Effect of Alkyl Hydroxybenzenes on Malting Processes

It has been shown that one of the alkyl hydroxybenzenes, C₇-AHB, can be used in malting for regulating barley growth. Depending on concentration (0.01–1.0%) and duration (from 10 min to 6 h), treatment of barley with a C₇-AHB solution stimulates embryo development (0.01–0.02%) or suppresses the growth of vegetative organs (>0.5%) and modulates enzyme activities in germinating grains. Stimulation of the activities of the amylolytic and protein–proteinase complexes in barley depending on the C₇-AHB concentration improves malt quality by increasing both the degree of its saccharification and protein dissolution.     

Regulatory effect of microbial alkyloxybenzenes of different structure on the stress response of yeast

The effect of alkyloxybenzenes (AHBs) belonging to the class of alkylresorcinols differing in the degree of hydrophobicity--C7-AHB and more hydrophobic Cl12-AHB--on the resistance of Saccharomyces cerevisiae cells to heat shock and oxidative stress of lethal intensity was studied. Depending on structure and concentration, AHB added 2 h before exposure to stress had either an antistress or stress-potentiating effect on yeast cells in the mid-logarithmic growth phase. C7-AHB at concentrations 0.25-0.5 g/l caused a two- to fivefold increase in the resistance of yeast cells to hydrogen peroxide (30-150 mM), whereas Cl2-AHB reduced it at all concentrations. C7-AHB and Cl2-AHB had a similar effect on yeast subjected to heat shock (45 degrees C, 30 min). It was found that the degree of the protective effect of C7-AHB and potentiating effect of Cl2-AHB depended on the nature of the stressor, being more pronounced in heat shock. The environmental significance of the antistress and stress-potentiating effects of microbial AHBs is discussed.     

Regulatory effect of microbial alkyloxybenzenes of different structure on the stress response of yeast

The effect of alkylhydroxybenzenes (AHBs) belonging to the class of alkylresorcinols differing in the degree of hydrophobicity—C7-AHB and more hydrophobic C12-AHB—on the resistance of Saccharomyces cerevisiae cells to heat shock and oxidative stress of lethal intensity was studied. Depending on structure and concentration, AHB added 2 h before exposure to stress had either an antistress or stress-potentiating effect on yeast cells in the mid-logarithmic growth phase. C7-AHB at concentrations 0.25–0.5 g/l caused a two-to fivefold increase in the resistance of yeast cells to hydrogen peroxide (30–150 mM), whereas C12-AHB reduced it at all concentrations. C7-AHB and C12-AHB had a similar effect on yeast subjected to heat shock (45°C, 30 min). It was found that the degree of the protective effect of C7-AHB and potentiating effect of C12-AHB depended on the nature of the stressor, being more pronounced in heat shock. The environmental significance of the antistress and stress-potentiating effects of microbial AHBs is discussed.     

Enzyme modification by natural chemical chaperons of microorganisms

We demonstrated for the first time that alkylhydroxybenzenes (the d1 microbial autoregulatory factors involved in stress responses of cells) are capable of stabilizing enzymes in aqueous media and increasing their catalytic activity. The stabilizing effect of a chemical analogue of alkylhydroxybenzenes, C7-AHB, was established in in vitro studies with enzymes of microbial origin: a protease produced by Bacillus licheniformis, cellulase produced by Trichoderma viride, and alpha-amylase produced by Bacillus subtilis. This effect manifested itself in considerable extension of the temperature and pH ranges of the enzymatic activity. The modulation of the catalytic activities of the stabilized enzymes depended on the C7-AHB concentration and on the time of preincubation of the complexes obtained. We demonstrated that not only enzymes but also their polymeric substrates formed complexes with C7-AHB, and this also significantly influenced the efficiency of hydrolytic reactions. We also conducted comparative studies on the efficiency of hydrolytic reactions in systems in which the structure of enzymes and/or substrates was modified with C7-AHB.     

