AP2 (APETALA2)/EREBPs (ethylene responsive element binding proteins) are the primary members of a family of transcription factors and OsAP211 was isolated from Oryza sativa L using the yeast one-hybrid system. It can specifically bind to the promoter containing three tandem repeats of DRE core sequence: TACCGACAT and activate the transcription of the downstream lacZ gene in the yeast one-hybrid system. OsAP211 contained a single open reading frame of 225 amino acids and encoded a protein containing a conserved AP2/EREBP domain featuring the DREB family. The semi-quantitative RT-PCR (s-Q RT-PCR) analysis indicated OsAP211 was strongly induced by low temperatures but not by NaCl and drought. It accumulates primarily in shoot tips during the tillering stage and young spikes during the booting stage. OsAP211 might function as a DRE-binding transcription factor in stress signal transduction pathways in rice.

A simple and reliable regeneration system from leaf bases of barley (Hordeum vulgare L.) has been developed. The in vitro regeneration frequencies of seven commercial barley genotypes were compared using segments from the first leaves of 5-d-old seedlings. The regeneration frequency ranged from 31.56 to 72.22 % among the barley genotypes. Murashige and Skoog medium supplemented with 6-benzyladenine (0.5 mg dm^-3) and kinetin (0.5 mg dm^-3) was optimum for the regeneration. Longitudinal cut of the segments or the removal of coleoptiles further increased plantlet regeneration frequency.

In 7-d-old seedlings of Brassica juncea chromium (VI) promoted photosystem 2 (PS 2) mediated photoreactions. The increase in PS 2 activity in the thylakoids from Cr-treated seedlings, in the presence of uncoupler (5 mM NH₄Cl), was similar to that recorded with the control thylakoids. Thus Cr enhanced PS 2 activity was not due to uncoupling of electron transport from photophosphorylation. Photon saturation kinetics revealed that the PS 2 activity of thylakoids from Cr-treated seedlings was significantly higher at almost all irradiances in comparison to that of controls. PS 2 activity of thylakoids from Cr-treated plants at 25 % of the saturating irradiance was in par with the PS 2 activity of the thylakoids from control plants at saturating irradiance. Thylakoids from both control and Cr-treated seedlings exhibited maximum PS 2 activity at pH 7.5. The PS 2 activity of thylakoids from Cr-treated plants remained high even at pH 8.0 and 8.5, demonstrating Cr enhances tolerance of PS 2 to alkaline pH.

Forty one simple sequence repeats were isolated from two microsatellite enriched libraries of date palm (Phoenix dactylifera L.). After screening, 17 selected microsatellite loci were characterized and evaluated on a set of 31 cultivars and clones from Algerian and Californian germplasm. All primer pairs produced an amplification product of the expected size and detected high polymorphism among the analysed samples. These nuclear simple sequence repeat (SSR) markers are expected to be a very effective tool for evaluating genetic diversity in date palm germplasm. Acrosstaxa amplification showed the usefulness of most SSR markers in 14 other species across the genus Phoenix.

In order to better understand the role of cold acclimation in alleviating freezing injury, two barley cultivars with different cold tolerance, i.e. a sensitive cv. Chumai 1 and a tolerant cv. Mo 103, were used. The freezing treatment increased leaf soluble protein content more in the tolerant cultivar than in the sensitive one. Cold acclimation increased H₂O₂ content of the two cultivars during freezing treatment, especially in Mo 103. Glutathione and ascorbate contents during freezing and recovery were significantly higher in cold-acclimated plants than in non-acclimated ones. Activities of peroxidase, ascorbate peroxidase and glutathione reductase were also higher in cold-acclimated plants than non-acclimated plants during freezing treatment. However, there was no significant difference between cold-acclimated plants and the control plants in catalase activity. It may be assumed that cold acclimation induced H₂O₂ production, which in turn enhanced activities of antioxidative enzymes and synthesis of antioxidants, resulting in alleviation of oxidative stress caused by freezing.

