Cell and Tissue Journal

Abstract Aim: The chlorophyll biosynthesis pathway is a main target for genetic modification to change plant photosynthesis and growth rate to support a greater demand for food in the growing world population. In this study, the effect of overexpression of GSA gene one of gene involved in biosynthesis pathway of chlorophyll on physiological condition of tobacco plant was investigated. 5-Aminolevulinate (ALA) is product of GSA gene. ALA is a precursor for all tetrapyrrole, these components have impotent roles in living cell, as pigments, light receptor (Phytochrome), prosthetic group of many different proteins (like cytochromes, hemoglobin, myoglobin, and leghemoglobin) and enzymes (for example Catalase, Ascorbate, Peroxidase and etc.). Nowadays, ALA has received wide attention for its widespread usage in agriculture, forestry and medication. ALA at low concentrations increases photosynthesis, growth, development, yield and productivity, also promoted fruit color appearance and quality and taste of products in treated plants under both normal and stressful conditions. ALA also improves antioxidant features, absorption of nutrient, water use efficiency and osmotic balance in plants.
Materials and methods: In this research, according to bioinformatics studies, MsGSA gene cDNA of Alfalfa (Medicago sativa L. cv. Isfahani) was selected to transfer to Xanthi tobacco (Nicotiana tabacum) plant, the binary expression vector pBI121 which has Kanamycin antibiotic resistance gene for selection in bacteria and plants, cutting sites for SacI and BamHI enzyme, CaMV35S promoter (cauliflower mosaic virus promoter), nos transcription termination sequences and ß-glucuronidase (GUS) reporter gene was used. After constructing the gene construct pBI121-GSA and confirming the transfer of the construct using PCR cloning methods, enzymatic digestion and sequencing were performed, then the corresponding construct was transferred to Agrobacterium tumefaciens strain LB4404 using Agrobacterium with the gene construct. The corresponding gene was transferred to the tobacco plant genome and the transgenic plants were selected on the medium containing kanamycin and the presence of the gene was confirmed by performing PCR in the regenerated plants. The rooted transgenic sprouts were transferred to the soil. The level of GSA gene expression in the resulting transgenic plants was evaluated by real-time PCR, and their growth rate and biochemical content were also evaluated.
Results: It was observed that the growth of transgenic plants increased significantly depending on the level of GSA gene expression, and the content of ALA (aminolevulinic acid) and chlorophyll a, b and total chlorophyll, which are the products of the corresponding gene expression. The results also showed the content of anthocyanin, flavonoids and phenol of plants have significantly increased in proportion to the increase in GSA gene expression compared to wild type tobacco plants.
Conclusion: The growth rate as well as the content of chlorophyll a, b, total chlorophyll, ALA, anthocyanin, flavonoids and phenol of transgenic GSA plants is proportional to the increase in the expression of the GSA gene. The results from this study indicate that an increase in transgenic growth rate as well as an increase in the secondary metabolites content in transgenic plants were influenced by GSA transferred gene and an increase in the content of ALA. These results imply that transgenic tobacco plants expressing MsGSA gene had higher resistance potential to stresses than the wild type tobacco plants.

Abstract Aim: the aim of this study was to investigate the effect of iron on cell division, interacellular beta-carotene and chlorophyll synthesis in unicellular green alga Dunaliella. Material and methods: In this study 4, 32, 64, 128, 256 and 512µM concentrations of iron was applied on D.bardawil and D.salina. The culture media were kept in a growth chamber in a light/ dark regime of 16/8 hours at 26±2 °C. Then beta-carotene, chlorophyll content and cell divisions were determined. Result: In both species the maximum cell growth was observed in 4 µM and the amount of chlorophyll as well as cell growth decreased by the increase of iron concentration in the medium. The maximum reduction of the chlorophyll and cell growth was observed in 512 µM, where as the maximum intracellular beta-carotene content was shown in 128 µM. Conclusion: Results showed that probably free radicals contents of both species have been increased in presence of iron. Iron treatment decreased the chlorophyll content to reduce the free radicals produced due to excitation of chlorophyll molecules.  Moreover, the cells produced high amount of beta-carotene as an antioxidant against free radicals in presence of Iron. It seems D.salina has better performance in presence of high concentration of iron than D.bardawil due to less synthesis of beta-carotene and more production of other antioxidants as well as reduction of chlorophyll production.  

