Thermal Adaptation and Fatty Acid Composition of Major Phospholipids in the Plain Sculpin <Emphasis Type="Italic">Myoxocephalus jaok</Emphasis> at Different Temperatures of Natural Habitat

The composition of phospholipids (PLs), fatty acids (FAs), molecular species of major membrane lipids phosphatidylcholine (PC) and phosphatidylethanolamine (PE) as well as the cholesterol (CL) level in the gills and liver of the plain sculpin Myxocephalus jaok were analyzed at different habitat temperatures (18, 9, 0°C). Polar lipids and cholesterol were shown to be actively involved in adaptation of the plain sculpin to changes in environmental temperature. A decrease in temperature evoked multidirectional changes in the level of monoenoic (MUFA) and polyenoic (PUFA) FAs, ω-3 PUFA, etheric PLs, and in the unsaturation index (UI) of FAs in PC and PE of th e plain sculpin organs. Changes in the composition of PL molecular forms were unidirectional in all organs but showed some organ specificity. Thus, PC showed an increase in the total percentage of SFA/PUFA and MUFA/PUFA containing predominantly 20:5, 22:5 and 22:6 of PUFA and a decrease in the percentage of SFA/MUFA and PUFA/PUFA as well as in the level of alkylacyl forms of PC. PE showed an increase in the percentage of MUFA/PUFA and a decrease in that of SFA/PUFA and PUFA/PUFA as well as in the level of alkenylacyl forms of PE. Despite a close FA composition of PC and PE, the repertoire of their molecular forms differed in an organ- and temperature-dependent manner. Molecular mechanisms of thermal adaptation in the plain sculpin organs were traced more distinctly at the level of PC and PE molecular forms rather than in their FA spectrum.     

Phospholipid and Fatty Acid Composition of Phosphatidylcholine and Phosphatidylethanolamine in the Black Plaice <Emphasis Type="Italic">Pleuronectes obscura</Emphasis> during Thermoadaptation

The phospholipid (PL) and fatty acid (FA) composition of major membrane lipid constituents, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), as well as the cholesterol/phospholipid (CL/PL) ratio were assayed in the muscles, gills and liver of the black plaice Pleuronectes (Liopsetta) obscura at different ambient temperatures (18, 9 and 0°C). PL and CL were shown to be actively involved in adaptation of the fish to changes in the seawater temperature. As temperature declines, the monounsaturated FA (MUFA) level increases while the polyunsaturated FA (PUFA) fraction in gills and liver PC and PE, on the contrary, decreases, resulting in diminished functional activity of the fish. However, in muscles this correlation is lacking. The PC and PE composition was shown to be organ- and ambient temperature-dependent. Major PC forms are saturated FA (SFA)/PUFA and MUFA/PUFA composed of a relatively small number of major molecular species. A temperature drop results in an increased SFA/PUFA level and decreased MUFA/PUFA and PUFA/PUFA levels in muscles and gills, and this may promote a drop in the viscosity of the outer lipid monolayer of membranes and in their functional activity. In contrast to PC, the PE composition in all organs tested is characterized by a decrease in the SFA/ PUFA level and an increase in MUFA/PUFA and PUFA/PUFA levels. Such changes promote the retention of functional activity of the inner lipid monolayer of membranes and are not synchronized with rearrangements in their outer monolayer. Due to intermolecular transfer of acyl radicals at a constancy of their composition, functional rearrangement of the lipid matrix appears to be achieved through changes in the membrane viscosity. Our data support the idea that different adaptation strategies in fish are driven by certain sets of PL molecular species.     

Alterations in wheat pollen lipidome during high day and night temperature stress

Understanding the adaptive changes in wheat pollen lipidome under high temperature (HT) stress is critical to improving seed set and developing HT tolerant wheat varieties. We measured 89 pollen lipid species under optimum and high day and/or night temperatures using electrospray ionization‐tandem mass spectrometry in wheat plants. The pollen lipidome had a distinct composition compared with that of leaves. Unlike in leaves, 34:3 and 36:6 species dominated the composition of extraplastidic phospholipids in pollen under optimum and HT conditions. The most HT‐responsive lipids were extraplastidic phospholipids, phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol, phosphatidic acid, and phosphatidylserine. The unsaturation levels of the extraplastidic phospholipids decreased through the decreases in the levels of 18:3 and increases in the levels of 16:0, 18:0, 18:1, and 18:2 acyl chains. PC and PE were negatively correlated. Higher PC:PE at HT indicated possible PE‐to‐PC conversion, lower PE formation, or increased PE degradation, relative to PC. Correlation analysis revealed lipids experiencing coordinated metabolism under HT and confirmed the HT responsiveness of extraplastidic phospholipids. Comparison of the present results on wheat pollen with results of our previous research on wheat leaves suggests that similar lipid changes contribute to HT adaptation in both leaves and pollen, though the lipidomes have inherently distinct compositions.     

