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International Journal of Phytoremediation (15497879) 25(3)pp. 381-392
The profiles of trace and major elements in three Odontarrhena species from the ultramafics of Western Iran (O. callichroa, O. penjwinensis and O. inflata) were evaluated to provide detailed information on their soil-plant relationships and potentials for agromining. The mean concentrations of Ni in leaf dry matter of these three species were 877, 3,270 and 2,720 mg kg−1, respectively. The mean concentrations of total soil Ni at sites Mazi Ban, Kamyaran and Ghala Ga were 1,470, 2,480, 1,030 mg kg−1, respectively. The Bioconcentration Factor (BCF) for Ni was >1 in O. penjwinensis and O. inflata, but not in O. callichroa. A positive relationship between shoot Ni and soil pH was found for all three species. They display Ni hyperaccumulation in the leaves, but with pronounced variation in the Ni concentrations attained. Odontarrhena penjwinensis emerged as the most promising potential candidate for future Ni agromining. The progress made in this study will enable further consideration of the three Odontarrhena species, especially O. penjwinensis, for any future commercial Ni agromining of the serpentinic ultramafic soils in Western Iran. © 2022 Taylor & Francis Group, LLC.
Journal of Geochemical Exploration (03756742) 237
The Ni hyperaccumulator Odontarrhena penjwinensis (Brassicaceae) is a species endemic to the ultramafic soils of Western Iran. Seven ultramafic outcrops and the populations of O. penjwinensis they support were investigated for Ni and other elemental concentrations to assess their potential for future Ni agromining operations. Nickel hyperaccumulation was confirmed in at least one individual plant sampled from all seven populations. The highest and lowest concentrations of Ni in leaves were recorded for two sites (3270 and 660 mg kg−1, respectively). The highest concentrations of Mn, Cr, and Co were 3110, 79, and 193 mg kg−1, respectively. A positive relationship was found between the concentrations of Ni and Fe, and Mg and Ca in roots and shoots. Correlation analysis of edaphic factors also revealed positive correlations between Ni concentration in the shoots, water-holding capacity, and soil pH, whereas it was negatively correlated for soil organic matter. The highest Ni yield (c. 0.4 g per plant), biomass (115 g per plant) and maximum plant height (43 cm) were recorded for one population where the total soil Ni concentration was 2550 mg kg−1. This O. penjwinensis population is likely to be a promising candidate for the development of Ni agromining in the region. © 2022 Elsevier B.V.
Sohrabi, D. ,
Jazini, M. ,
Mobasheri, S. ,
Tohidi, M. ,
Shariati, M. Applied Biochemistry and Biotechnology (02732289) 194(3)pp. 1178-1192
In the production of natural sausage casings, three layers of serosa, muscular, and mucosa are removed from gastro-intestinal wall of sheep as waste materials. The submocusa layer is taken for further processing. There is no report about generating added value out of these wastes. In this study, a novel approach was introduced for bioconversion of waste gastro-intestinal wall (WGW) to a value-added product. Alkaline hydrolysis of WGW was investigated and the hydrolysate was utilized for cultivation of Dunaliella salina, a value-added biomass. The hydrolysate that contained the highest total soluble protein was used for three sets of cultivations on different medium compositions, i.e., (1) cultivations on the modified Johnson’s medium enriched with different percentage of hydrolysate (0.5, 1, 2.5, 5, and 10 (%v/v)), (2) cultivations on modified Johnson’s medium which was free of nitrogen and carbon sources and enriched with different percentage of hydrolysate (0.5, 1, 2.5, 5, and 10 (%v/v), and (3) cultivation on modified Johnson’s medium which was free of nitrogen source and enriched with 2.5% hydrolysate. The results showed that WGW contained 60.7, 8.4, 15.8, and 15.2% protein, lipid, moisture, and ash, respectively and the enrichment of the medium with the hydrolysate (2.5%) increased biomass productivity by 20%. Additionally, substitution of 2.5% hydrolysate for nitrogen source (KNO3) resulted in the same biomass productivity. The results of this study revealed the potential of the hydrolysate as an alternative for KNO3 in cultivation of D. salina. Overall, this work proposed a novel approach for converting waste gastro-intestinal wall to value. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Protoplasma (16156102) 257(1)pp. 75-88
The development of nanotechnology and the upsurge of interest in titanium dioxide (TiO2) nanoparticles, especially the anatase and rutile crystalline phases, in consumer products such as paint and sunscreen, has polluted the aquatic environment and had adverse effects on living organisms, especially algae. Microalgae help to preserve the aquatic ecosystem. Accordingly, the present study investigated the effects of anatase and rutile TiO2 nanoparticles on the growth, photosynthetic pigment (chlorophyll), photosynthesis, and respiration rate of two algae species, Dunaliella salina (at NaCl concentrations of 1.5 and 0.5 M) and Dunaliella tertiolecta (at NaCl concentrations of 0.5 and 0.17 M). Treatment with 50, 100, 150, and 200 ppm of TiO2 and nano-TiO2 revealed that nano-TiO2 inhibited the growth and decreased the specific growth rate, chlorophyll, and photosynthesis of both algal species. The rate of decrease was significantly lower at higher concentrations of NaCl in both species; however, the greatest significant difference was observed at lower concentrations of NaCl in the anatase phase. The respiration rate increased for 2 weeks but, especially at lower concentrations of NaCl, the rate of increase declined at higher concentrations after exposure to both substances, especially in the anatase phase. The findings reveal that nano-TiO2 has a toxic effect on Dunaliella algae and its effect depends on the concentration of NaCl. The toxic effect was shown to decrease at higher concentrations of NaCl. © 2019, Springer-Verlag GmbH Austria, part of Springer Nature.