Protection of Saccharomyces cerevisiae against oxidative and radiation-caused damage by alkyl hydroxybenzenes

The effects of C7-alkylhydroxybenzene (C7-AHB) and p-hydroxyethylphenol (tyrosol), chemical analogs of microbial anabiosis autoregulators, on the viability of yeast cells under oxidative stress were investigated. The stress was caused by reactive oxygen species (ROS) produced under gamma irradiation of cell suspensions using doses of 10-150 krad at an intensity of 194 rad/s or by singlet oxygen generated in cells photosensibilized with chlorin e6 (10 micrograms/l). C7-AHB was found to exert a protective effect. The addition of 0.05-0.16 vol% of C7-AHB to cell suspensions 30 min before irradiation protected yeast cells from gamma radiation (50 krad). The protective effect of C7-AHB manifested itself both in the preservation of cell viability during irradiation and in the recovery of their capacity to proliferate after irradiation. In our studies on photodynamic cell inactivation, the fact that the phenolic antioxidant C7-AHB protects cells from intracellular singlet oxygen was revealed for the first time. The analysis of difference absorption spectra of oxidized derivatives of C7-AHB demonstrated that the protective mechanism of C7-AHB involves the scavenging of ROS resulting from oxidative stress. The fact that tyrosol failed to perform a photoprotective function suggests that the antioxidant properties of microbial C7-AHB are not related to their chaperon functions. The results obtained make an important addition to the spectrum of known antioxidant and antistress effects of phenolic compounds.     

Regulation of the functional activity of lysozyme by alkylhydroxybenzenes

In our study, we investigated the capacity of alkylhydroxybenzenes (AHB), which are microbial anabiosis autoinducers, for alteration of the enzymatic activity of the hen egg-white lysozyme, as well as the efficiency of hydrolysis of specific (peptidoglycan) and nonspecific (chitin) substrates catalyzed by lysozyme. AHB homologues (C7-AHB and C12-AHB), which differ in their hydrophobicity and effects in their interaction with lysozyme, were used as modifying agents. C7-AHB stimulated enzymatic activity within the whole range of concentrations used (10^?7?10^?3 M). More hydrophobic C12-AHB exhibited this ability only at low concentrations and inhibited fermentative activity at high concentrations, acting as a mixed-type inhibitor. Both AHB homologues caused changes in the hydrophobicity of lysozyme molecules. An increase in the affinity level between the C7-AHB-modified enzyme and the nonspecific substrate (colloidal chitin or cell wall polymers of Saccharomyces sp.) was observed, which manifested itself in the enhancement of the hydrolysis rate by 200–500% (as compared to the native enzyme). A significant effect on the efficiency of the lysozyme-catalyzed modifications of the substrate (peptidoglycan, colloidal chitin) structure as a result of its complexation with AHB was demonstrated. A stabilizing effect of C7-AHB and C12-AHB was revealed, which ensured a high level of activity of the AHB-modified enzyme (as compared to the control) after heat treatment (functional stability), as well as at nonoptimal temperatures of catalysis (operational stability). The biological significance of lysozyme modification with AHB and the practical aspects of its application are discussed.     

Enzyme Modification by Natural Chemical Chaperons of Microorganisms

We demonstrated for the first time that alkyl hydroxybenzenes (the d₁ microbial autoregulatory factors involved in stress responses of cells) are capable of stabilizing enzymes in aqueous media and increasing their catalytic activity. The stabilizing effect of a chemical analogue of alkyl hydroxybenzenes, C₇-AHB, was established in in vitro studies with enzymes of microbial origin: a protease produced by Bacillus licheniformis, cellulase produced by Trichoderma viride, and -amylase produced by Bacillus subtilis. This effect manifested itself in considerable extension of the temperature and pH ranges of the enzymatic activity. The modulation of the catalytic activities of the stabilized enzymes depended on the C₇-AHB concentration and on the time of preincubation of the complexes obtained. We demonstrated that not only enzymes but also their polymeric substrates formed complexes with C₇-AHB and this significantly influenced the efficiency of hydrolytic reactions. We also conducted comparative studies on the efficiency of hydrolytic reactions in systems in which the structure of enzymes and/or substrates was modified with C₇-AHB.     

Role of alkylhydroxybenzenes in bacterial adaptation to unfavorable growth conditions