An efficient micropropagation protocol for annatto (Bixa orellana L.) was achieved using nodal shoot tip explants. Shoot buds were obtained on the Murashige and Skoog (MS) medium supplemented with various concentrations and combinations of indole-3-acetic acid (IAA), N⁶-benzyladenine (BA) and triacontanol (TRIA). Maximum of 213 shoot buds along with 18 primary shoots were produced on MS medium containing 0.05 µM IAA, 8.87 µM BA, and 11.2 µM TRIA. The primary shoots elongated best on MS medium containing 6.66 µM BA and 2.45 µM indole-3-butyric acid (IBA). The regenerated shoots rooted best on MS medium supplemented with 4.9 µM IBA. The in vitro rooted plantlets were hardened and establishment rate under field conditions was 70 to 80 %.

In order to evaluate effects of γ-rays on adventitious root formation and ginsenoside production, embryogenic calli induced from cotyledon explants of Panax ginseng C.A. Meyer were treated with γ-rays of 0, 10, 30, 50, 70, and 100 Gy. The highest frequency of adventitious root formation of 75 % occurred at γ-irradiation of 30 Gy, which is considered adequate dosage for selecting mutant cell lines. Five mutated adventitious roots (MAR)3-lines out of the propagation of 142 adventitious root lines treated with 30 Gy were selected based a 100-fold increase in proliferation rate compared to control adventitious roots (CAR) and content of the seven major ginsenosides (Rb₁, Rb₂, R_c, R_d, R_e, R_f, and Rg₁) was determined. In the CAR and four of the MAR3-lines (except for MAR3-109), the Rb/Rg ratio was greater than 1.0, thereby indicating altered ginsenoside composition in these root lines. The HPLC analysis of the MAR3-13 and MAR3-26 lines confirmed different ginsenoside profiles, including the three unidentified ginsenoside candidates, Gm₁, Gm₂, and Gm₃. The ginsenosides of the MAR3-13 and MAR3-26 lines showed high hydroxyl and superoxide radical scavenging activities.

Specific activities and isoform patterns of peroxidases, acid phosphatases, DNases and RNases were studied in relation to in vitro rooting of Petunia × hybrida microshoots in the presence of 4 µM indole-3-butyric acid (IBA). Specific activities of the above enzymes increased in the course of rooting. Rhizogenesis could be related with an increased specific activity of peroxidases during the initiation phase, in parallel with increased lignin content. Twelve peroxidases, six anionic (A1-A6) and six cationic (C1-C6), seven acid phosphatases (ACP1-ACP7), seven RNases (R1-R7) and four DNases (D1-D4) isoforms were detected following native PAGE. Variation in the number of the above isoforms and their quantity was observed during different stages of rooting. Particularly, A2, A3, C3, C4, C5, ACP2, R1, R2, R3, and D4 isoforms appeared after the induction phase and could be related to emergence of root primordia. Additionally, R3 and D4 could be associated with cell division and differentiation, since these are only expressed in rooted microshoots. Moreover, the higher number of roots in IBA-treated microshoots could be related to the higher expression of RNase and DNase isoforms during initiation and expression phases.

In order to study chloroplast biogenesis, we chose natural variegated Epipremnum aureum (golden pothos) and regenerated pale yellow, variegated and green plants from all three types of tissue explants. The percentage of three types of regenerated shoots from three different explants was very close. Regenerated plants have been maintained for a year and show no sign of a colour switch. By comparing their protein profiles, two major differences between pale yellow and green plants were observed at the 15 and 40 to 50 kDa proteins. Moreover, pale yellow plants had unexpected high molecular mass proteins (greater than 60 kDa). Both variegated and green plants had more chlorophyll (Chl) a than Chl b, the ratios were about 1.46 and 1.93, respectively. In contrast, the pale yellow plants not only had less total Chl, but also the reduction of Chl a was much greater than Chl b, resulting in a higher content of Chl b than Chl a. Microscopic analysis revealed that pale yellow plants contained predominantly undeveloped chloroplasts with low Chl contents, even though their mesophyll cells were similar to green and variegated plants. PCR amplification of chloroplast DNA with 14 universal chloroplast primers did not reveal any difference among these regenerated plants.