Journal of Chemical Technology and Biotechnology (02682575) 94(7)pp. 2148-2157
Background: One of the challenges in commercial-scale cultivation of Dunaliella salina is low biomass productivity and concentration. In addition, cultivations in wastewaters may encounter some nutrient limitations. Hence, there is a need for a cultivation system which is capable of continuous provision of nutrients while the cells are retained in the system. In this study, the feasibility of using a cell retention system (CRS) for increasing biomass productivity and concentration of D. salina was investigated. The CRS was composed of cellulose acetate hollow fiber membranes (HFMs) coupled with a helical photobioreactor. Results: Using the produced HFMs with mean pore size of 124 nm and overall porosity of 78.9%, the rejection of D. salina microalgae was as high as 93.2%. Continuous cultivation of D. salina in the helical photobioreactor at a dilution rate of 0.48 day−1 resulted in a biomass productivity (concentration) of 4.9 × 107 cells L−1 h−1 (2.7 × 106 cells mL−1). Interestingly, cultivation at the same initial dilution rate (0.48 day−1) in the helical photobioreactor coupled with the CRS resulted in a biomass productivity (concentration) of 9.3 × 107 cells L−1 h−1 (6.7 × 106 cells mL−1). Conclusions: The results revealed the potential of the proposed system for enhancing biomass productivity by 90% and biomass concentration by more than twofold. The cultivation system is also proposed as a potential tool for cultivations in wastewaters. © 2019 Society of Chemical Industry. © 2019 Society of Chemical Industry
Ghotbi-ravandi, A.A. ,
Shariati, M. ,
Shobbar, Z. ,
Shahbazi, M. Environmental and Experimental Botany (00988472) 162pp. 313-320
Plastid terminal oxidase (PTOX) is a plastid-localized protein that acts as plastoquinol oxidase. The objective of this study was to determine the role of plastid terminal oxidase in response to drought stress and examine the differential response of PTOX pathway in both cultivated (Yousef and Morocco) and tolerant wild barley (spantaneum; HS) genotypes. Plants were subjected to different levels of soil water availability including control, mild and severe drought stress. Decrease in leaf relative water content as a result of progressive drought stressed led to decrease in stomatal conductance and increased enzymatic antioxidant machinery in all genotypes. Drought stress did not affect the PTOX transcript and protein level in cultivated genotypes Yousef and Morocco. However, PTOX gene expression and protein content significantly increased in HS genotype under severe drought. Assessment of PTOX activity via fast fluorescence induction curve in presence of PTOX specific inhibitor revealed that PTOX could efficiently oxidize plastoquinon pool and acts as alternative electron pathway in HS genotype. Results indicated that the role of PTOX in stress response was more significant in the wild barley than the cultivated barley varieties, where the emphasis has been on the desirable agronomic traits. © 2019 Elsevier B.V.
Brazilian Journal of Oceanography (16798759) 67
Many microalgae are rich in lipid. Due to their low growth rates in the autotrophic culture, the best alternative is to cultivate cells under different conditions such as heterotrophic or mixotrophic, which results in the highest yield of biomass and lipid in the shortest duration. In this study, Dunaliela bardawil (UTEX 2538) green microalgae was cultivated under different culture conditions, autotrophic, heterotrophic and mixotrophic, and effects on cell concentration, lipid production and reactive oxygen species (ROS), total chlorophyll and beta-carotene concentrations were investigated. Due to very low cellular growth, this alga is not recommended for heterotrophic culture. In terms of mixotrophic conditions containing different concentrations of glucose or acetate, the highest cell growth and lipid production in 60mM glucose was similar to the control (autotrophic condition), while the concentrations of chlorophyll and beta-carotene decreased. However, at all concentrations of acetate, a slight increase in cell growth was achieved, while the lipid content decreased. Additionally, the concentrations of chlorophyll and beta-carotene increased. A positive correlation was observed between beta-carotene biosynthesis and lipid production, as well as levels of reactive species of oxygen and lipid production in the presence of glucose and acetate. This study showed that for D. bardawil the mixotrophic culture with 60mM glucose was the most suitable type of culture for increasing lipid content and cell growth rates in less time (one week) © 2019, Universidade de Sao Paulo. All Rights Reserved.
