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Recent studies of the immune system of leguminous plants infected with nodular bacteria (rhizobia) are summarized. The possibility of blocking the invasion of rhizobia into plant organs not affected by the primary infection is discussed. The concept of local and systemic resistance of the leguminous plant to rhizobial infection is introduced. The Nod factors of rhizobia are considered, as well as the plant receptors that interact with these factors upon the formation of symbiosis of the plant and bacteria. The role of bacterial surface exopolysaccharides in the suppression of the protective system of the plants is discussed. The innate immunity of leguminous plant cells is assumed to affect the formation and functioning of the symbiosis of the plant and the bacteria.

The results of study interaction of genes CTR1, ALF3 and NPH4, IAR2 inheritance attributes of the root system Arabidopsis. It is set that there is a recession epistasis in the second generation of crossing of plants mutant lines ctr1-1 × alf3-1 (alf3-1 alf3-1 > CTR1_). At crossing of plants mutant lines nph4-1 × iar2-1 there is polymeric co-operation of genes NPH4 and IAR2 in the generation of F2.

Shallot virus X is a typical representative of Allexiviruses. The transcription levels of principal genes involved in the RNA silencing in healthy and shallot virus X-infected plants have been quantified by real-time polymerase chain reaction. There is a negative correlation between the reproduction rates of RNA virus and the levels of RNA-dependent RNA polymerase and DCL proteins in roots and leaves of infected plants. These observations indicate that Shallot X virus employs noncanonical ways of overcoming the antiviral defense of the plant by systemic RNA silencing.

The transcriptomes from different organs and tissues of western poplar, eucalyptus, soybean and common bean were studied. The expression level of cellulose synthase genes was notably different in different types of tissues and organs in studied plants. For common bean and eucalyptus transcriptome the domination of certain cellulose synthase genes was typical. These prevailing genes made up more than 50 % of the total expression pull of cellulose synthases. On the contrary, cellulose synthase expression pulls of wes-tern poplar and soybean were distributed between multiple genes. The different expression strategies of CesA-genes may reflect a phylogenetic processes that occurred in genomes studied.

In this study we presented data on the production of branched root hairs in the seedlings of A. thaliana under progressive water deficit. The overall production of branched hairs was quite high under stress conditions and amounted to 8,27 %. On the contrary, this form of root hairs was almost absent in the control group (0,27 %). The highest number of branched hairs was produced at the beginning of the stress action. Branched root hairs are quite uniform structures in the sense of their morphology. To solve the question how the branched hairs grow, the structure of actin cytoskeleton was explored. This structure was different in the root hair and in its branch, which is an indication that the hair stops its growth at the moment when the branching starts. We have also characterized the production of branched root hairs in hormonal mutants of Arabidopsis and found the involvement of auxin in this process.

The anatomical research of the vegetative organs of the cytoplasmatic hybrid in vitro plants containing the Brassica napus nucleus and the Lesquerella fendleri chloroplasts had been conducted in comparison to the parental forms. It was found, that the anatomical structure of the cybrid had been similar to rapeseed. Anomalous changes in the epithelial, parenchymal and connective tissue of the leaf, stalk, stem, and root of the cybrid were detected. The appearance of the anatomical defects can be explained by nuclear-cytoplasmatic incompatibility which is the cause of low adaptability of the cybrid to in vivo conditions and takes place due to alien chloroplast gene expression in the remote species.

It was shown phenotypic changes in the root system of seedlings Arabidopsis thaliana in transgenic lines with overexpression and suppressed gene expression of serine-threonine protein kinase KIN10 in conditions of energy shortage and under normal conditions. The normal growth and development of KIN10 overexpressing plants with in energy deficiency conditions were detected. The significant inhibition of the plant development under normal conditions for these plant lines was obsereved. The levels of KIN10 gene expression under normal conditions in different organs A. thaliana, particularly in the roots, stems, leaves and flowers were analyzed. The highest level expression of the gene was fixed in the leaves.

