Photosynthetic organisms synthesize the amphipathic antioxidants called tocopherols which are essential components of the human diet. To increase the α-tocopherol (vitamin E) content, Arabidopsis genes encoding homogentisate phytyltransferase (HPT) and tocopherol cyclase (TC) were constitutively expressed individually and in combination (HPT:TC) in tobacco plant by Agrobacterium mediated transformation. The transgene was confirmed by polymerase chain reaction (PCR), transgene expression was studied by reverse transcriptase (RT)-PCR, integration of the transgene in the plant genome was confirmed by Southern blot, and α-tocopherol content was quantified using high performance liquid chromatography (HPLC). The α-tocopherol content in transgenic tobacco plants expressing HPT, TC, and HPT:TC was increased by 5.4-, 4.0-, and 7.1-fold, respectively, when compared to the wild type (WT). These results indicate that, the HPT and TC activities are critical for enhancing the vitamin E content in tobacco plants.

Molecular farming provides a powerful tool for low cost production of recombinant proteins with pharmaceutical value. The use of transgenic plants has been increasingly tested as alternative system for obtaining biologically active human lactoferrin in plants. Precise selection of plant species, transformation techniques and expression cassettes, in addition to conduction of detailed glycosylation and immunogenicity studies, serves as basis of obtaining safe recombinant human lactoferrin in high concentrations for the use of pharmacy. On the other hand, expression of antimicrobial protein lactoferrin in plants is a promising opportunity for crop quality improvement by increasing plant disease resistance.

In the previous research, a novel gene GmPOI (GenBank acc. No. HM235775) encoding a Pollen_Ole_e_I conserved domain was identified in roots of soybean drought resistant cv. Jindou 23. In the present study, GmPOI was cloned and functionally characterized. Real-time quantitative PCR indicated that the expression of GmPOI was induced by drought, cold, salt and abscisic acid in wild-type soybean. The soybean plants overexpressing GmPOI showed higher tolerance to drought stress than wild types. We concluded that GmPOI is probably a novel gene that is involved in the response to various stresses in soybean.

A gene (named BcFLC1) homologous to the AtFLC gene, which encodes a floral repressor, was isolated from the nonheading Chinese cabbage (Brassica campestris L. ssp. chinensis) cv. NJ074. The gene showed high similarity to AtFLC. For studying the gene function, we designed to introduce the BcFLC1 gene into Arabidopsis thaliana. The results showed that BcFLC1 had effects on flowering time similar to AtFLC. We also found that Arabidopsis cold-tolerance was enhanced by BcFLC1 overexpression. Under low temperature stress, the BcFLC1 transgenic plants exhibited stronger growth than wild-type plants. The elevated cold tolerance of the BcFLC1 over-expressing plants was also confirmed by the changes of electrolyte leakage and malonyldialdehyde and proline content.

Drought stress enhances the production of superoxide radical (O₂ ^._) and superoxide dismutase catalyses dismutation of it to H₂O₂ and O₂, and hence provides a first line of defense against oxidative stress. Over-expression of a cytosolic copper-zinc superoxide dismutase, cloned from Potentilla atrosanguinea (PaSOD), in potato (Solanum tuberosum ssp. tuberosum L. cv. Kufri Sutlej) resulted in enhanced net photosynthetic rates (P_N) and stomatal conductance (g_s) compared to that in the wild type (WT) plants under control (irrigated) as well as drought stress conditions. Drought stress declined leaf water potential, P_N, g_s, photosystem II activity, and chlorophyll content, but increased proline and O₂ ^._ content more in WT than transgenic potato plants (SS5). The significantly higher SOD activity in SS5 coincided well with lower O₂ ^._ content suggesting its role in maintaining higher g_s and P_N in transgenic potato plants.

