Search

This study aimed to determine the priming effects on the biochemical composition (phenolics, essential oil and fatty acids) and its potential as a method to increase the level of nutraceuticals in anise seed extracts. For seed priming different methods were used including NaCl at three different concentrations and distilled water. After priming, seeds were dried for 24 h to reach their initial moisture content. Our results indicate that seed priming reduced the levels of total polyphenols and flavonoids. In contrast, it improved the level of condensed tannins, and reduced ascorbate and total ascorbate. Analysis of the essential oil revealed that trans-anethole was the major compound in non-primed and primed seeds. Priming reduced the number of detectable compounds with a clear tendency towards the production of trans-anethole, known for its antioxidant, antimicrobial and acetyl cholinesterase properties. Seeds pre-treatment modulated the production of lipids, presumably to maintain the integrity of membrane structures. It also induced an increase in chlorophyll and β-carotene. These results indicate the potential benefits of seed priming in increasing the level of chemical compounds in anise seeds and suggests that a similar strategy could potentially be used in increasing the level of target compounds in other pharmaceutical plant species. [ABSTRACT FROM AUTHOR]

The toxicity of four potentially toxic trace elements (Cu, Ni, Pb and Zn) to Annual Atriplex (A. hortensis and A. rosea) was examined to determine if this plant showed sufficient tolerance to be used to phytoremediate soils polluted with these heavy metals. The plant growth expressed as shoot and root dry weight of Atriplex plant was adversely inhibited when exposed to high concentrations of polluted soil. Significant increases in chlorophyll content were observed in leaves for three Atriplex varieties after the plants were exposed to stress treatments. The carotenoid and anthocyanin content also decreased. Red variety of Atriplex accumulated more anthocyanins in leaves than green and rosea ones. The lipid peroxidation increased, considerably at 100% polluted soil, which is a typical plant reaction to the oxidative stress. We proposed for the reduction state of photosynthetic parameters to be a useful tool in bioassay toxicity testing of metal polluted soil. These results demonstrate that heavy metal contamination of soil has adversely affected the photosynthetic parameters of annual Atriplex. The present study shows that exposure to heavy metals induced oxidative stress which was accompanied by growth inhibition, enhanced lipid peroxidation levels, increase content of chlorophyll, decrease content of carotenoids and anthocyanins. Finally, it was concluded that annual Atriplex has a high ability to tolerate Cu, Ni, Pb and Zn, so it might be a promising plant to be used for phytostabilization of metal contaminated soil. [ABSTRACT FROM AUTHOR]

Lactuca sativa L. is one of the most important sources of phytonutrients including vitamins, carotenoids, and anti-oxidants. However, lettuce growth and quality are strongly affected by soil fertility. In this study, the influence of iron (Fe) and/or magnesium (Mg) deficiencies on the growth, anti-oxidant properties, and ferric chelate reductase (FCR) and phosphoenolpyruvate carboxylase (PEPC) activities in lettuce plants was studied, after 15 d of treatment. Deficiencies in Fe and Mg decreased the accumulation of fresh weight and the concentration of chlorophyll. Intracellular Fe and Mg concentrations were affected by Fe- and/or Mg-deficiency, especially by the combined deficiency. This study also showed that Fe- and Mg-deficiencies had antagonistic effects on the activities of FCR and PEPC. The activity of catalase (CAT) was not significantly altered by Mg-deficiency, but a significant decline in CAT activity was recorded in Fe-deficient shoots. This decline increased with the concentration of Mg in the medium. Moreover, guaiacol peroxidase (GPX) and ascorbate peroxidase (APX) activities were reduced by Fe-deficiency at normal levels of Mg, but were increased by Mg-deficiency at normal or low levels of Fe. [ABSTRACT FROM AUTHOR]

With this investigation, we aimed to study more deeply the antioxidative response to moderate doses of NaCl or Na2SO4 in two cultivars of basil differentially sensitive to salinity. Tolerance to salinity was previously evaluated by the extent of growth inhibition whereas the antioxidant response was assessed studying the changes in the activities of superoxide dismutase (SOD) and catalase as well as in the amounts of tocopherols and lipoic acid. To make possible the comparison of the responses of basil cv. Genovese and cv. Fine to different salts, the experiment was carried out with equimolar concentrations of Na+. The results showed that changes caused by salinity were dependent on cultivar and exposure time. In particular, cv. Genovese was more sensitive to Na2SO4 excess than cv. Fine whereas both of them had higher SOD activity under NaCl salinity. Generally, Fine basil withstood salinity better than Genovese, being endowed with higher constitutive levels of reduced lipoic acid [dihydrolipoic acid (DHLA)] as well as of α- and γ-tocopherols. Moreover, cv. Fine showed the ability to utilise DHLA and to synthesise tocopherols during stressful conditions. Thus, more than one mechanism was involved in basil in the detoxification of reactive oxygen species during salt stress. In fact, when lipoic acid did not participate in the regeneration of reduced ascorbate and glutathione form, high amounts of tocopherols were present, likely protecting cell membranes from oxidative damage and making basil tolerant to moderate salinity. [ABSTRACT FROM AUTHOR]