The sequences of the PsSst1 and PsIgn1 genes of pea (Pisum sativum L.) homologous to the symbiotic LjSST1 and LjIGN1 genes of Lotusjaponicus (Regel.) K. Larsen are determined. The expression level of PsSst1 and PsIgn1 genes is determined by real-time PCR in nodules of several symbiotic mutants and original lines of pea. Lines with increased (Sprint-2Fix⁻ (Pssym31)) and decreased (P61 (Pssym25)) expression level of both genes are revealed along with the lines characterized by changes in the expression level of only one of these genes. The revealed features of the PsSst1 and PsIgn1 expression allow us to expand the phenotypic characterization of pea symbiotic mutants. In addition, PsSst1 and PsIgn1 cDNA is sequenced in selected mutant lines, characterized by a decreased expression level of these genes in nodules, but no mutations are found.

Fusarium wilt, caused by a soilborne pathogen Fusarium oxysporum f. sp. lilii, is the major disease of lily (Lilium L.). In order to isolate the genes differentially expressed in a resistant reaction to F. oxysporum in L. regale Wilson, a cDNA library was constructed with L. regale root during F. oxysporum infection using the suppression subtractive hybridization (SSH), and a total of 585 unique expressed sequence tags (ESTs) were obtained. Furthermore, the gene expression profiles in the incompatible interaction between L. regale and F. oxysporum were revealed by oligonucleotide microarray analysis of 585 unique ESTs comparison to the compatible interaction between a susceptible Lilium Oriental Hybrid 'Siberia' and F. oxysporum. The result of expression profile analysis indicated that the genes encoding pathogenesis-related proteins (PRs), antioxidative stress enzymes, secondary metabolism enzymes, transcription factors, signal transduction proteins as well as a large number of unknown genes were involved in early defense response of L. regale to F. oxysporum infection. Moreover, the following quantitative reverse transcription PCR (QRT-PCR) analysis confirmed reliability of the oligonucleotide microarray data. In the present study, isolation of differentially expressed genes in L. regale during response to F. oxysporum helped to uncover the molecular mechanism associated with the resistance of L. regale against F. oxysporum.

Plants regenerated from hairy roots and calluses of foxglove purple and periwinkle have been obtained. It was found that organogenesis in hairy root culture occurs spontaneously on hormone-free medium but with different efficiencies. The frequency of direct shoot formation from root cultures was up to 60% in Digitalis and 3.7% in Vinca. Addition of 1 mg/l BA, 0.1 mg/l NAA and 5% sucrose to B5 medium increased regenerative capacity of Vinca roots up to 19.1%. Regenerated plants showed morphological features typically seen in Ri-transgenic plants. They include growth and plagiotropism of the root system, increased shoot formation, changed leaf morphology and short internodes.

Polymorphism of rrs-rrl sequence of ribosomal operons (intergenic sequence, ITS) was studied among 81 isolates of Sinorhizobium meliloti (AK001-AK210) derived from the collection of alfalfa nodulating bacteria of the Laboratory of genetics of ARRIAM, by using species-specific primers FGPS 1490/FGPL132VM. Isolates were obtained from nodules of different species of wild host plants from Medicago, Melilotus and Trigonella genera grown in salinized North-Western region of Kazakhstan. The typical structure of ITS, similar to that of test strain Rm1021, was dominant in native rhizobia population, while in one third of the isolates (33.3%) this sequence was divergent. Among the latter, the ITS type of strain AK83 (RCAM00182) was dominant. Here, we show for the first time that isolates with reduced level of salt-tolerance had more diverse intergenic sequences of rrn-operons. No phylogenetic separation was observed between isolates grouped on the basis of their tolerance or sensitivity towards 0.6 M NaCl. However, the frequency of divergent ITS types within the two groups of rhizobia depended on the host symbiotic preference observed in natural environment, allowing to speculate about the existence of a chromosome types specific for S. meliloti isolates with differential salt tolerance. In conclusion, we propose that in the area subjected to secondary salinization, which are also the centre of introgressive hybridization of alfalfa, micro-evolutionary processes, affecting rrn-operons and associated with salt adaptation, are also occurring in symbiotic root nodule bacteria populations.

