Agave tequilana Weber is a monocot plant species member of the Asparagaceae family. One of the characteristics of monocot species is that their embryos show only one cotyledon. In this work, the occurrence of embryos with two cotyledons and fused cotyledons in A. tequilana is reported for the first time. The occurrence of dicotyledonar embryos in a species that by definition should have only one cotyledon could bring an opportunity to elucidate the mechanisms that have given the origin to the only one cotyledon present in monocots. Syncotyly is considered in this work as the possible mechanism that gave rise to the only cotyledon mostly present in this species.

The current work compared the physiological characteristics of plantain (Musa AAB) plantlets micropropagated in temporary immersion bioreactors (TIB) and on a gelled medium (GM). The plantlets were evaluated during in vitro growth (in the shoot elongation phase) and at the end of ex vitro acclimatization. TIB improved rooting and gave rise to longer shoots and higher dry mass. Respiration rate was the highest at the beginning of shoot elongation in both the TIB and GM plantlets. Photosynthetic rate in TIB was significantly higher than in GM from the midpoint of acclimatization, whereas a pyruvate kinase (PK) activity was lower. Starch accumulation was ca. two fold higher in corms than in leaves and always higher in the TIB than GM plantlets. The higher expression of genes coding for carbon metabolism enzymes PK and phosphoenolpyruvate carboxylase (PEPC) in TIB than in PM indicates a more important role of an autotrophic metabolism in the TIB plantlets when compared to the GM ones. The accumulated reserves were used during the first days of acclimatization leading to the higher survival rates and to the better plant quality of the TIB plantlets.

Somatic embryos were obtained from immature zygotic embryos of Cedrela fissilis Well. (Meliaceae), after a culture period of 12 months, with regular subcultures every 6-8 weeks. Callus was developed on explants in 2 months on Murashige and Skoog (MS) medium containing 2,4 dichlorophenoxyacetic acid (2,4-D) or picloram (PIC). When the calli were transferred to fresh medium, embryogenic tissue appeared on MS + 45 µM 2,4-D, or 22.5 µM 2,4-D + 0.4 µM 6-benzyladenine (BA), or 20.7 µM PIC after 6 months. Sub-culture of embryogenic tissue in MS medium supplemented with 4.5 µM 2,4-D resulted in the differentiation into somatic embryos after further 4 months. Repeated secondary somatic embryogenesis was achieved by regular subculture on this medium. Maturation and conversion of somatic embryos into plantlets was achieved on MS medium without plant growth regulators and the conversion frequency was approximately 12.5 %. The plantlets were successfully acclimatized in pots with soil. Histological studies showed that somatic embryos had no detectable connection with the mother explants and that somatic embryos in advanced stages were bipolar with shoot and root apical meristems, they contained vascular system and showed typical characteristics of a somatic dicotyledonous embryo.

Five in vitro culture systems with different ventilation rates were used to investigate the influence of vessel environment on photosynthesis, dark respiration, ethylene evolution, and rosmarinic acid (RA) production in sweet basil (Ocimum basilicum L.) micropropagated shoots. The systems under comparison were two bioreactors with either temporary (RITA™) or stationary (Growtek™) immersion, and three types of vessels (Magenta™, Microbox ECO ₂ ™, and PCCV25™) that are largely used for plant micropropagation. Shoots of green-leaved cv. Genovese and purple-leaved cv. Dark Opal were cultured on a modified Murashige and Skoog medium containing 0.25 mg dm^-3 6-benzylaminopurine. The instantaneous rates of photosynthesis, dark respiration, and ethylene production were determined by gas chromatography measuring CO₂ and ethylene concentrations in vessel headspaces. The tissue RA content was determined by HPLC in HCl-methanol extracts. The explant growth and morphology were significantly affected by culture conditions and cultivars. The largest biomass production was observed under the photomixotrophic culture conditions provided by Growtek™, whereas the highest RA content in shoot tissues was found in the RITA™ photomixotrophic system, where ethylene accumulated to the greatest extent.

Plant vacuoles play several roles in controlling development, pathogen defence, and stress response. γVPE is a vacuolarlocalised cysteine protease with a caspase-1 like activity involved in the activation and maturation of downstream vacuolar hydrolytic enzymes that trigger hypersensitive cell death and tissue senescence. This work provides evidence that γVPE is strongly expressed in Arabidopsis guard cells and is involved in water stress response. The γvpe knock-out mutants showed reduced stomatal opening and an increased resistance to desiccation suggesting a new role of γVPE in control of stomatal movements.