Effects of Cadmium on Polar Lipid Composition and Unsaturation in Maize （Zea mays） in Hydroponic Culture

This study aimed to evaluate the effect of Cd exposure （100 μmol/L） on polar lipid composition, and to examine the level of fatty acid unsaturation in maize （Zea mays L.）. In roots, the level of 16：0 and monounsaturated fatty acids （16：1 ＋ 18：1） decreased in phosphatidylcholine （PC） and phosphatidylethanolamine （PE）. In contrast, the proportion of unsaturated 18-C fatty acid species showed an opposite response to Cd. The content, on the other hand, of PC, PE, digalactosyldiacylglycerol （DGDG）, and steryl lipids increased in roots （2.9-, 1.6-, 5.3-, and 1.7-fold increase, respectively）. These results suggest that a more unsaturated fatty acid composition than found in control plants with a concomitant increase in polar lipids may favor seedling growth during Cd exposure. However, the observed increase in the steryl lipid （SL） ： phospholipid （PL） ratio （twofold）, the decrease in monogalactosyldiacylglycerol （MGDG） ： DGDG ratio, as well as the induction of lipid peroxidation in roots may represent symptoms of membrane injury. In shoots, the unsaturation level was markedly decreased in PC and phosphatidylglycerol （PG） after Cd exposure, but showed a significant increase in sulfoquinovosyldiacylglycerol （SQDG）, MGDG and DGDG. The content of PG and MGDG was decreased by about 65%, while PC accumulated to higher levels （4.4-fold increase）. Taken together, these changes in the polar lipid unsaturation and composition are likely to be due to alterations in the glycerolipid pathway. These results also support the idea that the increase in overall unsaturation plays some role in enabling the plant to withstand the metal exposure.     

Changes in plasma-membrane lipid composition: a strategy for acclimation to copper stress

Wheat seedlings were grown hydroponically in the presence of 50 microM Cu2+. The copper stress resulted in plasma-membrane (PM) changes of the root cells as altered lipid composition, a decreased phosphatidylcholine (PC)/phosphatidylethanolamine (PE) ratio from 0.7 to 0.3, a decreased fatty acyl unsaturation and a decrease in the lipid/protein ratio. Membrane vesicles made from total lipid extracts of isolated PMs of wheat grown under copper excess showed a remarkably low permeability to polar molecules like glucose, as compared with the control, and no difference in proton permeability. Permeability studies of vesicles of plasma-membrane lipids, which were selectively modified by addition of specific lipids such as PC and PE, were also performed. The results are discussed with emphasis on the role of the increased PE proportion.     

Thermoadaptation and fatty acid composition of main phospholipids of the small-scaled redfin <Emphasis Type="Italic">Tribolodon brandti</Emphasis> under natural and experimental conditions

The fatty acid (FA) composition of the main membrane phospholipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), was investigated in the muscle, gills, and liver of the small-scaled redfin Tribolodon brandti (Dybowskii, 1872) at different temperatures under natural and experimental conditions. It was established that a water temperature decrease in the natural habitat was accompanied by an increase in polyunsaturated fatty acid contents and the unsaturation index, mainly at the expense of FAs of the ω3 series (20:5ω3 and 22:6ω3), and by a decrease in saturated fatty acid levels in PC and PE. A similar, but less pronounced tendency was revealed in experiments with a rapid lowering of water temperature. These findings suggest the weak adaptation ability of the small-scaled redfin to a drastic shift of environmental temperature. Temperature changes produced the greatest alterations in the FA composition of phospholipids in the liver and the smallest changes occurred in muscle tissue.     

