Hexokinase (HXK, EC 2.7.1.1) plays an important role in the metabolism and glucose signalling. To examine the characteristics of HXK gene family in rice, the subcellular localizations of ten hexokinases (OsHXK1 - OsHXK10) were determined using OsHXK::GFP fusion proteins in tobacco mesophyll protoplasts. As was previously demonstrated, OsHXK4 was detected in the chloroplast stroma, OsHXK5 and OsHXK6 in the mitochondria, and OsHXK7 and OsHXK10 in the cytoplasm. In the present study, OsHXKs were clearly divided into three types (A, B, C) based on their N-terminal sequences. The new type-C HXKs in plants, OsHXK1, OsHXK7 and OsHXK8, which lack the plastidic transit peptide and the membrane anchor domain, were detected not only in the cytoplasm but also in the nucleus. The type-B HXKs, OsHXK2, OsHXK3, OsHXK9 and OsHXK10, which contained a membrane anchor domain, were distinctly localized in the mitochondria. These results suggest that OsHXKs localized in different cell compartments may be involved in the glucose signalling-related gene expression during growth and development of rice.

The scale segments of the bulblets of Hyacinthus orientalis L. cv. Anna Marie were examined to improve their growth and development with cold-pretreatment and sucrose. The cold-pretreated (4 °C for 4 months) segments showed higher growth and better development of the bulblets on medium without sucrose than ones stored at 20 °C. A rapid decrease in starch content of bulb pieces was found during the first 2 weeks in all cultures and thereafter the content decreased gradually. A scanning electron microscopic observation during the bulblet growth and development showed a gradual decreasing trend of the starch granules from 2 to 16 weeks of the cultures. SDS-PAGE electrophoresis revealed the presence of a characteristic polypeptide of approximately 45 kD, which is assumed to be a major storage protein in the bulblets.

Measurements of dependence of photosynthetic electron transport on irradiance and analyses of stable isotope ratios (δ¹⁸O, δ¹³C, δ¹⁵N) were performed on 4 to 6-year-old pine trees (Pinus sylvestris L.) in the primeval forest reserve of Białowieża and on 21-year-old pine trees of a plantation of different provenances at the Sękocin Forest Station near Warsaw, Poland. Small differences in maximum photosynthetic electron transport rates, ETR_max were related to growth. Stable isotope analyses suggest that water relations play an important role for the performance of P. sylvestris at the sites studied. The intraspecific comparisons showed a very high variability of photosynthetic capacity between needles of given trees and between individual trees under similar conditions. Differences between specific provenances were also observed. This is relevant for ecological niche occupation in a wide geographical growth range, where P. sylvestris is actually occurring. The high physiological plasticity demonstrated reveals a conspicuous trait of this tree species.

To gain a comprehensive understanding of plant response to Cd, physiological and proteomic changes in wheat (Triticum aestivum L.) leaves exposed to a range of Cd concentrations (10, 100 and 200 μM) were investigated. Leaf elongation was decreased, whereas the H₂O₂ and malondialdehyde content increased significantly at higher Cd concentrations. Changes in protein profiles were analyzed by two-dimensional electrophoresis. Twenty-one proteins which showed 1.5-fold change in protein abundance in response to Cd were identified. These proteins can be functionally grouped into three groups: 1) oxidative stress response, 2) photosynthesis and sugar metabolism and 3) protein metabolism and others. These results provide a new insight into our understanding of the molecular basis of heavy metal response in plants.

Using apical and axillary nodes as explants, a rapid and efficient method for propagation of Amorpha fruticosa L. has been developed. When grown on Murashige and Skoog (MS) medium supplemented with 8 mg dm^-3 benzyladenine, 100 % explants responded with 4.94 shoots per explant after 6-weeks culture, and explants taken from the in vitro proliferated shoots subsequently produced multiple shoots when cultured on the same medium. The addition of casein hydrolysate (200 mg dm^-3) enhanced the number of shoots up to 8.77 per subculture, and coconut milk was found to promote the shoot elongation and make them grow more vigorously, 82.53 % excised shoots were rooted on half-strength MS medium containing 2.0 mg dm^-3 indoleacetic acid after 3 weeks of incubation. After acclimatization, all of the rooted plantlets established in soil, exhibiting uniform morphological and growth characteristics.