Biologia (13369563) 74(12)pp. 1579-1590
The effects of autotrophic, heterotrophic, and mixotrophic conditions were examined on micro green alga Dunaliella salina (UTEX 200) in terms of cell growth, total chlorophyll concentration, and lipid production. Results revealed a minimum growth rate of microalgae in the heterotrophic condition which is not recommended for D. salina. When the cells were cultured in mixotrophic conditions containing different concentrations of acetate or glucose, in 100 mM acetate or 60 mM glucose, the highest levels of growth rate and lipid production were obtained compared with autotrophic culture; however, the chlorophyll concentration decreased. Moreover, a significant correlation between ROS production and lipid synthesis was observed. When the combined acetate and glucose was added to the culture, no increase in growth rate and lipid synthesis was observed. This might be due to substrate inhibition. In the presence of glucose, the acidification of culture and bleaching occurred. Results indicated that lipid production is not affected by acidified conditions. In general, our results confirmed that mixotrophic culture with 100 mM acetate or 60 mM glucose is the most appropriate culture for D. salina concerning high lipid production as well as high growth rate in the shortest period of time. © 2019, Plant Science and Biodiversity Centre, Slovak Academy of Sciences.
Russian Journal of Marine Biology (16083377) 45(6)pp. 470-480
Abstract: Dunaliella salina is a unicellular microalga with the potential of industrial applications. Commercial-scale cultivation of D. salina requires extensive efforts on cost reduction. This can be achieved by minimization of nutrient cost and maximization of specific growth rate and productivity. To this end, in this study, mixotrophic cultivation of D. salina on crude glycerol (by-product of calcinated-fatty acid (CaFA) production process) was investigated in shake flasks and the influences on protein, carotenoid and chlorophyll contents of the cells were studied. The highest maximum specific growth rate and biomass productivity was achieved by cultivation on 2.5 g/L crude glycerol. The protein content was more than two folds and the carotenoid content was more than 60% higher than that of autotrophic cultivation. Subsequently, continuous cultivation of D. salina on crude glycerol in a helical photobioreactor was performed at the dilution rate of 0.52/d. The biomass productivity of 2.3 × 106 cell/(mL d) was achieved which was more than 75% of the values for previously reported autotrophic cultivations. Conclusively, continuous cultivation of D. salina on by-product of CaFA production process could be a potential process technology for production of D. Salina. © 2019, Pleiades Publishing, Ltd.
Asia-Pacific Journal of Chemical Engineering (19322135) 13(6)
Chicken fat, a source of unsaturated fatty acid, is obtained from cooked poultry by-products. A fat molecule consists of a glycerol and three fatty acids. This work aimed to introduce a novel chemical–biochemical process technology for full exploitation of chicken fat building blocks, that is, conversion of fatty acids to fatty acid calcium salts (FACSs) and utilization of glycerol for cultivation of microalgae (Dunaliella salina). FACSs are fed to cows as rumen-protected fat. Response surface methodology was used for optimization of calcium salt production in pilot scale reactor. A pilot-scale helical photobioreactor was used for cultivation of D. salina. The results pointed out that from each 1,000 g of chicken fat, approximately 840 g of FACS and approximately 39 g of D. salina powder can be obtained. The proposed process technology is a potentially economic alternative for current commercial FACS production processes where glycerol in their waste is not exploited. © 2018 Curtin University and John Wiley & Sons, Ltd.
Environmental and Experimental Botany (00988472) 155pp. 142-157
Heat shock proteins (HSPs) have vital roles during plant adaptation to biotic and abiotic stresses, as well as stress-free conditions. In the present study, we used a heterologous strategy of virus induced gene silencing to investigate the role of different classes of HSPs in Nicotiana benthamiana. Different growth and physiological parameters in silenced plants were evaluated under both control and salt stress conditions. Among the treatments, silencing of HSP70, especially under salinity regime, was found to have stronger impacts on growth, protein concentration, the accumulation of photosynthetic pigments, proline and total soluble carbohydrates content, malondialdehyde, the activity of antioxidant enzymes, performance index, relative water content and the ratio of K+/Na+, suggesting a more prominent role for HSP70 in both stressful and stress-free life cycle of the plants. Principal component analysis and hierarchical clustering indicated that HSP70 gene was silenced, the plants might effectively respond to stress by a higher accumulation of compatible solutes, like proline to protect the cell membranes and proteins from damage. © 2018 Elsevier B.V.