Identification of cytokinins in differentiated leaf cells has received little attention. We have carried out immunohistochemical localization of cytokinins in leaves of transgenic tobacco plants in which the level of increased due to induced in their roots the expression of ipt-gene controlling cytokinin synthesis. Immuno-labeling of cytokinins with the help of antibodies raised against zeatin riboside was characteristic of mesophyll cells. The label was localized in cytoplasm adjacent to cell walls and was absent in vacuoles. Immunohistochemical staining also revealed the presence of cytokinins in guard cells. Induction of cytokinin synthesis enhanced the immunohistochemical staining of both mesophyll cells and guard cells, which was accompanied by elevated stomatal conductance. The possibility of a direct effect of cytokinins on stomatal conductance and their indirect influence through photosynthesis in the mesophyll cells is discussed.

Morphological and symbiotic traits were studied in local endemic forms of the pea originating from Egypt, Syria, Afghanistan, and Palestine. A number of endemic forms exceeded the zoned Druzhnaya variety of the fodder pea in productivity of the seeds in field and greenhouse experiments. In order to improve nodulation and nitrogen fixation, endemic forms were crossed with the supernodulating K301 mutant marked by the nod4 gene. Recurrent selection of lines up to F5,6 generations was conducted with an estimation of productivity, nodulation, and nitrogen fixation. The most promising recurrent lines with a high productivity, active nodulation, and high nitrogen fixation were obtained during the crossing of endemic forms with the recurrent line marked by the nod4 gene. The line was previously created during the crossing between the Druzhnaya variety and the supernodulating K301 mutant marked by the nod4 gene.

Biological activity of protein extracts from transgenic plants of chicory Cichorium intybus L. and lettuce Lactuca sativa L. with human interferon alpha2b gene was investigated against vesicular stomatitis virus. It was shown that the extracts from the hairy roots of chicory and lettuce transformed by A. rhizogenes possess the antiviral activity 1620...5400 IU/g weight, and the extracts from leaves of the plants transformed by A. tumefaciens--till 9375 IU/g weight. Dependence of plant extract biological activity on the transformation vector was shown.

Comparative studies of the frequency and spectrum of pathological mitosis (PM), as well as of nucleoli number in the interphase cells of seedling roots have been performed in two natural populations of Norway spruce (Picea abies (L.) Karst.) of Ukrainian Polesie and introduction plantation in the Donbass. Low levels of PM in the seed progeny populations (0.32-0.38%) and slightly higher in the progeny plantation (0.40%) have been installed. Number of nucleoli was slightly higher in the plants of natural populations (5.35-5.85) than that of the plantation (4.95). The frequency of PM in the offspring of low-heterozygous plants was higher (0.43%) than in highly heterozygous individuals (0.28%).

"Hairy" roots of lettuce Lactuca sativa and regenerated plants with interferon-alpha2b gene had been obtained via Agrobacterium rhizogenes-mediated transformation. According to the results of PCR and rt-PCR analyses the studied plants had ifn-alpha2b gene. The regenerated plants differed from the plants of wild type by elongated internodes, early flower-bearing stem formation and purple coloration of leaves in artificial illumination conditions.

The dose dependencies of the aberrant anaphases frequency in the root meristem in 48 hours after irradiation in the range of doses of 4-10 Gy is characterized by threshold and plateau at 33% aberrant anaphase. The plateau indicates the activation of the recovery processes. Topology of cell rows in the primary meristem of the dose to 8 Gy are conserved and recovered damages. New cell rows are formed by local cell pools in the distal meristem, pericycle cells and subepidermy. It grows by intrusive character displacing the rows of damaged cells. Apparently the competition between clones of normal and aberrant cells plays the primary role in the mechanisms of recovery. Resulting to competition the promotion of aberrant cells to the extension zone is slowed down or blocked. So critical level of damage of the root apical meristem was defined about 50% of aberrant anaphase. Exceeding of this level leads to lethal consequence for meristem and it is accompanied by the inclusion of more radical process of restoration through regeneration. Regeneration leads to complete replacement of the apex tissues including the extension zone.