Twenty accessions of the sparsely cultivated diploid Musa cultivars Matti (AA) and Rasakadali (AB) were subjected to random amplified polymorphic DNA (RAPD) assay. A total of 14 random primers were used for the estimation of interand intracultivar variations. Out of 86 bands generated, 64 were polymorphic (74.4 % polymorphism). The cluster analysis grouped the cultivars into two major clusters: cluster I with 10 accessions of Matti and 2 of Rasakadali and cluster II comprising the remaining 8 accessions of Rasakadali. The coefficient of genetic similarity (GS) was from 0.73 to 0.99, suggesting low level of intercultivar variation. The accessions of Rasakadali with mean GS of 0.89 were genetically more diverse than those of Matti (GS = 0.93).

The possible involvement of nitric oxide in response of Solanum nigrum seedlings to Fe deficiency was investigated. Iron deficiency resulted in decreased shoot height and chlorophyll content and increased proliferation of root hairs and H₂O₂, K⁺ and Ca²⁺ content. NO donor S-nitrosoglutathione (GSNO) was effective in preventing Fe deficiency-induced increase in content of H₂O₂ and the ion uptake. The protective effects of GSNO were reversed by cPTIO, an NO scavenger, and tungstate, a nitrate reductase (NR) inhibitor.

β-1,3-Glucanase activity was detected in extracts of different tissues of healthy mature petunia flowers except the filament. The stigma was studied further as it had the highest enzyme activity and there is a paucity of information on the occurrence of this enzyme in this tissue. Specific activity of the enzyme was found to increase within the stigmatic tissue from early development until just before anthesis. Following non-denaturing polyacrylamide gel electrophoresis at pH 8.8, extracts of dehiscent stigma seem to contain three acidic isoforms of β-1,3-glucanase. Crude extracts of stigma was passed through a pachyman affinity column. A fraction of affinity-purified active β-1,3-glucanase enzyme was found to have no antifungal activity against Trichoderma viride, Phloma clematidina and Cladosporium fulvum.

The effect of in vitro cultivation of donor shoots on subsequent morphogenesis in leaf explants of quince (Cydonia oblonga Mill.) clone BA29 was investigated. Proliferating donor shoots were cultured in ventilated or closed vessels under different photosynthetic photon flux densities (PPFD; 200 and 100 µmol m^-2 s^-1) with 0, 15, 30 g dm^-3 sucrose. Shoots grown in ventilated vessels, especially with sucrose at 15 or 30 g dm^-3, were better developed with fully expanded leaves compared to those in standard closed vessels. Leaves collected from pre-treated donor shoots were used to assess regeneration capacity. Somatic embryo production was highest in leaves harvested from shoots cultured in closed vessels with 30 g dm^-3 sucrose and in ventilated vessels with 15 and 30 g dm^-3 sucrose and under high PPFD which was, in comparison with the control treatment (closed vessel, 30 g dm^-3 sucrose and low PPFD), about 2 to 2.5 times higher. A similar response was observed for root regeneration.

Anthocyanin accumulation and expression pattern of anthocyanin biosynthesis genes were investigated in developing coleoptiles of wheat (Triticum aestivum L.). In epidermal cell layers of the growing coleoptiles of cv. Hope, anthocyanins started to accumulate between day 2 and 3 after germination, reached their maximum on day 6 and then decreased while another cultivar, Chinese Spring (CS) did not accumulate anthocyanin pigments. None of the six anthocyanin biosynthesis genes was upregulated in coleoptiles of both cvs. grown in the dark, whereas all genes were activated by light in coleoptiles of cv. Hope. Transcript levels of all the six genes were relatively low on day 2, increased from days 3 to 5 and then declined to almost non-detectable levels on day 6. In coleoptiles of CS grown in the light, the early biosynthesis genes (EBGs) were expressed, but the three late biosynthesis genes (LBGs) were not.