Transgenic rice (Oryza sativa L. subsp. indica cv. White Ponni) constitutively expressing the rice thaumatin-like protein gene (tlp-D34, PR-5) individually or in combination with the rice chitinase gene (chi11, PR-3) was generated using an Agrobacterium vir helper strain with multiple copies of pTiBo542 virB and virG. Transformation with the tlp-D34 gene alone and tlp-D34 + chi11 genes yielded five and seven single-copy transgenic lines, respectively. Southern blot analysis with two probes, one flanking the right T-DNA border and the second flanking the left T-DNA border, confirmed that all transgenic plants harboured single and complete T-DNA copies. Homozygous transgenic lines were first identified in the T₁ generation by Southern blot analysis and were subsequently confirmed by segregation analysis of T₂ plants. Accumulation of transcripts encoded by the transgenes was confirmed in T0 plants and homozygous T₂ plants by Northern blot analysis. The homozygous T2 plants harbouring tlp-D34 + chi11 genes showed 2.8- to 4.2-fold higher chitinase activity. Western blot analysis revealed the accumulation of thaumatin-like protein and chitinase in the respective transgenic plants. Upon infection with Rhizoctonia solani, the disease index reduced from 100 % in control plants to 65 % in a T₃ homozygous transgenic line T4 expressing the tlp-D34 gene alone. In a T2 homozygous transgenic line CT22 co-expressing tlp-D34 and chi11 genes, the disease index reduced to 39 %.

A minimal gene cassette comprised of the ubiquitin (Ubi) promoter + green fluorescent protein (Gfp) gene + Nos terminator DNA sequences, derived from the plasmid vector pPZP201-Gfp was utilized for transformation of creeping bentgrass using particle bombardment. Bentgrass calli bombarded individually with equivalent amounts of the cassette or whole plasmid DNA were compared for Gfp expression and the GFP-positive calli were subsequently regenerated into plants. Percentage of GFP expressing calli and the number of GFP spots/calli were significantly higher in calli that were bombarded with the minimal gene cassette when compared to the whole plasmid. The Gfp expression was stable up to the T₂ generation in minimal gene cassette transformants and there was a lower degree of gene silencing. Southern blot analysis of transgenic plants derived from minimum gene cassette bombardment revealed the presence of single or few copy of the transgene and fairly simple integration patterns. In comparison, whole plasmid transformants had multiple copies and complex integration patterns of the transgene. These results illustrate the advantages of using simple gene cassette for stable plant transformation in bentgrass with possible applications to other plant species.

Six genes, which encode enzymes involved in ascorbic acid (AsA) biosynthesis, including guanosine diphosphate (GDP)-mannose pyrophosphorylase (GMP), GDP-mannose-3',5'-epimerase (GME), GDP-galactose guanylyltransferase (GGT), L-galactose-1-phosphate phosphatase (GPP), L-galactose dehydrogenase (GDH) and L-galactono-1,4-lactone dehydrogenase (GLDH) were transformed into Arabidopsis thaliana, to evaluate the contribution of each gene to AsA accumulation. Additionally, two combinations, GGT-GPP and GGT-GLDH, were co-transformed into Arabidopsis with a reliable double-gene transformation system. AsA content of GGT transgenic lines was 2.9-fold higher as compared to the control, and co-transformation led up to 4.1-fold AsA enhancement. These results provided further evidence that GGT is the key enzyme in plant AsA biosynthesis.

Soil salinity is a major abiotic stress and salt overly sensitive (SOS) pathway plays an important role in imparting tolerance to salinity by reinstating cellular ionic equilibrium. Salt overly sensitive 1 (SOS1) gene of SOS pathway has been implicated in increasing salt tolerance in plants. In this study, a 734 bp fragment of SOS1 promoter (SbUSOS1) was isolated from a halophyte Salicornia brachiata Roxb. In silico analysis of SbUSOS1 predicted several cis-acting regulatory elements such as DOF motif, GT elements, ABRE-like sequence, and root specific motifs. Functional validation of SbUSOS1 into tobacco stems and leaves using the GUS reporter gene showed that this promoter is induced by salt stress (250 mM NaCl) but not by ABA (500 μM) and cold (4 °C) stresses. This study indicated that SbUSOS1 was functional with predicted cis-acting elements that could be responsible for its salt-inducible nature. It can be used for the development of salt stress tolerant transgenic plants.