The adaptogenic effect of the chemical analogues of alkylhydroxybenzenes (AHBs), bacterial extracellular autoregulators (the individual compound C7-AHB and its technical preparation Sidovit), was demonstrated for two pseudomonad species, Pseudomonas aeruginosa and P. fluorescens. The protective effect of AHBs resulted in increased growth rate and biomass accumulation in bacteria grown under suboptimal conditions within the species tolerance range. The adaptogenic effect of AHBs (10–50 μmg/l) was more pronounced under more unfavorable growth conditions. In the case of P. fluorescens, the individual compound C7-AHB increased the biomass yield by 30% under alkaline conditions (pH 9.5), when the growth rate decreased by 80–90% compared to the optimum (pH 5.5–7.5). The Sidovit preparation, containing a mixture of natural AHBs with C7-AHB as the main component, increased the growth rate of P. aeruginosa by 40–60% at nonoptimal temperatures (45 and 10°C) or under enhanced salinity (1% NaCl). The action of AHBs as regulators of the rpoS and SOS response stress regulons was demonstrated to be among the mechanisms of their adaptogenic effect, as was demonstrated with the relevant reporter genes in the model strains E. coli C600 thi, thr, leuΔ(pro-lac) with the osmE-lacZ and umuD-lacZ hybrid operons, respectively. AHBs are technologically and economically acceptable as adaptogenic supplements for bacterial preparations used in soil bioremediation and oil spillage removal under conditions unfavorable for microbial growth, including increased salinity, extreme pH, and fluctuating sub- or supraoptimal temperatures.     

Effect of alkylhydroxybenzenes, microbial anabiosis inducers, on the structural organization of Pseudomonas aurantiaca DNA and on phenotypic dissociation induction

We revealed a relationship between alkylhydroxybenzene (AHB)-induced changes in the structural organization of supramolecular complexes (SC) of the DNA of Pseudomonas auraniaca and the phenotypic dissociation of this bacterium. The addition of 0.1-0.3 mM hexylresorcinol (C6-AHB), a chemical analogue of microbial anabiosis autoinducers, caused the formation of cystlike refractile cells (CRC) in these gram-negative, nonsporulating bacteria. Inoculating pseudomonad CRC on solid nutrient media resulted in phenotypic dissociation of the microbial population that yielded several variants with different colony structure and morphology. This manifested itself in the conversion of the original S-colony-forming phenotype into the R form and in the formation of less pigmented colonies. These transitions were possibly linked to AHB-induced structural changes in the DNA. In vitro studies revealed that AHB could interact with DNA SC, resulting in their structural modification that manifested itself in changes in their elastoviscosity. DNA supramolecular complexes isolated from proliferating, stationary-phase, and anabiotic P. aurantiaca cells differed in their elastoviscosity and capacity to interact with AHB homologues with different hydrophobicity, such as hexylresorcinol and methylresorcinol (C1-AHB). The DNA SC from actively proliferating cells were characterized by smaller elastoviscosity compared with those from stationary-phase and anabiotic cells, due to the difference in the DNA superspiralization degree and the physiological age of the bacteria involved. C6-AHB produced a pronounced relaxing effect on the DNA SC from exponential-phase P. aurantiaca cells. The less hydrophobic C1-AHB produced a similar effect on the DNA SC from stationary-phase cells. The curve of the dose-effect dependence of C6-AHB had a breaking point within the submillimolar (10(-4) M) concentration range. These concentrations induce the formation of cystlike anabiotic pseudomonad cells that are characterized by an unstable genotype and dissociate into distinct variants upon inoculation on solid media.     

Dormant state and phenotypic variability of Staphylococcus aureus and Corynebacterium pseudodiphtheriticum

Ability to produce dormant forms (DF) was demonstrated for non-spore-forming bacteria Staphylococcus aureus (a nonpathogenic strain) and Corynebacterium pseudodiphtheriticum (an organism of the normal oropharyngeal flora). The salient features of the sthaphylococcal and corynebacterial DF were (1) prolonged (4 months) preservation of viability; (2) resistance to damaging factors (heat treatment); and (3) specific morphology and ultrastructure. The optimal conditions for DF formation were (1) transfer of stationary-phase cultures into saline solution with CaCl₂ (10–300 mM) (for S. aureus); (2) growth in SR1 synthetic medium with fivefold nitrogen limitation (for C. pseudodiphtheriticum); and (3) incubation with (1–5) × 10^?4 M of C₁₂-AHB, an alkylhydroxybenzene akin to microbial anabiosis autoinducers. Increase of C₁₂-AHB concentration to 7 × 10^?4–2 × 10^?3 M resulted in “mummification” of cells with irreversible loss of viability without autolytic processes. Germination of dormant forms was followed by increasing of phenotypic variability, as seen from (1) diversity of colony types and (2) emergence of antibiotic-resistant clones on selective media. The share of kanamycin-resistant S. aureus variants was most numerous (0.002–0.01%) in 4-month DF suspensions in SALINE with CaCl₂. In the C. pseudodiphtheriticum DF produced under the effect of C₁₂-AHB, the share of kanamycin-resistant variants was also found to increase. These data point to an association between the emergence of antibiotic-resistant variants of bacteria and their persistence in dormant state mediated by starvation stress and regulated by AHB.     