Anther-derived pre-embryogenic masses (PEMs) of callus, established via suspension cultures, were encapsulated to form synthetic seeds suitable for cryopreservation. The synchronised suspension culture proliferation necessitated the optimisation of plant growth regulators for different cultivars. The growth phase and density of the culture were also important as well as the exposure of cells to vitrification solution containing 0.75 M sucrose with 0.1 M CaCl₂ and 2.0 % sodium alginate (pH 5.7). Pre-treatment of the encapsulated cells for 2 d with Nitsch and Nitsch (NN) medium containing 0.75 M sucrose solution followed by dehydration for 4 h in a laminar flow box provided maximum cell viability, which varied from 0 to 40 %. The embryo proliferation from the cryopreserved beads involved warming them and then transfer to NN medium containing glutamine (50 mg dm^-3) and activated charcoal (2.5 %). The maximum number of embryos obtained was 31-53 per bead. Subculture into the same medium induced secondary embryogenesis, which was initiated from the meristematic region, radicle, and root cap. Proliferation and maturation of secondary embryos was faster than of primary embryos. No phenotypic variation or abnormal structures compared to the control were observed in the regenerated plantlets.

Effects of zinc (12-180 μM) alone and in mixtures with 12 μM Cd on metal accumulation, dry masses of roots and shoots, root respiration rate, variable to maximum fluorescence ratio (F_V/F_M), and content of photosynthetic pigments were studied in hydroponically cultivated chamomile (Matricaria recutita) plants. The content of Zn in roots and shoots increased with the increasing external Zn concentration and its accumulation in the roots was higher than that in the shoots. While at lower Zn concentrations (12 and 60 μM) the presence of 12 μM Cd decreased Zn accumulation in the roots, treatment with 120 and 180 μM Zn together with 12 μM Cd caused enhancement of Zn content in the root. Presence of Zn (12-120 μM) decreased Cd accumulation in roots. On the other hand, Cd content in the shoots of plants treated with Zn + Cd exceeded that in the plants treated only with 12 μM Cd. Only higher Zn concentrations (120 and 180 μM) and Zn + Cd mixtures negatively influenced dry mass, chlorophyll (Chl) and carotenoid content, F_V/F_M and root respiration rate. Chl b was reduced to a higher extent than Chl a.

The effects of different growth conditions (ventilated and closed vessels, medium with 0, 15 and 30 g dm^-3 sucrose) during proliferation of donor quince (Cydonia oblonga Mill.) shoots (stage I) on net photosynthetic rate and soluble sugars content were evaluated. In order to assess the influence of these physiological parameters on morphogenesis, leaf explants harvested from donor shoots were induced to form somatic embryos and adventitious roots under ventilated and closed Petri dishes (stage II). Natural ventilation and low sucrose contents (0-15 g dm^-3) promoted the photosynthetic rate of quince shoots whereas biomass accumulation was the highest in those shoots cultured with 30 g dm^-3 sucrose in both vessel types and 15 g dm^-3 sucrose under natural ventilation. Increasing sucrose content in the medium induced greater accumulation of sucrose in leaf tissues of donor shoots. The content of reducing sugars was higher than that of sucrose, and it appeared to be higher in shoots cultured under natural ventilation compared to those in closed vessels. Somatic embryogenesis and root regeneration were influenced by stage I and II treatments. A significant correlation between sucrose content in the leaves of donor shoots and the number of somatic embryos regenerated was found, suggesting that identification of biochemical and physiological characteristics of donor shoots associated with increased regeneration ability might be helpful for improving morphogenesis in plant tissue culture.