The Arabidopsis thaliana (L.) Heynh. atExt1 extensin gene is expressed in a cell and tissue-specific manner, in response to developmental cues, and is inducible by a wide range of biotic and abiotic stresses. Over-expression of this gene has been shown to alter stem morphology and to limit the invasiveness of virulent bacterial pathogens, indicating that this cell wall protein gene plays an important role in plant development and defense. A detailed sequence analysis of 3.2 kb of the atExt1 gene promoter region has identified a large number of putative 5'cis-acting elements. Based on the location of clusters of putative promoter control elements, seven atExt1 5' promoter truncations were constructed, fused upstream of the β-glucuronidase (GUS) reporter gene, and transformed into A. thaliana. Transgenic plants carrying the various promoter constructs were challenged by wounding and pathogen attack and analysed for GUS expression - this analysis revealed a complex pattern of regulation, involving positive and negative control regions. Northern analysis using wounded tissues from transgenic Arabidopsis plants carrying the 3.2 kb-promoter::GUS construct confirmed the transcriptional activation of the transgene.

Transgenic plants of Tricyrtis hirta carrying the intron-containing β-glucuronidase (GUS) gene under the control of the CaMV35S promoter have been cultivated for two years. Four independent transgenic plants produced flowers 1-2 years after acclimatization, and all of them contained one copy of the transgene as indicated by inverse polymerase chain reaction (PCR) analysis. All the four transgenic plants showed stable expression of the gus gene in leaves, stems, roots, tepals, stamens and pistils as indicated by histochemical and fluorometric GUS assays, although differences in the GUS activity were observed among different organs of each transgenic plant. No apparent gus gene silencing was observed in transgenic T. hirta plants even after two years of cultivation.

The response of higher plants to ionising radiation depends on factors related to both radiation properties and plant features including species, cultivar, age, and structural complexity of the target organ. Adult plants of dwarf tomato were irradiated with different doses of X-rays to investigate possible variations in leaf morpho-anatomical traits, photosynthetic efficiency, and genomic DNA. In order to assess if and how responses depend on leaf developmental stage, we analysed two types of leaves; nearly mature leaves (L1) and actively developing leaves (L2), whose lamina size corresponded to 70 and 25 %, respectively, of the lamina size of the fully expanded leaves. The results show that the X-rays prevented full lamina expansion of the L2 leaves at all doses and induced early death of tissue of plants irradiated with doses higher than 20 Gy. Most anatomical modifications were not clearly dose-dependent and the radiation-induced increase in phenolic compounds was irrespective of dose. At high doses of X-rays (50 and 100 Gy), photochemical efficiency decreased significantly in both leaf types, whereas total chlorophyll content significantly decreased only in the L2 leaves. The random amplification of polymorphic DNA data show that the X-rays induced mutagenic effects in the L2 leaves even at low doses despite the absence of severe phenotypic alterations. Genetic structure found in the population of samples corroborates the results of anatomical and eco-physiological analyses: the 20 Gy dose seems to mark the threshold dose above which genetic alterations, structural anomalies, and perturbations in the photosynthetic apparatus become significant, especially in the actively expanding leaves.

As key nuclear transcription factors, the ethylene-insensitive3/EIN3-like (EIN3/EIL) proteins play important roles in ethylene signal transduction pathway in various plants. In order to better understand the role of EIN3/EILs, one EIN3-like gene (designated ZmEIL1) was isolated from maize (Zea mays L.). The full-length cDNA of ZmEIL1 was 1 999 bp in length and encoded 647 amino acids. Sequence comparison of ZmEIL1 protein with other EIN3/EILs proteins revealed high conservation of five α-helices that could form a V-shaped cleft in a 3-D model, just like AtEIL3 in Arabidopsis thaliana. This protein showed transcriptional activation and activation domain located on the 507 - 647 amino acids in yeast. Furthermore, ZmEIL1 could interact with ZmERF1 in the yeast systems, which was downstream response factor in ethylene signal transduction pathway. Its mRNA could be highly induced in maize seedlings by ethephon and 1-methylcyclopropene treatments. Meanwhile, ZmEIL1 showed relatively high expression at 20 d after pollination in maize kernel. These results show that ZmEIL1 played an important role in the growth and development by participating in ethylene signalling pathway in maize.