The effect of anabiosis autoinducers on the bacterial genome

The mutagenic activity of chemical analogues of microbial anabiosis autoinducers (the autoregulatory d1 factors of cell differentiation), which act to inhibit cell proliferation, to enhance cell tolerance, and to induce the transition of cells to anabiotic state, was studied using the Ames test. In the range of concentrations studied (0.1 to 100 micrograms/ml), alkyl-substituted hydroxybenzenes (AHBs) differing in hydrophobicity, i.e., methylresorcinol (C1-AHB) and hexylresorcinol (C6-AHB), as well as unsubstituted resorcinol, showed different growth-inhibiting and mutagenic effects. C6-AHB was found to inhibit the growth of Salmonella typhimurium TA100 and to induce its mutagenesis at a rate of 1.8 revertants/nmol. C1-AHB taken at low concentrations not only failed to inhibit bacterial growth but even stimulated it and exerted an antimutagenic effect. Unsubstituted resorcinol virtually did not influence bacterial growth and showed weak mutagenic activity. The growth-inhibiting effect of elevated C6-AHB concentrations correlated with the degree of the transition of the original phenotype producing S-type colonies to a phenotype producing R-type colonies. The role of AHB homologues, as microbial autoregulators with mutagenic activity, in the regulation and correlation of two processes (the phenotypic dissociation of microbial populations and the formation of resting microbial forms) is discussed. The accumulation of AHBs in senescent microbial cultures may induce adaptive mutations, change the expression of genes, and promote the development of minor cell subpopulations (phenotypes), thus providing for the adaptation of these cultures to varying environmental conditions.     

The role of bacterial growth autoregulators (alkyl hydroxybenzenes) in the response of staphylococci to stresses

The investigation of the response of a batch culture of Staphylococcus aureus to exogenous alkyl-substituted hydroxybenzenes (AHBs), chemical analogues of anabiosis autoinducers, showed that C1-AHB at concentrations from 5 microM to 1.5 mM did not influence the culture growth, whereas the more hydrophobic C6-AHB inhibited it at concentrations of 0.5 mM and higher. Either of the AHBs drastically enhanced the phenotypic dissociation of staphylococcal cultures, which manifested itself in an increase in the fraction of cells producing small nonhemolyzing colonies of G type when plated on solid media with erythrocytes. In a submerged staphylococcal culture, the relative number of cells producing G-type colonies varied from 10 to 90%, depending on the concentration of the AHB added. The growth of S. aureus in the presence of AHBs also enhanced cell tolerance to heat shock (heating at 45 or 60 degrees C for 10 min). The role of AHBs, which are structural modifiers of membranes and possess chaperone activity, in the mechanisms responsible for cell tolerance and phenotypic dissociation of microbial populations is discussed.     

Impact of bacterial autoregulatory molecules (homoserine lactones and alkylhydroxybenzenes) on the oxidative metabolism of the cell effectors of natural immunity

We investigated the impact of bacterial regulators homoserine lactones (HSLs) and alkylhydroxybenzenes (AHBs) (which are present in human fluids at pico- and nanomolar concentrations) on neutrophile oxidative metabolism. The HSL and AHB effects were determined using a test based on induced luminol-dependent chemoluminescence of neutrophiles in human peripheral blood. In this test, neutrophiles were preincubated with chemical analogs of bacterial autoregulators with different lengths of the hydrocarbon radical, such as HSL · HCl, C6- and C12-HSL, and C1-, C6-, and C12-AHB. We revealed that they suppressed the chemoluminescence and, accordingly, the oxidative metabolism of neutrophiles. This effect was more significant with HSLs than with AHBs. Within each of the two groups, the effect increased with an increase in the length of the hydrocarbon chain of the homologues. High concentrations of long-chain autoregulators of both types produce a cytotoxic effect that is associated with apoptosis in the case of C12-HSL and with cell membrane damage in the case of C12-AHB. The effects of low HSL and AHB concentrations involve their protein-modifying properties and result in changes in the activities of neutrophile oxidative enzymes. To a lesser extent, these effects are due to the pro- and antioxidant activities of HSLs and AHBs, respectively. In light of the results obtained, the HSL and AHB effects are to be considered as a novel mechanism of regulating the activities of cell effectors of natural innate immunity. In symbiotic and parasitic systems, the mechanism involves the bimodal pattern of the effects of HSLs and AHBs that vary depending on their structure and concentrations.     

