Development of efficient, easy, and safe gene delivery methods is of great interest in the field of plant biotechnology. Considering the limitations of the usual transfection methods (such as transgene size and plant type), several new techniques have been tested for replacement. The success of some biological and synthetic nanostructures such as cell-penetrating peptides and carbon nanotubes in transferring macromolecules (proteins and nucleic acids) into mammalian cells provoked us to assess the ability of an engineered chimeric peptide and also arginine functionalized single-walled carbon nanotube in gene delivery to intact tobacco (Nicotiana tabacum var. Virginia) root cells. It was suggested that the engineered peptide with its special cationic and hydrophobic domains and the arginine functionalized single-walled carbon nanotube due to its nano-cylindrical shape can pass plant cell barriers while plasmid DNA (which codes green fluorescent protein) has been condensed on them. The success of gene delivery to tobacco root cells was confirmed by fluorescence microscopy and western blotting analysis.
The biochemical and molecular responses of five commercially well-known pomegranate cultivars to severe water stress were studied. The cultivars were subjected to 14-day water stress by withholding irrigation, followed by re-watering for 7 days. Results showed clear differences in metabolites contents and activities of antioxidant enzymes among various pomegranate cultivars during severe water stress and recovery. According to our results, increased accumulation of proline in pomegranate was not related to osmotic adjustment during severe water stress. Except for 'Ghojagh', leaves grown under severe water stress conditions showed symptoms of oxidative stress such as reduced chlorophyll concentration. The improved performance of 'Ghojagh' under drought stress may be associated with an efficient osmotic adjustment. The up-or down regulated expression of cytosolic glutathione reductase (cytosolic GR) and glutathione peroxidase were observed under drought conditions. Moreover, the suppressed expression of cytosolic GR was also noted. Comparatively, 'Rabab' exhibited higher antioxidant capacity and an efficient ROSscavenging mechanism under drought stress. Lower levels of membrane lipid peroxidation in 'Ghojagh' and 'Rabab' under drought stress and the marked reduction of malondialdehyde concentration after re-watering represents that these cultivars have a good tolerance to drought stress. As a first step towards the study of the biochemical and molecular responses of pomegranate plants to water stress, this research provides new information into the mechanisms of drought tolerance in the plants.
Licorice is a well-known medicinal plant, containing various secondary metabolites of triterpenoid and phenolic families. The aim of this study is to evaluate the effect of salinity stress on the expression of key genes involved in the biosynthetic pathway of triterpenoids such as glycyrrhizin, betulinic acid, soyasaponins, and phytosterols in licorice root, as well as providing a phonemic platform to characterize antioxidant properties, glycyrrhizin, and total phenolic content. This study also includes measuring the gene expression level and glycyrrhizin content in leaves and roots of control plants. The studied genes included squalene synthase (SQS1 and SQS2), β-amyrin synthase (bAS), lupeol synthase (LUS), cycloartenol synthase (CAS), β-amyrin 11-oxidase (CYP88D6), and β-amyrin 24-hydroxylase (CYP93E6). Our results revealed that all of the mentioned genes were upregulated following the stress condition with different transcription rates. The highest increase (12-fold) was observed for the expression of the LUS gene, which is related to the betulinic acid pathway. Also, the highest content of glycyrrhizin was observed at 72 h posttreatment, which was consistent with the upregulated transcription levels of the glycyrrhizin pathway genes especially SQS1 and CYP88D6 at the same time. Correlation and stepwise regression analysis proved the key role of SQS1 gene in the biosynthetic pathway of glycyrrhizin. Antioxidant activity and phenolic content also were increased following stress condition. A comparison between the expression levels of SQS1 and other genes involved in the production of glycyrrhizin, phytosterols, and soyasaponins revealed a similar transcription trend, which shows the gene expression in the roots was significantly higher than the leaves. In contrast, SQS2 and LUS genes displayed a higher expression in leaf tissues. The genes related to betulinic acid biosynthetic pathway exhibited an expression rate different from other triterpenoid pathway genes, which could be observed in the leaves and roots of control plants and the roots of salt-treated plants. Furthermore, results showed that these two SQS genes have different expression rates due to different plant tissues (roots and leaves) and stress conditions. Importantly, in contrast to previous reports, we detected the glycyrrhizin in leaf tissues. This result may indicate the presence of a different genetic background in native Iranian licorice germplasm. Keywords Gene expression . Glycyrrhiza glabra . Glycyrrhizin . Quantitative real-time PCR . Secondary metabolites Abbreviations bAS β-Amyrin synthase CAS Cycloartenol synthase CYP88D6 β-Amyrin 11-oxidase CYP93E6 β-Amyrin 24-hydroxylase FDP Farnesyl diphosphate GA3 Gibberellic acid HPLC High-performance liquid chromatography LUS Lupeol synthase MeJA Methyl jasmonate OSCs Oxidosqualene cyclases QRT-PCR Quantitative reverse transcription PCR SQS Squalene synthase
Low temperature as one of the most important environmental factors limits the productivity of plants across the world. Aegilops, as a wild species of Poaceae, contains low temperature-responsive genes. In this study, we analyzed morphological (wilting, chlorosis, and recovery) and physiological (ion leakage) characteristics to identification of a cold-tolerant genotype. In this experiment, we introduced two transcription factors (TFs) in Aegilops species for the first time. Bioinformatics analysis demonstrated that our nucleotide sequences have high similarity with CBF14 (C-repeat-binding factor) and NAC2 (NAM, ATAF, and CUC) in Triticum aestivum. Based on the physiological and morphological data, one genotype (Aladizgeh) was identified as the most resistant genotype which was selected for further gene expression analysis. The real-time PCR results indicated that the CBF14 gene was not expressed 3 h following cold treatment, but the highest expression was observed after 6, 12, and 24 h of cold treatment; however, a sudden decrease was observed in its expression after 30 h. The NAC2 gene also was not expressed 3 h after cold stress, but the highest expression was at 24 h and similar to the CBF14 gene; its expression suddenly decreased after 30 h. Our results indicated that this genotype can tolerate -4 °C for 3 h, but the CBF14 and NAC2 genes were activated when treated for longer durations. Expression of TFs studied in this experiment had decreased after 30 h, in which cell death seems to be the important reason.
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