Investigations on the effects of water-deficit stress conditions on the physiological characteristics of plants may provide a means to understand the basis of drought resistance. Atriplex spp. have been used as a resource for the rehabilitation of degraded land. The responses of two varieties of Atriplex hortensis [green orach (A. hortensis L. var. purpurea) and red orach (A. hortensis L. var. rubra)] to four levels of soil moisture (100, 80, 60, or 40% of field capacity) were investigated. The experiment was conducted under greenhouse conditions. Growth declined progressively with the application of increasing water stress. Water-stressed plants exhibited significant reductions in height and biomass. Water-deficit stress also caused a significant decline in total leaf area, but had no significant effect on leaf water content in red orach. Reductions in soil water content caused reductions in the relative water content (RWC) of leaves in both varieties of A. hortensis. but the decrease in RWC was more pronounced in green orach than in red orach. The results of this study indicate differences in drought tolerance between the two varieties of A. hortensis. Based on these findings, the more drought-tolerant red orach may be grown, preferentially, under water stress conditions or in water-limiting soils. [ABSTRACT FROM AUTHOR]

Oxidative stress is induced by a wide range of environmental factors including heavy metals stress. Therefore, antioxidant resistance mechanisms may provide a strategy to enhance metal tolerance, and processes underlying antioxidant responses to metal stress must be clearly understood. In the present study, the effects of heavy metals generating antioxidative defense systems (i.e., superoxide dismutase, ascorbate peroxydase, glutathione reductase and catalase) were studied in the leaves of Atriplex plants grown in polluted soil with different metals (Cu, Ni, Pb, Zn). The results obtained show that exposure of plants to different levels of metal reduced the dry matter production and height of shoots. The decrease in root growth caused by toxicity of metals was more severe than the decrease in shoot growth. Atriplex plant showed gradual decrease in height following metal treatments, a 4-week exposure of A. hortensis (red) to 25%, 50%, 75% and 100% contaminated soil gave a respective mean values of 21,4, 12,2, 9,3 and 6,5 cm, these values were lower than the 39,00 cm observed for the control. Of the antioxidant enzymes, the results showed that only superoxide dismutase (SOD), and probably ascorbate peroxidase (APX), were diminished by metal toxicity. However, the activity of catalase (CAT) and glutathione reductase (GR) was increased by metal stress. Hence, the plants of the three annual arroach species or varieties used, all showed an intermediate level of tolerance according to the imposed treatments. The antioxidative activity seems to be of fundamental importance for adaptive response of Atriplex plants against environmental stress. [ABSTRACT FROM AUTHOR]

In the present study, the effects of elevated zinc concentrations on germination, physiological and biochemical parameters were investigated in basil (Ocimum basilicum L.). Results indicate that zinc excess (1-5 mM ZnSO 4 ) did not affect germination process, but it drastically reduced vigor index and radicle elongation, and induced oxidative stress. Exposure of basil plants to 400 and 800 µM Zn decreased aerial parts and roots dry biomass, root length and leaf number. Under these conditions, the reduction of plant growth was associated with the formation of branched and abnormally shaped brown roots. Translocation factor < 1 and bioconcentration factor > 1 was observed for 100 µM Zn suggested the possible use of basil as a phytostabiliser. Excess of Zn supply (> 100 µM) decreased chlorophyll content, total phenol and total flavonoid contents. Additionally, an increased TBARS levels reflecting an oxidative burst was observed in Zn-treated plants. These findings suggest that excess Zn adversely affects plant growth, photosynthetic pigments, phenolic and flavonoid contents, and enhances oxidative stress in basil plants.

