The gene of Zinnia elegans L. coding for S-like extracellular ribonuclease (ZRNase II) was used to produce transgenic tobacco plants with an increased ribonuclease activity. The protein-coding part of ZRNase II included the signal peptide sequence so the transgenic protein was located extracellularly. The cDNA of ZRNase II was cloned under the control of 2'-promoter of the mannopine synthase (MAS 2') gene from Ti-plasmid of Agrobacterium tumefaciens. It was shown that the resultant transgenic plants had an increased ribonuclease activity of the crude extracts and the induction of MAS 2' promoter by wounding additionally increased the activity. The plants of two transforming lines characterized by different ribonuclease activities were used to analyze the transgene influence on plant resistance to tobacco mosaic virus. The plants demonstrated either absence of disease symptoms or a significant delay in their appearance, depending on the virus content in the inoculum and ribonuclease activity.

An ascorbate-deficient semi-dwarf mutant asfL-1 was detected in 250 Gy γ-ray treated grass pea (Lathyrus sativus L.) cv. BioR-231. The mutant contained only 42 % of leaf and 20 % of root ascorbate content of mother control (MC). I investigated the possible causes of ascorbate deficiency and its effect on growth and antioxidant defense in control and 150 mM NaCl-treated seedling after 60 d growth period. Ascorbate deficiency was due to significant reduction in activities of monodehydroascorbate reductase and dehydroascorbate reductase as well as increase in ascorbate oxidase, leading to considerable decrease in redox state. Despite low ascorbate pool and decrease in ascorbate peroxidase activity, shoot and root biomass production in asfL-1 mutant were similar to MC plants, even at NaCl treatment. High accumulation of glutathione (GSH) coupled with high activities of GSH reductase, catalase, GSH peroxidase and peroxidase in both tissues of the mutant permitted efficient recycling of GSH and scavenging of H₂O₂ through well integrated catalase/peroxidase system, despite high superoxide dismutase activity under NaCl treatment. The collapse of this system led to inhibition of growth in NaCl-treated mother plants. Together, the results suggested that asfL-1 plants undertook a major reshuffle in its antioxidant defense machinery, which effectively counterbalanced the negative impact of ascorbate deficiency and remained unperturbed by NaCl treatment to maintain normal growth and biomass production.

The Potato virus X (PVX)-based vector was used for the construction of N- and C-terminally modified PVX coat protein (XCP) chimeras. N-terminal XCP modifications do not influence the viral life cycle, whereas the simple XCP C-terminal fusion impedes the viral replication. We designed several C-terminally modified XCP chimeras and tested their viabilities in various Nicotiana benthamiana genotypes. Our results showed the negative impact of 3'-terminal modification of XCP on the chimera's life cycle. To ensure chimeric constructs stability, the second copy of the last 60 nucleotides of XCP followed by the 3'-untranslated region (UTR) was added downstream of the recombinant sequence. Simultaneously, the first copy of the last 60 nucleotides of XCP was mutated in order to prevent recombination between the two identical sequences. The movement protein of Tobacco mosaic virus expressed in transgenic N. benthamiana plants positively affected the cell-to-cell spread of C-terminally modified XCP chimeras.

Protoplast fusion between incongruent Solanum bulbocastanum and S. tuberosum haploids was accomplished to produce hybrids combining elite traits from both parents. We identified 11 somatic hybrids out of 42 regenerants analyzed through ISSR markers. Some hybrids had loss or gain of fragments compared to the parents, likely due to rearrangements and deletions of chromosome segments after fusion, and/or to somaclonal variation during hybrid regeneration. Increased heterotic vigor for some traits as well as high diversity was observed as the effect of both ploidy and fusion combination. Microsporogenesis analysis indicated the occurrence of multivalent configurations and several meiotic abnormalities, such as chromosomes bridges and various spindle orientations. Since all hybrids were sterile, in vitro anther culture was employed for haploidization as a possible strategy to overcome barriers to hybridizations. Haploids were obtained from all the tetraploid S. bulbocastanum (+) S. tuberosum somatic hybrids tested, although with differences in both the number of embryos per 100 anthers cultured and the number of differentiated green plantlets. This is the first report on the successful production of haploid plants from S. bulbocastanum (+) S. tuberosum hybrids.

