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Nadia Kallala Wissal M’sehli Karima Jelali Marwa Batnini Mounawer Badri Issam Nouairi Haythem Mhadhbi 《Plant Species Biology》2019,34(3):95-109
Iron (Fe) deficiency is one of the major environmental stresses affecting plant production in the world. The selection of tolerant genotypes is considered an effective remediation strategy for this stress. The present study was carried out in order to investigate the biodiversity within Medicago truncatula plants in response to Fe deficiency, to identify tolerant genotypes and to assess the main tolerance mechanisms. To do this, a screening test was performed on 20 M. truncatula genotypes cultivated in minimal medium. Biometric and physiological markers were analyzed, including plant biomass, chlorophyll and root architecture. Results showed a biodiversity among the 20 genotypes. Interestingly, Fe deficiency tolerance was highest in TN8.20 and A17 genotypes. However, the lowest tolerance behavior was observed in TN1.11 and TN6.18. In order to investigate the main tolerance mechanisms, an experiment was conducted in the hydroponic system on already selected genotypes. Assessment of Fe deficiency tolerance was performed mainly on plant growth parameters, Fe (III)-chelate-reductase activity, rhizosphere acidification and antioxidant system defense. The relative better tolerance of A17 and TN8.20 to Fe deficiency was positively correlated with their capacity to maintain higher Fe-acquisition efficiency in roots via rhizosphere acidification and the stimulation of Fe (III)-chelate-reductase activity. Moreover, tolerant genotypes showed the lowest decreases in chlorophyll content and photosynthetic activity (CO2 assimilation) compared to the sensitive ones. The efficiency of antioxidant capacity of the tolerant genotypes was revealed in stimulation of catalase (CAT) and peroxidase (POX) activities as well as accumulation of polyphenols, leading to the maintenance of cell integrity under Fe deficiency. 相似文献
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Sabah Yousfi M'sehli Wissal Henda Mahmoudi Chedly Abdelly Mohamed Gharsalli 《Plant Physiology and Biochemistry》2007,45(5):309-314
Iron chlorosis is very common on alkaline soils such as calcareous ones, since iron availability is limited by high pH. Under these conditions of iron deficiency, graminaceous plant species induce special mechanisms for iron acquisition, involving enhanced release of iron chelators called phytosiderophores. On the other hand, it is known that most of salt soils have alkaline pH. So, plants growing on this kind of soils are often subjected simultaneously to salinity and iron deficiency. This work aimed at (i) studying the physiological responses of barley (Hordeum vulgare L.) to iron deficiency, and (ii) evaluating the effect of salt on the iron nutrition and the phytosiderophore release. For this purpose, seedlings of Hordeum vulgare L. were cultivated under controlled conditions, either in a complete nutrient solution with or without NaCl, or in an iron free nutrient solution containing or not NaCl. The plant morphological aspect, chlorophyll content of young leaves, iron status, biomass production, and phytosiderophore release by roots were assessed. Plants subjected to Fe deficiency exhibited a severe chlorosis, accompanied by a significant biomass reduction. These plants developed more lateral roots than the control with a highly stimulated phytosiderophore release. However, the latter was greatly diminished when iron deficiency was associated to salinity. A depressive effect of salt on iron acquisition in plants subjected only to salt stress which was also observed and further confirmed by the important decrease of efficiency in iron acquisition. These results suggest that salinity may reduce capacity of plants to acquire iron from alkaline soils by inhibiting phytosiderophore release. 相似文献
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Nidhal Salem Kamel Msaada Wissal Dhifi Ferid Limam Brahim Marzouk 《Acta Physiologiae Plantarum》2014,36(2):433-445
In the present study, we were interested in the effect of salt stress on phenolic and carotenoid contents, antioxidant and antimicrobial activity of two varieties of Carthamus tinctorius (Jawhara and 104) flowers. For this purpose, C. tinctorius flowers from plants grown under four saline treatments (0, 5, 10 and 15 g/L NaCl) were collected at two development stages. As salinity increased up to 10 g/L, results showed that total phenols, flavonoids, condensed tannins and carotenoid contents increased with salinity. Such variability might be of great importance in terms of valorizing this plant as a source of naturally secondary metabolites. Furthermore, our results showed an enhancement of antioxidant activity which was evaluated by four different test systems (DPPH, β-carotene–linoleic acid, chelating and reducing power assays) with increasing stress severity. Obtained results showed that, for the two varieties, salt effect was more pronounced at post flowering stage than full flowering one. The sensitivity test of the methanolic extracts of the harvested flowers was applied against seven human pathogenic bacteria and three yeast strains. Salinity reduced significantly the antimicrobial activity of flower extracts. 相似文献