The role of glutathione (GSH) in the adaptation of wild type Arabidopsis thaliana plants to Cd stress was investigated. The nutrient solution (control or containing 50 or 100 μM Cd) was supplemented with buthionine sulfoximine (BSO; 50, 100, 500 μM, to decrease the GSH content in plants) or GSH (50, 100, 500 μM, to increase its content in plants) in order to find how GSH content could regulate Cd stress responses. BSO application did not influence plant biomass, while exogenous GSH (especially 500 μM) reduced root biomass. BSO (500μM) in combination with Cd (100 μM) increased Cd toxicity on root growth (by over 50 %), most probably due to reduced GSH content and phytochelatin (PC) accumulation (by over 96 %). On the other hand, combination of exogenous GSH (500 μM) with Cd (100 μM) was also more toxic to plants than Cd alone despite a significant increase in GSH and PC accumulation (up to 2.7 fold in the roots). This fact could indicate that the natural content of endogenous GSH in wild type A. thaliana plants is sufficient for Cd-tolerance. A decrease in this GSH content led to decreased Cd-tolerance of the plants but an increase in GSH content did not enhance Cd-tolerance, and it showed even toxic effect on the plants.

Plants are subjected to several abiotic stresses that adversely affect growth, metabolism and yield. The dynamic research in plant genetics complemented by genome sequencing has opened up avenues to address multiple problems caused by abiotic stresses. Though many drought-induced genes have been phytoengineered in a wide range of plants, the drought signal transduction pathways, and the alteration of plant sensing and signaling systems to adverse environments still remain an intriguing subject for comprehensive investigation. To impart enhanced drought tolerance in plants, a thorough perception of physiological, biochemical and gene regulatory networks is essential. Recent functional genomics tools have facilitated the progress in our understanding of stress signaling and of the linked molecular regulatory networks. This has revealed several stress-inducible genes and various transcription and signaling factors that regulate the drought stress-inducible systems. Translational genomics of these drought specific genes using model plants have provided encouraging outcomes, but the in-depth knowledge of the specific roles of various metabolites in plant stress tolerance will lead to evolvement of strategies for the phytoengineering of drought tolerance in plants in future.

In order to clarify the role of endogenous growth inhibitors A-2α and A-2β in a dwarf pea plant, red light (emission peak 657 nm) treated, 9-d-old seedlings of dwarf pea (Pisum sativum L. cv. Progress No. 9) were transferred to darkness, and the resulting changes in growth rate and concentrations of A-2α and A-2β were monitored. The growth rate of the epicotyls increased, and the concentration of the inhibitors in the epicotyls decreased, according to sigmoidal time courses. The relationship between the logarithms of the concentration of the inhibitors and the corresponding growth rate was linear. These results suggest that A-2α and A-2β, may play an important role in the growth recovery process of the dwarf pea cultivar after termination of red light irradiation.

Differences among three clones of Gentiana punctata L. hairy root shoot regenerants were investigated in relation to their growth patterns, production of secondary metabolites and 2D protein profiles. Prominent differences in growth parameters were stable thus qualifying regenerant clones as true somaclones. Marked differences in protein spots were registered among the regenerant clones but not in comparison with the non-transformed control. Southern blot hybridization of regenerants showed the absence of rolA, B and C genes, initially present in the main hairy root lines. Orf13 and rolD were present and orf8 was missing in all three regenerant clones whereas orf3 was missing only in clone 2. Although lacking the three major rol genes, plants of regenerant clones retained characteristics of the hairy root phenotype.

The present study applies RAPD technique and morphometric analysis to study the diversity of some accessions belonging to section Solanum. A total of 252 products were amplified with 23 12-mer arbitrary primer pairs, among which 210 were found to be polymorphic. Sixteen morphological characters were measured and used to compile a dendrogram. Both the morphological and RAPD marker analysis clearly separated the different accessions into similar groups. The results indicate that the analyzed cultivars with unknown origin could be derived from S. retroflexum. We found morphological differences among the S. scabrum subsp. scabrum accession which were not reflected in the molecular data. Presumably these accessions represent cultivated forms selected for their habit, fruit quantity and/or quality and leaf size, respectively.