Feverfew (Tanacetum parthenium) is a medicinal plant belonging to the Asteraceae family. To improve understanding terpene metabolism in feverfew, the relative gene expression of four key genes coding 3-hydroxy-3-methylglutarylcoenzyme A reductase (HMGR) and germacrene A synthase (GAS) from the mevalonic acid pathway (MVA), as well as 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR) and hydroxy-2-methyl-2-(E)-butenyl-4-diphosphate reductase (HDR) from the methyl erythritol phosphate pathway (MEP), were examined. Target organs and tissues included young leaves (not fully expanded), mature leaves (fully expanded), flowers, stems, roots, and glandular trichomes. HMGR, DXR, and HDR were isolated and sequenced for the first time in feverfew. Real-time quantitative PCR analysis revealed differential expression of these genes in feverfew tissues and developmental stages.

Water transport across the cell membranes is regulated largely by a family of proteins known as aquaporins (AQPs). Plasma membrane intrinsic protein (PIP) is an important subfamily of plant AQPs localized on the plasma membrane. To investigate the molecular mechanism of water regulation in seed germination, seven genes encoding PIP were initially cloned and sequenced from the germinating seed cDNA pool of Brassica napus. They belong to the PIP1 and PIP2 subfamilies. The transcription of the seven cloned genes plus three previously identified AQP genes from B. napus were analyzed in different organs and different stages of seed germination by quantitative real-time PCR (qRT-PCR). The results show that the expressions of the ten AQP genes were lower or scarcely detected in dry seeds, but were up-regulated during germination as well as in young seedlings. In addition, the expression of these ten AQP genes in response to an abiotic stress during seed germination was investigated and the results also show differential responses to abiotic stress treatments. Our findings suggest that these ten genes play different roles during plant development and response to abiotic stresses in B. napus.

Durum wheat (Triticum turgidum L. var. durum) is mainly produced under rainfed but often sub-optimal moisture conditions in the Mediterranean basin. A set of 114 durum wheat recombinant inbred lines (RILs) developed from the cross of cultivars Omrabi5 × Belikh2 were tested for the ability to tolerate moisture deficiency at the germination and early seedling growth stage. The stress was imposed by exposing the germinating grain to 12 % polyethylene glycol. It induced a measurable reduction in root length, shoot length, and the percentage of normal seedlings. The germination and seedling growth of Belikh2 were more strongly inhibited than those of Omrabi5, and both parents were outperformed by > 50 % of the RILs. A quantitative trait locus (QTL) analysis was carried out by first assembling a linkage map from 265 informative microsatellites. Composite interval mapping revealed nine QTL spread over seven chromosomes. Five of these were associated with coleoptile length, and one of the five explained nearly 29 % of the relevant phenotypic variance. The coleoptile length was significantly correlated with the seedling growth, plant height, and thousand kernel mass derived from field-grown plants of the same RIL population.

The ZEITLUPE (ZTL) protein is involved in the control of circadian period, hypocotyl elongation and flowering time in Arabidopsis thaliana. The aim of the present work was the identification of the InZTL gene and localization of its mRNA in the model short-day plant Ipomoea nil. The deduced InZTL protein of 622 amino acid residues contained a LOV domain at the N-terminal part, followed by an F-box domain and six carboxy terminal kelch repeats. Amino acid sequence of InZTL showed 84 % homology with Mesembryanthemum crystallinum ZTL (McZTL) and 83 % with Arabidopsis thaliana ZTL (AtZTL). Fluorescence in situ hybridization (FISH) to InZTL mRNA showed its high accumulation in the vascular bundles as well in the guard cells of the cotyledon. Immunolocalization of ZTL protein indicated a similar distribution pattern of ZTL protein as InZTL mRNAs.