Genetic diversity and phylogeny of rhizobia that nodulate 18 species of wild-growing bean plants of South Urals from 8 genera belonging to 4 tribes (Loteae, Genisteae, Galegeaev and Hedysareae) was studied. It was demonstrated that for the wild-growing plants of Galegeae and Hedysareae tribes symbiotic interaction with various strains of nodule bacteria that closely related to bacteria of Mesorhizobium sp. was typical of the plants of Genisteae tribe--to bacteria of Bradyrhizobium sp. In the nodules of Lortus ucrainicus from Loteae tribe we have found a rhizobium that is closely related to the bacteria of Mesorhizobium sp., and at Coronilla varia rhizobia strains obtained by us were close by sequence of a 16S pRNA gene to Rhizobium sp. In the nodules of some kinds of the investigated plants we found also minor species of a rhizobia, which structure is under the great influence of conditions of the host plant growth.

Transgenic plants were regenerated from Cichorium intybus L. hairy roots transformed with genes of tuberculosis antigenes ESAT6 and Ag85B or human interferon alpha2b. The plant regeneration was light-dependent and occurred on the media without growth regulators. The DNA PCR and RT-PCR analyses have shown the presence and expression both selective and target genes in all root lines and regenerated plants.

"Barbate roots" in tobacco and colza transgenic on lectin gene were obtained with the use of a wild strain of Agrobacterium rhizogenes 15834 transformed with pCAMBIA1305.1 plasmid containing the full-size lectin gene (psl) from the Pisum sativum. Influence of expression oflectin gene on colonization oftransgenic roots with symbiont of pea (Rhizobium leguminosarum) was investigated. The number of adhered bacteria onto the roots transformed with lectin gene was 14-fold and 37-fold higher in comparison with the control; this confirms the interaction of R. leguminosarum with pea lectin at the surface of the transformed roots of tobacco and colza. The developed experimental approach, based on the simulation of recognition processes and early symbiotic interactions with lectins of pea plants, may, in perspective, be used for obtaining stable associations of economically valuable, nonsymbiotrophic plant species with rhizobia.

Polymorphism analysis was performed in Rhizobium leguminosarum bv. viceae populations isolated from geographically distant regions of Ukraine and Middle Asia. Examination of cultural, biochemical, and symbiotic traits revealed interpopulation differences, which were attributed to the difference in conditions between natural ecosystems and agrocenoses. Vetch has high species diversity and is not cultivated in Middle Asia, and the corresponding rhizobial population displayed higher genetic diversity and higher polymorphism of adaptive traits ensuring saprophytic development in soil and the rhizosphere, including melanin synthesis (35%) and active exopolysaccharide production (90%). Strains of the Ukrainian population had a lower exopolysaccharide production (10%), did not produce melanin, had higher herbicide resistance, and utilized glucose and succinate (main components of plant root exudation) as carbon sources. Strains capable of efficient symbiosis with Vicia villosa Roth. had a higher frequency in the Middle Asian than in the Ukrainian population, especially among strains isolated from soil (80 and 35%, respectively). In addition, strains of the Middle Asian population better competed for nodulation. It was assumed that the formation of rhizobial populations in vetch cultivation regions (Ukraine) is aimed at adaptation to ectosymbiotic (rhizospheric) interactions with plants and anthropogenic stress factors, while strains of the vetch original center (Middle Asia) are mostly adapted to the endosymbiotic interaction and to natural edaphic stress factors.

Immunohystochemical localization of cytokinins in cells of different root zones of wheat plants showed intensive immunostaining of zeatin in the apical root zone and its subsequent decline with the increase in the distance from the root tip. More intensive labeling of metaxylem and parenchyma cells of the root central cylinder was observed on the sections of the zone where root hairs appeared. Above this zone the decline in immunostaining of the cells of the central cylinder was paralleled by the signs if finalization of differentiation of the xylem vessels shown by lignin deposition. The data of immunohystochemical staining were confirmed by the results of enzyme immunoassay of different cytokinin forms. Likely sources of zeatin accumulation are considered. Possibility of additional (alongside with that in apical root zone) synthesis of cytokinins in the vascular tissues of root and the role of cytokinins in stimulation oflignification are discussed.