Effect of hypo- and hyperthyroid states on phospholipid composition in developing rat heart

The aim of this study was to examine the effect of hypo- and hyperthyroidism on the phospholipid composition in developing rat heart. The hypothyroid state (PTU) was induced by 0.05% 6-n-propyl-2-thiouracil in drinking water given to nursing mothers from the postnatal day 2–21. The hyperthyroidism (T₃) was made by daily injection of 3,3,5-triiodo-L-thyronine (10 g/100 g body wt) to newborns in the same time period. Age matched intact littermates were taken as euthyroid controls. PTU decreased the concentration of total phospholipids (PL), choline phosphoglycerides (PC), ethanolamine phosphoglycerides (PE) and diphosphatidylglycerol (DPG) and increased the proportion of plasmalogen component of PE (PLPE). T₃ increased the concentration of PL, PC, PE, DPG and decreased PLPE in comparison with euthyroid controls. The ratio of saturated/unsaturated fatty acids (FA) in PE was decreased in PTU and increased in T₃ group. The ratio of n-6/n-3 polyunsaturated FA in PC, PE and phosphatidylinositol (PI) was increased in PTU due to increase of 18:2n-6 and decrease of 22:6n-3 proportion. T₃ decreased this ratio because of decline in 20:4n-6 and rise in 22:6n-3 proportion. Both hypo- and hyperthyroidism decreased the ratio of 20:4n-6/18:2n-6 in the majority of phospholipids. PTU decreased the unsaturation index in PC, PI and phosphatidylserine. It is concluded that thyroid state plays an essential role in the development of membrane phospholipid components in cardiac membranes during the early postnatal period.     

Effect of inoculation ofAzospirillum spp. on nitrogen accumulation by field-grown wheat

Summary Two experiments were performed to examine the effects of inoculation of field grown wheat with various Azospirillum strains. In the first experiment the soil was sterilized with methyl bromide to reduce the Azospirillum population and¹⁵N labelled fertilizer was added to all treatments. Two strains ofAzospirillum brasilense isolated from surface sterilized wheat roots and theA. brasilense type strain Sp7 all produced similar increases in grain yield and N content. From the¹⁵N and acetylene reduction data it was apparent that these increases were not due to N₂ fixation. In the second experiment performed in the same (unsterilized) soil, twoA. brasilense strains (Sp245, Sp246) and oneA. amazonense strain (Am YTr), all isolated from wheat roots, produced responses of dry matter and N content while the response to the strain Sp7 was much smaller. These data confirm earlier results which indicate that if natural Azospirillum populations in the soil are high (the normal situation under Brazilian conditions), strains which are isolated from wheat roots are better able to produce inoculation responses than strains isolated from other sources. The inoculation of a nitrate reductase negative mutant of the strain Sp245 produced only a very small inoculation response in wheat. This suggests that the much greater inoculation response of the original strain was not due to N₂ fixation but to an increased nitrate assimilation due to the nitrate reductase activity of the bacteria in the roots. Consultant Inter-American Institute for Cooperation in Agriculture IICA/EMBRAPA World Bank Project.     

Seasonal changes in oleosomic lipids and fatty acids of perennial root nodules of beach pea

Seasonal changes in the fatty acid composition of phospholipids (PL), monoglycerides (MG), diglycerides (DG), free fatty acids (FA) and triglycerides (TG) separated from oleosomes (lipid bodies) of perennial root nodules of beach pea (Lathyrus maritimus) were analysed. Thin layer chromatography (TLC) revealed that PL and MG are the major lipids in nodule oleosomes. The fatty acid profile and overall double bond index (DBI) varied among lipid classes depending upon the season. High DBI in PL and MG found during late winter and early spring indicated that they may play a major role in winter survival and regeneration of perennial nodules. The DBI of DG was high at the end of the fall season and the DBI of FA and TG was high in summer months. The dominant fatty acids are C16:0 followed by C18:0 and C18:1. The levels of many unsaturated fatty acids such as C18:1, C18:2 and C18:3 increased while saturated fatty acid C18:0 decreased during winter. These unsaturated fatty acids possibly play an important role in the protection of nodule cells from cold stress. Nodules seem to retain some fatty acids and selectively utilize specific fatty acids to survive the winter and regenerate in spring.     