The functions of cytosolic heat shock protein AtHsp90.3 in response to heavy metal stress were characterized by using expression of AtHsp90.3 gene in yeast and Arabidopsis thaliana. AtHsp90.3 supported the Saccharomyces cerevisiae Hsp90 knockout strain R0005 growth and maintaining cells membrane integrity under cadmium and arsenic stresses, which was compatible with the components of ScHsc82 machinery. However, constitutive overexpression of AtHsp90.3 in Arabidopsis impaired plant tolerance to Cd stress with lower germination rate and shorter root length, decreased contents of phytochelatins (PCs) and glutathione (GSH), inhibited activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), and increased content of malondialdehyde (MDA). These results suggested that proper homeostasis of Hsp90 was critical for cellular response and/or tolerance to heavy metal stress in plants.

The role of hydrogen peroxide in the regulation of glucose-6-phosphate dehydrogenase (G6PDH) activity in the red kidney bean (Phaseolus vulgaris L.) roots under salt stress (100 mM NaCl) was investigated. Salt stress caused the increase of the activities of G6PDH and antioxidative enzymes including ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), superoxide dismutase (SOD), as well as H₂O₂ production. The application of H₂O₂ (1 mM) also enhanced the activities of G6PDH as well as antioxidative enzymes. In the presence of exogenous CAT, H₂O₂ content was decreased, and the enhanced activities of G6PDH and antioxidative enzymes induced by NaCl or by exogenous H₂O₂ were also abolished, suggesting that the enhancement of the above enzyme activities under salt stress was a result of the increased endogenous H₂O₂ levels. Further results showed that the effects of NaCl and H₂O₂ on the activities of antioxidative enzymes were diminished by Na₃PO₄ (a G6PDH inhibitor), suggesting G6PDH activity is required in enhancing the activities of antioxidative enzymes. The enhanced membrane leakage, lipid peroxidation, H₂O₂ and O₂ - contents, G6PDH and antioxidative enzyme activities under salt stress were all recovered to control level when the red kidney bean seedlings treated with 100 mM NaCl for 6 d were transferred to the control conditions for 8 d.

Arabidopsis shoots regenerate from root explants through a two-step process consisting of pre-incubation on an auxin-rich callus induction medium (CIM), followed by transfer to a cytokinin-rich shoot induction medium (SIM). The auxin receptor gene TIR1 was up-regulated when explants were transferred to SIM. The CIM pre-incubation is required for its up-regulation. The tir1-1, TIR1 knockdown mutant, reduced the efficiency of shoot regeneration in tissue culture, while its over-expression mutant significantly improved efficiency. TIR1 promoter::GUS fusion analysis demonstrated that TIR1 expression was in the shoot and the newly emerging leaves. After 10 d on SIM, several cytokinin related genes (CDKB1;1, CKS1, IPT4 and ARR15), which associate with shoot regeneration, were up-regulated in plants over-expressing TIR1 and some of these were down-regulated in the tir1-1 mutant. Thus, TIR1 appears to be involved in regulating shoot regeneration.

Alternative oxidase (AOX) transfers electrons from ubiquinone to oxygen in the respiratory chain of plant mitochondria. It is widely accepted that AOX functions as a mechanism decreasing the formation of reactive oxygen species (ROS) produced during respiratory electron transport. However, there are no experimental data to provide unambiguous proof of this hypothesis. We have studied growth characteristics, ROS content, and stress sensitivity in Arabidopsis transgenic lines with reduced or increased levels of AOX. We demonstrated that AOX-deficient plants grown in soil had an extended reproductive phase. Changes in AOX activity did not affect ROS content or stress sensitivity in the whole plants. However in the suspension culture, cells overexpressing AOX had significantly lower ROS content, whereas the AOX-deficient cells had higher ROS contents compared to the wild-type (WT) cells. Prooxidant treatment led to the increase in ROS content and to the reduction of viability more in the cells overexpressing AOX than in WT and AOX-deficient cells. Thus, we demonstrated that differences in the metabolism of whole plants and cultured cells might affect AOX functioning.