Multiple allele-inherited male sterility has been widely used by breeders of Brassica rapa L. ssp. pekinensis, but the molecular mechanisms of male sterility are not yet clear. In this study, we isolated the full-length cDNA of a new gene (not included in the Brassica database). This gene, comprising 1 054 bp, encodes a 39.99 kDa protein with a Gly-Asp- Ser-Leu (GDSL)-lipase domain that is a member of the lipolytic protein GDSL family. The sequence of candidate gene is the most similar to extracellular lipase 6 (EXL6) of Arabidopsis and was therefore designated BrEXL6 and submitted to NCBI (accession No. JX131630.1). Reverse transcription semi-quantitative PCR and Western blot analysis showed that BrEXL6 and its encoded protein were significantly more expressed in fertile buds than in sterile buds. Quantitative PCR and in situ hybridization showed that BrEXL6 was highly expressed in the anthers of fertile buds, especially anthers at the pollen-development stages, but only weakly expressed in other tissues and floral organs of fertile plants and whole sterile plants. These results suggest that BrEXL6 is a pollen development-related gene. The results of this study provide clues for understanding the mechanisms underlying multiple allele-inherited male sterility.

The anatomic and functional leaf characteristics related to photosynthetic performance of Castanea sativa growing in vitro and in nursery were compared. The irradiance saturated photosynthesis in in vitro grown plantlets was significantly lower compared to nursery plants (65 vs. 722 μmol m^-2 s^-1). The maximum photosynthetic rate (P_Nmax) was 4.0 and 10.0 μmol(CO₂) m^-2 s^-1 in in vitro microshoots and nursery plant leaves, respectively. Carboxylation efficiency (C_E) and electron transport rate (ETR) were three-folds higher in nursery plants than in microshoots. The nonphotochemical quenching (NPQ) was saturated at 80 μmol m^-2 s^-1 in microshoots suggesting limited photoprotection by thermal dissipation. The microshoots had wide open, spherical stomata and higher stomatal density than nursery plants and they had almost no epicuticular wax. Consequently, the microshoots had high stomatal conductance and high transpiration rate. These anatomic and functional leaf characteristics are likely major causes of the low survival rates of plantlets after ex vitro transfer.

Zea mays L. is less tolerant to drought than Sorghum bicolor L. In the present study, we investigated the response of both plants to drought stress applied under field conditions by withholding water for 10 d. The plant growth in terms of shoot fresh and dry masses was more severely reduced in maize than in sorghum, consistently with reduction of leaf relative water content. Gas exchange was also more inhibited by drought in maize than in sorghum. The water use efficiency (WUE) of maize fluctuated during the day and in response to the drought stress. In contrast, sorghum was able to maintain a largely constant WUE during the day in the well-watered plants as well as in the stressed ones. Studying the expression of four aquaporin genes (PIP1;5, PIP1;6, PIP2;3, and TIP1;2) revealed that PIP1;5 in leaves and PIP2;3 in roots were highly responsive to drought in sorghum but not in maize, where they might have supported a greater water transport. The expression pattern of PIP1;6 suggests its possible role in CO₂ transport in control but not droughty leaves of both the plants. TIP1;2 seemed to contribute to water transport in leaves of the control but not droughty plants. We conclude that PIP1;5 and PIP2;3 may have a prominent role in drought tolerance and maintenance of WUE in sorghum plants.

Selenium (Se) is an essential trace element for humans and animals. A hydroponic experiment was performed to study the effects of sulphur (S) on Se uptake, translocation, and assimilation in wheat (Triticum aestivum L.) seedlings. Sulphur starvation had a positive effect on selenate uptake and the form of Se supplied greatly influenced Se speciation in plants. Compared with the control plants, Se uptake by the S-starved plants was enhanced by 4.81-fold in the selenate treatment, and selenate was readily transported from roots to shoots. By contrast, S starvation had no significant effect on selenite uptake, and selenite taken up by roots was rapidly converted to organic forms and tended to accumulate in roots. X-ray absorption near edge spectroscopy (XANES) analysis showed that organic forms of selenium, including selenocystine, Se-methyl-selenocysteine (MeSeCys), and selenomethionine-Se-oxide, were dominant in the plants exposed to selenite and accounted for approximately 90 % of the total Se. Whereas selenate remained as the dominant species in the roots and shoots exposed to selenate, with little selenate converted to selenite and MeSeCys. Besides, sulphur starvation increased the proportion of inorganic Se species in the selenate-supplied plants, but had no significant effects on Se speciation in plants exposed to selenite. The present study provides important knowledge to understand the associated mechanism of Se uptake and metabolism in plants.