Adaptational Changes in Lipids of <Emphasis Type="Italic">Bradyrhizobium</Emphasis> SEMIA 6144 Nodulating Peanut as a Response to Growth Temperature and Salinity

Phospholipids provide the membrane with its barrier function and play a role in a variety of processes in the bacterial cell, as responding to environmental changes. The aim of the present study was to characterize the physiological and metabolic response of Bradyrhizobium SEMIA 6144 to saline and temperature stress. This study provides metabolic and compositional evidence that nodulating peanut Bradyrhizobium SEMIA 6144 is able to synthesize fatty acids, to incorporate them into its phospholipids (PL), and then modify them in response to stress conditions such as temperature and salinity. The fatty acids were formed from [1-¹⁴C]acetate and mostly incorporated in PL (95%). Phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and cardiolipin (CL) were found to be the major phospholipids in the bacteria analyzed. The amount and the labeling of each individual PL was increased by NaCl, while they were decreased by temperature stress. The amount of PC, PE, and PG under the combined stresses decreased, as in the temperature effect. The results indicate that synthesized PL of Bradyrhizobium SEMIA 6144 are modified under the tested conditions. Because in all conditions tested the PC amount was always modified and PC was the major PL, we suggest that this PL may be involved in the bacteria response to environmental conditions.     

Effects of Water Stress and Abscisic Acid on Transpiration Regulation in Wheat

The transpiration response to recurrent light periods was studied'n water-stressed wheat seedlings. Seedlings were stressed by three methods: addition of mannitol to the root medium, root cooling and drving of the roots in air. All three methods induced almost equal effects on transpiration regulation during alternating dark and light intervals. Exogenous abscisic acid supplied to the shoots of excised plants had qualitatively the same effect as water stress. Water stress and ABA increased the time lapse between light-on and the onset of transpiration increase and lowered the amplitude of transpiration increase in light. Weak light introduced before strong light shortened the delay times.     

Imposition of water stress in wheat seedlings improves the efficacy of uniconazole-induced thermal resistance

Winter wheat ( Triticum aestivum L. cv. Fredrick) seedlings (seed) treated with different concentrations of uniconazole (S-3307) were water stressed by withholding water for 2, 4 and 6 days. Subsequently, the water-stressed seedlings were exposed to heat shock at 45°C for 3 h. Chlorophyll fluorescence, stress-ethylene and percentage survival were the parameters used to monitor the efficacy of protection against thermal stress by uniconazole. In the control seedlings, water stress for 2 days prior to heat shock provided minimal protection, whereas uniconazole protected both water-stressed and non-stressed seedlings from heat injury. However, the degree of protection by uniconazole was enhanced if the seedlings were subjected to water stress (2–4 days) prior to the heat shock. In addition to protection against heat injury, uniconazole also reduced stress-induced (water and heat) ethytene levels.     

Wheat inoculation with Azospirillum brasilense Sp6 and some mutants altered in nitrogen fixation and indole-3-acetic acid production

Abstract Inoculation of wheat seedlings with Azospirillum brasilense Sp6 produced an increase in the number and length of the lateral roots as a plant response. Inoculation with a Nif⁻ mutant, A. brasilense SpF103, which is producer of indole-3-acetic acid (IAA), yielded a very similar plant response. However, inoculation with a Nif⁻ mutant, A. brasilense SpF57, which is a low producer of IAA, did not elitic any response from the plant. The data suggest that the root system response of wheat seedlings to bacterial inoculation is due mainly to production of auxin-type substances by the microorganism.     

Interaction of <Emphasis Type="Italic">Azospirillum brasilense</Emphasis> and <Emphasis Type="Italic">Glomus intrarradix</Emphasis> in Sugar Cane Roots

Fifteen-day-old variety NA 56-79 sugar cane seedlings were inoculated with Azospirillum brasilense and Glomus intrarradix. This article aims at examining changes in sugar cane root seedlings inoculated with Glomus intrarradix and Azospirillum brasilense, the increase in microbial biomass and the acetylene reduction process as well. The internal root colonization was studied 20 days after inoculation using scanning and a transmission electron microscope. Both microorganisms entered the sugar cane root through the emergent lateral roots. The microorganisms were capable of coexisting both intra and intercellularly, producing changes in the cell wall, thus allowing colonization and interaction between the organisms. These changes increased the number of microorganisms inside the root as well as acetylene nitrogen reduction. Sugar cane plant biomass increased with joint-inoculation. The number of endophytic microorganisms and nitrogen fixing activity increased when they were colonized by Azospirillum and Glomus together.     