Abstract Aim: Dunaliella as a phytoplanktonic unicellular alga is important in aquatic organism nutrition (special in salinity waters). Chlorophyll (chl) content in relation to other algal biomass characteristics was studied under different culture media conditions for better strain selection.
Material and methods: Different Iranian and foreign strains alga were exposed to nitrate deficiency, light, iron and salt increasing treatments. Then some physiological characters such as chls contents, cell number, dry weight, photosynthesis and respiration were measured in control and treated samples.
Results: Different stresses caused decreasing cell number, chls contents and also changing in chla/chlb ratio from 5 to 15. The amount of chla and total chl on a per cell basis (10^-6 cells), at all conditions and the chla amount per ml, only at control showed positive or possitive is correct significant correlation with strains dry weight. Chla or total chl per 10⁶ cells had negative significant correlation with cell numbers per ml in all of conditions.
Conclusion: Algal biomass evaluation that almost is assessed by chla content, do not have a direct relationship with the cell number or dry weight at all cases. Therefore, the higher dry weight, chl content and also cell divisions introduced as better and more suitable indicators for strain selection than others. Strains 10 and 11, having more dry weight at both conditions (control and treatments) nearly with the higher chl content, then 4, 6 and 13 could be introduced.
 

Abstract Aim: Reduction in ozone layer diameter as a result of increasing amount of pollutant causes veduced absorbance of sun light UV rays by this layer. Consequently, living organisms, such as plants are damaged. Occurring photochemical changes in plants are some adaptation, defense and confronting reactions against these damages. So, studies of these changes are important in higher plants.
Material and methods: Studing ten cultivation groups seed and field plants consist of control and UV-C treated (totally 1-20 hours) of Coronilla varia L. were prepared in equal soil and cultivation condition. All of ninety-day old plants were used for chlorophyll-metry and flavonoid studies using 2-dimentional paper and thin layer chromatography methods.
Results: Chlorophyllmetric results showed a decrease in chlorophyll content in UV-C treated plants in comparison with the control. Comparising the leaf flavonoids showed that the number and kind of leaf flavonoid changes in UV-C treated plants in comparison with the control. These changes include Loteulin and Vitexin in treated plants and absence of them in control, Kaempferol presence in the treated field plants and absence of them in the others, Chrysin in the control and absence of them in the treated plants and the disappearing of Apeginin, Isorhamnetin, Rhamnetin, Narengenin, Myricetin and Quercetin in treated field samples.
Conclusion: It is believed that phytochemical changes consisting of flavonoids kind and number varieties are defensive reactions of plant against physiological stresses such as UV-C.
 

Abstract Aim: In this study we have used two wheat varieties with different tolerance to salt in different concentration of solt.
Material and Methods: Giza 168, Seds 1 plants have been grown for seven days in Hoagland solution and some of them were grown in Hoagland solution supplemented with 200 mM extra salt. Cutted leaf segments from these plants incubated with 600 mM salt. Dark-grown pre-adapted, with 200mM extra salt, plants were illuminated to determine the chlorophyll accumulation in two varieties.
Results: The maximum photochemical efficiency, Fv/Fm, stayed the same for all measurements. Measurement of relative ETR showed that the tolerant variety, Seds 1, had higher values for ETR than the susceptible variety (Giza 168). Also the measurement showed that the salt adapted samples of both varieties better withstood the excess of salt applied than the non-adapted samples.
The chlorophyll content was higher for the tolerant variety compared to the susceptible. The chlorophyll accumulation of the tolerant samples pre-adapted with or without salt showed no dramatic differences. The susceptible sample, Giza 168, however, accumulated more chlorophyll if pre-adapted to salt before being exposed to high salt concentration.
Conclusion: PSII seems to be stable and unaffected at the functional level by salt stress. The tolerant variety is better adapted to salt stress. It seems to be due to the advantage of having a more efficient photosynthetic apparatus.