Understanding the molecular basis of polarity induction in plant cells is a research aspect that extends from signal perception and transduction to morphogenesis. A gradient of cytoplasmic ion fluxes generated through ion channels plays a crucial role in subsequent events leading to polar growth. Convincing evidence is now available implicating temporal and spatial distribution of Ca²⁺ in cytoplasm, generated by localized activity of calcium channels, as the early biochemical events associated with polarity induction. Ion channel antagonists are common tools for studying ion channel structure and function. Coupled with a fluorescent dyes, calcium channel antagonists (phenylalkylamine and dihydropyridine), have been used to localize L-type calcium channels. Additionally, the advent of Confocal Laser Scanning Microscopy has made possible the visualization of Ca²⁺ channels in plant cells. Persisting problems of dye loading and their cellular compartmentation have been addressed by developing a variety of experimental protocols. Present article highlights the current state of our understanding of these concepts, methodologies and their applications in different aspects of plant development.

An efficient in vitro plant regeneration system has been developed using dark preincubated leaf explants of Rhodiola crenulata, a traditional Tibetan medicinal plant. The leaf explants, preincubated in the dark for 5 d, developed an average of 9.1 shoots per explant on a medium containing 15 μM N ⁶-benzyladenine (BA) and 2.5 μM gibberellic acid (GA₃). The biochemical mechanism underlying dark-induced shoot organogenesis was investigated by measuring polyphenol oxidase (PPO) activity. Dark preincubation significantly reduced PPO activity in leaf explants during the initial period of shoot organogenesis and reduced browning compared to explants cultured in the light. Up to 88.4 % of the regenerated shoots formed roots and developed into complete plantlets on a medium containing 5 μM indoleacetic acid (IAA) within 25 d. Approximately 82 % of the regenerated plantlets survived transplantation and grew vigorously in the greenhouse.

During the first year of hybrid poplar development, we assessed radial growth dynamics quantified by the proportion of secondary xylem tissue within the stem area, the vessel area percentage, the content of both lignin and cellulose, the lignin monomeric composition, and the macromolecular properties of cellulose. The intraannual radial growth dynamics in the proportion of secondary xylem tissue was fitted by the Gompertz regression line whereas changes in the vessel area percentage were fitted maximally by a cubic regression line. Under constant temperature and photoperiod, this study revealed that nonlinear patterns of radial growth dynamics are the result of a developmental programme which drives cambial activity and ageing. The increased proportion of guaiacyl units found may be important for the greater stability of the lignin structure in the first year of hybrid poplar development. The tensile strength of juvenile wood was ensured by the trade-off between a slight increase in the degree of polymerization of cellulose and a slight decrease in the content of cellulose during ageing.

Proteins WCS120 and DHN5 are known as the major cold-inducible dehydrins in wheat and barley plants, respectively. WCS120 and DHN5 relative accumulation increased exponentially along with a growth temperature decline in the range from optimum to cold temperatures. Even at optimum growth temperatures, the most frost-tolerant wheat and barley cultivars can be distinguished from the remaining ones according to dehydrin relative accumulation. The highly tolerant wheat and barley cultivars started accumulating dehydrins at higher growth temperatures and reached higher dehydrin amounts than the less tolerant ones. Statistically significant correlations between lethal temperature for 50 % of the samples (LT50) and dehydrin relative accumulation have been found at all growth temperatures (5, 10, 15 and 20 °C) for WCS120 in wheats and at 5 and 10 °C for DHN5 in barleys. Analogous relationships between dehydrin relative accumulation at different growth temperatures and plant acquired frost tolerance have been proved for wheat WCS120 and barley DHN5.

In order to produce human lactoferrin (Lf) in alfalfa (Medicago sativa L.), a construct containing human Lf cDNA under the control of cauliflower mosaic virus 35S promoter was engineered. As selectable marker bar gene, whose expression in plant cells confers tolerance to L-phosphinothricin (ppt) was used. Plants from a highly embryogenic alfalfa clone from the Bulgarian cultivar Obnova 10 were transformed using Agrobacterium tumefaciens mediated leaf disc method. Transgenic alfalfa plants were established from ppt-resistant calli via indirect somatic embryogenesis. The presence of human Lf cDNA in the genome of the selected regenerants was confirmed by polymerase chain reaction (PCR). Reverse transcriptase (RT)-PCR and Western blot showed expression of human Lf in leaf tissue. Studies on antibacterial effect of the recombinant glycoprotein were conducted and resistance of the transgenic alfalfa plants to two phytopathogens, Pseudomonas syringae pv. syringae and Clavibacter michiganensis, was demonstrated. The obtained results suggest that the expression of human Lf in alfalfa could be beneficial not only for producing recombinant protein for clinical application but also for crop quality improvement.