Xylem sap outflow from fine lateral roots (FLRs) isolated from hydroponically grown young maize (Zea mays L.) plants was visualized by local brightening of test solutions contrasted with purified Indian ink particles. Flow into the vessels was indicated by the adsorption of Evans Blue in their walls. The fraction of the FLRs able to exude xylem sap in a mineral medium with 30 mM mannitol decreased with increasing incubation time. This change was strongly retarded, when the FLRs were incubated in a medium containing glucose instead of mannitol. There was a broad range of variation of the osmotic potential of the test solutions (Ψ_so), wherein the fraction of the FLRs showing an initially reversed flow of the xylem sap varied between zero and unity. A median (M) of the osmotic potential of the xylem sap in FLRs (Ψ_sx) was estimated. It represents the value of Ψ_so that was lower than Ψ_sx in half of the roots of a sample before their transfer to the test solutions (Ψ_sxo). M was dependent on the osmotic potential of the medium used for growth or pre-incubation of the FLRs. Its value was not dependent on the molecular size of the osmolytes used to adjust Ψ_so, including dextran 8, which is excluded from cell walls. In all of the studied plants, M was lower than the osmotic potential of the xylem sap collected from the root before isolation of the FLRs. To explain this finding it is assumed that FLRs with Ψ_sxo > M had a higher hydraulic conductivity and a larger volume contributed to the exuded sap than those with Ψ_sx < M.

The present study investigated the effects of aluminum on lipid peroxidation, accumulation of reactive oxygen species and antioxidative defense systems in root tips of wheat (Triticum aestivum L.) seedlings. Exposure to 30 μM Al increased contents of malondialdehyde, H₂O₂, suproxide radical and Evans blue uptake in both genotypes, with increases being greater in Al-sensitive genotype Yangmai-5 than in Al-tolerant genotype Jian-864. In addition, Al treatment increased the activity of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), glutathione reductase (GR) and glutathione peroxidase (GPX), as well as the contents of ascorbate (AsA) and glutathione (GSH) in both genotypes. The increased activities SOD and POD were greater in Yangmai-5 than in Jian-864, whereas the opposite was true for the activities of CAT, APX, MDHAR, GR and GPX and the contents of AsA and GSH. Consequently, the antioxidant capacity in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH)-radical scavenging activity and ferric reducing/antioxidant power (FRAP) was greater in Jian-864 than in Yangmai-5.

The work evaluated the role of enzymatic and non-enzymatic antioxidants in cashew (Anacardium occidentale) leaves under 0, 50, 100, 150 and 200 mM NaCl. Salt stress increased protein oxidation and decreased the lipid peroxidation, indicating that lipids are less susceptible to oxidative damage. The superoxide dismutase (SOD) activity was not changed, ascorbate peroxidase (APX) activity steadily decreased while the catalase (CAT) activity strongly increased with the increasing NaCl concentration. High salinity also induced alterations in the ascorbate (AsA) and glutathione (GSH) redox state. The salt resistance in cashew may be associated with maintaining of SOD activity and upregulation of CAT activity in concert with the AsA and GSH antioxidants.

Sodium/proton antiporter activity in the plasma membrane and tonoplast of cucumber seedling roots treated with 200 mM NaCl for 24 h was determined. It was observed that plasma membrane and tonoplast antiporter activity was only present in membranes from salt-treated plants. In addition, the plasma membrane antiporter protein was present in membranes after induction with NaCl, whereas tonoplast antiporter protein was observed in control and at elevated level in NaCl-treated plants. Moreover, based on the affinity of studied antiporter proteins to sodium ions, it could be assumed that excess sodium ions are firstly translocated from the cytosol to the vacuole and then excluded to the apoplast through the plasma membrane.