Genes encoding plant WRKY transcription factors are important for stress response. In the current study, two WRKY transcription factor genes (JrWRKY6 and JrWRKY53) were identified from walnut (Juglans regia L.), and their function and involvement in stress responses were characterized. Under NaCl stress, JrWRKY6 and JrWRKY53 were upregulated in a short time (within 6 h of seedling exposure to salt) except in roots, in which the highest induction occurred at 24 and 48 h of salt exposure. The gene expression patterns under polyethylene glycol stress were similar to those under NaCl stress. Under heat stress, both genes were induced in all tissues, except for JrWRKY6 in leaf tissue of seedlings treated for 24 and 48 h. Both genes were also induced in all plants exposed to cold stress, except for JrWRKY6 in root tissue of seedlings exposed for 6 h and JrWRKY53 in root tissue exposed for 48 h. JrWRKY6 and JrWRKY53 also showed varied responses to abscisic acid (ABA), with the maximum expression being for JrWRKY6 in the roots of plants treated for 1 h, and JrWRKY53 in the leaves of plants treated for 3 h. Furthermore, under NaCl, sorbitol, heat, cold, and ABA treatments, yeast cells transformed with JrWRKY6 and JrWRKY53 showed an improved growth activity and density relative to the empty-vector-containing control yeast. Moreover, JrWRKY6 or JrWRKY53 could bind to the W-box motif. These results suggest that JrWRKY6 and JrWRKY53 can response positively to abiotic stressors and improve the plant tolerance to salinity, osmotic stress, and abnormal temperatures in a mechanism that likely involves the ABA signalling pathway and W-box binding activity.

Both lignin and silicon (Si) are major players in the resistance of plants to mechanical stress (MS). Focusing on the phenolic metabolism, here we studied the short-term effects of a local MS on tobacco (Nicotiana rustica L. cv. Basmas) plants with Si (+Si, 1 mM Na₂SiO₃) and without Si (‒Si) treatments in order to see how Si may modify local and systemic responses. One week after starting the Si treatment, a half of the plants were exposed to a mechanical pressure applying 980 Pa for 24 h on the upper side of the 3^rd leaf of each plant (+MS). The rest of the plants remained unstressed (‒MS). Plants were harvested 24 h and 72 h after starting the MS and the leaves directly exposed to the mechanical stress (DMS) and those indirectly exposed to the mechanical stress (IMS) from below and above the DMS leaf were analyzed for phenolic metabolism along with the corresponding leaves from‒MS plants. In the DMS leaf, the activities of polyphenol oxidase, phenylalanine ammonia lyase, and cytosolic and covalently-bound peroxidases increased by the MS, while decreased by Si. In accordance with this in the DMS leaf, the content of soluble and cell wall-bound phenolics and lignin were enhanced by the MS but decreased by Si. Interestingly, Si influenced the pattern of response to the MS depending on whether the leaves were directly treated by the MS or not. Silicon treatment augmented MS-induced lignin accumulation in the DMS leaf while rather inhibited lignin formation in the IMS leaves. These data show that Si modified MS-mediated changes in the phenolic metabolism differently in local and systemic leaves.