Isoflavone synthase (IFS; CYP93C) plays a key role in the biosynthesis of phenolic secondary metabolites, isoflavonoids. These compounds, which are well-known for their benefits to human health and plant defence, are produced mostly in legumes. However, more than 200 of them have been described in 59 other plant families without any knowledge of their respective IFS orthologue genes (with the sole exception of sugar beet). In this study, we selected IFS from Pisum sativum L. (CYP93C18) for functional expression. CYP93C18 was isolated, cloned, and introduced into Arabidopsis thaliana. The presence of the gene was shown by Southern blot analysis and its expression in the transgenic Arabidopsis was proven by RT-PCR and Western blots. The functional activity of the heterologous IFS was verified by HPLC-MS analysis of the metabolite levels: the isoflavone genistein and its derivatives tectorigenin and biochanin A were detected in the overexpressing lines. In addition, 35S::CYP93C18::GFP fused proteins were transiently expressed in the leaves of Nicotiana benthamiana and the localization of the GFP signal was observed on the endoplasmic reticulum using confocal microscopy which is consistent with the data from the literature and with our in silico predictions. The putative mode of attachment of IFS to the endoplasmic reticulum membrane is suggested. The undemanding methodology presented in this paper is applicable to the functional analysis of newly-identified isoflavone synthase genes from various species.

Information on plant responses to combined ozone and cadmium stresses are scarce and limited to herbaceous species. In this research, two poplar clones (I-214 and Eridano), differently sensitive to O₃, were grown for 5 weeks in pots supplied with 0, 53.5, and 160.5 mg(Cd) kg^-1 (soil d.m.) and then exposed to 15-d O₃ fumigation (0.06 mm³ dm^-3, 5 h a day). The effects of the two stressors, alone or in combination, on Cd, Ca, Fe, and Zn accumulation in above-nad below-ground organs, photosynthesis, leaf pigments, and accumulation of H₂O₂ and NO were investigated. Cadmium induced a reduction in stomatal conductance and a significant accumulation of H₂O₂ and NO in both clones nad negatively affected the carotenoid content in I-214. Ozone, on the other hand, counteracted Cd accumulation in the above-ground organs and significantly increased the xanthophyll de-epoxidation state indicating photoinhibition in O₃-treated plants. Surprisingly, O₃ alone or in combination with Cd decreased H₂O₂ accumulation in I-214. The NO production was generally stimulated by Cd, whereas it decreased following O₃ exposure in I-214. The overall data indicate that Cd and O₃ induced clone specific responses. Moreover, when they were applied in combination, antagonistic rather than synergistic effects were observed.

Annexins play a crucial role in plant development and response to environmental stimuli. In this study, a total of 23 annexin genes (GmANN1 - GmANN23) were identified from the soybean genome database and for two of them (GmANN11 and GmANN14), complete cDNAs were cloned. GmANN1 - GmANN23 encoded a set of predicted proteins which showed high similarity to other known annexins. Most GmANN genes contained four putative annexin repeats. Generally, a type II Ca²⁺-binding site is found to exist in the first and fourth repeats. GmANN1, 10, 11, 12, and 14 showed different organ-specific expression patterns. Furthermore, expression of these five GmANNs was significantly induced by drought and abscisic acid. Expression of four annexins (GmANN1, 11, 12, and 14) was induced by cold and expression of three annexins (GmANN1, 11, and 12) responded to high salinity.

6-Methoxy-2-benzoxazolinone (MBOA) inhibited germination of rice (Oryza sativa L.), wheat (Triticum aethiopicum Jakubz), rye (Secale cereale L.), onion (Allium cepa L.), wild oat (Avena fatua L.), barnyard grass [Echinochloa crus-galli (L.) Beauv.], ryegrass (Lolium rigidum Gaudin), cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), tomato (Lycopersicum esculentum Mill.), carrot (Daucus carota L.) and amaranth (Amaranthus retroflexus L) and the inhibition increased with increasing MBOA concentrations. MBOA also inhibited the induction of α-amylase in these plant seeds and the inhibition increased with increasing MBOA concentrations. There were variations in sensitivity of these plant species to MBOA, and species of family Poaceae (barnyard grass, wild oat, rice, rye, ryegrass, and wheat) were less sensitive to MBOA than the other plant species.