Brazilian Archives of Biology and Technology (15168913) 60
Effect of salt stress on biomass, cell number, contents of total lipid, omega-3 fatty acids, including ALA (Alpha Linolenic Acid), EPA (Eicosapentaenoic Acid) and DHA (Docosahexaenoic Acid) and their biosynthetic pathway intermediates (palmitic acid, stearic acid, oleic acid and linoleic acid) of two microalgae Dunaliella salina and Chlorella vulgaris were investigated. Dilution stress from 1.5 to 0.5 M NaCl and salt stress from 1.5 to 3 M NaCl were incorporated into the D. salina medium. Salt stress of 200 mM NaCl was also applied to C. vulgaris culture. Results indicated that increasing salt concentration resulted in the reduced growth rate of C. vulgaris and substantial increase of the total lipid content in both species. Proper growth rate of D. salina observed at 1.5 M of NaCl, but higher and lower concentrations led to the decreased growth rate of D. salina. In addition, considerable increase in the degree of fatty acid unsaturation and thereby the total omega 3 fatty acid content of D. salina was observed under salt stress. Salt stress had little positive effect on the amount of total omega-3 fatty acid of C. vulgaris due to the slight increase of the EPA content. Results showed that salt stress is an effective way for enhancing the total lipid and omega-3 fatty acid production in D. salina.
Acta Physiologiae Plantarum (18611664) 39(8)
In this work, we investigated the importance of phytoene desaturase (PDS) during salt stress in plants. For this aim, we transiently suppressed the corresponding gene of Nicotiana benthamiana using a Tobacco Rattle Virus silencing system. After salinity stress, the silenced plants were assayed for different growth and physiological parameters. The silenced plants were found to be induced more stunted and feeble shoots and roots than the negative controls. The results indicated that the concurrent incidence of salinity stress and viral infection did not have an additive influences on the plant growth and physiological parameters. Importantly, our results showed a more detrimental influence of salinity on plant growth and physiology after PDS silencing. Compared to the control, salt-stressed plants contained more proline, and malondialdehyde, less amount of photosynthetic pigments, higher Na+/K+ ratios in shoots and roots and lower relative water content after PDS silencing. The activity of antioxidant enzymes were also decreased in the plants coped with salinity or Tobacco Rattle Virus. It was also represented that simultaneous silencing of the PDS gene and salinity treatment resulted in a significant decrease of the performance index (PIABS) and an increase of dissipation per active reaction center (DIo/RC) reflecting severe injuries in photosynthetic machinery under such a condition. Overall results suggested that PDS silencing could increase the sensitivity of plants to salinity. © 2017, Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.
Ghotbi-ravandi, A.A. ,
Shahbazi, M. ,
Pessarakli, M. ,
Shariati, M. Journal of Plant Nutrition (01904167) 39(8)pp. 1174-1185
To study the effects of progressive drought stress on photosystem II behavior of wild type (Spantaneum) and cultivated barley (Morocco), different levels of soil water availability, including control, moderate, mild, and severe water stress (70%, 50%, 30%, and 10% water holding capacity of soil, respectively) and rehydration were used. Polyphasic OJIP fluorescence transient of Morocco plants exhibited a considerable increase in fluorescence intensity at O, J, and I steps under mild and severe stress relative to slight increase in wild barley. Values of fluorescence parameters and quantum efficiencies, including minimal fluorescence, relative variable fluorescence at phase J and I, maximal quantum yield of photosystem II (PSII), performance index, electron transport yield, and excitation transfer efficiency were influenced by water stress in both genotypes. These parameters were significantly less affected in wild type barley by progressive drought stress compared to Morocco. After re-watering, both genotypes were able to restore from severe drought in most of the traits. Based on our findings, highly correlated values of relative water content (RWC) and independent JIP-test parameters (P < 0.01) indicate that the chlorophyll a fluorescence induction technique is sensitive to plant water status and performance index represent an accurate and reliable indicator for early stress detection and also explore plant vitality under water stress. © 2016, © Taylor & Francis.
Theoretical and Experimental Plant Physiology (21970025) 27(1)pp. 61-73
Effects of n-propyl gallate, a plastid terminal oxidase inhibitor involved in chlororespiration, on photosystem II efficiency in Dunaliella bardawil under low or high illumination was investigated. Rapid chlorophyll a fluorescence transients were recorded and analyzed according to JIP-test, which can quantify the photosystem II performance. The fluorescence transients O-J-I-P drastically decreased and almost reached a plateau when low light-grown cells were exposed for 96 h to 1, 2 and 4 mM n-propyl gallate. Very similar reductions in the efficiency of quantum yield of primary photochemistry (Φpo), the quantum yield for electron transport (ΦEo) and the inferred water-splitting complex activity (Fv/Fo) were found in the same inhibitor concentrations. However, no statistically significant change in fluorescence intensity and photosystem II efficiency was found when algal cells were exposed to the inhibitor concentrations up to 2 mM under high light intensity. The results indicated that inhibitory effects of n-propyl gallate on photosystem II electron flow in D. bardawil cells are dependent on environmental conditions. It is also demonstrated that n-propyl gallate is a multi-target inhibitor of growth kinetics as well as photosynthesis. In addition, we found that the donor side of photosystem II acts as main target place of the inhibitor. © 2015, Brazilian Society of Plant Physiology.