An efficient protocol for encapsulation of nodal segments of Vitex negundo L. has been developed for the production of non-embryogenic synthetic seeds. The encapsulations of nodal segments were significantly affected by the concentrations of sodium alginate and calcium chloride. A 3 % Na₂-alginate with 100 mM CaCl₂ has been found to be optimum concentration for the production of uniform synthetic seed. For germination, the synseeds were cultured on Murashige and Skoog (MS) basal medium supplemented with kinetin (KIN) and α-naphthalene acetic acid (NAA) either singly or in various combinations. MS medium containing 2.5 μM KIN in combination with 1.0 μM NAA was found to be the optimum for maximum (92.6 ± 3.71 %) plantlet conversion frequency. Well developed regenerated plantlets were hardened, acclimatized and established in field, where they grew well without any detectable variation.

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.

The shrub Chimonanthus praecox L. (wintersweet) which is native to Chinese montane forests produces its flowers in the midst of winter. This indicates that the floral organs of this species are adapted to growth and development under freezing temperatures. Here, we report the isolation and preliminary characterisation of a 33 kDa apoplastic antifreeze chitinase (CpCHT1) from the petals and its corresponding cDNA. The chitinase activity of CpCHT1 was confirmed by activity staining. Antifreeze activity was validated in terms of the formation of bipyramidal ice crystals and high thermal-hysteresis values. CpCHT1 was also found to affect the germination of fungal spores of four major plant pathogens. In addition, the gene and protein are expressed constitutively not only in flowers, but also in leaves, bark and root tissues. From these data we hypothesize that this protein is multifunctional and may protect wintersweet from freezing injury and provide nonspecific disease resistance.

The elucidation of molecular mechanisms underlying the leaf development can be facilitated by the detailed anatomical study of leaf development mutants. We present an analysis of leaf anatomy and morphogenesis during early developmental stages in has mutant of Arabidopsis thaliana. The recessive has mutation affects a number of aspects in plant development, including the shape and size of both cotyledons and leaves. The earliest developmental observations suggest almost synchronous growth of the first two leaf primordia of has mutant. No significant disruption of the cell division pattern in the internal tissue is observed at the earliest stages of development, with the major anatomical difference compared to wild type primordia being the untimely maturation of mesophyll tissue cells in has mutant. At the stage of leaf blade formation, structure disruption becomes clearly evident, by irregular arrangement of the cell layers and the lack of polarity in juvenile has leaves. One distinguishing feature of the mutant leaf anatomy is the absence of mesophyll tissue differentiation. Altered has mutant leaf morphology could be at least partially accounted for by the ectopic STM activity that was found at the base of leaf primordia during early stages of leaf development in has plants.

Direct somatic embryogenesis in celandine (Chelidonium majus L.) was achieved in epicotyl explants of seedlings after prolonged cultivation on Murashige and Skoog medium with or without plant growth regulators. Somatic embryos developed into plantlets which entered additional cycles of somatic embryogenesis. Cultures consisting of plantlets with prolonged embryogenic potential were maintained for five years on plant growth regulator free medium. Embryos which developed into rooted plantlets could be acclimated in a glasshouse enabling thus a continuous propagation scheme to be established.

1, 5, or 10 mM arginine and 25, 50, or 100 μM cysteine were added in the Murashige and Skoog medium. By increasing arginine concentration the number of shoots per explant increased. Inclusion of 50 μM cysteine in the medium resulted in maximum number of shoots but it was not significantly different in comparison to 10 mM arginine. The chlorophyll content was significantly increased in explants treated with 10 mM arginine in comparison to the control, 1 mM arginine and 25 μM cysteine. By increasing arginine and cysteine concentrations of the medium, N, K, and Ca contents of explants increased but no significant changes in P, Mg, Fe, Mn, Zn, and B contents were observed.

