الهام محجل کاظمی

The high mobility and solubility of cadmium pose a serious threat to the health of humans and other organisms. There are no signs of toxicity when cadmium metal accumulates in the tissues of plants and enters the human food chain. Cadmium transfer rates from vegetables to the human diet depend on their accumulation. Thus, inorder to investigate heavy metal absorption by lettuce, this research evaluated the levels of cadmium accumulating in various lettuce organs.

The seeds of lettuce (Lactuca sativa Linn) were cultivated in autoclaved pots containing perlite and cocopeat (with a ratio of 2 to 1). The pots were kept under greenhouse conditions of 25±1 (day temperature) and 20±1 (night temperature) and light/dark conditions were placed. About three weeks after the plants reached the three-leaf stage, the seedlings were treated with cadmium chloride in 3 replicates. Four concentrations (0, 30, 60 and 90 μg/g perlite) were used every 3 days. After 5 stages of treatment and 28 days after cultivation, the third leaf of the plants was used for the studies.

Cadmium increased lettuce's phenol, flavonoid and antioxidant content significantly as compared to the control sample. Furthermore, by increasing the concentrations of cadmium, lettuce showed an increase in total protein, soluble sugar, free amino acids, proline, malondialdehyde, and hydrogen peroxide as compared to the control sample. Due to the increasing amount of cadmium applied to lettuce plants, an increase in the amount of cadmium in the roots was greater than in the aerial parts.

In general, the results of this research indicated that lettuce is a cadmium accumulating plant with the ability to accumulate heavy metals in its roots and aerial parts. Contaminated with heavy metals, it seems necessary to protect the health of consumers.

The transition from vegetative to reproductive stage in Saintpaulia ionantha H.Wendl is controlled by factors such as FLORICAULA (FLO). The process of determining the fate of the flower meristem and its formation pattern is determined by the FLO and the induction of homeotic regulators. In this research, FLO sequencing, protein characteristics, secondary structure, intracellular position and phylogenetic tree have been evaluated by bioinformatics tools for the first time in African violet. The results showed that the intracellular location of this protein is predicted in the nucleus. This protein (FLO) belongs to the FLO/LFY family. The secondary structure of the protein consists of 53% alpha helix and 4% beta sheets. Examining the phylogeny tree, species related to one family were placed in one branch. Also, protein sequence alignment has shown that the sequence is highly conserved in plants of the same family. Identifying the characteristics of FLO protein can be important as the main factor in planning the function of the tissue and then controlling the function of this protein.

The study of embryonic and endosperm development in different plant species is important from a phylogenetic and systematic point of view. The aim of the present study was to investigate the histological evaluation of seed development in Tribulus terrestris L. by microscopic analysis. Samples were studied at different developmental stages after fixation by different histological techniques. The results showed that the ovules were anatropous, bilayer and axially placentation. Endosperm was observed in the early stages, which was a nuclear type that changed to a cell type during embryonic development. In the latest stages, remnants of the endosperm were observed as a net-like structure around the cotyledons. According to histological studies, divisions occurred faster in the basal cell than in the apical cell. The suspender was completely degenerated during the torpedo embryo stage. According to cyto-chemical studies, accumulation of starch grains in the seed coat was observed in the early stages of embryonic development. Moreover in the mature embryo, storage components contained protein bodies and lipid compounds. The seed coat consists of two layers, the outer layer of which contains calcium oxalate crystals. Fluorescent microscopic analysis showed that a cumulative lipid nature of waxes was observed in the grain. It seems that the study of features such as the pattern of organ formation in this plant can be effective in understanding the heterogeneity between species of the Zygophyllaceae family.

The mutation in the meristem layers creates different genetic backgrounds (chimera) in the plant tissue. The mutation in L1 layer of shoot apical meristem generates a periclinal chimera. UF3GT is an effective enzyme in floral coloration, inducing anthocyanin accumulation in petals. This study investigates direct and indirect regeneration systems and different explants to propagate two cultivars of periclinal chimera (Saintpaulia ionantha), namely Taro taraneh and Aghaz, using in vitro culture. The evaluation of UF3GT gene expression pattern by Real-Time PCR revealed the role of anthocyanin accumulation in the petal coloration of chimera plants. Results pertaining to both cultivars showed that inflorescence and leaf explant had the highest and lowest percentage of pinwheel phenotype, respectively. In addition, mutant characteristics were faded in the leaf regeneration of periclinal chimera. Furthermore, the highest percentage of periclinal chimera was generated in direct regeneration. Gene expression analysis revealed that UF3GT was expressed in the colorful part of chimera petal, while UF3GT expression was significantly reduced in the muted part. HPLC chromatogram also detected that cyanidin and delphinidin components were not present in the white part of either cultivar. The anthocyanin biosynthesis pathway appears to be blocked and anthocyanin accumulation does not occur in the petals. Inflorescence is likely to induce a pinwheel pattern in regenerated plants, probably owing to its lateral bud. It seems that different meristem layers are associated with the formation of epidermis and induce pinwheel phenotype.