The results of Allium-test screening of new 2,4- and 2,6-dinitroaniline derivates on antimitotic activity and phytotoxicity are presented in the work. It is revealed that all studied compounds which are derivates of 2,4-dinitroaniline, 2,6-dinitro-(4-fluoromethyl)-aniline as well as (methylsulfonyl) nitrobenzol, can evoke a change in mitotic index value, an appearance of cytogenetic damages and also have phytotoxic effect on Allium cepa seedling roots. On data obtained the continuation of investigation the action of N-(2,4-dinitrophenyl)-orto-aminobenzoic acid, N,N-diethyl-2,6-dinitro-4-(trifluoromethyl)-aniline and 1-methylsulfonyl-3-nitrobenzol as potential herbicides is proposed.

Comparative analysis of allozyme variability was carried out by 18 loci from such tree-groups as 3 Pinus sylvestris L. natural steppe populations and a sample of 36 resistant trees from artificial stands in root fungus (Heterobasidion annosum (Fr.) Bref.) damage centres. Resistant trees are characterized by the least portion of polymorphic allozyme loci, by allele and genotype number, and by similar to midpopulational level observed and expected heterozigosity. Resistant tree sample differed from natural populations on composition and frequencies of multi-locus genotypes Dia-1, Lap-1, Acp, which are making the most contribution to researched tree-stands subdivision.

A cDNA clone containing a fructose-1,6-bisphosphate aldolase (ALD) gene, designated ClAldC, was isolated from a medicinal plant Codonopsis lanceolata. ClAldC is predicted to encode a precursor protein of 358 amino acid residues, and its sequence shares high degrees of homology with a number of other ALDs. The expression of ClAldC in different C. lanceolata organs was analyzed using reverse transcriptase (RT)-PCR. The results showed that ClAldC expressed high in stems of intact plant, while expressed at low level in leaves and roots. In addition, the expression of ClAldC under different abiotic stresses was analyzed at different time points. Three tested abiotic stimuli, anoxygenic stress, hydrogen peroxide and chilling, triggered a significant induction of ClAldC within 2-8 h post-treatment. However, there was no induction under other four stresses, NaCI, wounding, light and dark. The positive responses of ClAldC to the three abiotic stimuli suggested that C. lanceolata ClAldC may help to protect against environmental stresses such as anoxia, chilling and oxidative stress.

Introduction of the vector constructions with rhamnolipid genes (rhlA and rhlB) into tobacco plants has resulted in development of genetically modified plants which were tolerant to high concentrations of aluminium. While under aluminium concentration of 200 mM in a soil (ionit resin) all control plants perished, transgenic tobacco plants continued to grow and were fertile.

The study was devoted to investigation of the contents of radionuclides and of heavy metals and to evaluate the frequency of chromosomal aberrations in samples of Elodea canadensis, a submerged plant, collected in different parts of the Yenisei River. The samples were collected in the area subjected to radioactive impact of the Mining-and-Chemical Combine (MCC) at Zheleznogorsk and in the control area, upstream of the MCC. The investigations shown that elodea biomass in the area affected by MCC operation contained a long inventory of artificial radionuclides typical for the MCC discharges. The upstream of the MCC, in the control sampling area, the sediments and the elodea biomass contained only one artificial radionuclide--137Cs. Thus, the exposure doses to elodea shoots and roots upstream of the MCC are small (not more than 8 microGy/d) and the main contribution info the dose is made by natural radionuclides. At the MCC discharge site (the village of Atamanovo) and at the downstream of it, the total dose rate increases almost an order of magnitude, reaching its maximal values--72 microGy/d for elodea shoots and 58 microGy/d for its roots. Cytogenetic investigations of elodea roots shown that at the MCC discharge site (the village of Atamanovo) and at downstream of it the occurrence of chromosomal aberrations in ana-telophase and in metaphase cells of elodea was considerably higher than in the control area. It is highly probable that this simultaneous dramatic increase in the total exposure rate and the occurrence of chromosomal aberrations in elodea is associated with the radiation factor. It is suggested that elodea is affected not only by the radiation factor but also by the chemical factor--toxicity of heavy metals.