In Arabidopsis thaliana in vitro culture, shoots were induced from the shoot apical meristem (SAM) of germinating seeds in the presence of 2,4-dichlorophenoxyacetic acid. Primary shoot primordia developed leaf-like structures, from which secondary shoot primordia were produced. Regenerated shoots were recovered when the material was transferred to a medium lacking auxin. Adventitious roots formed from a callusing basal region of the secondary shoots. The CUC1 transcription factor was expressed at the apex of the primary shoot primordium and at the boundary between the regenerated SAM and the developing leaf primordia. The DR5::GUS transgene was used to localize sites of maximum auxin occurrence. Auxin was firstly detected in the dividing cells beneath the SAM epidermis, which coincided with sites where primary shoot primordia were initiated. In the regenerated shoots, auxin response was not detected in the basal region of the stem, suggesting that the regenerating structures were shoots rather than somatic embryos. Direct shoot regeneration from the A. thaliana SAM requires a localized accumulation of auxin.

Nitrogen remobilization during senescence has been studied in perennial herb Paris polyphylla. We analyzed changes in N content, amino acids, N-remobilization enzymes and effects of gibberellic acid (GA) during natural senescence. There was a gradual decrease in the contents of N, chlorophyll and soluble proteins and activities of glutamine synthetase (GS; EC 6.3.1.2) and glutamate dehydrogenase (GLDH; EC 1.4.1.2). Activity staining and Western blots showed that GS2 activity decreased, whereas GS1 activity was relatively stable over time. In contrast, the C/N ratio and total amino acid content increased. Among individual amino acids, the proportions of glutamine (Gln) and asparagine (Asn) increased, and proportions of arginine, aspartate and glycine decreased. Treatment with GA slowed the senescence and retarded decreases in the activities of GS and GLDH and the contents of N, chlorophyll and soluble proteins. Conversely, this treatment slowed increases in the C/N ratio, total free amino acid content, and proportions of Gln and Asn. We conclude that low N resorption efficiency during senescence of P. polyphylla results from a sharp decrease in N remobilization enzyme activity.

The Nicotiana tabacum transgenic plants expressing a Cucurbita pepo antisense PHYA RNA were obtained. The seedlings of transgenic tobacco with reduced phytochrome A (PHYA) content displayed decreased sensitivity to continuous broad-band far-red radiation (λ > 680 nm). Under far-red irradiance transgenic seedlings showed less elongation of the hypocotyls, more rapid plastid development, more chlorophyll accumulation, less repression of lightdependent NADPH:protochlorophyllide oxidoreductase than wild-type plants that was in accordance with PHYA control of plant development. Dynamics of the far-red radiation dependent changes in low temperature chlorophyll fluorescence spectra for the transgenic and wild-type seedlings were consistent with the more rapid formation of photosynthetic apparatus in the seedlings with reduced PHYA.

Although crosstalk between cytosolic and plastidic terpenoid pathways has been validated in many plant species, we report here for the first time a striking elevation of the nucleus-encoded artemisinin biosynthesis relevant DBR2 mRNA following the incubation of plants with fosmidomycin (FM). FM decreased singlet oxygen (¹O₂) scavengers such as β-carotene and α-tocopherol and subsequently invoked ¹O₂ burst. The treatment of plants with fluridone (FD) neither decreased α-tocopherol content nor triggered ¹O₂ emission. In conclusion, FM can up-regulate ¹O₂-sensitive nuclear genes responsible for artemisinin biogenesis by mitigating the accumulation of plastidic scavenging terpenoids, thereby eliciting ¹O₂ generation and initiating ¹O₂ retrograde signaling.