Regulation of phase variation in type I pili formation in <Emphasis Type="Italic">Escherichia coli</Emphasis>: Role of alkylresorcinols,microbial autoregulators

Formation of virulence-associated type I pili in Escherichia coli should be considered as one of the most efficient models for investigating the mechanisms of regulating the heterogeneity of populations of genetically identical microbial cells. The present work focused on the role of alkylhydroxybenzenes (AHBs), density-dependent intercellular regulators, in controlling phase variations in type I pili formation (fimbriogenesis). The tested AHB homologue was C12-AHB; a genetically constructed strain E. сoli dsp250 containing the fimA-lacZ hybrid operon was used. In this operon, the fimA gene encodes the main subunit of the pili protein, and its expression results in β-galactosidase synthesis; pili-forming cells, therefore, become blue on the medium with the Х-gal substrate. Expression of fimA depends on the inversion of the fimS region that is located upstream of it. If the inversion is on, pili formation takes place, if it is off, no pili are formed. An increase in C12-AHB concentration (within the 5 × 10^–5–2 × 10^–4 M range) in the exponential-phase culture of strain dsp250 causes a dose-dependent change in the dominant phenotype that is displayed by up to 98–99% of the cells. Cells with this phenotype form colonies with a blue center and white edges. Up to 60% of the cells with this phenotype assume a metastable state and up to 11% and 44% of them transition to the alternative phenotypes of pili-forming and pili-less cells, respectively. The influence of C12-AHB on off-switching, i.e. the formation of the avirulent phenotype, was observed irrespective of the growth conditions of strain dsp250. Addition of glucose to the LB medium (5 or 10 mg/mL) resulted in catabolic repression via regulation by the cAMP-CNR complex and predictably induced pili formation in 49 and 75% of the cells, respectively. Against this background, C12-AHB caused a dose-dependent decrease in the share of pili-forming cells to 33–61% and an increase in the share of pili-less cells to 32–61%. If glucose was added in excess (2.5, 5 or 10 mg/mL) to the diluted LB/2 medium, pili formation was completely repressed, while C12-AHB still induced the off inversion to the pili-less phenotype in up to 30% of the cells. The conclusion can be drawn that C12-AHB is not involved in the pathway of fimbriogenesis regulation via cAMP. Since C12-AHB functions as an extracellular alarmon (activating the rpoS regulon and the SOS response as shown earlier, see Golod et al., 2009), its mechanism of action apparently involves stress signal transduction. It induces the synthesis of global regulators RpoS and H-NS and of intracellular alarmon (p) ppGpp; these factors are responsible for the on → off inversion and the proliferation of pili-less cells.     

The alkylation of cell macromolecules in barley embryos with mutagenic N-methyl (14C)-N-Nitrosourea

In barley embryos, treated with N-methyl (¹⁴C)-N-nitrosourea, the alkylation of nucleic acids was much higher than that of proteins and lipids. At a concentration inhibiting the growth of M₁ seedlings to 50%, 0.27% of DNA-guanine was methylated to N-7-methylguanine. In barley DNA, alkylatedin vitro, the presence of 3-methyladenine and 0-6-methylguanine was chromatographically detected.     

The function of anabiosis autoinductors in microorganisms under blockade of metabolism

Alkyl-substituted hydroxybenzenes (AHBs), which are auto-inducers of microbial dormancy (d1 factors), were found to stabilize the structure of protein macromolecules and modify the catalytic activity of enzymes. In vitro experiments showed that C6-AHB at concentrations from 10(-4) to 10(-2) M, at which it occurs in the medium as a true solution and a micellar colloid, respectively, nonspecifically inhibited the activity of chymotrypsin, RNase, invertase, and glucose oxidase. C6-AHB-induced conformational alterations in protein macromolecules were due to the formation of complexes, as evidenced by differences in the fluorescence spectra of individual RNase and C6-AHB and their mixtures and in the surface tension isotherms of C6-AHB and trypsin solutions. Data on the involvement of dormancy auto-inducers in the post-translational modification of enzymes and their inhibition will provide further insight into the mechanisms of development and maintenance of dormant microbial forms.     