The changes observed photosystem I activity of lettuce plants exposed to iron deficiency were investigated. Photooxidation/reduction kinetics of P700 monitored as ΔA820 in the presence and absence of electron transport inhibitors and acceptors demonstrated that deprivation in iron decreased the population of active photo-oxidizable P700. In the complete absence of iron, the addition of plant inhibitors (DCMU and MV) could not recover the full PSI activity owing to the abolition of a part of P700 centers. In leaves with total iron deprivation (0μM Fe), only 15% of photo-oxidizable P700 remained. In addition, iron deficiency appeared to affect the pool size of NADP(+) as shown by the decline in the magnitude of the first phase of the photooxidation kinetics of P700 by FR-light. Concomitantly, chlorophyll content gradually declined with the iron concentration added to culture medium. In addition, pronounced changes were found in chlorophyll fluorescence spectra. Also, the global fluorescence intensity was affected. The above changes led to an increased rate of cyclic electron transport around PSI mainly supported by stromal reductants., (Copyright © 2013 Elsevier GmbH. All rights reserved.)

Background: Fe deficiency affects food growth and quality in calcareous soils. In this study, the effect of Fe deficiency on growth parameters, phenolic content and antioxidant capacities of two lettuce shoots varieties (Romaine and Vista) were investigated., Results: Fresh matter production, pigment (chlorophyll and carotenoid) and Fe2+ content were significantly reduced by Fe deficiency in both varieties. However, restriction of these parameters was particularly pronounced in Romaine variety as compared to Vista. Moreover, Fe deficiency caused decreases in the activity of antioxidant enzymes such as catalase and guaiacol peroxidase, whereas ascorbate peroxidase and malondialdehyde concentrations were not significantly affected. On the other hand, Fe deficiency in Vista variety induced an increase in polyphenol and flavonoid content as compared to Romaine variety. In addition, total antioxidant capacity and antiradical test against DPPH radical decreased in leaves of Romaine variety after 15 days of treatment., Conclusion: These results suggest that the higher polyphenol content in Vista variety supports the involvement of these components in the stability of antioxidant capacities and then in its protection against oxidative damage generated by Fe deficiency in lettuce plants., (© 2012 Society of Chemical Industry.)

Background: Three annual Atriplex species-A. hortensis var. purpurea, A. hortensis var. rubra and A. rosea-growing on soil with various levels of the heavy metals copper, lead, nickel, and zinc, have been investigated., Results: Metal accumulation by Atriplex plants differed among species, levels of polluted soil and tissues. Metals accumulated by Atriplex were mostly distributed in root tissues, suggesting that an exclusion strategy for metal tolerance widely exists in them. The increased concentration of heavy metals in soil led to increases in heavy metal shoot and root concentrations of Ni, Cu, Pb and Zn in plants as compared to those grown on unpolluted soil. Accumulation was higher in roots than shoots for all the heavy metals. None of the plants were suitable for phytoextraction because no hyperaccumulator was identified. However, plants with a high bioconcentration factor and low translocation factor have the potential for phytostabilization. Similarly, the correlation between metal concentrations and translocations in plants (BCFs and TFs) using a linear regression was also statistically significant., Conclusion: Among the plants studied, var. purpurea was the most efficient in accumulating Pb and Zn in its shoots, whereas var. rubra was most suitable for phytostabilization of sites contaminated with Cu and Ni., (Copyright © 2011 Society of Chemical Industry.)

Fenugreek (Trigonella foenum graecum) seedlings were exposed to increasing NaCl concentrations in the growth medium to examine the effect of salt stress on the electron transport reactions of photosynthesis. Activities of both photosystem II (PSII), measured by chlorophyll fluorescence, and photosystem I (PSI), measured by P700 photooxidation, were decreased by salt stress. The inhibition proceeded in a two step manner. At the lower salt concentrations used and shorter exposition periods, electron transfer between the quinone acceptors of PSII, Q(A) and Q(B), was strongly retarded as shown by an increased amplitude of the OJ phase of the OJIP chlorophyll fluorescence induction traces and slowed chlorophyll fluorescence relaxation kinetics following a single turn-over flash. The above indicated a disturbance of the Q(B) binding site likely associated with the first step of photoinhibition. In the second step, strong photoinhibition was observed as manifested by increased F(0) values, declined F(v)/F(0) and loss of photoactive P700., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The effect of iron deficiency on photosynthetic electron transport in Photosystem II (PS II) was studied in leaves and thylakoid membranes of lettuce (Lactuca sativa, Romaine variety) plants. PS II electron transport was characterized by oxygen evolution and chlorophyll fluorescence parameters. Iron deficiency in the culture medium was shown to affect water oxidation and the advancement of the S-states. A decrease of maximal quantum yield of PS II and an increase of fluorescence intensity at step J and I of OJIP kinetics were also observed. Thermoluminescence measurements revealed that charge recombination between the quinone acceptor of PS II, Q(B), and the S(2) state of the Mn-cluster was strongly perturbed. Also the dark decay of Chl fluorescence after a single turnover white flash was greatly retarded indicating a slower rate of Q(A)(-) reoxidation.

