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N. Djebali H. Mhadhbi C. Jacquet T. Huguet M. E. Aouani 《Journal of Phytopathology》2007,155(10):633-640
This study was undertaken to assess the involvement of hydrogen peroxide (H2O2), peroxidase (POX; EC 1.11.1.7) and superoxide dismutase (SOD; EC 1.15.1.1) in Medicago truncatula in relation with susceptibility to Phoma medicaginis infection. Several M. truncatula lines were studied in terms of their response to P. medicaginis infection. Fifteen days after inoculation (dai), differences in susceptibility were found. DZA45.5 was the least susceptible line and F83005.5 was the most susceptible line. Microscopic analysis of fungal development was performed in inoculated detached leaves of the DZA45.5 and F83005.5 lines. No significant difference was observed in events from conidia germination to penetration. Differences became apparent during the colonization process as the pathogen was able to sporulate rapidly increasing its concentration on the tissue of F83005.5 in comparison with DZA45.5. To characterize the susceptibility of the two lines, histochemical detection of H2O2 was made in detached leaves. H2O2 detection showed an early accumulation of this component in cells of DZA45.5 at 1 dai. However, H2O2 was detected in few, if any, cells in the tissues of the most susceptible line, F83005.5. The activity of POX and SOD were determined spectrophotometrically in leaves of intact inoculated plants of both lines. Phoma medicaginis inoculation of DZA45.5 and F83005.5 did not affect POX activity level in leaves when compared with control uninoculated plants. SOD activity showed a significant decrease in F83005.5 and DZA45.5 leaves at 4 dai and 9 dai, respectively, in comparison with control plants. In control plants POX activity was significantly higher in the least susceptible line DZA45.5 in comparison with F83005.5. Early and higher production of H2O2 and elevated basal POX activity in cells of the least susceptible line, DZA45.5 could explain its ability to be less favourable to the colonization and reproduction of P. medicaginis in comparison with the most susceptible line, F83005.5. 相似文献
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Djebali W Zarrouk M Brouquisse R El Kahoui S Limam F Ghorbel MH Chaïbi W 《Plant biology (Stuttgart, Germany)》2005,7(4):358-368
The effects of cadmium (Cd) uptake on ultrastructure and lipid composition of chloroplasts were investigated in 28-day-old tomato plants (Lycopersicon esculentum var. Ibiza F1) grown for 10 days in the presence of various concentrations of CdCl2. Different growth parameters, lipid and fatty acid composition, lipid peroxidation, and lipoxygenase activity were measured in the leaves in order to assess the involvement of this metal in the generation of oxidative stress. We first observed that the accumulation of Cd increased with external metal concentration, and was considerably higher in roots than in leaves. Cadmium induced a significant inhibition of growth in both plant organs, as well as a reduction in the chlorophyll and carotenoid contents in the leaves. Ultrastructural investigations revealed that cadmium induced disorganization in leaf structure, essentially marked by a lowered mesophyll cell size, reduced intercellular spaces, as well as severe alterations in chloroplast fine structure, which exhibits disturbed shape and dilation of thylakoid membranes. High cadmium concentrations also affect the main lipid classes, leading to strong changes in their composition and fatty acid content. Thus, the exposure of tomato plants to cadmium caused a concentration-related decrease in the fatty acid content and a shift in the composition of fatty acids, resulting in a lower degree of fatty acid unsaturation in chloroplast membranes. The level of lipid peroxides and the activity of lipoxygenase were also significantly enhanced at high Cd concentrations. These biochemical and ultrastructural changes suggest that cadmium, through its effects on membrane structure and composition, induces premature senescence of leaves. 相似文献
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Olfa Tabbene Imen Ben Slimene Kais Djebali Maria‐Luisa Mangoni Maria‐Camino Urdaci Ferid Limam 《Biotechnology progress》2009,25(5):1267-1274
An antimicrobial activity produced by Bacillus subtilis B38 was found to be effective against several bacteria, including pathogenic and spoilage microorganisms such as, Listeria monocytogenes, Salmonella enteridis, and clinical isolates of methicillin‐resistant Staphylococcus species. Nutrients such as carbon, nitrogen sources, and inorganic salts enhanced the production level of the antibacterial activity by B. subtilis B38. A first screening step showed that lactose, ammonium succinate, and manganese most influenced both cell growth and antibacterial activity production. These three factors varied at two levels in eight experiments using full factorial design. Results indicated that maximum cell growth (OD = 10.2) and maximum production of antibacterial activity (360 AU/mL) were obtained in a modified medium containing 1.5% (w/v) lactose, 0.15% (w/v) ammonium succinate, and 0.3 mg/L manganese. Depending on the indicator strain used, the antibacterial activity was 2‐ to 4‐fold higher in the modified culture medium than in TSB medium under the same conditions. Thin layer chromatography‐bioautography assay showed the presence of three active spots with Rf values of 0.47, 0.7, and 0.82 in TSB medium. However, the inhibition zone of two spots (Rf values of 0.7 and 0.82) was slightly larger in the modified medium. Moreover, a large zone of inhibition with an Rf value of 0.3, was observed in this modified medium, instead of the spot having an Rf value of 0.47. These results suggest that the nutrients act as environmental factors, quantitatively and qualitatively affecting the production of antibacterial compounds by B. subtilis B38. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 相似文献
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Aeluropus littoralis is a perennial halophyte, native to coastal zones. Although it is usually exposed to high saline, this plant grows normally without toxicity symptoms. In order to assess leaf salt excretion, different growth parameters, Na(+), K(+), Ca(2+), Mg(2+) and Cl(-) concentrations, as well as excreted ions were examined in plants grown for 2 months in the presence of various salinity levels (0-800 mM NaCl). In addition, salt crystals, salt glands and other leaf epidermal structures were investigated. Results showed that total plant growth decreased linearly with increase to medium salinity. This reduction concerns mainly shoot growth. In addition, this species was able to maintain its shoot water content at nearly 50% of the control even when subjected to 800 mM NaCl. Root water content seemed to be unaffected by salt. Sodium and chloride ion contents in shoots and in roots increased with salinity concentrations, in contrast to our observation for potassium. However, calcium and magnesium contents were not greatly affected by salinity. Excreted salts in A. littoralis leaves were in favor of sodium and chloride, but against potassium, calcium and magnesium which were retained in plants. Sodium and chloride were excreted from special salt glands, which were scattered on the both leaf surfaces. In addition to salt glands, papillae were the most frequent epidermal structure found on A. littoralis leaves, and are likely involved in A. littoralis salt resistance. 相似文献
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Salt impact on photosynthesis and leaf ultrastructure of <Emphasis Type="Italic">Aeluropus littoralis</Emphasis> 总被引:1,自引:0,他引:1
The effects of salinity (400 mM NaCl) on growth, biomass partitioning, photosynthesis, and leaf ultrastructure were studied
in hydroponically grown plants of Aeluropus littoralis (Willd) Parl. NaCl produced a significant inhibition of the main growth parameters and a reduction in leaf gas exchange (e.g.