The Role of Bacterial Growth Autoregulators (Alkyl Hydroxybenzenes) in the Response of Staphylococci to Stresses

The investigation of the response of a batch culture of Staphylococcus aureus to exogenous alkyl-substituted hydroxybenzenes (AHBs), chemical analogues of anabiosis autoinducers, showed that C₁-AHB at concentrations from 5 M to 1.5 mM did not influence the culture growth, whereas the more hydrophobic C₆-AHB inhibited it at concentrations of 0.5 mM and higher. Either of the AHBs drastically enhanced the phenotypic dissociation of staphylococcal cultures, which manifested itself in an increase in the fraction of cells producing small nonhemolyzing colonies of G type when plated on solid media with erythrocytes. In a submerged staphylococcal culture, the relative number of cells producing G-type colonies varied from 10 to 90%, depending on the concentration of the AHB added. The growth of S. aureus in the presence of AHBs also enhanced cell tolerance to heat shock (heating at 45 or 60°C for 10 min). The role of AHBs, which are structural modifiers of membranes and possess chaperone activity, in the mechanisms responsible for cell tolerance and phenotypic dissociation of microbial populations is discussed.     

Occurrence of (+)-7-iso-jasmonic acid inVicia faba L. and its biological activity

The plant growth regulator (–)-jasmonic acid (JA) and its stereoisomer (+)-7-iso-jasmonic acid (7-iso-JA) have been isolated from young fruits ofVicia faba L. and identified by TLC, GC, GC-MS, and chemical transformation. Different isolation procedures gave different ratios of JA/7-iso-JA because of partial isomerization of (+)-7-iso-JA to (–)-JA. Optimal conditions, excluding artificial isomerization, were checked by the addition of [U-¹⁴C]-7-iso-JA. The naturally occurring isomer ratio was determined to be 65% (–)-JA: 35% (+)-7-iso-JA in immature broad bean fruits. The biological activities of both isomers of JA have been studied using several bioassays. Growth of wheat and GA₃-stimulated dwarf rice seedlings is inhibited more effectively by (+)-7-iso-JA than by (–)-JA. In growing seedlings of barley and oat, both isomers caused a senescence-like bleaching effect characterized by chlorophyll and carotenoid decrease. The free acids are more active than their methyl esters in intact barley plants in contrast to results obtained in leaf segment tests. Highest activity was obtained with (+)-7-iso-JA.     

PEG预处理对青稞种子萌发和幼苗生理特性的影响

选择国内外28份青稞品种材料幼苗第一片展开叶,分别测定其相对含水量和失水率,并选择其中对水分胁迫敏感与不敏感的材料各1份,研究不同浓度(5%～30%)聚乙二醇(PEG)预处理对青稞种子萌发、幼苗生长和生理特性的影响,探讨短期水分胁迫对青稞生长发育的调节作用。结果显示:(1)28个青稞材料中‘旱地紫青稞’幼苗叶片的相对含水量最高(60.16%)、‘大麻青稞’最低(38.98%),而离体失水率‘旱地紫青稞’最低(8.80%)、‘大麻青稞’最高(20.20%)。说明‘大麻青稞’对水分胁迫最敏感,而‘旱地紫青稞’最不敏感。(2)随着胁迫程度的增加,青稞种子的萌发率和生根率,幼苗的根长、苗高和鲜重均呈先增加后降低的趋势,‘旱地紫青稞’和‘大麻青稞’种子分别在15%和10%PEG处理下发芽和生根最佳且均与对照差异显著(P<0.05),两品种的幼苗根长、苗高和鲜重均在10%PEG处理下表现最佳,但‘大麻青稞’与对照差异不显著。(3)‘旱地紫青稞’幼苗叶片可溶性蛋白和叶绿素含量随PEG处理浓度增加而逐渐增加,而丙二醛含量和相对电导率则逐渐降低,并在30%PEG处理下效果差异极显著(P<0.01);‘大麻青稞’叶片可溶性蛋白和叶绿素含量随PEG处理浓度增加呈先增加后降低的趋势,丙二醛含量和相对电导率呈先降低后增加的趋势,并在20%PEG处理下最佳。研究表明,短时间低浓度PEG处理对青稞种子萌发、幼苗生长及可溶性蛋白、叶绿素、丙二醛含量和相对电导率等生理指标的改善均有一定的促进作用;高浓度PEG处理却具有抑制作用,且高浓度PEG胁迫条件下,耐旱性强比耐旱性弱品种的自我调控能力更强。