A suppression subtraction hybridization (SSH) cDNA library of alfalfa (Medicago sativa L.) cv. Zhongmu NO.1 had been constructed to identify differentially expressed genes under stress. Based on the sequence of a 460 bp expressed sequence tags (ESTs), a cDNA of 1652 bp was cloned by rapid amplification of cDNA ends (RACE) method. This gene (MsPBL) was predicted to encode a 434-amino-acid protein, which contained a Phox and Bem1 (PB1) domain. PB1 domain is a functional domain comprising about 80 amino acid residues, which exists in many signal transduction proteins and mediates dimerization in the proteins. PB1 domain is mostly involved in two cell signal transduction pathways: MAPK and NF-KB. When fused to the green fluorescent protein, we found MsPBL localization in the nucleus of onion (Allium cepa L.) epidermal cells. The transcripts of MsPBL rose significantly when alfalfa was treated with 300 mM NaCl, 0.1 mM ABA, and 20 % polyethylene glycol (PEG-6000). These results indicated that MsPBL may be functional within the nucleus as a signal transduction protein to allow alfalfa to rapidly respond to the environmental stress signals.

Seedlings of mangrove plant Bruguiera gymnorrhiza cultured in sand with Hoagland's nutrient solution were treated with 1 to 30 mM Cd(NO₃)₂ or Pb(NO₃)₂ for 2 months. In all Cd/Pb treatments, the malondialdehyde content increased while the chlorophyll content declined. Peroxidase (POD) and superoxide dismutase (SOD) activities in roots increased at moderate Cd/Pb concentrations (1-10 mM), whereas decreased at higher concentrations (20-30 mM). Catalase (CAT) activity in roots was inhibited by 1-10 mM Cd but enhanced by 1-10 mM Pb. The activities of POD, SOD and CAT in leaves were less affected by Cd and Pb than in roots. A new SOD and three CAT isoenzymes were induced by Pb. In contrast, no additional SOD and CAT isoenzymes were induced by Cd.

The manipulation of cytokinin contents via Agrobacterium-mediated transformation is an efficient tool for delaying leaf senescence and improving the resistance to environmental stresses. In the present study, cotton transformants harbouring the Agrobacterium tumefaciens isopentenyl transferase (IPT) gene under the control of the promoter of Gossypium hirsutum cysteine proteinase (Ghcysp) were generated. PCR and Southern blot analysis indicated that the foreign DNA fragment was successfully integrated into the cotton genome. The chlorophyll and cytokinin contents, and ROS-scavenging enzymatic activities were significantly increased in transgenic cotton lines, which resulted in a significant delay in leaf senescence. The growth characteristics of transgenic cotton lines resembled the non-transgenic lines except delaying premature senescence and the lint yield and fiber quality of transgenic lines were improved. In addition, the transgenic lines had higher biomasses, IPT transcripts, and endogenous cytokinin contents compared with those of non-transgenic lines under 200 mM NaCl stress.

Changes in antioxidative enzymes activities during Tacitus bellus direct shoot organogenesis from leaf explants were examined. During the early stages of shoot organogenesis there was a decrease in superoxide dismutase (SOD) and an increase in catalase (CAT) activity, and later during organogenesis there was an increase in peroxidase (POD) and polyphenol oxidase (PPO) activity. Two highly regulated turning points may be distinguished regarding activities and isoforms of antioxidative enzymes: the initiation of shoot organogenesis and the shoot bud formation. Our data suggest the role of specific CAT, POD, SOD and PPO isoforms in separate processes during T. bellus direct shoot organogenesis.