The genetic control of high tolerance of toxic aluminum ions in barley Hordeum vulgare L. has been studied. Cultivar Faust I (c-24612) and accession 9736 from Karelia have been compared with aluminum-sensitive cv. Colsess IV (accession c-24626). Analysis of F1, F2BC1, F3, and F4 progenies has shown that the development of roots of cv. Faust I in water medium with aluminum ions is determined by one (AlpF1) or two (AlpF1, AlpF2) genes. The development of roots of accession 9736 is determined by two genes, AlpK1 and AlpK2. The genes have not been not tested for nonidentity. The high tolerance of Faust I shoots are determined by one major tolerance factor and one dominant inhibitor gene, which hampers the manifestation of the dominant tolerance gene. The penetrance of the inhibitor gene may be incomplete. The aluminum sensitivity of roots and 7-day shoots of cv. Faust I is determined by different genetic factors. The response of barley plants to aluminum ions may be determined by small-effect genes.

In vitro regeneration techniques have been optimized for seven strains and cultivars of sugar beet (Beta vulgaris L.) bred in Russia. The frequency of shoot regeneration from somatic cells and tissues of sugar beet varies from 10 to 97% depending on the explant type, culture-medium composition, and genotype. The in vitro regeneration potential has been estimated in plants with different genotypes. The effect of medium composition (phytohormones and carbohydrates) on the frequency of the formation of a morphogenic callus competent for plant regeneration has been determined. The effect of the types and concentrations of various cytokines (zeatin, kinetin, and 6-benzylaminopurine) on direct shoot regeneration from cotyledon nodes has been estimated. The culture-medium composition has been optimized for direct shoot regeneration from petioles. The effects of different concentrations of abscisic acid on the frequency of shoot regeneration from a morphogenic callus has been studied. Micropropagation has been used to obtain petiole explants and reproduce the shoots obtained by direct regeneration from cotyledon nodes, petioles, and calluses. Improved shoot-regeneration methods can be used for both agrobacterial and bioballistic genetic transformation of the sugar beet genotypes studied.

Morphological (plant height and vegetative biomass amount) and symbiotic (number of nodules and nitrogenase activity) traits of six symbiotic pea mutants and the original cultivar Rondo were studied at different vegetation periods. Of the mutants studied, one (K10a) was supemodular and the remaining five (K1a, K2a, K5a, K7a, and K27a) were hypemodular. Essential distinctions in the absolute values and time course of the changes in individual morphological and symbiotic traits of different pea mutants were demonstrated. The supemodular type is inferior to the original cultivar in plant height and production of vegetative biomass, but exceeds it in nodulation and nitrogen fixation. The hypemodular mutants either surpass the original cultivar with respect to the production capacity or display similar results. The symbiotic traits-number of nodules and nitrogen fixation activity--of these mutants are higher compared with the Rondo cultivar. The mutants K1a, K2a, and K27a were demonstrated to be useful in breeding pea for an increase in nitrogen fixation.

Hydrogen peroxide (H2O2) content and catalase activity were studied in pea (Pisum sativum L.) seedlings with normal (cultivar Marat) and disrupted (pea mutants) process of nodulation, which were inoculated with the nitrogen-fixing bacterium Rhizobium leguminosarum strain CIAM 1026. Differences in hydrogen peroxide content and catalase activity in pea seedlings with different ability for nodulation, which were inoculated with rhizobia, were found. It was assumed that H2O2 and catalase are involved in defensive and regulatory mechanisms in the host plant.

