains but also introduces commonly used strategies to improve microbial tolerance,including adaptive evolution,reprogramming of the industrial host based on genetic circuits,global transcription machinery engineering(gTME)and bioprocess integration.Furthermore,by integrating the advantages of these strategies and reducing the cost of system operation,the tolerance of industrial strains,combined with production efficiency and process stability,will be greatly improved,and the development prospects of biorefinery will be more widespread.

Overview of yeast environmental stress response pathways and the development of tolerant yeasts

Yeast is widely used for industrial production of various types of products,such as ethanol and enzymes.However,its fermentation efficiency is strongly reduced by harmful environmental stresses.Specifically,harmful environmental stresses damage important cellular components,such as cell wall,cell membrane,proteins,etc.Then,these damages cause cellular metabolic disorders or even death.In the past decades,there has been a portfolio of studies on the environmental stress tolerance of yeasts,which mainly aimed at cell damages caused by different environmental stresses,different ways to improve yeast environmental stress tolerance or a tolerance mechanism for certain environmental stress.However,a comprehensive overview of how yeasts respond to environmental stresses is lacking,and the correlation of tolerance mechanism between different environmental stresses is unclear.In this review,we summarized the general damages induced by most of environmental stresses,the existing major mechanisms of environmental stress tolerance from the perspective of key signalling pathways,and the common ways to improve the resistance to environmental stresses in yeast cells.The tolerance mechanisms of yeast cells to different environmental stresses are diverse,but sometimes they share the same signalling pathway.Cells use sensors on the cell surface to recognize environmental stresses and transmit signals to the nucleus to cause changes in gene expression.By summarizing the main signalling pathways,including MAPK pathway,cAMP/PKA pathway,YAP1/SKN7 pathway,it will provide a powerful reference for future efforts to promote yeast environmental stress tolerance and study yeast tolerance mechanisms.

Cu(Ⅱ), Fe(Ⅲ) and Mn(Ⅱ) combinations as environmental stress factors have distinguishing effects on Enterococcus hirae

Pollution by various heavy metals as environmental stress factors might affect bacteria. It was established that iron（Fe（Ⅲ））, manganese（Mn（Ⅱ）） and copper（Cu（Ⅱ）） ion combinations caused effects on Enterococcus hirae that differed from the sum of the effects when the metals were added separately. It was shown that the Cu2＋–Fe3＋combination decreased the growth and ATPase activity of membrane vesicles of wild-type E. hirae ATCC9790 and atp D mutant（with defective FoF1-ATPase） MS116. Addition of Mn2＋–Fe3＋combinations within the same concentration range had no effects on growth compared to control（without heavy metals）. ATPase activity was increased in the presence of Mn2＋–Fe3＋, while together with0.2 mmol/L N,N′-dicyclohexylcarbodiimide（DCCD）, ATPase activity was decreased compared to control（when only 0.2 mmol/L DCCD was present）. These results indicate that heavy metals ion combinations probably affect the FOF1-ATPase, leading to conformational changes. Moreover the action may be direct or be mediated by environment redox potential.The effects observed when Fe3＋was added separately disappeared in both cases, which might be a result of competing processes between Fe3＋and other heavy metals. These findings are novel and improve the understanding of heavy metals ions effects on bacteria,and could be applied for regulation of stress response patterns in the environment.

Lipidomics in archaeal membrane adaptation to environmental stresses and growth conditions:A review of culture-based physiological studies

Membrane lipids are thought to be a crucial part of the homeoviscous adaptation of archaea to extreme conditions.This article reviews the recent lipidomic studies of physiological membrane adaptations of archaea,assesses the biomolecular basis of an organic paleothermometer,TEX86,and contemplates the future directions of archaeal lipidomics.The studies of extremophilic archaea have revealed that at least three different molecular mechanisms are involved in membrane adaptation of archaea:(1)regulation of the number of cyclopentane rings of caldarchaeol,(2)alteration of the diether-to-tetraether lipid ratio,and(3)variation of the proportion of saturated and unsaturated lipids.However,most of the studies have focused on a limited number of archaeal ether-linked lipids,such as glycerol dialkyl glycerol tetraethers(GDGTs),which only represent a fraction of the entire lipidome.Environmental factors such as growth temperature and pH have been most frequently reported,but biotic factors,including growth phases,nutrition,and enzymatic activities affecting the membrane lipid composition are often overlooked.Membrane lipids of mesophilic ammonia-oxidizing marine Thaumarchaeota have been applied in the reconstruction of past sea surface temperatures.However,recent culture-based physiological studies have demonstrated that non-thermal biotic factors,including dissolved oxygen,ammonia oxidation rate and the growth rate,are the main drivers of GDGT cyclization in Nitrosopumilus maritimus.Moreover,other related strains or ecotypes exhibit a markedly different set of stress adaptations.A trend is now developing to examine the whole lipid profile(lipidome)for studies of archaeal physiology and biochemistry related to lipid biosynthesis(lipidomics)to gain a better understanding of the biological mechanisms underpinning the applications of membrane lipid-based proxies in biogeochemical or ecological research.

Role of oxidative stress on growth responses of spring barley exposed to different environmental stressors

Aims oxidative stress is one of the most important mechanisms in a plant’s reaction to the effects of different stressors;however,its role in plants’resistance is still poorly understood.The objective of this study is to evaluate an influence of oxidative stress induced by stress factors of different origin-ozone,ultraviolet(uV)-b radia-tion,drought,cadmium(Cd)and copper(Cu),to growth of spring barley and to check the hypothesis,that intensification of oxidative stress is the main factor of growth depression induced by strong treatments of different stressors;meanwhile,mitigation of oxidative stress determines eustress-induced growth stimulation.Methods a pot experiment was carried out in phytotron chambers with a controlled environment.spring barley(Hordeum vulgare l.)plants were exposed to different doses of investigated environmental stress factors(O_(3),uV-b radiation,drought,Cd and Cu),and their effects on shoots growth,accumulation of superoxide(O_(2)^(˙−)),intensification of lipid peroxidation and antioxidative protection(superoxide dismutase,glutathione reductase and catalase activi-ties and concentration of carotenoids)were measured.analysis of variance(aNoVa)with classical eta-squared(η2)values was used to evaluate and to compare the contribution of non-specific oxi-dative stress and stressor-specific mechanisms on plants growth.Important Findingslow doses of most stressors stimulated antioxidative protection and growth of barley shoots,reduced the concentration of o2˙−and/or intensity of lipid peroxidation.Whereas an impair-ment of growth and intensification of oxidative stress as well as a reduction in concentration of carotenoids and further increase in activity of antioxidative enzymes were noticed when the intensity of the stressors was increased.In the cases of ozone and uV-b stress,the effects of oxidative stress on plant growth was mitigated by strong antioxidative protection-highly increased catalase(CaT)and superoxide dismutase(SOD)activities,respectively.In the cases of drought and Cu,relatively strong oxidative stress was the major cause of plant growth depression.additionally,mitigation of oxidative stress due to increased SOD activity was likely to be one of the main causes of growth stimulation induced by low doses of uV-b,Cd and Cu stress.Possible reasons for o3-induced growth stimulation were increased CaT activity and concentration of carotenoids.generalizing the effects of different stressors,the contribution of non-specific oxidative stress on plant growth was stronger com-pared with stressor-specific action mechanisms:oxidative stress determined 42%of the changes in plants’dry biomass,whereas the contribution of stressor-specific mechanisms accounted for 35% of variability in barley growth.