In order to provide additional information on the coloration of chrysanthemum flowers, the flavonoid composition and the expression of six structural genes involved in anthocyanin pathway in the ray florets of a pink flowering (cv. H5) and two white flowering (cvs. Keikai and Jinba) Chrysanthemum grandiflorum cultivars were examined. HPLCDAD/ESI-MSⁿ analysis showed that cyanidin 3-O-(6"-O-malonylglucoside) and cyanidin 3-O-(3",6"-O-dimalonylglucoside) were the two major flavonoids presented in H5, while white flowering cultivars contained flavones instead of anthocyanins. Nine flavone derivatives were detected in the three cultivars, the amount of each flavone varied upon cultivars, and seven of these were identified as luteolin 7-O-arabinosylglucuronide, apigenin 7-O-glucoside, luteolin 7-O-malonylglucoside, apigenin 7-O-malonylglucoside, chrysoeriol 7-O-malonylglucoside, acacetin 7-O-rutinoside and acacetin 7-O-malonylglucoside. The two white flowering cultivars showed similar total flavonoid content, which was about two fold higher than that in H5. A high expression of the genes encoding dihydroflavonol 4-reductase and 3-O-glucosyltransferase was detected only in H5 but not in Keikai or Jinba. Chalcone synthase, chalcone isomerase, flavanone 3-hydroxylase, and flavonoid 3'-hydroxylase were expressed in all flowers, suggesting that the lack of anthocyanin in white flowering cultivars cannot be due to any blockage of their expression.

The aim of this study was to test the hypothesis that salinity can affect indirectly the nitrate acquisition by a negative modulation triggered by glutamine accumulation. Cowpea plants were exposed to a mild NaCl concentration (50 mM) in order to restrict growth and N-demand. After 21 d, pretreated plants and control plants were supplied with 0, 5 and 10 mM of Ca(NO₃)₂ for 3 d in absence of NaCl. Salt pretreated plants showed a great limitation in acquisition of NO₃ ^-, indicated by decline in the nitrate uptake rate, NO₃ ^- accumulation, nitrate reductase activity and protein content. The restriction of NO₃ ^- utilization was positively associated with increased glutamine synthetase activity and glutamine accumulation, especially in roots.

Histone H3 lysine 4 methylations catalyzed by histone lysine methyltransferases (HKMTs), like the Arabidopsis thaliana ATX1 and ATX2, are important epigenetic modifications related to chromatin decondensation and gene activation. In order to study this epigenetic mechanism in monocot cereal plants, we performed homology searches of ATX1 and ATX2 against the Brachypodium distachyon L. Beauv and rice (Oryza sativa L. spp. japonica) genomes, discovering single homologues for each cereal crop representing both Arabidopsis sequences. Using this information, we employed the rolling circle amplification - rapid amplification of cDNA ends (RCA-RACE) method to isolate, clone and characterize HvTX1 from RNA extracted from barley (Hordeum vulgare L.) tissues and studied its expression during seed development and under drought stress. The cloned cDNA sequence contained a 3 093 bp ORF homologous to ATX1 and ATX2. Characterization of the translated HvTX1 transcript sequence revealed the multi-domain nature of the putative protein, including all conserved regions characteristic for ATX1 and ATX2. By comparative genomic analysis and homology searches in EST databases we located, with high probability, the gene coding for HvTX1 on the barley chromosome 5H. Constant elevation of HvTX1 expression was observed during seed development. Expression of HvTX1 after drought stress was analyzed by quantitative real-time polymerase chain reaction (qPCR) in two different barley cultivars with varying drought stress tolerance, revealing HvTX1 drought-induction in a tolerance-specific manner.

Cucumber seedlings were pretreated with 3 μM 5-aminolevulinic acid (ALA) followed by cultivation at normal (25/18 °C) or high (42/38 °C) day/night temperature to investigate the protective effects of ALA on heat stress in plants. Heat elevated the contents of malondiadehyde (MDA), superoxide radical (O₂ ^.-) and hydrogen peroxide (H₂O₂) in leaves of all plants but less in ALA-pretreated plants. Heat treatment resulted in higher antioxidant enzyme activities and proline and soluble sugar contents and weaker growth inhibition in ALA-pretreated plants than in those treated with heat alone. These results indicate that ALA pretreatment increased the tolerance of seedlings to heat stress.