The present study was conducted to examine differential responses of roots and leaves of Artemisia annua to different arsenic concentrations (50, 100, and 150 μΜ) and treatment durations (1, 3, 5, or 7 d). The values of bioconcentration factor and translocation factor calculated on the basis of total As-accumulation in roots and shoots suggested that A. annua is a good As-accumulator. Above and below ground plant biomass was enhanced at 100 μΜ As but at 150 μΜ As was significantly reduced. As-treatment caused membrane damage more in the roots than in the leaves as reflected by higher degree of lipid peroxidation in the roots than in the leaves. In response to As stress, plants activated antioxidative defense for detoxification of induced reactive oxygen species (ROS), As sequestration via phytochelatins (PCS) as well as production of a wide range of secondary metabolites. All of them were activated differently in roots and leaves. Among enzymatic antioxidants, leaves significantly elevated superoxide dismutase (SOD), ascorbate peroxidase, and glutathione reductase, whereas in roots SOD, catalase, and peroxidase played significant role in ROS detoxification. Plants activated As-sequestration pathway through thiols, glutathione, and PCS and their respective genes were more induced in leaves than in roots. Further gas chromatography in tandem with mass spectroscopy analysis revealed differential modulation of secondary metabolites in leaves and roots to sustain As-stress. For example, roots synthesized linoleic acid (4.85 %) under As-treatment that probably stimulated stress-signalling pathways and in turn activated differential defense mechanisms in roots to cope up with the adverse effects of As.

Phytocyanins (PCs) are ancient blue copper-binding proteins in plants that bind to single type I copper atoms and function as electron transporters. PCs play an important role in plant development and stress resistance. Many PCs are considered to be chimeric arabinogalactan proteins (AGPs). Previously, 38, 62, and 84 PC genes were identified in Arabidopsis thaliana, Oryza sativa, and Brassica rapa, respectively. In this study, we identified 30 putative PC genes in the orchid Phalaenopsis equestris through comprehensive bioinformatics analysis. Based on phylogeny and motif constitution, the P. equestris phytocyanins (PePCs) were divided into five subclasses: 10 early nodulin-like proteins, 10 uclacyanin-like proteins, five stellacyanin-like proteins, four plantacyanin-like proteins, and one unknown protein. Structural and glycosylation predictions suggested that 16 PePCs were glycosylphosphatidylinositol-anchored proteins localized to the plasma membrane, 22 PePCs contain N-glycosylation sites, and 14 are chimeric AGPs. Phylogenetic analysis indicated that each subfamily was derived from a common ancestor before the divergence of monocot and dicot lineages and that the expansion of the PC subfamilies occurred after the divergence of orchids and Arabidopsis. The number of exons in PC genes was conserved. Expression analysis in four tissues revealed that nine PC genes were highly expressed in flowers, stems, and roots, suggesting that these genes play important roles in growth and development in P. equestris. The results of this study lay the foundation for further analysis of the functions of this gene family in plants.

Real time quantitative PCR (qPCR) is widely used in gene expression analysis for its accuracy and sensitivity. Reference genes serving as endogenous controls are necessary for gene normalization. In order to select an appropriate reference gene to normalize gene expression in Casuarina equisetifolia under salt stress, 10 potential reference genes were evaluated using real time qPCR in the leaves and roots of plants grown under different NaCl concentrations and treatment durations. GeNorm, NormFinder, and BestKeeper analyses reveal that elongation factor 1-alpha (EF1α) and ubiquitin-conjugating enzyme E2 (UBC) were the most appropriate reference genes for real time qPCR under salt stress. However, β-tubulin (βTUB) and actin 7, which were widely used as reference genes in other plant species, were not always stably expressed. The combination of EF1α, UBC, uncharacterized protein 2, DNAJ homolog subfamily A member 2, and glyceraldehyde-3-phosphate dehydrogenase should be ideal reference genes for normalizing gene expression data in all samples under salt stress. It indicates the need for reference gene selection for normalizing gene expression in C. equisetifolia. In addition, the suitability of reference genes selected was confirmed by validating the expression of WRKY29-like and expansin-like B1. The results enable analysis of salt response mechanism and gene expression in C. equisetifolia.

Brassinolide (BL) alleviates salt injury in cotton seedlings; however, little is known about the molecular mechanisms of this response. In this study, digital gene expression analysis was performed to better understand the regulatory pathways of BL in NaCl-stressed cotton (Gossypium hirsutum L.). Compared with control plants (CK), a total of 1 162 and 7 659 differentially expressed genes (DEGs) were detected in the leaves and roots of NaCl-treated plants, respectively. Most of the DEGs in NaCl-treated plants, compared to CK, were regulated by BL. Moreover, expression patterns of DEGs in BL+NaCl treated plants were similar to those in CK plants; however, the responses of DEGs in the leaves and roots of NaCl-treated plants to BL differed. In the roots, BL-regulated DEGs were involved in protein biosynthesis, whereas in the leaves, BL promoted photosynthesis in NaCl-stressed cotton. BL treatment also significantly increased the overall biomass, chlorophyll a + b content in leaves, and the protein content in roots in NaCl-stressed cotton. The downregulation of stress-responsive genes in BL+NaCl-stressed leaves was also found. These results suggest that BL can alleviate NaCl injury in cotton plants.