decreased rates of photosynthesis and stomatal conductance). However, NaCl salinity affected neither the composition of photosynthesis
pigments nor leaf water content. The reduction in leaf gas exchange seemed to correlate with a decrease in mesophyll thickness
as well as a severe disorganisation of chloroplast structure, with misshapen chloroplasts and dilated thylakoid membranes.
Conspicuously, mesophyll chloroplasts were more sensitive to salt treatment than those of bundle sheath cells. The effects
of NaCl toxicity on leaf structure and ultrastructure and the associated physiological implications are discussed in relation
to the degree of salt resistance of A. littoralis. 相似文献
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Djebali S Lagarde J Kapranov P Lacroix V Borel C Mudge JM Howald C Foissac S Ucla C Chrast J Ribeca P Martin D Murray RR Yang X Ghamsari L Lin C Bell I Dumais E Drenkow J Tress ML Gelpí JL Orozco M Valencia A van Berkum NL Lajoie BR Vidal M Stamatoyannopoulos J Batut P Dobin A Harrow J Hubbard T Dekker J Frankish A Salehi-Ashtiani K Reymond A Antonarakis SE Guigó R Gingeras TR 《PloS one》2012,7(1):e28213
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Djebali W Gallusci P Polge C Boulila L Galtier N Raymond P Chaibi W Brouquisse R 《Planta》2008,227(3):625-639
The effects of cadmium (Cd) on cellular proteolytic responses were investigated in the roots and leaves of tomato (Solanum lycopersicum L., var Ibiza) plants. Three-week-old plants were grown for 3 and 10 days in the presence of 0.3–300 μM Cd and compared to
control plants grown in the absence of Cd. Roots of Cd treated plants accumulated four to fivefold Cd as much as mature leaves.
Although 10 days of culture at high Cd concentrations inhibited plant growth, tomato plants recovered and were still able
to grow again after Cd removal. Tomato roots and leaves are not modified in their proteolytic response with low Cd concentrations
(≤3 μM) in the incubation medium. At higher Cd concentration, protein oxidation state and protease activities are modified
in roots and leaves although in different ways. The soluble protein content of leaves decreased and protein carbonylation
level increased indicative of an oxidative stress. Conversely, protein content of roots increased from 30 to 50%, but the
amount of oxidized proteins decreased by two to threefold. Proteolysis responded earlier in leaves than in root to Cd stress.
Additionally, whereas cysteine- and metallo-endopeptidase activities, as well as proteasome chymotrypsin activity and subunit
expression level, increased in roots and leaves, serine-endopeptidase activities increased only in leaves. This contrasted
response between roots and leaves may reflect differences in Cd compartmentation and/or complexation, antioxidant responses
and metabolic sensitivity to Cd between plant tissues. The up-regulation of the 20S proteasome gene expression and proteolytic
activity argues in favor of the involvement of the 20S proteasome in the degradation of oxidized proteins in plants.
This paper is dedicated to Nathalie Galtier (1964–2005), who was senior researcher at the INRA Research Center, Villenave
d’Ornon, France. 相似文献
10.
The effects of salt uptake on the morphology and ultrastructure of leaf salt glands were investigated in Aeluropus littoralis plants grown for two months in the presence of 400 mM NaCl. The salt gland is composed of two linked cells, as observed in some other studied Poaceae species. The cap cell, which protrudes from the leaf surface, is smaller than the basal cell, which is embedded in the leaf mesophyll tissues and bears the former. The cuticle over the cap cell is frequently separated from the cell wall to form a cavity where salts accumulate prior to excretion. The basal cell cytoplasm contains an extensive intricate or partitioning membrane system that is probably involved in the excretion process, which is absent from the cap cell. The intricate membrane system seems to be elongated and heavily loaded with salt. The presence of 400 mM NaCl induced the disappearance of the collecting chamber over the glands and an increase in the number of vacuoles and their size in both gland cells. In the basal cell, salt greatly increased both the density and size of the intricate membrane system. The electron density of both gland cells observed under salt treatment reflects a high activity. All these changes probably constitute special adaptations for dealing with salt accumulation in the leaves. Despite the high salt concentration used, no serious damage occurred in A. littoralis salt gland ultrastructure, which consolidates the assumption that they are naturally designated for this purpose. 相似文献