Ecological Engineering (09258574) 67pp. 76-79
The ability of two Dunaliella salina strains (AS-B1 and IR-1) and Dunaliella bardawil (UTEX-2538) in the sedimentation of different concentrations (0, 500, 1000, 2000, 3000 and 4000μM) of aluminum were studied for duration 120min. In these strains, increase in aluminum concentration was concomitant with the reduction of cell number in supernatant as the index of the sediment aluminum by algal cells-Al3+ ions binding; cell agglutination and sedimentation caused by presence of aluminum. The ability of D. bardawil was higher in sedimentation of aluminum. The results of adding EDTA to cell suspensions for binding the aluminum confirmed the role of binding algal cells to aluminum in cell agglutination and sedimentation and consequently aluminum bioremediation. In addition, the results imply that the cell agglutination and sedimentation in D. bardawil is higher than Dunaliella salina. It seems this strain has a greater capability for sedimentation of aluminum and can utilize aluminum from aquatic environments for bioremediation. © 2014 Elsevier B.V.
Journal of Agronomy and Crop Science (1439037X) 200(6)pp. 403-415
Drought stress is one of the most important abiotic factors which adversely affect growth, metabolism and yield of crops worldwide. The objective of this study was to determine the effects of drought stress on photosynthesis in barley and examine the differential responses of photosynthetic apparatus in relatively tolerant (Yousof) and susceptible (Morocco) barley genotypes. Plants were subjected to different levels of soil water availability including control, mild and severe drought stress. In both genotypes, drought stress led to decrease in chlorophylls, β-carotene and stomatal conductance accompanied by decrease in CO2 assimilation rate. Significant increase in α-tochoperol content was only observed in Yousof cultivar under drought stress. Initial slope and plateau phase of CO2 response curve of drought-stressed plants as well as polyphasic chlorophyll a fluorescence transient curve (OJIP test) and fast fluorescence induction kinetics were influenced by drought stress. These parameters were more affected in Morocco cultivar by drought stress compare with Yousof. Drought stress also resulted in reduction of D1 protein content in both genotypes and accelerated photoinhibition process. Based on our results, stomatal conductance is the main factor limiting photosynthesis in Yousof genotype under mild drought stress. However, in Morocco, in addition to stomatal limitation, damage to photosystem II (PSII), reduced electron transport and carboxylation efficiencies were important parts of limitation in photosynthesis. Severe drought stress resulted in structural and biochemical impairment of light-dependent reactions as well as carboxylation process of photosynthesis in both genotypes. Alpha-tocopherol showed an important protective role against drought stress in Yousof cultivar as a relatively drought-tolerant cultivar. © 2014 Blackwell Verlag GmbH.
Malaysian Applied Biology (01268643) 43(1)pp. 97-105
Microalgae assimilate different types of nitrogen by interacting in different areas. The interactive effect of uptake rate and biomass production of Chlorella vulgaris was investigated under summer and fall environmental conditions. C. vulgaris was cultivated in a media containing 1 mM NH4Cl, 0.5 mM NH4Cl + 0.5 mM KNO3, and 1 mM KNO3 as the nitrogen source. Nitrate and ammonium was more rapidly utilized when both were available. C. vulgaris preferred ammonium to nitrate in the fall condition, but both nitrate and ammonium were completely assimilated in the summer condition. The uptake rate of nitrate and ammonium in the summer condition was significantly higher (p < 0.01) than in the fall condition and the summer/ fall ratio for nitrate uptake (290%) was significantly higher (p < 0.01) than for ammonium (120%). In all experiments, biomass production in the summer condition was significantly higher than fall condition (p < 0.01). The highest biomass was during the summer condition (5 g/l (f wt)) from the medium containing NO3 - as the nitrogen source. C. vulgaris recorded faster growth in the NO3 - and (NO3 - + NH4 +) media than in the NH4 + medium. The summer/fall ratio of biomass production was 235%, 300%, and 265% for the media containing NO3 -, NH4 +, and (NO3 - + NH4 +), respectively.
Journal of Plant Research (09189440) 126(1)pp. 179-186
Electron transport in photosystem II (PSII) and photosystem I (PSI) was estimated in terms of chlorophyll fluorescence and changes in P700 redox, respectively, in the unicellular green alga Dunaliella salina in the presence or absence of a nitrogen source in the culture medium. In a nitrogen-containing medium, the quantum yield of PSII (ΦII) and that in PSI (ΦI) were at the same level in low light, but cyclic electron transport around photosystem I (CET-PSI) was induced under high light as estimated from an increase in ΦI/ΦII. High light might further enhance the rate of electron transport in PSI by inducing the state 2 transition, in which the distribution of light energy is shifted to PSI at the expense of PSII. Nitrogen deficiency resulted in a decrease in ΦII and an increase in ΦI. As a consequence, the rate of CET-PSI was expected to increase. The high CET-PSI under N deficiency was probably associated with a high level of energy quenching (qE) formation in PSII. © 2012 The Botanical Society of Japan and Springer.