The experiment was conducted to identify the response of three cultivars of okra [Abelmoschus esculentus (L.) Moench] to exogenous hormones [gibberellic acid-(GA₃) and prohexadione-Ca] applied as foliar spray. Stem and leaf dry masses and stem length were significantly enhanced by the application of exogenous GA₃, but prohexadione-Ca inhibited growth. Control and prohexadione-Ca treated okra plants took more time to bloom than did GA₃ treated plants. In the fruits of all the cultivars a decrease in fructose content was observed, while protein content remained almost unchanged after the application of the two growth regulators. The small changes in chlorophyll a fluorescence characteristics observed under prohexadione-Ca suggested a weakening of the photochemical processes near the photosystem 2 reaction centre. The lowering of ratio between maximum time to reach maximum fluorescence, F_m (T_max) and Area (sum of F_m-F_t for t = 0 to t = T_max) caused by GA₃ was probably due to the increase of Area rather than to changes in T_max.

Frost tolerance of ten Bulgarian winter wheat (Triticum aestivum L.) cultivars (Milena, Pobeda, Sadovo-1, Enola, Kristal, Laska, Svilena, Russalka, No301 and Lozen) and five foreign cultivars (Mironovskaya 808, Bezostaya-1, Rannaya-12, Skorospelka-35 and Chinese Spring) was studied in two experimental seasons following natural cold acclimation and in one experiment carried out in controlled acclimation conditions. Considerable intercultivar variability in plant survival was observed after freezing at -21 °C following sufficient cold acclimation, or at -18 °C following insufficient or controlled acclimation. In seven cultivars, the effects of chromosome 5A on frost tolerance were investigated in their F₂ hybrids with chromosome 5A monosomic lines of cultivars with high, intermediate and low frost tolerance. The effects of chromosome 5A depended on the stress severity and the genetic background of the hybrids and varied even in cultivars of similar frost tolerance and vernalization requirements. Effects of other chromosomes besides 5A on frost tolerance were assumed. The analysis of six microsatellite loci located in the interval from centromere to Vrn-1 on of chromosomes 5AL, 5BL and 5DL showed that the major loci determining frost tolerance in Bulgarian winter wheats were Fr-A2 on chromosome 5AL, and, to a lesser extent, Fr-B1 on chromosome 5BL. A strong association of the 176 bp allele at locus wmc327 tightly linked to Fr-A2 with the elevated frost tolerance of cvs. Milena, Pobeda, Sadovo-1, Mironovskaya-808 and Bezostaya-1 was revealed. Relatively weaker association between frost tolerance and the presence of the 172 bp allele at locus Xgwm639 tightly linked to Fr-B1 was also observed.

The pollen tube grows rapidly, exclusively at its tip, to deliver its sperm for fertilization. The polarized tip growth of pollen tubes is dependent on the highly dynamic actin cytoskeleton. Plant LIM proteins (named after initials of containing proteins Lin11, Isl-1, and Mec-3) have been shown to regulate actin bundling in different cells, however, their roles in pollen tube growth have remained obscure. Here, we report the function of Arabidopsis LIM proteins PLIM2a and PLIM2b in pollen tube growth. The PLIM2a mutation resulted in short and swollen Arabidopsis pollen tube with defective actin bundles. The expression of the construct green fluorescent protein (GFP)-PLIM2b led to fluorescence of the actin bundles in germinating pollen and also the long actin bundles along the growing pollen tubes in Arabidopsis, but not of the short and sparse actin bundles that characterize the tip regions of the pollen tubes. There is a partially redundant function between PLIM2a and PLIM2b in the shank actin bundle organization during Arabidopsis pollen tube growth, as PLIM2b could rescue for the defective shank actin bundles in PLIM2a mutation pollen tubes. This report suggests critical roles of PLIM2a/PLIM2b in actin configuration during Arabidopsis pollen germination and tube growth.

Effects of phosphorus and thiourea application (either alone or in combination) were studied on clusterbean (Cyamopsis tetragonoloba Taub.) plants subjected to water stress by withholding irrigation at pre- and post-flowering stages in pot culture trial. Water stress significantly decreased shoot water potential, relative water content of leaves, net photosynthetic rate, contents of total chlorophyll, starch and soluble proteins as well as nitrate reductase activity at both the growth stages. Application of phosphorus and thiourea or combined application increased most of these parameters. Results revealed synergistic effects of P and thiourea in enhancing net photosynthesis, leaf area, chlorophyll content and nitrogen metabolism leading to significant improvement in plant growth and seed yield under water stress condition.