In this study, the effect of TiO2 nanoparticles, as nanoparticles that are the most widely used in industry, on the morphological, and anatomical and biochemical properties of the baby sun rose Aptenia cordifolia was studied by method of spraying in four different concentrations.

Titanium dioxide nanoparticles were sprayed on the baby sun rose plant twice a week. Growth parameters and chlorophyll content, phenol and flavonoids were measured. To study the anatomical structure of the plant; manual cutting, composite staining and Stomatal count were performed. Data analysis was performed using SPSS 16 software and the Duncan test.

Treatment of titanium dioxide nanoparticles significantly increased photosynthetic pigments of chlorophyll a and b in the treated plants. The highest amount of phenol and flavonoids in the fourth leaf was related to the plant treated with 0.05% titanium dioxide nanoparticles. Also, the treatment of titanium dioxide nanoparticles increased the vascular diameter in the root and decreased the vascular diameter in the stem of some treatments.

The different morphological, biochemical, and anatomical responses of the baby sun rose to indicate the plant's genetic potential for growth in an environment contaminated with titanium dioxide nanoparticles.

One of the main strategies to improve plant tolerance is the expression of stress-induced genes, which play a significant role in the ionic balance of plants. SOS3 is one of the important components of SOS-regulated ionic homeostasis pathway. Therefore, the expression of this gene could be an important step towards producing salt-resistant plants. In this work, we have transformed tomato (Solanum lycopersicum) by Agrobacterium (GV3101 and LBA4404) containing plasmids with SOS3 genes. The maximum regeneration rate was determined in cotyledons of CH genotype. The simultaneous use of cotyledons and hypocotyls in the culture medium had the best outcome. In addition, the best time was found to be one day after inoculation. Also, the best transgenic variety was detected for Agrobacterium GV3101, which can be attributed to the interaction between the genus Agrobacterium and the tomato variety. Transgenic plants were transferred to a culture medium containing sequestrene, which caused the acceleration of the seedling growth in particular. The presence of the SOS3 in the transgenic plants was verified by PCR and RT-PCR methods.

Pest attack is able to damage plant cell structures and also affects the growth and plant differentiation. The Psyllopsis is one of the plant-attacking pests which feeds on plant sap and causes the leaf morphological deformation and induces the formation of galls. The aim of this study is investigation of the anatomical and morphological changes produced in leaflets of pest-infected plants (Fraxinus rotundifolia) in different stages of pest infection. The light and fluorescent microscopic analysis was carried out from infected and non-infected leaflets and staining was performed by using eosin-hematoxylin, safranin fast green, black sudan and comasi berliante blue. The results showed that upon the attack of the pest, its saliva entered in the infected site and induced chlorosis. In addition, the galls were formed in both lower and upper sides of the leaves, and hypertrophy and hyperplasia were observed in palisade and spongy cells as well as hypertrophy in vascular bundles of the leaves. Moreover, reduction in intercellular space in the peripheral Psyllopsis feeding area of parenchymal cells and increase in cell wall thickness of parenchymal and epidermal cells were observed. All of these changes can be considered as a suitable ecological niche for Psyllopsis establishment.