Protocol was developed for high frequency in vitro multiplication of an endemic species, Zingiber rubens Roxb. The sprouted buds of the rhizomes were cultured on Murashige and Skoog (MS) medium supplemented with 6-benzyladenine (BA; 0.5-5.0 mg dm^-3), indole-3-acetic acid (IAA; 0.5-2.0 mg dm^-3), kinetin (KIN; 1.0-3.0 mg dm^-3), naphthaleneacetic acid (NAA; 0.5-1.0 mg dm^-3) and adenine sulphate (ADS; 80-100 mg dm^-3). MS basal medium supplemented with 3 mg dm^-3 BA and 0.5 mg dm^-3 IAA was optimum for shoot elongation. The elongated shoots (1-2 cm) were transferred to multiplication medium containing 2 mg dm^-3 BA, 1 mg dm^-3 IAA and 100 mg dm^-3 ADS. The multiplication rate remained unchanged in subsequent subcultures. Upon ex vitro transfer, 85 % of plants survived. Genetic stability of micropropagated clones were periodically evaluated at an interval of 6 months up to 30 months in culture using random amplified polymorphic DNA (RAPD) and inter simple sequence repeat (ISSR) analysis and genetic uniformity in all regenerants was confirmed.

The growth and ion content of salt sensitive Lycopersicon esculentum Mill. cv. M82 and salt tolerant L. pennellii Correll accession LA716 were examined under both control and stress conditions (150 mM NaCl). L. esculentum grew more vigorously than L. pennellii under optimal conditions, however, L. pennellii was able to maintain its growth better than cultivated tomato when the plants were exposed to salinity. Sodium content of both L. esculentum and L. pennellii increased as a result of NaCl stress. In addition, both species showed reduced potassium and calcium content due to salinity. The physiological traits were also measured in a population of 52 L. pennellii introgression lines grown under both normal and stress conditions. A total of 311 quantitative trait loci (QTL) were identified for the studied traits: plant height, stem diameter, leaf number, leaf and root fresh and dry mass, and sodium, potassium and calcium contents. Some of the loci (124) were identified under both control and stress conditions while 86 QTL were identified only under non-stress conditions and 101 loci were identified only under NaCl stress.

The effect of 5-azacytidine (5-azaC) on the alleviation of damaging effects of NaCl treatment was studied in two wheat (Triticum aestivum L.) cultivars differing in salt tolerance (salt-tolerant Dekang-961 and sensitive Lumai-15). The plants were pre-treated or not with 50 μM 5-azaC and then subjected to salt stress induced by 100 or 150 mM NaCl. Salinity caused reduction in biomass accumulation and increase in malondialdehyde content in root tissues in both cultivars, but less in pre-treated seedlings. The activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in the roots of both cultivars increased during salt stress, but the rate of increase was higher in Dekang-961. Plants treated with 5-azaC had higher root SOD, CAT and POD activities under salt stress than untreated plants. Content of 5-methylcytosine (5mC) decreased in both cultivars under salt stress, and the level of demethylation was higher in Dekang-961 than that in Lumai-15. Moreover, the degree of methylation was lower in both cultivars under salt stress after 5-azaC application compared to only salt-treated groups. These findings suggested that 5-azaC could protect plants from salt stress.

The purpose of the present study was to investigate the in vitro and the in vivo effects of cadmium, zinc, mercury and lead on δ-aminolevulinic acid dehydratase (ALA-D) activity from radish leaves. The in vivo effect of these metals on growth, DNA and protein content was also evaluated. The results demonstrated that among the elements studied Cd²⁺ presented the highest toxicity for radish. 50% inhibition of ALA-D activity (IC₅₀) in vitro was at 0.39, 2.39, 2.29, and 1.38 mM Cd²⁺, Zn²⁺, Hg²⁺ and Pb²⁺, respectively. After in vivo exposure Cd²⁺, Zn²⁺, Hg²⁺ and Pb²⁺ inhibited ALA-D by about 40, 26, 34 and 15%, respectively. Growth was inhibited by about 40, 10, 25, and 5% by Cd²⁺, Zn²⁺, Hg²⁺, and Pb²⁺, respectively. DNA content was reduced about 35, 30, 20, and 10% for Cd²⁺, Zn²⁺, Hg²⁺, and Pb²⁺, respectively. The metal concentration in radish leaves exposed to Cd²⁺, Zn²⁺, Hg²⁺, and Pb²⁺ was 18, 13, 6, and 7 μmol g^-1, respectively. The marked ability of radish to accumulate Cd²⁺ and Zn²⁺ raises the possibility of using this vegetable as a biomonitor of environmental contamination by these metals.