Using aseptic plantlets obtained from stem node explants of hybrid red miniature rose (Rosa hybrida cv. Fairy Dance), the effects of shoot physiological status, medium ingredients, and culture thermoperiod on in vitro flowering were evaluated. Shoot height, subculture media for shoot multiplication, sucrose concentration, plant growth regulators (PGRs), mineral substances in media, and thermoperiod had a significant effect on the percentage of in vitro flowering. Shoots 3 ± 0.2 or 2 ± 0.2 cm in height cultured on Murashige and Skoog (MS) medium containing 2.0 mg dm^-3 6-benzyladenine (BA), 0.2 mg dm^-3 α-naphthaleneacetic acid (NAA), and 20 g dm^-3 sucrose were more suitable for in vitro flowering than shoots 4 ± 0.2, or 5 ± 0.2 cm in height. The most suitable sucrose concentration for in vitro flowering was 50 g dm^-3 and the most suitable PGRs were a combination of 3.0 mg dm^-3 BA and 0.1 mg dm^-3 NAA. Increasing the potassium nitrate to ammonium nitrate ratio or increasing the phosphate concentration in MS medium had a positive effect on in vitro flowering. The percentage of in vitro flowering was significantly higher at day/night temperature of 28/20 °C than at other constant temperatures. The percentage of in vitro flowering shoots reached 68.33 % despite the occurrence of abnormal flowers and some unique developmental patterns. It makes miniature rose a potentially new in vitro experimental platform for research on the molecular mechanisms of flowering ornamental plants.

Callus cultures initiated from shoot base explants of Curcuma aromatica Salisb. were maintained on Murashige and Skoog (MS) media supplemented with 2 mg dm^-3 2,4-dichlorophenoxyacetic acid alone or with 0.5 mg dm^-3 kinetin. Plantlets were regenerated from 60 and 180-d-old callus on MS media supplemented with 3 mg dm^-3 benzyladenine and 0.5 mg dm^-3 α-naphthalene acetic acid. Approximately 8-10 plantlets were produced after 30-40 d of culture per 50 mg of callus inoculated. Out of 113 regenerants analyzed 85 plants were exclusively diploid and 28 were predominantly diploid revealing presence of polyploid nuclei. Frequency of polyploid cells were more in regenerants obtained from 180-d-old callus then from 6-d-old callus which might be attributed to the ageing of callus.

Actin is the most abundant protein in eukaryotic cells and is a key cytoskeletal component controlling cell morphology and motility. In this study, four MiACT genes were isolated from mango by homological cloning and designated as MiACT1, MiACT4, MiACT7, and MiACT9. Sequence alignments and phylogenetic analysis demonstrated that the four MiACT genes of mango were highly similar to each other at the nucleotide and amino acid levels. All of four MiACT proteins showed high similarity to the known actin proteins from other species. Reverse transcription polymerase chain reaction revealed that the four MiACT genes were constitutively and stably expressed in all organs tested. Application of plant growth regulators and four stress treatments had a remarkable effect on the expression of MiACT4, MiACT7 and MiACT9, whereas expression of MiACT1 was unresponsive. In contrast, the expression profiles of the four MiACT genes were not regulated by diurnal rhythms. Moreover, the expression of MiACT1 was not affected by heavy metal treatments and the transcript level of MiACT1 was rather stable in different days during the post-harvest period either under treatment or not. Our results suggest that the four actin genes play important roles throughout the entire life cycle of mango; the constitutively and stably expressed MiACT1 is the best candidate as an internal standard for differential gene expression analysis in mango.

Treatment with 0.5 mM salicylic acid (SA) significantly alleviated growth inhibition induced by drought in wheat seedlings, manifested by less decreassed fresh mass, dry mass, plant height, root length, and less increased lipid peroxidation. Under drought stress, SA significantly increased the content of ascorbate (ASA) and glutathione (GSH). We determined the full-length cDNA sequences of genes encoding the glutathione-S-transferase 1 (GST1) and 2 (GST2) and we also measured the transcription of eight genes related to ASA-GSH cycle. The results indicated that exogenous SA significantly enhanced the transcription of GST1, GST2, glutathione reductase (GR), and monodehydroascorbate reductase (MDHAR) genes during almost the entire drought period, but only increased those of dehydroascorbate reductase (DHAR) at 12 h, glutathione peroxidase (GPX1) at 48 h, phospholipid hydroperoxide glutathione peroxidase (GPX2) at 12 and 24 h, and glutathione synthetase (GSHS) at 12, 24, and 48 h. This implies that SA alleviates the detrimental effects of drought stress on wheat seedling growth by influencing the ASA-GSH cycle.