A rapid and efficient plant regeneration protocol for a wide range of alfalfa genotypes was developed via direct organogenesis. Through a successive excision of the newly developed apical and axillary shoots, a lot of adventitious buds were directly induced from the cotyledonary nodes when hypocotyl of explants were vertically inserted into modified Murashige and Skoog (MS) medium supplemented with 0.025 mg dm^-3 thidiazuron (TDZ) and 3 mg dm^-3 AgNO₃. When the lower part of shoots excised from explants were immersed into the liquid medium with 1.0 mg dm^-3 α-naphthaleneacetic acid (NAA) for 2 min, and then transferred to hormone free half-strength MS medium, over 83.3 % of the shoots developed roots, and all plantlets could acclimatize and establish in soil. The protocol has been successfully applied to eight genotypes, with regeneration frequencies ranging from 63.8 to 82.5 %.

In this study, photosynthetic performance, pigment content, chlorophyll a fluorescence, and leaf anatomy in peanut (Arachis hypogaea) subjected to zinc (Zn) stress were investigated. Zn stress resulted in reduction of photosynthetic and transpiration rates, pigment contents and root biomass. Zn-induced xerophyte structure in peanut leaves (i.e. thick lamina, upper epidermis, and palisade mesophyll, as well as abundant and small stomata) also contributed to decreased transpiration rate and stomatal conductance. This in turn, partially contributed to the limitation of photosynthesis.

The objective of this study was to determine the development of the antioxidant enzymes induced by drought stress in white clover (Trifolium repens L.) leaves. Water stress was imposed during 28 d by decreasing the daily irrigation. Leaf water potential (Φ_w) gradually decreased from -0.46 to -2.33 MPa. For the first 7 d, dry mass (DM), H₂O₂ and lipid peroxidation were not significantly affected by water deficit. From 14 d of treatment, water stress decreased dry mass and increased content of reactive oxygen species (O₂ ^.- and H₂O₂) and oxidative stress (malondialdehyde content). The ascorbate peroxidase (APOD) was activated most rapidly, already during the first week of water stress, but then its activity slowly decreased. Activation of superoxide dismutase (SOD) and catalase (CAT) by water deficit continued during the 14 d (Φ_w ≥ -1.65 MPa) and then their activities remain on the similar level. The activity of guaiacol-peroxidase (GPOD) increased mostly under progressive water stress and was correlated with increase in lipid peroxidation and growth restriction.

Cuttings from two contrasting Populus cathayana Rehder populations originating from Hanyuan (wet climate) and Ledu (dry climate) in western China were grown in a greenhouse to determine the effects of drought, shade and their interaction on the morphological and physiological traits of leaves. The dry climate population was more droughttolerant than the wet climate population, as indicated by smaller decreases in the leaf relative water content (RWC) and net photosynthetic rate (PN), as well as by greater increases in antioxidative enzyme activities and free proline content under drought. On the other hand, the negative effects of shade on leaf traits were more pronounced in the dry climate population, which suggested that the dry climate population was more light-demanding. In addition, moderate shade alleviated the drought stress of P. cathayana not only by improving the leaf RWC but also by maintaining the positive carbon balance. In contrast, severe shade aggravated drought stress as indicated by a pronounced decrease in leaf size, carbon and nitrogen contents, maximum PN, free proline content and antioxidative enzyme activities.

An attempt has been made to determine if drought-induced proteins could be used as a selection marker to differentiate between tolerant and sensitive cultivars. Three Indian tomato (Lycopersicon esculentum Mill.) cultivars (Pusa Ruby, Arka Vikas and Pusa Early Dwarf) were subjected to drought stress in vivo as well as in vitro and the pattern of polypeptide expression was determined using one-dimensional SDS-PAGE. In all the three cultivars, a new 29 kDa polypeptide accumulated in leaves, in response to gradual drought stress and its accumulation was fastest in Pusa Ruby. Drought stress also resulted in an increase in ion leakage from leaf discs of all the three cultivars but the rate was lower in Pusa Ruby than in other two. Therefore, it was concluded that Pusa Ruby is most tolerant to drought stress among the three tomato cultivars investigated.