The response of Arabidopsis thaliana plants to elevated sulfur dioxide could be related to their endogenous salicylic acid (SA) content and signaling. The wild type (WT, ecotype Columbia) and its mutant snc1 with high SA content, npr1-1 with a blockage in SA signaling, transgenic line nahG with low SA content and double mutant snc1nahG plants were exposed to 0.5 mm³ dm^-3 SO₂ for 3 h d^-1 for 14 d in a growth chamber. Under unstressed conditions, total SA contents in snc1 and npr1-1 were 7- and 2-fold higher than those in WT, respectively, but in nahG SA content was only 28 % of that in WT. The expression of nahG in snc1 plants decreased SA content to the WT level. Increased SA contents were observed in snc1, npr1-1 and WT after 12-h SO₂ exposure, whereas no major changes were detected in nahG and snc1nahG plants. The snc1 plants exhibited higher tolerance to SO₂ exposure than snc1nahG plants and especially nahG and npr1-1 plants according to plant biomass, total chlorophyll content and photosynthetic rate. The SO₂ exposure decreased net photosynthetic rate, maximum photochemical efficiency (F_v/F_m) and actual quantum efficiency of photosystem 2 (Φ_PS2). SO₂-induced oxidative damage in the tested plants was confirmed by increased malondialdehyde (MDA) content and electrolyte leakage. Increases in superoxide dismutase (SOD) and peroxidase (POD) activity, reduced glutathione (GSH) content and a ratio of reduced/oxidized glutathione (GSSG) might be responsible for the decreased contents of H₂O₂ and alleviation of oxidative injury in snc1 plants compared with other lines exposed to SO₂. These observations implied that endogenous SA content and signaling may play an essential role in plant responses to SO₂ stress.

The photosynthetic performance and related leaf traits of Incarvillea delavayi Bur. et Franch were studied at different water regimes to assess its capacity for photosynthetic acclimation to water stress. The initial response of I. delavayi to water stress was the closure of stomata, which resulted in down-regulation of photosynthesis. The stomatal limitation (S_L) represented the main component to photosynthetic limitations but non-stomatal limitation (NS_L) increased quickly with the increasing water stress, and had similar magnitude to SL under severe water stress (soil moisture 25-30 % of field capacity). Chlorophyll (Chl) a fluorescence parameters characterizing photosystem (PS) 2 photochemical efficiency (Φ_PS2), electron transport rate (J) and photochemical quenching (qP) decreased with the increasing water stress, indicating impaired photosynthetic apparatus. However, the water-stressed plants had a increased mesophyll CO₂ diffusional conductance, Chl a/b ratio, leaf nitrogen partitioning in RuBPCO and bioenergetics in later grown parts, indicating that I. delavay had a substantial physiological plasticity and showed a good tolerance to water stress.

A floating sterile mutant of Ulva pertusa, which grows faster than the wild type and also during summer periods, was grown in the laboratory under "white light" (WR as reference), broad band isoquantic red (600 - 700 nm, RR) and blue (400 - 500 nm, BR) radiation. The observed specific growth rates at WR, BR, and RR were 8.6, 2.15, and 1.2 %, respectively. A stimulatory effect of BR on the growth at low irradiance (60 μmol m-2 s-1) was observed during the 15 d of culture. Around 42.1 % of total nitrogen was used by Ulva mutant in WR, but under BR and RR it was around 27.0 and 16.7 %, respectively. However, the utilization of nitrogen under BR was significantly higher than under RR. Considerable CO2 fluctuation in the light and dark periods was observed in all the cultures, and it was higher under WR, followed by BR and RR. The possible growth promoting effect of BR includes nitrogen uptake and the consumption of HCO3- which in turn leads to reduced air CO2 concentration in the medium.