Glutathione transferases (GSTs) mainly catalyze the nucleophilic addition of glutathione to a large variety of hydrophobic molecules participating to the vacuole compartmentalization of many toxic compounds. In this work, the putative tolerance of transgenic tobacco plants over-expressing CsGSTU genes towards the chloroacetanilide herbicide alachlor was investigated. Our results show that the treatment with 0.0075 mg cm^-3 of alachlor strongly affects the growth of both wild type and transformed tobacco seedlings with the sole exception of the transgenic lines overexpressing CsGSTU2 isoform that are barely influenced by herbicide treatment. In order to correlate the in planta studies with enzyme properties, recombinant CsGSTs were in vitro expressed and tested for GST activity using alachlor as substrate. The recombinant GSTU2 enzyme was twice more active than GSTU1 in conjugating alachlor to GSH thus indicating that CsGSTU2 might play a crucial role in the plant defense against the herbicide. Moreover, as a consequence of the infiltration with a bacterial suspension of the P. syringae pv. tabaci, transgenic tobacco plants but not wild type plants bestowed the capability to limit toxic metabolite diffusion through plant tissues as indicated by the absence of chlorotic halos formation. Consequently, the transgenic tobacco plants described in the present study might be utilized for phytoremediation of residual xenobiotics in the environment and might represent a model for engineering plants that resist to pathogen attack.

The current research was carried out to reveal the possible impacts of cold plasma on growth and physiology of wheat, as a new approach in plant science. Short and long-term impacts of different types of plasma (nitrogen and helium) with surface power density of 0.4 W cm^-2, exposure times (15, 30, 60, and 120 s), and repetitions (1, 2, and 4 times with 24 h intervals) were evaluated. Single-time applied helium or nitrogen derived plasma significantly promoted total root and shoot lengths, in contrast to four times application, and the root system was more sensitive than the shoot one. In addition, seedlings were more sensitive to nitrogen derived plasma, compared with helium. The physiological responses to plasma treatment were analyzed via protein assay and peroxidase or phenylalanine ammonia lyase (PAL) activities measurements. Plasma generated signaling molecules, especially ozone, nitric oxide, and/or UV radiation induced promotions in the peroxidase and PAL activities as well as increase in protein content in leaves, especially when times and/or repetitions increased. Plants were perished by the nitrogen derived plasma at the highest exposure time and number of repetitions. However, the seedlings with inhibited growth not only caught up control one month after, but even the growth rate and biomass accumulation in the shoot and leaves were accelerated. Increased leaf soluble phenol content was recorded in plasma treated seedlings, especially at longer times and more repetitions.

MADS-box genes encode a family of transcription factors that regulate diverse growth and developmental processes in plants, including flowering. In this study, comprehensive characterization and expression profiling analyses of seven sugar apple (Annona squamosa L.) MADS-box genes were performed using rapid amplification of cDNA ends method. Domain and phylogenetic analyses grouped these seven MADS-box genes into six different clades and they showed high similarity with orthologs in Arabidopsis. Expression patterns of these MADS-box genes were investigated during different flower developmental stages and in various reproductive organs, including petal, stamen, sepal, and pistil. Most of the MADS-box genes studied were least expressed in the sepal and AsAGL67 and AsAGL80 expression was weak in all tissues. AsSEP1 and AsAGAMOUS showed highest expressions in the stamen and pistil, and AsAGL12 showed stamen-specific expression. Dynamic expression patterns of MADS-box genes in different reproductive stages suggest involvement in flower development. Interestingly, a number of these MADS-box genes showed responses to gibberellin, abscisic acid, and salicylic acid treatments, suggesting control of their expression by phytohormones.