Recently, the truncated hemoglobin gene (trHb) was discovered in plant species, however, its role has not yet been determined. In this study, the gene expression of wheat trHb (TatrHb) was analyzed under various biotic and abiotic stresses. TatrHb transcript levels increased in NaCl-treated leaves and gibberellic acid (GA₃)-treated roots. In addition, sodium nitroprusside (SNP), a nitric oxide donor, induced an increase in TatrHb transcript levels in roots and leaves. A yeast two-hybrid assay (YIIH) was used to screen a hypoxia-treated wheat seedling library with the goal of determining the putative function of TatrHb. In this YIIH assay, photosynthesis-related genes that showed high homology to the Hordeum vulgare chloroplast photosystem I PSK-I subunit and Zea mays photosystem II subunit PsbS1 were detected and their interactions with TatrHb were confirmed. Subcellular localization of a TatrHb-green fluorescent protein (GFP) fusion protein and bimolecular fluorescence complementation (BiFC) assay suggested that TatrHb is involved in photosynthesis. The TatrHb-GFP fusion protein was localized in the plastids and the yellow fluorescent protein signal indicated that the TatrHb protein interacted with PSK-I and PsbS1 in the chloroplast.

In vitro morphogenetic ability of plant cells has been demonstrated in diverse species of angiosperms and gymnosperms but no such report is available in the genus Selaginella till date. We have established an in vitro morphogenic root culture where indole butyric acid (IBA) induced profuse branched and unbranched roots in Selaginella microphylla. We observed inter-convertibility of root apical meristem (RAM) to shoot apical meristem (SAM) in presence of IBA and showed that intact roots are also capable of transformation. Friable callus was obtained from roots on prolonged (∼50 weeks) root cultures. By isolating total RNA from each of the developmental stages, we performed cDNA synthesis followed by random amplification, sequencing, and BLAST analysis of differentially expressed transcripts to correlate morphological events with the changes on molecular level. The results revealed sequence matches to genes involved in diverse cellular processes such as transcription, translation, photosynthesis, replication, secondary metabolism, stress response, and plant defense suggesting ancient origins of such proteins and the evolutionary conservation of biological function.

Calcium is a critical component in a number of plant signal transduction pathways and the calcineurin B-like protein (CBL) family is a unique group of calcium sensors regulating a family of CBL-interacting protein kinases (CIPKs). In this study, two poplar CBL genes, PeCBL6 (GenBank acc. No. DQ907710) and PeCBL10 (GenBank acc. No. DQ899956), were characterized in transgenic Arabidopsis thaliana, particularly with regard to its role in abiotic stress resistance. Expression of the two CBL genes in poplar was induced by cold, drought, or high salinity, but not by abscisic acid (ABA) treatment. In Arabidopsis thaliana, PeCBL6 was found in the nucleus and PeCBL10 in the tonoplast. Transgenic Arabidopsis plants overexpressing PeCBL6 or PeCBL10 showed enhanced tolerance to high salinity, drought and low temperature. These results suggested that PeCBL6 and PeCBL10 may function as positive regulators of salt, drought and temperature responses.

Diploid wheat Triticum monococcum L. is a model plant for wheat functional genomics. Chlorophyll-deficient mutant (clm1) was identified during manual screening of the ethyl methanesulphonate (EMS)-treated M₂ progenies of T. monococcum accession pau14087 in the field. The clm1 mutant, due to significantly decreased chlorophyll content compared with the wild-type (WT), exhibited pale yellow leaves which slowly recovered to green before flowering. The clm1 mutant showed early flowering, reduced number of tillers, trichome length and density, and different shape as compared with the WT. At the same time, clm1 mutant culm had more chlorophyll-containing parenchymatous tissues compared to WT, presumably to absorb more sunlight for photosynthesis. Genetic analysis indicated that the clm1 mutation was monogenic recessive. The clm1 mutant was mapped between Xgwm473 and Xwmc96 SSR markers, with genetic distances of 2.1 and 2.6 cM, respectively, on the 7A^mL chromosome.