We examined the effects of repeated inbreeding on fitness components of the long-lived perennial Succisa pratensis (Dipsacaceae). Plants from six populations differing in size were used to establish lines with expected inbreeding coefficients f of 0, 0.5 and 0.75. The effects of different inbreeding levels were measured for seed set, seed mass, percentage germination and seedling relative growth rate. Seed set decreased following one generation of inbreeding and seedling growth rate decreased after two generations of inbreeding. Our study indicated that the mutational load is difficult to purge and that continued inbreeding tends to affect important traits in S. pratensis. Although the partial dominance hypothesis for inbreeding depression seems to account for the results, the overdominance hypothesis cannot be ruled out completely. Overall, we conclude that the response of a long-lived plant, such as S. pratensis, to repeated inbreeding does not differ from that of other plant species with shorter life spans, surely because the mechanisms that account for inbreeding depression are universal for all plant species.

The regulation of contents and activities of peroxidase (POX), diamine oxidase (DAO) and polyamine oxidase (PAO) were determined in relation to polyamines and lignin content in wheat (Triticum aestivum L.) grains. Two cultivars WH 542 (heat susceptible) and PBW 343 (heat tolerant) were used. Activities of POX, DAO and PAO were substantially higher in PBW 343 as compared with WH 542 and appeared to be independently regulated. POX and PAO showed peak activities at mid-milky stage (15 d post anthesis) while the activity of DAO showed continuous decline. Histochemical localization of POX and PAO in situ revealed their presence in the chalazal cell walls, crease and seed coat. Substantially higher activities of enzymes in PBW 343 correlated well with a higher degree of lignification in the chalazal cells as compared to WH 542.

The influence of combined and individually applied drought and heat stress was studied in two wheat (Triticum aestivum L.) cultivars: resistant cv. Katya and susceptible cv. Sadovo. Relative water content decreased and electrolyte leakage increased due to individual and combined application of both stresses. Initial heat shock protein profile has been outlined via SDS electrophoresis of leaf extracts. The results obtained were confirmed by immunoblotting with anti-HSP70 monoclonal antibodies, anti-HSP110 polyclonal antibodies and anti-α β-crystalline polyclonal antibodies. The effect of simultaneously applied water stress and heat shock resembled the alterations in protein expression provoked only by water stress and differed significantly from the changes occurring after the individual application of heat stress.

Plants have capability to optimize its architecture by using CDK pathways. It involves diverse types of cyclin dependent kinase enzymes (CDKs). CDKs are classified in to eight classes (CDKA to CDKG and CKL) based on the recognized cyclin-binding domains. These enzymes require specific cyclin proteins to get activated. They form complex with cyclin subunits and phosphorylate key target proteins. Phosphorylation of these target proteins is essential to drive cell cycle further from one phase to another phase. During cell division, the activity of cyclin dependent kinase is controlled by CDK interactor/inhibitor of CDKs (ICK) and Kip-related proteins (KRPs). They bind with specific CDK/cyclin complex and help in controlling CDKs activity. Since cell cycle can be progressed further only by synthesis and destruction of cyclins, they are quickly degraded using ubiquitination-proteasome pathway. Ubiquitylation reaction is followed by DNA duplication and cell division process. These two processes are regulated by two complexes known as Skp1/cullin/F-box (SCF)-related complex and the anaphase-promoting complex/cyclosome (APC/C). SCF allows cell to enter from G1 to S phase and APC/C allows cell to enter from G2 to M phase. When all these above processes of cell division are going on, genes of cyclin dependent kinases gets activated one by one simultaneously and help in regulation of CDK pathways. How cell cycle is regulated by CDKs is discussed.

We isolated and characterized a novel Ran GTPase homologous gene, FaRan from tall fescue (Festuca arundinacea Schreb.). Reverse transcriptase polymerase chain reaction (RT-PCR) analysis indicated that FaRan is broadly expressed in old mature leaves, young leaves, plumules, stems, infloresence meristems, but at different levels. Transcript of FaRan is higher in young meristems than in old ones. Ectopic expression of FaRan resulted in increased number of axillary buds and reduced apical dominance in transgenic Arabidopsis plants. These results suggest that FaRan in F. arundinacea may be involved in the initiation of meristem and subsequent growth as well as development. In addition, it also suggests that FaRan can be used potentially to improve turfgrass quality.