An efficient genetic transformation method for african tobacco Nicotiana africana Merxm. has been established. African tobacco is a valuable source for cytoplasmic male sterility (CMS) and nuclear encoded resistance to potato virus Y (PVY). N. africana transgenic plants have been obtained using both Agrobacterium-mediated and direct transformation of leaf explants with gold particle bombardment using particle inflow gun. Plasmid vectors containing phosphinothricin resistance gene (bar gene) coding region without promoter and independent 35S promoter between lox sites (lox-bar-35S-lox) and nptII gene were used. Transgenic plants were selected according to growth capacity on the selective medium containing 50 mg/l kanamycin. PCR analyses of kanamycin-resistant plants confirmed the presence of nptII and bar genes in their genome. Agrobacterium-mediated transformation of root explants has proved to be the most efficient transformation method for N. africana.

Genetic transformation of plants mediated by Ri plasmid of Agrobacterium rhizogenes occupies a special place in plant cell engineering, since this technique based on a natural phenomenon allows cultivation of separately growing roots on hormone-free media. Application of wild-type unmodified agrobacterial strains allows us to obtain root cultures capable of long-term growth in vitro due to an increased sensitivity of the cells to auxins while other biochemical properties remain unaltered. A collection of pRi T-DNA transformed roots of certain dicotyledons was constructed; some strains of it are used to study synthesis of secondary metabolites in root cells. The in vitro cultivated roots could synthesize root-specific metabolites, which allows their large-scale application for biotechnological production of ecologically pure crude drugs. Cocultivation of pRi T-DNA transformed roots with arbuscular mycorrhizal fungi makes possible vital study of all stages of obligate symbiont development and interaction with plant roots. Mixed axenic culture of AM fungi and pRi T-DNA transformed plants can be used to construct a collection of the most valuable endomycorrhizal fungal species and to produce considerable quantities of homogeneous fungal inoculums.

A group of 13 recessive lethal mutants was selected on the basis of the collection of Arabidopsis thaliana transgenic plants with insertions of T-DNA vector plasmid pLD3 or pPCVRN4, which was produced by agrobacterial transformation of germinating seeds. The use of media containing exogenous hormones made it possible to compensate the lethal effect, identify phenotypes, and characterize six lines of recessive lethal germlings using genetic and molecular-genetic methods.

Transposon mediated insertional mutagenesis is one of the approaches for the unique gene cloning. A wild species of Cruciferae family Orychophragmus violaceus (L.) O.E. Schulz, which is of interest for practical breeding as a donor of improved plant oil, was an object of the investigation. Plasmid construction used in the experiments included selective NPT II gene, reported GUS gene serving as an excision marker, structural BAR gene located within the dSpm element and Spm transposase. The GUS gene of this plasmid had not his own promoter and became functional only after Spm-transposition. Transformed Orychophragmus violaceus (L.) O.E. Schulz. plants were obtained by direct mesophyll protoplast transformation as well as Agrobacterium tumefaciens-mediated root explant transformation. Gene transfer and the transposition event were confirmed by the GUS activity and the PCR analysis. Relative transformation efficiency using protoplasts was 5.8%.

The effects of the phytohormones 6-benzylaminopurine (BAP) and 24-epibrassinolide (EB) on the nucleolar sizes in the interphase nuclei of root meristem were studied using the silver-staining procedure in wheat species with different ploidy levels (a polyploid series). In addition, the effects of the phytohormones on the cell mitotic activity in the roots of 5-day-old seedlings were studied. The higher the wheat species ploidy level, the higher its sensitivities to BAP and EB were. In diploid wheat, the maximum increase in the nucleolar organizing region (NOR) activity was observed after treatment with considerably higher phytohormone concentrations compared to tetra- and hexaploid wheat species. The phytohormone treatment increased both the sizes and the number of nucleoli in meristematic cells of seedling roots in all wheat species studied. It was assumed that the differences between the responses of wheat species with three different ploidy levels to different concentrations of phytohormones were related to their effects on the methylation/demethylation of cytosine residues in the rDNA promoter region.

The gene coding for the secreted Serratia marcescens endonuclease was fused with the mannopine synthase promoter of Agrobacterium tumefaciens Ti plasmid and transferred to Nicotiana tabacum SR1 plants. The promoter is leaf- and root-specific. The resulting transgenic plants demonstrated elevated nuclease activity. The level of the transgene product was determined in the transgenic lines.