Agrobacterium is one of the gram negative genuses of soil bacteria that causes a number of diseases in plants through the use of horizontal gene transfer. The rol genes of Agrobacterium rhizogenese, rolA, rolB and rolC, are the major causes of ‘hairy root’ symptomes in infected plants. It has been demonstrated that rol genes could have a possitive effect on secondary metalbolism in plants. The homologue of rol genes has also been found in some plants such as the genus Nicotiana and in a member of the Scrophulariacceae, Linaria vulgaris. Here we examined the effect of A. rhizogeneses rolC gene and its homologue in tobacco, trolC gene, on pigmentats content, production of some secondary metabolites and antioxidant activity in ‘in vitro’ cultered 4 weeks old seedlings. In these plants, the transgenes were located under the contol of dexamethasone inducible prompter. Methanol extracts of aerial parts of seedlings were prepared and DPPH radical scavenging method was used to evaluate the antioxidant activity. Experiments were done in a completely randomized design with 3 replications. Results showed that in induced transgenic lines, pigments content (chlorophyll a, chlorophyll b, caretenoid and anthocyanin) were decreased and total phenols contents were significantly increased compared to non induced plants (control) and DPPH radical scavenging activity exhibited a remarkable increase in induced plants. However the level of flavonoids didn’t show a significant change. These results indicate that plant homologue of bacterial rolC gene, trolC, functions as rolC and can be used as an alternative to enhance the level of secondary metabolite in plants.

The formation of the seed is part of the process of reproduction in seed plants. The study of the ontogeny of endosperm and embryogenesis was considered in current research using microscopic techniques. The samples were collected from different developmental stages. Then, the fixed samples were studied by different histochemical methods. The observations indicated that the ovule was of the anatropous and bitegmic type. The outer layers were removed in the early stages. Thus, the seeds of Z. fabago were categorized of testal type. During the early developmental stages, the endosperm was of nuclear type and then changed into the cellular type. This makes it easier for the embryo to connect with endosperm tissue in early stages. The endosperm develops gradually toward the central spaces and occupies the entire space of the embryo sac. In fact, the endosperm tissue remains until mature embryo stage and was not degenerated. Also globular, heart-shaped, torpedo-shaped and mature embryo stages along with the RAM, hypocotyl, and SAM were observed. Cytochemical tests indicated that in the later stage of seed development, the formation of starch grains and the strongly thickening of cell walls were occurred, causing considerable reduction of cell cavities as well as hardening of this tissue. In the other hand, the cell storage in the endosperm tissue was more lipid-based than proteinaceous compounds. But in mature embryo no carbohydrate was detected.

Agrobacterium rhizogenes is a soil-borne, gram negative bacterium which induces hariy root disease in plants. A DNA sequence in the bacterial plasmid called T-DNA (transferred DNA) is transferred in to the plant genome upon infection. T-DNA carries the rooting-locus (rol) genes: rolA, rolB and rolC. Somme plants also contain, naturally, the homologues of rol genes. In this study, the effects of bacterial rolC gene and its homologous in tobacco, trolC, was evaluated in transgenic plants in a completely randomized design experiment with 3 replications. The expression of rolC and trolC genes in transgenic tobacco seedlings was under the control of dexamethasone inducible promoter. Different concentrations of dexamethasone (0, 1, 3, 10 and 30 µM) were used in order to induce the expression of transgenes. Our results showed that the presence of only very low quantity of dexamethasone (1µM) in the culture medium induces the expression of genes and affect significantly the growth of seedlings. Phenotypically, the length of seedlings was shorter in both transgenic plants than control and the roots of transgenic seedlings were twisted and the leaves were smaller and pale green. Since these characteristics are present in both transgenic seedlings, we can conclude that the bacterial rolC gene has preserved its ancestral function after insertion into the plant genome during evolution.

Environmental stresses are considered among the most important factors limiting agricultural production. Tomato, an important agricultural product, is sensitive to high salinity levels in soil. During salinity stress, several physiological phenomena occur in plants, including oxidative damage to cellular components due to ''reactive oxygen species'' or ROS production. Plants produce antioxidant enzymes such as catalase, ascorbate peroxidase and superoxide dismutase to counter the destructive effects of ROS. This study was carried out to evaluate the rate of germination and the expression of CAT1 and APX1 genes in two tomato cultivars, caljN3 and superstrain B. To evaluate the rate and the percentage of the germination, the seeds were cultured on filter paper in a completely randomized design with three replications and the rate and percentage of germination, radicle length and plumule length were measured after 15 days. To perform the molecular study, total RNA was extracted from plants grown in control conditions and under salinity stress. The results demonstrated that by increasing the salinity, reductions in germination percentage, germination rate, radicle length and plumule length were observed in both CaljN3 and Superstrain B cultivars, although the CaljN3 cultivar showed the lowest decrease. Interestingly, upon increasing the stress level, the rates of expression of the CAT1 and APX1 genes in the caljN3 cultivar were nearly twice and 10 times, respectively, higher than for the Superstrain B cultivar. These results could be one of the reasons for the superior growth and salt stress tolerance of caljN3 cultivar compared to SuperstrainB cultivar.