To reveal the maternal donor of species in genus Kengyilia, the chloroplast trnL-F sequences of 14 Kengyilia species and several related diploid species were analyzed by using Maximum Parsimony (MP) and Bayesian Inference (BI) methods. The species in Kengyilia were clustered in different clades, which indicated that Agropyron (P) is the likely maternal genome donor to Kengyilia melanthera, K. mutica and K. thoroldiana, while the maternal donor to Kengyilia batalinii, K. nana, K. kokonorica, K. kaschgarica, K. hirsuta, K. alatavica, K. gobicola, K. zhaosuensis, K. rigidula, K. longiglumis and K. grandiglumis was St or Y Roegneria genome.

Changes in hydraulic conductivity (K_h) and pH were measured in stem segments of laurel (Laurus nobilis L.) during perfusion with iso-osmotic solutions of KCl, NaCl and sucrose. Sucrose had no effect on K_h while 100 mM NaCl or KCl induced up to 22 and 35 % increase of K_h with respect to deionized water, respectively. Increases in K_h were accompanied by a sharp drop in pH from 6.0 (inlet solution) to 5.0 (outlet solution). The same effect was observed with both KCl and NaCl solutions but not in the case of sucrose. Also, similar changes of K_h and pH were observed for stems killed after immersion in hot water. Our results might provide further evidence for ion-mediated regulation of xylem hydraulic conductivity based on the hydrogel properties of pectins at the pit membrane level.

Occurrence and genomic organization of dispersed elements containing ZpS1 satellite repeats have been investigated in a wide representation of species of the old plant genus Zamia (Zamiaceae, Cycadales). In Z. paucijuga, the ZpS1 repeat is organized as long satellite DNA arrays and as short arrays inserted into AT-rich dispersed elements. A comparative study by Southern analysis shows that these unusual dispersed elements containing the ZpS1 repeat are present with different organizations in all investigated Zamia species. In some species these elements are present with a low copy number, while in other species secondary amplification events, involving specific sequence clusters, appear to have generated characteristic dispersed elements in a high copy number. Among Zamia species, several groups share similar restriction patterns, as the Zamia loddigesii complex and the Caribbean species suggesting a general correlation between organization and genomic representation of the dispersed repeated sequence and the pattern of phyletic relationships in the genus. However, the finding of different patterns also among closely related species suggests a complex history of amplifications and losses of these dispersed repetitive elements that cannot be always easily traced through the phylogenetic reconstruction of this ancient plant group.

Shoot and root mass of tobacco plants treated with only 0.05 µM boron was decreased by 25 and 50 %, respectively, when compared to plants sufficiently supplied with B (2 and 5 µM). Leaf B content of 0.05 µM B-treated plants decreased (about 80-90 %) when compared to 2 µM B treated plants; this drop of B content were not as marked (about 25-45 %) in roots. Leaf and root nitrate contents in B-deficient plants were 45-60 % and 35-45 % lower, respectively, than those from 2 and 5 µM B treated plants. It is suggested that B deficiency might decrease nitrate uptake rather than nitrate reductase activity in tobacco plants.

In the present study, we investigated tiller formation in rice cultivated under red radiation (R), red supplemented with 10 % of blue radiation (RB), and white radiation (W). In addition, expression of three genes related to tiller formation, OSH1, MOC1, and OsTB1, was analyzed at both vegetative and reproductive stages. RB promoted the outgrowth of tiller buds and increased tiller numbers significantly. Transcription of MOC1 and OsTB1 in RB was higher than in R, whereas OSH1 expression was independent on radiation quality.