Melatonin (MT), a tryptophan derivative, plays an important role in the function and survival of organisms. To better understand the role of MT in cold tolerance, the melon (Cucumis melo L.) were sprayed with various concentrations of MT (0, 50, 100, 200 or 400 μM), exposed to cold stress (day/night temperature of 12/6 °C) for 7 d, and then returned to optimal conditions (28/18 °C) for 7-d recovery. The foliar application of MT (especially 200 μM) significantly alleviated cold-induced growth suppression, and MT-treated plants recovered more quickly than untreated plants. Further, MT-treated plants had higher chlorophyll content, photosynthetic rate, stomatal conductance, as well as maximal quantum yield of photosystem (PS) II photochemistry, and efficiency of excitation energy capture of open PS II centres under cold stress than untreated plants. Furthermore, exogenous MT significantly reduced malondialdehyde content and markedly increased the activities of antioxidant enzymes superoxide dismutase (SOD), guaiacol peroxidase (POD), and catalase (CAT) under cold stress. MT also increased expression of antioxidant genes CmSOD, CmPOD, and CmCAT under cold stress. The results indicate that MT pretreatment alleviated the detrimental effects of cold stress and accelerateds the recovery mainly by enhancing photosynthesis and antioxidant capacity in melon leaves.

Two main dormancy states, innate and imposed dormancy, were characterized in turions (winter buds) of the aquatic carnivorous plant Aldrovanda vesiculosa L. (Droseraceae) kept at 3 ± 1 °C in a refrigerator over the winter. As a result of the breaking of imposed dormancy by a temperature increase (at 15 - 20 °C), some of the turions rose to the water surface within 1 - 3 d and germinated. Turion leaves contained large lacunae with a slimy reticulum and were filled by water over winter. As a result of breaking imposed dormancy, the proportion of gas volume in inner turion leaves rose from 10 - 20 % to 100 % of leaf lacunae volume. The aerobic dark respiration rate of the turions [0.74 - 1.5 μmol O₂) kg^-1(FM) s^-1] slightly increased during innate dormancy after 1 - 2 d at 20 °C, while it was almost constant during the breaking of imposed dormancy. The anaerobic fermentation rate of the turions was only 1.5 - 7 % of the oxygen respiration rate and also was constant during the breaking of imposed dormancy. In turions, the content of glucose, fructose, and sucrose was the same for the two states of dormancy, but starch content was greatly reduced for the imposed dormancy (10 - 11 vs. 32 % DM). It may be suggested that a temperature increase causes an increase of fermentation or respiration which is responsible for the evolution of gas in turion lacunae and, thus, for turion rising.

Several different concentrations of α-tocopherol were applied to Carex leucochlora after plants had been treated with high salinity (0.8 % NaCl) in a greenhouse for one month. The results revealed that 0.8 mM α-tocopherol treatment showed the greatest alleviation of growth inhibition and cell membrane damage induced by salt stress. In comparison with NaCl alone, the 0.8 mM α-tocopherol application significantly decreased the content of hydrogen peroxide and the rate of superoxide radical generation, and increased the content of chlorophyll b, carotenoids, free proline, and soluble protein, but had no effect on the content of chlorophyll a and soluble sugar. These results suggest that α-tocopherol could effectively protect C. leucochlora plants from salt stress damage presumably by quenching the excessive reactive oxygen species to protect the photosynthetic pigments and by enhancing the osmotic adjustment.

Proanthocyanidins (PAs) are the main products of the flavonoid biosynthetic pathway in many plants. However, their biological function during environmental stresses in plants is rarely reported. In the present study, the effects of pretreatment with PAs on the response of cucumber (Cucumis sativus L.) seedlings to high irradiance (HI), polyethylene glycol (PEG), and cold stress were investigated. The PAs pretreament alleviated stress-induced oxidative damage in plant cells and increased the activity of alternative oxidase (AOX) and content of abscisic acid (ABA). Furthermore, PAs-pretreated seedlings suffered less damage by the stress conditions, maintained higher content of chlorophyll a+b and AOX proteins in comparison with the control. Therefore, our findings suggest that PAs might contribute to plant tolerance to environmental stresses.