Salinity inhibits plant growth due to osmotic and ionic effects. However, little is known about the impact of genotype and salinity on biochemical and molecular processes in the leafy vegetable lettuce. We report here evaluations of two lettuce types, Verte (NaCl tolerant) and Romaine (NaCl sensitive), under iso-osmotic 100 mM NaCl and 77 mM Na(2)SO(4) treatments. As compared to Romaine, NaCl-treated Verte displayed better growth, contained lower levels of inorganic cations in leaves, and possessed superior antioxidative capacity due to enhanced carotenoid and phenolics biosynthesis and more active antioxidative enzymes resulting in reduced membrane damage. Both genotypes had relatively similar growth patterns under Na(2)SO(4) treatment, but Romaine showed enhanced root lignification, greater malondialdehyde formation, and suppressed Fe-superoxide dismutase expression in roots as compared with Verte.

The efficiency of composted municipal solid wastes (MSW) to reduce the adverse effects of salinity was investigated in Hordeum maritimum under greenhouse conditions. Plants were cultivated in pots filled with soil added with 0 and 40tha(-1) of MSW compost, and irrigated twice a week with tap water at two salinities (0 and 4gl(-1) NaCl). Harvests were achieved at 70 (shoots) and 130 (shoots and roots) days after sowing. At each cutting, dry weight (DW), NPK nutrition, chlorophyll, leaf protein content, Rubisco (ribulose-bisphosphate carboxylase/oxygenase) capacity, and contents of potential toxic elements were determined. Results showed that compost supply increased significantly the biomass production of non salt-treated plants (+80%). This was associated with higher N and P uptake in both shoots (+61% and +80%, respectively) and roots (+48% and +25%, respectively), while lesser impact was observed for K+. In addition, chlorophyll and protein contents as well as Rubisco capacity were significantly improved by the organic amendment. MSW compost mitigated the deleterious effect of salt stress on the plant growth, partly due to improved chlorophyll and protein contents and Rubisco capacity (-15%, -27% and -14%, respectively, in combined treatment, against -45%, -84% and -25%, respectively, in salt-stressed plants without compost addition), which presumably favoured photosynthesis and alleviated salt affect on biomass production by 21%. In addition, plants grown on amended soil showed a general improvement in their heavy metals contents Cu2+, Pb2+, Cd2+, and Zn2+ (in combined treatment: 190%, 53%, 168% and 174% in shoots and 183%, 42%, 42% and 114% in roots, respectively) but remained lower than phytotoxic values. Taken together, these findings suggest that municipal waste compost may be safely applied to salt-affected soils without adverse effects on plant physiology.

Morpho-physiological responses to bicarbonate-induced Fe deficiency were investigated in five Vitis vinifera L. Tunisian varieties (Khamri, Blanc3, Arich Dressé, Beldi, and Balta4). One-month-old woody cuttings were cultivated for 85days on a free calcareous soil irrigated with tap water containing increasing bicarbonate levels (0, 4, 8, 12, and 16mM NaHCO(3)). After this screening, a second experiment compared root biochemical responses of two contrasting genotypes (tolerant-sensitive) dealing with bicarbonate-induced iron deprivation (20microM Fe+/-10mM HCO(3)(-)) for 75days. Using morpho-physiological criteria, grapevine tolerance to HCO(3)(-)-induced Fe shortage appeared to be genotype-dependent: Balta4 and Beldi varieties showed the highest leaf-chlorosis score (especially at the extreme HCO(3)(-) levels), in contrast to Khamri variety. Growth parameters (shoot height, total leaf area, leaf number, and biomass production) as well as juvenile leaf chlorophyll content were also differently affected depending on both genotype and bicarbonate dose. At 16mM HCO(3)(-), Khamri was the less sensitive variety, contrasting with Balta4. On the other hand, chlorophyll content correlated positively with HCl-extractible Fe content of the juvenile leaves, suggesting that the grapevine response to iron deficiency may partly depend on to the plant ability to adequately supply young leaves with this element. Root biochemical responses revealed a relatively higher root acidification capacity in Khamri (tolerant) under Fe-deficiency while no significant changes occurred in Balta4 (sensitive). In addition, Fe(III)-reductase and phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31) activities were strongly stimulated by Fe-deficiency in Khamri, while remaining constant in Balta4. These findings suggest that biochemical parameters may constitute reliable criteria for the selection of tolerant grapevine genotypes to iron chlorosis.