In red clover (Trifolium pratense L.) four unique cDNAs encoding phenylalanine ammonia lyase (PAL, EC 4.3.1.5) were identified (PAL1-4). PAL2-4 encode nearly identical proteins (> 97 %) that are only 89 % identical to that encoded by PAL1. Under normal growing conditions, in young leaves and flowers PAL1 mRNA accumulates to higher levels than that of PAL2-4 whereas in mature leaves and stems, mRNA levels are similar for PAL1 and PAL2-4. Treatment of red clover seedlings with yeast elicitor preparation results in an approximately six-fold induction of PAL2-4 transcripts within 1 h of treatment but only a modest induction of PAL1 transcripts. These results suggest that while both classes of enzymes play a role in biosynthesis of phenylpropanoid compounds under normal growing conditions, PAL2-4 enzymes are also involved in pathogen defense responses.

After identifying regions of cDNA conserved between the symbiotic gene DMI1 of the model species Medicago truncatula and the homologous genomic region of Arabidopsis thaliana, universal primers were designed from 8 of 12 exons to allow the routine amplification of plant homologs. As an example, the complete homologous sequence from the pea (Pisum sativum L.) was amplified and sequenced, although the poorly conserved 5'-end and 5'-flanking region of the gene had to be amplified using a modified TAIL-PCR strategy. The identity of this amplified homolog with the SYM8 gene was independently confirmed by the presence of a single nucleotide change in the coding sequence of the mutant line Risnod27 (sym8) that cosegregated with the asymbiotic phenotype. Five insertions in pea introns responsible for increasing the total length of SYM8 by 1443 bp, compared to the M. truncatula homolog DMI1, belong to known transposon and retrotransposon families of pea and legumes in general. In view of the predicted function of SYM8 as an ion channel, the Risnod27 mutation (His309Tyr) appears to be localized in the selectivity filter domain. This finding confirms the essential role of histidine 309 in the symbiotic function of SYM8 and provides a guide to its ionic specificity. In view of the Risnod27 symbiotic phenotype, we hypothesize that SYM8 does not have identical functions in the transduction of rhizobial and mycorrhizal signals. The variability of the N-proximal region of the known legume homologs of DMI1 suggests an interaction with a variable ligand.

The effect of esculetin and some related coumarins (coumarin, 7-hydroxycoumarin and scopoletin) on growth of pumpkin (Cucurbita maxima Duch.) seedlings and the activities of pumpkin glutathione S-transferases (GSTs) were investigated. Coumarin and esculetin affected the growth of seedlings. The hypocotyls of affected seedlings became weak and bent at the mid region, roots became very soft with brownish discoloration, and finally seedlings died. Among the compounds tested, only esculetin inhibited CmGSTU3 and CmGSTU2 activities measured with 1-chloro-2,4-dinitrobenzene (CDNB) and at a concentration of 22 µM, it inhibited the activity of CmGSTU3 by 50 %.

The leaves of axenically grown Coleus blumei were inoculated with Agrobacterium rhizogenes strain A4 and hairy root were established. PCR and Southern hybridization analysis confirmed transgenic nature of hairy root clones. Cultures of normal roots, induced by α-naphthaleneacetic acid on leaf explants, and hairy roots were evaluated for growth and rosmarinic acid content. Significantly better growth and up to 2.8 higher amount of rosmarinic acid was detected by HPLC analysis in hairy root clones. Methyl jasmonate stimulated rosmarinic acid accumulation in 6 out of 11 tested clones, while yeast extract induced RA accumulation in two and diminished it in 5 out of 11 tested hairy root clones.

The response of Camellia sinensis (L.) O. Kuntze cultivars Chinary and Assamica to Cu and Al stresses was investigated. Exposure to 100 µM CuSO₄ or 100 µM AlCl₃ led to accumulation of reactive oxygen species (ROS) more in Assamica than in Chinary. Proline content was higher in Chinary compared to Assamica, while chlorophyll and protein contents decreased upon Cu and Al exposure in both the cultivars. Expression of glutathione biosynthetic enzymes γ-glutamylcysteinyl synthetase (γ-ECS) and glutathione synthetase (GSHS) was elevated. Phytochelatin synthase (PCS), an enzyme involved in phytochelatins synthesis by using glutathione as a substrate was up-regulated at its transcript level more in Chinary than in Assamica. These results suggest that Chinary could be more tolerant than Assamica.