Brazilian Journal of Plant Physiology (16779452) 24(3)pp. 193-202
We studied the effects of n-propyl gallate, which is a plastid terminal oxidase inhibitor involved in chlororespiration, on photosynthesis and physiological parameters in Dunaliella salina grown under different salinities and under low or high irradiance using chlorophyll a fluorescence transient measurements and pigment analysis. The inhibitor up to 1 mM had an additive significant effect on the photosynthetic efficiency in the cell suspensions grown under low salinity and irradiance. However, in the presence of high n-propyl gallate concentration (4 mM), there was a negative effect on all physiological aspects. In contrast, this high concentration of the inhibitor could enhance efficiency of electron transport and growth parameters under high irradiance. On the other hand, with salinity increase, the unfavorable effects of high inhibitor concentration on the efficiency of photosystem II were less evident than of low salinity. Interestingly, n-propyl gallate high concentration had a positive effect on fluorescence and on physiological parameters when high salinitiesgrown cells were exposed to high irradiance. The results suggest that there is a rational correlation between increase of salinity and algae ability to bypass n-propyl gallate inhibited plastid terminal oxidase function and also direct influence of its lethal concentration on photosystem II compartment. The ability is especially substantial when the increase of salinity is accompanying high irradiance. Furthermore, these data show that algal responses to inhibitor concentrations are different under various environmental conditions.
Iranian Journal of Science and Technology, Transaction A: Science (10286276) 36(1)pp. 73-76
The changes of Chl a fluorescence induction curve in response to different salinity levels in Canola (Barassica napus, L.) plants were investigated. The canola seedlings were exposed to salt stress (100 mM and 200 mM NaCl) for 7 days and Chl a fluorescence induction kinetics was analysed. By using the OJIP-test, various parameters like V J, area, N, φ Po, φ Eo, ψ o, RC/ABS and PIABS were calculated and compared at different salinity levels and compared with the control plants. The results showed that the parameters related to the donor site of electron in PSII [F v/F o, φ Po and φ Po /(1-φ Po)] were constant and unaffected by salt stress. In contrast, the parameters dependent on the acceptor site of the electron such as V J, area, N, φ Eo, ψ o and ψ o /(1- ψ o) significantly decreased with an increase in salt concentration. Also, the multi parametric index PIABS (performance index) showed enough sensitivity to salt stress as a useful parameter to screen the activity of photosynthetic apparatus in canola plant. Based on our results, we suggest that in response to salt stress the electron acceptor site of PSII, especially at fractions of the transfer of electron from Q A to Q B and Q A redox turnovers is more affected. In conclusion, this fraction of electron transport chain of PSII is possibly the first and major target of salt stress at photosynthetic apparatus in canola plant.
Molecular Biology Reports (03014851) 39(3)pp. 2169-2178
VIGS (virus induced gene silencing) is considered as a powerful genomics tool for characterizing the function of genes in a few closely related plant species. The investigations have been carried out mainly in order to test if a pre-existing VIGS vector can serve as an efficient tool for gene silencing in a diverse array of plant species. Another route of investigation has been the constructing of new viral vectors to act in their hosts. Our approach was the creation of a heterologous system in which silencing of endogenous genes was achieved by sequences isolated from evolutionary remote species. In this study, we showed that a TRV-based vector cloned with sequences from a gymnosperm, Taxus baccata L. silenced the endogenous phytoene desaturase in an angiosperm, N. benthamiana. Our results showed that inserts of between 390 and 724 bp isolated from a conserved fragment of the Taxus PDS led to silencing of its homolog in tobacco. The real time analysis indicated that the expression of PDS was reduced 2.1- to 4.0-fold in pTRV-TbPDS infected plants compared with buffer treated plants. Once the best insert is identified and the conditions are optimized for heterologous silencing by pTRV-TbPDS in tobacco, then we can test if TRV can serve as an efficient silencing vector in Taxus. This strategy could also be used to silence a diverse array of genes from a wide range of species which have no VIGS protocol. The results also showed that plants silenced heterologously by the VIGS system a minimally affected with respect to plant growth which may be ideal for studying the genes that their complete loss of function may lead to decrease of plant growth or plant death. © Springer Science+Business Media B.V. 2011.
In Vitro Cellular and Developmental Biology - Plant (14752689) 47(5)pp. 561-568
A highly promising procedure to obtain seedlings of Taxus baccata L. has been developed, which involves a combination of in vitro embryo culture and growth under hydroponic conditions. Embryos isolated from freshly collected seeds were 100% sterile, even though the seeds were not treated with acid or soaked in water prior to culturing. The embryo germination level of non-leached seeds was slightly lower (85%) than those leached in running water for 7 d (100%). The leached embryos germinated with extended roots while the non-leached embryos had abnormal shapes. The embryos cultured on media supplemented with an absorbent (PVP or activated charcoal) had extended roots and shoots and were a larger size without any browning, as compared to those grown without the supplement; activated charcoal gave better results. There were no significant differences in germination rates of T. baccata embryos between the media with differing strengths of macronutrients; however, for further development of the shoot, it was necessary to sub-culture the seedlings in MS in the light. To obtain seedlings with longer roots, they had to be maintained in one-half strength MS in darkness. Approximately 90% of the plants survived when grown hydroponically for 2 mo. The surviving plants showed well-extended roots and were a good starting material for genomic, proteomic, and conservational studies as well as Taxol permeabilization investigations. © 2011 The Society for In Vitro Biology.