RISING WATER TEMPERATURES ALTER LIPID DYNAMICS AND REDUCE N‐3 ESSENTIAL FATTY ACID CONCENTRATIONS IN SCENEDESMUS OBLIQUUS (CHLOROPHYTA)1

The biosynthesis of nutritionally important polyunsaturated fatty acids (PUFAs) in phytoplankton is influenced by environmental temperature. We investigated the potential of climate warming to alter lipid dynamics of Scenedesmus obliquus (Turpin) Kütz. by comparing lipid and fatty acid (FA) profiles as well as FA metabolism (using [1‐¹⁴C] acetate) at 20°C and 28°C. We documented an overall decline (53%–37%) in the proportion of n‐3 PUFA (in particular, of α‐linolenic acid [ALA; 18:3n‐3]), and a concomitant increase in saturated fatty acids (SAFAs) in total lipids (TLs) at 28°C, consistent with enhanced incorporation of radioactivity from [1‐¹⁴C] acetate into total 16:0, 18:1, and decreased incorporation into 18:2 and 18:3 FA (from 36% to 22% of the total) at 28°C. Glycerophospholipids were also affected by warming; ALA and stearidonic acids (SDAs; 18:4n‐3) both decreased (by 13% and 15%, respectively) in phosphatidylcholine (PC) and (by 24% and 20%, respectively) in phosphatidylethanolamine (PE). The characteristic FA in phosphatidylglycerol (PG; 16:1n‐13t) increased (by 22%) at 28°C. The activities of desaturases, which add double bonds to FA moieties, comprised the major suite of reactions affected by the temperature increase in TL and polar lipid (PL) classes. Climate modelers predict an increase in the number of extreme heat days in summer at temperate latitudes, with parallel projected increases in water temperatures of shallow water bodies. Our results suggest that the overall decrease in the essential n‐3 FA ALA in S. obliquus at higher water temperatures may lower food quality for higher tropic levels, adding another climate‐warming stress.     

Aluminum mediates compositional alterations of polar lipid classes in maize seedlings

Changes in lipid composition were investigated on maize roots and shoots under aluminum stress. After 4d exposure to 100 microM Al, root growth was inhibited while shoot growth was not affected. In roots, the decrease of the DBI (double bond index) of total fatty acids may signal a decrease in membrane fluidity. The total lipids (TL) decreased by 49%, but phospholipids (PL), phosphatidylcholine (PC) and phosphatidylinositol (PI) increased to approximately 3-fold. The MGDG increased to 2-fold but no significant change was found in the DGDG. The steryl lipids (SL) increased by 69%. The SL/PL ratio decreased from 2.64 to 1.52 and the MGDG/DGDG ratio increased from 0.45 to 1.06 in roots of Al-stressed plants. Al leads to oxidative stress in roots of treated plants as indicated by the increase of malondialdehyde (MDA) concentrations. In shoots, changes in fatty acid composition were associated with an increase of the DBI in all lipid classes except that of the DGDG decreased. The PG was the lipid class which shows the large variation of fatty acid composition. No significant changes were found either for TL, PL, SL or MDA concentrations in shoots of Al-treated plants. While PE levels did not show significant change, PI and PG increased and PC decreased. However, the Al caused 87% decrease in the GL levels. The MGDG and DGDG decreased to 19- and 8-fold, respectively. The deleterious effects of Al on polar lipids could be caused by a direct intervention of Al on plasma membrane and/or alteration of cell metabolism.     

