جستجوی مقالات مرتبط با کلیدواژه « embryogenesis » در نشریات گروه « علوم پایه »

Persian oak (Quercus brantii L.) is the most important Zagros forest tree in Iran. Therefore, in order to maintain the survival of this specie, use the laboratory methods such as tissue culture and somatic embryogenesis is suitable. So, two separate experiments were designed includes somatic embryogenesis and encapsulation of somatic embryos. Somatic embryogenesis experiment was done in CRD with 4 replications. In this experiment immature zygotic embryos as explant source and 2,4-D in 4 level (0, 0.25, 0.5 and 0.75 mg l-1) were used. Encapsulation test was done in factorial based on CRD with 4 replications; factors include sodium alginate in 3 concentrations (3.5, 4 and 4.5 %) and CaCl2 in two concentrations (50 and 100 Mm). Results of somatic embryogenesis showed that the maximum number of somatic embryos and the highest somatic embryogenesis percentage (66.6%) were observed in 0.25 mg l-1 2,4-D. Results of encapsulation showed that, sodium alginate 3.5% with CaCl2 50 mM was the best treatment for encapsulation of somatic embryos and had highest germination percentage (100%).

The production of double haploid plants can be used as an effective method for plant breeding. In this research, in order to produce chickpea haploid plants, 1mm-long anthers of Bivanij cultivar containing the microspores at uni-nucleate stage were isolated from suitable buds (3mm in length) and exposed to different centrifuge (150g, 300g and 600g each for 3, 6 and 10 minutes) and electrical shock pretreatments (0, 100, 150 and 200V) in the 2ml microtubes containing 1.5ml of RM-IK medium. The treated anthers were then cultured in an EDM culture medium containing 10mg/l 2, 4-D and 10mg/l silver nitrate to induce callus and embryos. Results showed significant differences between different levels of centrifugation, different levels of electric shock and their interactions for the studied traits. The highest percentage of embryogenesis was observed in centrifuge pretreatments of 150g for 6 minutes, 300g for 3 minutes, 150g for 3 minutes in combination with 150V electrical shock, 300g for 6 and 10 minutes and combination of 150g centrifuge pretreatment for 3 minutes with electric shock of 200V, while the highest percentage of plant regeneration was obtained from centrifuge pretreatment of 300g for 6 minutes and also the combination of centrifuge pretreatment of 150g for 3 minutes with electric shock of 150V.

Persian leek (Allium ampeloprasum) has a special place in Iraninan's food chain. Many accessions by different characteristics have been cultivated and adapted in different regions of Iran. In order to investigate the breeding of this vegetable, an experiment was conducted in a randomized complete block design in three replications. For this purpose, 7 accessions of Persian leeks were selected. Various growth regulator componds2, 4 D at 0, 2 and 4 mg/lit and BA with 0, 2 and 4 mg/l were used in culture medium. The treatments were done on unopened flowers' umbrella and embryogenesis, regeneration and callus percentages of micro samples and the number of haploid plants were measured. The results indicated that Shadegan accessions in culture medium including 4 mg/l BA and 2 mg/l D-4,2 had the highest Percentage of embryogenesis (12.81 %) and regeneration (12.6%). The highest percentage of callus (0.51%) and lowest percentage of callus (0.16%) have been observed in arak and shadegan accession, respectively. Out of 42525 flowers cultivated, 1001 embryo (2.35%), 972 regenerate (97.1%) and 946 plants (94.5%) have survived. Eventually, seven haploid plants were observed. The highest number of haploid was observed in culture medium with 4 mg /liters BA and 2 mg/liters 2.4.D. in Guilan accession.