Physiologia Plantarum (00319317) 135(3)pp. 272-280
Dunaliella species accumulate carotenoids and their role in protection against photooxidative stress has been investigated extensively. By contrast, the role of other antioxidants in this alga, has received less attention. Therefore, the components of the ascorbate-glutathione cycle, along with superoxide dismutase (E.C. 1.15.1.1) and peroxidase (E.C. 1.11.1.11) activity were compared in two strains of Dunaliella salina. Strain IR-1 had two-fold higher chlorophyll and β-carotene concentration than Gh-U. IR-1 had around four-fold higher superoxide dismutase, ascorbate peroxidase and pyrogallol peroxidase activities than Gh-U on a protein basis. Ascorbate and glutathione concentrations and redox state did not differ between strains and there was little difference in the activity of ascorbate-glutathione cycle enzymes (monodehydroascorbate reductase [E.C. 1.6.5.4], dehydroascorbate reductase [E.C. 1.8.5.1] and glutathione reductase [E.C. 1.8.1.7]). The response of these antioxidants to high light and low temperature was assessed by transferring cells from normal growth conditions (28°C, photon flux density of 100 μmol m-2 s-1)to 28°C/1200 μmol m-2 s-1; 13°C/100 μmol m-2 s-1; 13°C/1200 μmol m-2 s-1 and 28°C/100 μmol m-2 s-1 for 24 h. Low temperature and combined high light-low temperature decreased chlorophyll and β-carotene in both strains indicating that these treatments cause photooxidative stress. High light, low temperature and combined high light-low temperature treatments increased the total ascorbate pool by 10-50% and the total glutathione pool by 20-100% with no consistent effect on their redox state. Activities of ascorbate-glutathione cycle enzymes were not greatly affected but all the treatments increased superoxide dismutase activity. It is concluded that D. salina can partially adjust to photooxidative conditions by increasing superoxide dismutase activity, ascorbate and glutathione. © 2009 Physiologia Plantarum.
Biotechnology and Bioprocess Engineering (12268372) 13(5)pp. 540-544
In this study, carotenoid and glycerol production in two unicellular green algae (Dunaliella salina and D. viridis) isolated from the Gave-Khooni salt marsh grown in media containing five different salt concentrations (0.17, 1, 2, 3, and 4 M NaCl) were evaluated under sterile conditions. Algae growth decreased as the medium salinity increased. Optimum growth of D. salina and D. viridis were obtained at 2 and 1 M NaCl, respectively. As salinity increased, glycerol and carotenoid production were increased in D. salina, whereas lower values for these products were produced in D. viridis under the same conditions. Furthermore, the cell color of D. salina changed from green to orange-red following accumulation of carotenoid, but the color of D. viridis was not changed. Thereby, it seems that the Iranian D. salina may be suitable for carotenoid production (betacarotene) on a large scale. In addition, since carotenoid compounds enhance the efficiency of photosynthesis and glycerol synthesis, it appears that the pathway for glycerol production and mechanisms of salt tolerance in D. viridis are unique from those of D. salina. © The Korean Society for Biotechnology and Bioengineering and Springer-Verlag Berlin Heidelberg GmbH 2008.
World Journal of Microbiology and Biotechnology (09593993) 22(9)pp. 1003-1006
Three strains of Dunaliella salina (I, G and A) were cultivated under the climatic conditions of Iran, in open ponds to compare the β-carotene production and the specific rate of growth. The experiments were accomplished in two separate stages. In the first stage, the cells were grown in ponds on nutrient-rich medium containing 2 M NaCl to obtain the necessary biomass. In the second stage, cells were stressed on nutrient-poor medium containing 2.5 M NaCl for β-carotene induction. The results showed that the specific growth rate of strain I was the highest during the first stage, whereas during the second stage, the growth rates of three strains were approximately the same. The overall results indicated that strain G had the highest potential for β-carotene accumulation of the strains tested and hence it was concluded that this strain is more suitable for outdoor cultivation under the climatic conditions of Iran than the other two. © Springer 2006.
Pakistan Journal of Biological Sciences (18125735) 9(8)pp. 1492-1496
Four strains of Dunaliella salina (I, G1, A and MUR8) were cultivated under the three salinity regimes (1, 2 and 3 M NaCl) to examine the effect of salinity on the β-carotene synthesis per cell and to compare the β-carotene production per culture volume and the rate of growth. During the 30 days of the experiments the batch cultures maintained in the 300 flasks containing 100 of Johnson's medium under the low irradiance (100 μmol photon m-2 s-1) with a 12/8 h light/dark regime and a continuous shaking. The results showed that the inductive effect of salinity on β-carotene accumulation per cell was strain dependent and when the values for the strains IR-1 and Gh-U were slightly higher at 3 M NaCl compare to lower salinities, there were no direct relationships between the concentrations of salt and the β-carotene contents per cell in other two strains (MUR-8 and Au-W). On the other hand, increase the salinity result in serious decreasing in the cell number and the β-carotene content per culture volume of all strains during the experiment. The highest β-carotene content per (14.2 mg L-1) was obtained at 1 M NaCl in the suspension culture of the strain Au-W. © 2006 Asian Network for Scientific Information.