Lipid metabolism during aging of high-alpha-linolenate-phenotype potato tubers

Previous studies demonstrated that high levels of alpha-linolenate in cell membranes of potato tubers (achieved by overexpressing fatty acid desaturases) enhances lipid peroxidation, oxidative stress, and tuber metabolic rate, effectively accelerating the physiological age of tubers. This study details the changes in lipid molecular species of microsomal and mitochondrial membranes from wild-type (WT) and high-alpha-linolenate tubers during aging. The microsomal and mitochondrial polar lipids of high-alpha-linolenate tubers were dominated by 18:3/18:3 and 16:0/18:3 molecular species. Relative to WT tubers, high-alpha-linolenate tubers had a substantially higher 16:0/18:n to 18:n/18:n molecular species ratio in mitochondria and microsomes, potentially reflecting a compensatory response to maintain membrane biophysical properties in the face of increased unsaturation. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) accounted for 53 and 37% of polar lipids, respectively, in mitochondria from younger WT and high-alpha-linolenate tubers. The relative proportions of these phospholipids (PL) did not change during aging of WT tubers. In contrast, PE increased to dominate the PL pool of mitochondria during aging of high-alpha-linolenate tubers. While aging effected an increase in mitochondrial 18:3-bearing PCs and PEs in WT tubers, the concentration of 18:3-bearing PCs fell with a concomitant increase in 18:3-bearing PEs during aging of high-alpha-linolenate tubers. These age- and high-alpha-linolenate-induced changes had no effect on the respiration rate and functional integrity of isolated mitochondria. Differential increases in the respiration rates of WT and high-alpha-linolenate tubers during aging were therefore a consequence of unsaturation-dependent alterations in the microenvironments of cells. Microsomal 18:3-bearing PCs, PEs, digalactosyldiacylglycerols (DGDG), and monogalactosyldiacylglycerols all increased in WT tubers during aging. In contrast, a selective loss of 18:3-bearing PCs and DGDGs from microsomes of high-alpha-linolenate tubers likely reflects a greater susceptibility of membranes to peroxidative catabolism during aging. Aging resulted in an increase in sterol/PL ratio in microsomes from WT tubers, due primarily to a decline in PL. In high-alpha-linolenate tubers, the increase in sterol/PL ratio during aging was due to increases in Delta 5-avenasterol and stigmasterol, indicating membrane rigidification and likely contributing to increased membrane permeability. Age-induced changes in 18:3-bearing lipids in membranes of transformed tubers are discussed relative to the development of oxidative stress and accelerated aging.     

1-Aminocyclopropane-1-Carboxylic Acid Transported from Roots to Shoots Promotes Leaf Abscission in Cleopatra Mandarin (Citrus reshni Hort. ex Tan.) Seedlings Rehydrated after Water Stress

The effect of water stress and subsequent rehydration on 1-aminocyclopropane-1-carboxylic acid (ACC) content, ACC synthase activity, ethylene production, and leaf abscission was studied in Cleopatra mandarin (Citrus reshni Hort. ex Tan.) seedlings. Leaf abscission occurred when drought-stressed plants were allowed to rehydrate, whereas no abscission was observed in plants under water stress conditions. In roots of water-stressed plants, a high ACC accumulation and an increase in ACC synthase activity were observed. Neither increase in ACC content nor significant ethylene production were detected in leaves of water-stressed plants. After rehydration, a sharp rise in ACC content and ethylene production was observed in leaves of water-stressed plants. Content of ACC in xylem fluid was 10-fold higher in plants rehydrated for 2 h after water stress than in nonstressed plants. Leaf abscission induced by rehydration after drought stress was inhibited when roots or shoots were treated before water stress with aminooxyacetic acid (AOA, inhibitor of ACC synthase) or cobalt ion (inhibitor of ethylene-forming enzyme), respectively. However, AOA treatments to shoots did not suppress leaf abscission. The data indicate that water stress promotes ACC synthesis in roots of Cleopatra mandarin seedlings. Rehydration of plants results in ACC transport to the shoots, where it is oxidized to ethylene. Subsequently, this ethylene induces leaf abscission.     

Effect of lectins from <Emphasis Type="Italic">Azospirillum brasilense</Emphasis> to peroxidase and oxalate oxidase activity regulation in wheat roots

Lectins were extracted from the surface of nitrogen-fixing soil bacteria Azospirillum brasilense Sp7 and from its mutant A. brasilense Sp7.2.3 defective in lectin activity. The ability of lectins to stimulate the rapid formation of hydrogen peroxide related to increase of oxalate oxidase and peroxidase activity in the roots of wheat seedlings has been demonstrated. The most rapid induced pathway of hydrogen peroxide formation in the roots of wheat seedlings was the oxalic acid oxidation by oxalate oxidase which is the effect of lectin in under 10 min in a concentration of 10 μg/ml. The obtained results show that lectins from Azospirillum are capable of inducing the adaptation processes in the roots of wheat seedlings.