Thymus daenensis Celak is a valuable medicinal plant containing high thymol content in the essential oil. The domestication and breeding of high quality and homogenous varieties is necessary for its commercial production. The purpose of this study was to regenerate haploid plants from microspore culture. Since, most plant species show the best embryogenesis response at the uninuclear stage of microspore development, in the present study microspore developmental stages were determined. Based on the obtained results, the buds with uninuclear microspores were those of with 1.3-1.4 mm in diameter and 3.8-4.4 mm in length. In order to induce microspore embryogenesis, different pretreatments of temperature (30 and 4°C), hormones (2,4-D: 25, 35 and 45 ppm) and different media (NLN-13, FHG, B5) were investigated. The results indicated that there was a significant difference in response of microspores to different induction media, pre-treatments and their interactions. The highest numbers of multi-cellular structures were observed in the NLN-13 medium and temperature treatment of 30 ºC for 8 days and 2, 4-D treatment of 25 mg/l. Finally, heart shaped embryos were only observed in FHG medium with heat pretreatment for 8 days. Future studies are needed to increase the number of multi-cellular structures and successful regeneration of haploid plants.

Haussknechtia elymaitica Boiss. belongs to Apiaceae family.Considering the importance of recognizing the developmental stages in the development of biology knowledge Haussknechtia elymaitica Which is a rare and endemic species of Iran, was selected for this research. The samples of vegetative and reproductive organs at different stages of development were gathered and investigated by cell-histology methods. The investigation of the anatomical structure of vegetative organs showed that the secretory cavity are arranged between the parenchymal tissues of the leaf. Section of flower buds revealed that anthers had 4 pollen sacs, the division of pollen mother cell was of the simultaneous type, microspore tetrads were of tetragonal type and the tapetum layer was secretory. The ovary was found to be two chambered and two-carpeled; the ovule to be anatropous and to have one membrane. In embryogenic investigationit was found that the embryos were globular, cordate, cotyledonary and torpedo-shaped and the transition between globular embryos to cordate embryos was found. The vegetative organs were observed to have the general structure of dicotyledons. The development patterns of ovule and embryo sac follow the Polygonum type. Tetrahedral, Tetragonal and Liner microspore tetrads were observed. All stages of embryogenesis were covered in this study.

Pimpinella anisum L. belongs to Apiaceae family. The samples of vegetative and reproductive organs at different stages of development were gathered and investigated by cell-histology methods. The investigation of the anatomical structure of vegetative organs showed that the secretory ducts are arranged between the parenchymal tissues of the leaf. Section of flower buds revealed that anthers had 4 pollen sacs, the division of pollen mother cell was of the simultaneous type, microspore tetrads were of tetragonal type and the tapetum layer was secretory. The study of the ultrastructure of pollen grains with SEM showed that they had 3 pores. The ovary was found to be two-chambered and two-carpeled the ovule to be anatropous and to have one membrane. In embryogenic investigation it was found that the embryos were globular, cotyledonary and torpedo-shaped and the transition between globular embryos to cordate embryos was found. The vegetative organs were observed to have the general structure of dicotyledons. The development patterns of ovule and embryo sac follow the Polygonum type. Tetrahedral microspore tetrads were observed. The ultrastructure of pollens was found to be similar to those of Smyrnium, a genus of Apiaceae family. All stages of embryogenesis were covered in this study.

Our aim in this study was to analyze and quantify mRNA expression of SALL4 in mesencephalon, during different stages of chicken embryogenesis. In this experimental study, incubated Ross fertilized eggs were applied in 37°C-37.5°C in 60-65% humidified atmosphere after beginning of embryogenesis. Mesencephalon part of the brain tissue was collected from the eggs, daily. Total RNA extraction and cDNA synthesis was performed from resected tissues. The synthesized cDNA was used as template for quantitatively analysis of SALL4 mRNA expression by real-time PCR. The Real-time PCR analysis of SALL4 mRNA expression in mesencephalon tissues indicated that the level of gene expression is significantly variable during embryogenesis. While the basal level of SALL4 mRNA expression was detected during the rest of embryogenesis, the maximum copy number of SALL4 mRNA was quantified on 19th day of chicken development. Having analyzed the level of SALL4 mRNA expression in different stages of chicken embryogenesis, we can extrapolate that a probable relationship may be existed between expression of SALL4 in nerve centers of mesencephalon brain and development of optic organs.