Pakistan Journal of Biological Sciences (18125735) 9(11)pp. 2048-2054
Under circumstances where electron transport is restricted, such under low temperature condition, oxidative stress may occur even at optimal or low-light intensities. Short-term-effects of light intensities (20 or 100 μmol m -2 sec-1), on the levels of 6 enzymatic, two nonenzymatic antioxidants, chl a, chl b, total carotenoid and β-carotene, on the antioxidant response of Dunaliella salina under cold temperature (13°C) were quantified after 24 h stress treatments. The activity of superoxide dismutase (SOD) increased, under 13°C/100 μmol m-2 sec-1, whereas ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), superoxide dismutase and pyrogallol peroxidase activities were induced under 13°C/20 μmol m-2 sec-1. The cells exhibited an increase in reduced ascorbate and reduced glutathione (GSH) coincident with a marked increase in oxidized glutathione (GSSG), at 13°C/100 μmol m -2 sec-1. There were no marked changes in ascorbate or glutathione pools at 13°C/20 μmol m-2 sec-1, which are similar to those at 28°C/100 μmol m-2 sec-1. Chlorophylls and carotenoids reduction were also observed under chilling treatments, which were more reduced by the higher light intensity (13°C/100 μmol m-2 sec-1). The results of present study indicated various antioxidants responds to different combinations of chilling and low light intensities, in D. salina. These responses are very sensitive to small increase in the light intensity. © 2006 Asian Network for Scientific Information.
Iranian Journal of Science and Technology, Transaction A: Science (10286276) 30(1)pp. 57
The individual effects of cadmium concentrations (0, 0.005, 0.05and 0.5 mg. L-1) on the growth (cell number and chlorophyll content) and beta-carotene synthesis of two strains (Iranian and Australian) of green algae D.salina have been studied for a duration of 36 days. The effects of these cadmium concentrations on the amount of cell magnesium and calcium have also been evaluated. An increase in cadmium concentration resulted in a significant reduction in the cell number and chlorophyll content of D. salina. In comparison with control, in both strains, the increase of beta-carotene content of cells was observed in the first few days of the experiment, moreover, the amount of magnesium and calcium in cells decreased. The results indicated that the addition of 0.5 mg. L-1 of cadmium in the medium results in a 50 percent reduction in cell number after 96h. The decrease in growth rate and the increase in beta-carotene content of cells is probably due to the formation of free radicals and deficiency of essential elements such as magnesium and calcium, which is caused by high concentrations of cadmium in the medium. © Shiraz University.
Pakistan Journal of Biological Sciences (18125735) 9(5)pp. 893-897
In the seed industry, seed pelleting is a method used for better crop establishment. Due to problems with the cultivation of Trifolium repens seeds in cold regions, seed pelleting was used. In the first stage of experiment, the effect of some allelopathic compounds including Ephedrine, Vanillin, Caffeine, ABA, extracts of Eucalyptus camadulensis leaf, Onobryichis sativa seed and Juglans regia leaf on germination indicators (percentage germination, germination start, coefficient of velocity and coefficient of allometry) of Trifolium repens seeds were tested. Results showed that among tested allelochemicals Vanillin, ABA and Eucalyptus camadulensis leaf extract were suitable allelochemicals for seed pelleting. In the second stage, seeds were coated with those allelochemicals using seed pelleting method, with no negative effect on seedling growth or on percentage germination. Germination of seeds coated with these allelochemicals was delayed with respect to control but seeds pelleted with Eucalyptus camadulensis leaf extract exhibited delayed germination for longer time than the other treatments. © 2006 Asian Network for Scientific Information.
IRANIAN JOURNAL OF SCIENCE AND TECHNOLOGY (03601307) 27(1)pp. 185-190
The effect of pH (ranging from 3 to 10), salinity (0.5, 2 and 4M NaCl) and light intensity (20, 60 and 300μmol quanta. m-2. s-1) on the growth curve of three species of D. salina, D.parva and D.psuedosalina were studied. Also, the effect of high temperature ranging from 35 to 60 °C on the motility and integrity of these three species at different salinity of 0.1, 0.5, 1, 1.5, 2, 3 and 4M NaCl in the medium, were studied. The results show that D.salina and D.parva could grow at pH ranges of 6 to 9 with optimum of 7 to 8 and D.psuedosalina at pH of 5 to 10 with optimum of 7 to 8. All three species had optimum growth rate at about 0.5 to 2.0M NaCl. The results also show that, in all three species cell motility and resistance to high temperature increased with increasing NaCl concentration in the medium.