Thellungiella halophila and Arabidopsis thaliana were irrigated with medium containing NaCl at various concentrations. The salt treatment resulted in a restriction of rosette biomass deposition in both species. In A. thaliana leaves, this inhibition was stronger than for T. halophila and was associated with strong inhibition of both leaf initiation and leaf expansion. At highest medium salinity, A. thaliana accumulated Na(+) and Cl(-) at higher levels than T. halophila, but similar leaf dehydration was observed in the two species. Proline accumulation, which increased with NaCl concentration, did not differentiate the two species. The magnitude of the electrolyte leakage and the level of lipid peroxidation (assessed through hydroxy fatty acid content) were modest in T. halophila and quite marked in A. thaliana. The detrimental effects of the salt on photosynthetic activity and stomatal conductance of A. thaliana leaves were much more important than in T. halophila leaves. The abundance of the CDSP32 thioredoxin, a critical component of the defence system against oxidative damage and lipid peroxidation, was found to be higher in T. halophila than in A. thaliana under control conditions and salt treatment. These results suggest that the rosette leaves of T. halophila exhibit more efficient protective mechanisms against Na(+) metabolic toxicity than those of A. thaliana.

Thellungiella halophila seedlings grown on a solid substrate for 25 days on standard medium were challenged with NaCl. Growth, tissue hydration, ion accumulation, photosynthesis, lipid peroxidation and antioxidant enzymatic activities were studied on rosette leaves. Three accessions of Arabidopsis thaliana were cultivated under the same conditions. During the first two weeks of salt treatment, the growth of T. halophila leaves was restricted by NaCl. No significant difference appeared between T. halophila and A. thaliana concerning biomass deposition, or hydric and ionic parameters. However, all A. thaliana plants displayed foliar damage, and died during the third week of salt (50mM NaCl) treatment. Almost all (94%) T. halophila plants remained alive, but did not display any sign of altered physiological condition. Tissue hydration, chlorophyll content, stomatal conductance, photosynthetic quantum yield, and photosynthetic rate were very similar to those of control plants. Lipid peroxidation, estimated from thermoluminescence, was very low and insensitive to salt treatment. Only slight changes occurred in antioxidant enzymatic activities (SOD, several peroxidases, and catalase). From the absence of physiological disorder symptoms, we infer that salt was efficiently compartmentalized in leaf vacuoles. In salt-treated A. thaliana, the photosynthetic quantum yield was diminished, and lipid peroxidation was augmented. These observations reinforce the conclusion that T. halophila could accumulate salt in its leaves without damage, in contrast to A. thaliana.

Phosphoenolpyruvate carboxylase (PEPc: EC 4.1.1.31) activity was monitored during seed maturation of two varieties (Hybridol and Pactol) of rapeseed (Brassica napus L.), widely cultivated in Tunisia. In the Hybridol variety, PEPc activity did not exceed 5 micromol h(-1) per gram of fresh weight (FW) during the first stages of maturation. It then highly increased to reach more than 30 micromol h(-1) g(-1)/FW. On the contrary, in the Pactol variety, the evolution of PEPc activity showed a classical curve, i.e. an increase during the most active phase of lipid accumulation in maturating seeds, followed by a rapid decrease until the end of seed maturation. In both varieties, the seed oil was characterised by a high content of oleic acid (C(18:1)), linoleic (C(18:2)) and linolenic acids (C(18:3)). Saturated fatty acids were also present, although decreasing with maturation course. The analysis of the triacylglycerols (TAG) showed that trioleoylglycerol (OOO) and dioleoyllinoleoylglycerol (OOL) were the major species (ca. 35% and ca. 25% of the total respectively). The evolution pattern of fatty acids and TAG contents was similar to that of PEPc activity. Taken together, our findings suggest that PEPc may be involved in fatty acid and triacylglycerol biosynthesis during seed maturation of both rapeseed varieties.

Plants of two wheat species (Triticum aestivum cv. Tanit and T. durum cv. Ben Bachir), differing in their sensitivity to NaCl were cultivated in the presence or absence of 100 mM NaCl for 21 days. Soluble proteins extracted from leaves were analyzed by two-dimensional electrophoresis in order to detect NaCl-induced changes in the polypeptide patterns. In all, 500 spots were detected. Results showed species-dependent differences. The greatest alterations in the polypeptide profiles following salt stress were found in the most sensitive cultivar: among the 12 spots (molecular mass, 15-31 kDa) specifically considered in the acidic region of the gel, 11 declined, even disappeared in the NaCl-sensitive leaf profiles, while in the tolerant species only five spots were affected by the salt treatment and five remained untouched; moreover in the latter, two new polypeptides were shown to be induced by NaCl.