In this research، ultrastructure of rapeseed (Brassica napus L. cv. PF704) microspores following the gametophytic and embryogenic developmental pathways in vitro was compared with the gametophytic development in vivo via electron microscopy. In reprogramming of rapeseed microspores to the embryogenesis pathway، there are some defined changes influencing the cell activities and structure. Some of these changes can be considered as microspore embryogenesis pathway in rapeseed. In this study، rapeseed microspores were isolated at different days after in vitro culture and prepared for electron microscopy studies. During the different developmental stages of rapeseed microspores، Differences in specific cellular properties such as cell size and shape، nuclear architecture، starch accumulation، presence of vacuoles were studied to characterize different stages of microspore embryogenesis and other pathways occurring in vitro. Results، showed the presence of abundant starch grains in a defined cytoplasmic region appeared as a specific property of the gametophytic development in vitro، as well as of the non-induced microspores of in vitro cultures under embryogenic-inductive conditions.

An efficient maize regeneration system was developed using mature embryos. The use of mature embryos from dry seeds possesses several advantages: mature embryos are easy to handle and available throughout the year and in bulk quantities. In this study، mature dry seeds of five maize inbred lines (K126، L105، B73، Mo17 and S61) were used. Embryos were removed from surface-sterilized mature seeds and sliced into halves. They were used as explants to initiate callus on induction medium containing 4 mg/l 2،4-dichlorophenoxyacetic acid (2،4-D). Mature embryos were incubated at 27 °C in darkness. The induction frequency of primary calli was over 90% for all tested inbred lines. Then، the primary calli were transferred onto subculture medium supplemented with 2. 0 mg/l 2،4-D concentrations 0. 2 or 0. 5 mg/l of 6-benzylaminopurine (BA) or Thidiazuron (TDZ) and 10 mg/l AgNO3. Embryogenic callus readily formed plantlets on regeneration medium supplemented with 0. 2 or 0. 5 mg/l BA or TDZ. The regenerated plantlets were transferred to half-strength Murashige and Skoog (MS) medium supplemented with 0. 6 mg/l indole-3-butyric acid (IBA) to develop roots. The frequency of green shoot formation ranged from 18. 3-40. 25%. The highest mean percent (40. 25%) was observed for S61 genotype on medium containing 0. 2 mg/l TDZ and 10 mg/l AgNO3. This efficient regeneration system provided a solid basis for genetic transformation of maize.

Potato is one of the most important crops in Iran. Optimization of tissue culture in order to achieve high frequency regeneration is the first step for genetic transformation. Here, regeneration of two important potato cultivars that are widely cultivated in Iran (Agria and Marfona) was investigated. Internodes, leaves, and microtubers explants of potato were treated with different hormone components. It was found that in the medium A, regeneration efficiency of internodes and leaves explants at 1mg/l TDZ is higher than the other TDZ concentrations. In the medium C, regeneration percentage of internodes (95.8% in Agria, 100 % in Marfona), leaves (83.3 % in Agria, 91.6 % in Marfona) and microtubers (82.6 % in Agria, 86.3 % in Marfona) has shown more efficient than medium A. On the other hand, regeneration time in medium C was 35 days less than that in medium A. We observed different stages of somatic embryogenesis for all explants at C medium. Finally, we were recommended the medium C as an efficient medium for high regeneration of these cultivars of potato.

The Hyoscyamus genus has been always regarded because of the therapeutic effects and its contained tropan alkaloids. Utilizing genetic engineering methods for production of plants for production of plant belonging to this genus with higher medical values and propagation of this plant in a fast and cost-effective manner is very important. Somatic embryogenesis is a great help in this field. The aim of the current study is to gain knowledge about mechanism of somatic embryogenesis via protein changes' assessment in different stages of embryo formation. In this study stem culture on MS medium containing BAP and IAA lead to embryogenesis.Quantitative protein evaluation in different stages of embryo development showed changes in protein content. The qualitative evaluation of protein was performed using electrophoresis of two types of polyacryl amide gel in discontinued system (PAGE and SDS-PAGE). Molecular mass of peptide as well as peptide separated bonds were calculated, and it cleared that during embryogenesis different proteins and peptides undergo up-regulation, down-regulation and modulation. In addition, main and fundamental proteins and peptides were known.