Selective systems for screening Arabidopsis thaliana (L.) Heynh. mutants with altered sensitivity to the oxidative stress (OS) inductors norflurazon (NF), acifluorfen (AF), and plumbagin (PB) were developed and a collection of 28 mutants was obtained. Dwarf and necrotic forms predominated among the NF-tolerant mutants, while pigment mutants and those with changed root morphology prevailed among the AF-tolerant and PB-sensitive mutants, respectively. Genetic and biochemical analysis of certain mutants was performed; quantitative and qualitative changes in the content of superoxide dismutase and peroxidase isoforms have been revealed. These data, complemented by the data on the cross-tolerance (sensitivity) of the mutants to paraquat, indicate a correlation between tolerance to the OS inductors and the functions of antioxidant systems.

In roots of 5-6-day old seedlings of three cultivars of the winter wheat, varying in drought-resistance: Bezostaya 1 (low resistant), Mironovskaya 808 (resistant), and Albidum 114 (highly resistant) water permeability of two transport channels of plasmodesmata was studied at the action of cytochalasin B, which is known to inhibit polymerization of cytoskeleton actin filaments, by a pulse method of NMR, on the background of increasing water loss in the seedlings. It has been found that the registered coefficients of water self diffusion, two of which (D2 and D3) depend on the water permeability of different transport channels of plasmodesmata, differ in opposite directions. This may suggest that in roots of drought-resistant plants, after a moderate water loss, a diffusive water flow through the cytoplasmic symplast increases (demonstrated by an increase of D2), while that through the vacuolar symplast decreases (seen by an increase of D3). After a high water loss in seedlings, we noticed an even greater increase in water permeability of the cytoplasmic symplast, and a decrease in water permeability of the vacuolar symplast, however, in the roots of low resistant cultivars these changes were poorly expressed, if at all. Under stress-less conditions cytochalasin B would result in an increased water transport through the cytoplasmic channel of plasmodesmata due apparently to a destruction of their actin-myosin sphincters. Both weak and average degrees of water loss would strengthen the cytochalasin B exerted influence on plasmodesmal water conductance, that may testify to a synergetic action of these two factors. After a significant water loss this action was kept only partially, because the inhibitor, on blocking the cytoplasmic channel, did increase at the same time the effect of water stress, limiting water flows through the vacuolar symplast and, simultaneously, raising the water inflow to the apoplast.

The effects of different concentrations (10(-6)-10(-3) M) of salts of six metals (cadmium, lead, nickel, aluminum, copper, and zinc) on the root growth of onion (Allium cepa L.) seedling and cell division, chromosome and nucleus morphology in root tip cells were studied. The obtained results showed that tested compounds inhibit the root growth, reduce the mitotic activity of meristem cells and cause the chromosome and nucleus irregularities. On the basis of these data two rows of metal salt toxicity were proposed--for effective concentrations (EC50) of toxic action: CuSO4 > CdCl2 > NiSO4 > Pb(CH3COO)2 > Al(NO3)3 > ZnSO4, and for sublethal and lethal effects of investigated substances: CuSO4 > Pb(CH3COO)2 > CdCl2 > ZnSO4 > NiSO4 > Al(NO3)3.

Selection for an increased frequency of mutant semilethal allele Adh1-S of the gene for alcohol dehydrogenase (ADH) was conducted in inbred families of sugar beet. Starting from the fourth generation, viable plants of mutant Adh1-SS homozygotes appeared. In the sixth generation of selection, the combinative ability of mutant homozygotes SS, normal homozygotes FF, and heterozygotes FS was estimated. The hybrids of mutant homozygotes outperformed the hybrids of normal homozygotes in all parameters examined (germinating capacity of seeds, length and weight of 1-week shoots, chlorophyll content in leaves, and root weight). The hybrids of heterozygotes had intermediate values of the parameters. The results obtained are discussed with regard to the mechanisms underlying the recovery of viability of mutant homozygotes and the formation of a compensating gene complex (CGC).