Plantain (Musa ABB CEMSA 3/4) plantlets were micropropagated in temporary immersion bioreactors (TIB) or in gelled medium (GM). After ex vitro transfer ROS accumulation was determined by infiltrating leaves with nitroblue tetrazolium (NBT) and 3,3'-diaminobenzidine (DAB). Stomatal cells were more stained with NBT and DAB in GM plants than in TIB plants, but the difference disappeared at the end of acclimatization. At the end of the in vitro phase, GM plantlets showed higher activities of ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR), while activities of catalase (CAT), superoxide dismutase (SOD) and glutathione transferase (GT) were higher in TIB grown plantlets. At the end of acclimatization GT, SOD, CAT and MDHAR stabilized at low values of activity in plantlets derived from both treatments. Concerning the correspondent genes, GM plantlets showed higher expression of all transcripts with the exception of CuZnSOD. The immunobloting of peroxiredoxins (PRXs) showed that chloroplast-located PRXs were expressed at higher levels in TIB plantlets, some showing polymerization. In conclusion, TIB grown plantlets had an improved anti-oxidative response when compared with GM.

Arabidopsis thaliana plants (wild type accessions Col and N1438) were grown in nutrient solution for 34 d with or without 50 mM NaCl. Salt stress inhibited plant growth rate more in Col than in N1438 and a decrease in K⁺, Ca²⁺ and nitrogen contents was observed in both accessions. NaCl diminished accumulation of malate, fumarate and citrate only in Col accession. To measure the effect of NaCl on transcript level of superoxide dismutase (SOD) isoforms and copper chaperone for SOD genes, a semi-quantitative polymerase chain reaction (RT-PCR) method was developed using cDNA normalized against the EF1a gene in parallel with quantitative real time RT-PCR (Q-PCR) technique. Both methods gave the same results. The abundance of transcripts of the three genes coding for Cu/Zn-SOD responded similarly to NaCl in both accessions: CSD1 gene was overexpressed, and CSD2 and CSD3 genes were repressed. However, the genes coding for Fe-SOD (FSD1), Mn-SOD (MSD1) and Cu-chaperone for SOD (CCS) responded to NaCl differently in Col and N1438: the former gene was overexpressed in Col and repressed in N1438, and the opposite behaviour was observed for the latter two genes.

LAF1 (Long after far-red radiation 1) is a R2R3 Myb transcription factor and a signal transducer of far-red radiation. To investigate the role of LAF1 in leaf and root development, the leaf growth and vein patterning in laf1 mutants under short day conditions were examined. The length of rosette leaves was reduced and the width of the midvein was increased in laf1 mutants compared to their wild-type (WT) counterparts. In addition, cell size and cell number were both decreased in the laf1 mutant in comparison to the WT plant. A comparative analysis of gene expression showed that the transcript levels of PIN and IAA genes, encoding auxin carrier and response proteins, were decreased in laf1 mutants. LAF1 expression was also shown to be induced by 1-naphthaleneacetic acid. These results suggest that both auxin transport and auxin responses are impaired in laf1 mutants, and that LAF1 is involved in the regulation of leaf and root development mediated by auxin signaling under short day conditions.

A floating green alga Ulva pertusa Kjallman was grown in the laboratory under various irradiations: "white light" (as reference, broad spectral band, WLC), red radiation (600-700 nm, RRC) and blue radiation (400-500 nm, BRC). During 15 d of culture, the specific growth rate of WLC varied highly when compared to BRC and RRC. The contents of chlorophyll (Chl) and proteins, and the nitrate reductase (NR) activity were significantly higher in BRC than in RRC while the content of saccharides was slightly higher in RRC than BRC. U. pertusa in WLC had the highest contents of saccharides, proteins, and Chl, and the highest NR activity. In the WLC, closely arranged well organized thylakoids were seen whereas in the BRC, although the number of thylakoid layers was similar to WLC, they were widely separated from each other. In contrast to this, in the RRC, the thylakoids were less prominent and were also densely covered with ribosomes.