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Mesfar W Shirazi-Adl A 《Computer methods in biomechanics and biomedical engineering》2006,9(4):201-209
The effects of changes in cruciate ligament material and prestrain on knee joint biomechanics following ligament reconstruction surgery by a tendon are not adequately known. A 3D nonlinear finite element model of the entire knee joint was used to investigate the joint response at different flexion angles under a quadriceps force while varying ACL and PCL initial strains or material properties. The ACL and PCL forces as well as tibiofemoral contact forces/areas substantially increased with greater ACL or PCL initial strains or stiffness. The patellofemoral contact force slightly increased whereas the tibial extensor moment slightly decreased with tenser or stiffer ACL. Reverse trends were predicted with slacker ACL. Results confirm the hypotheses that changes in the prestrain of one cruciate ligament substantially influence the force in the other cruciate ligament and the entire joint and that the use of the patellar tendon (PT) as a replacement for cruciate ligaments markedly alters the joint biomechanics with trends similar to those predicted when increasing prestrains. Forces in both ACL and PCL ligaments increased as one of them became tenser or stiffer and diminished as it became slacker. These results have important consequences in joint biomechanics following ligament injuries or replacement and tend to recommend the use of grafts with smaller prestrains (i.e. slacker than intact) when using the PT as the replacement material with stiffness greater than that of replaced ligament itself. 相似文献
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The cervical spine functions as a complex mechanism that responds to sudden loading in a unique manner, due to intricate structural features and kinematics. The spinal load-sharing under pure compression and sagittal flexion/extension at two different impact rates were compared using a bio-fidelic finite element (FE) model of the ligamentous cervical functional spinal unit (FSU) C2–C3. This model was developed using a comprehensive and realistic geometry of spinal components and material laws that include strain rate dependency, bone fracture, and ligament failure. The range of motion, contact pressure in facet joints, failure forces in ligaments were compared to experimental findings. The model demonstrated that resistance of spinal components to impact load is dependent on loading rate and direction. For the loads applied, stress increased with loading rate in all spinal components, and was concentrated in the outer intervertebral disc (IVD), regions of ligaments to bone attachment, and in the cancellous bone of the facet joints. The highest stress in ligaments was found in capsular ligament (CL) in all cases. Intradiscal pressure (IDP) in the nucleus was affected by loading rate change. It increased under compression/flexion but decreased under extension. Contact pressure in the facet joints showed less variation under compression, but increased significantly under flexion/extension particularly under extension. Cancellous bone of the facet joints region was the only component fractured and fracture occurred under extension at both rates. The cervical ligaments were the primary load-bearing component followed by the IVD, endplates and cancellous bone; however, the latter was the most vulnerable to extension as it fractured at low energy impact. 相似文献
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Wissal M’Sehli Sabah Youssfi Silvia Donnini Marta Dell’Orto Patricia De Nisi Graziano Zocchi Chedly Abdelly Mohamed Gharsalli 《Plant and Soil》2008,312(1-2):151-162
The main objective of this work was to compare the tolerance to lime-induced Fe deficiency of two lines of Medicago ciliaris (TN11.11 and TN8.7). We studied the effects of Fe deficiency on: (1) root biomass and rhizosphere acidification, (2) accumulation in the roots and the exudation into the rhizosphere of organic compounds (citric acid, malic acid and phenols), (3) changes under Fe deficient conditions in the activities of two enzymes, the first related to organic acid metabolism (malate dehydrogenase: MDH) and the other to proton extrusion (H+-ATPase activity). After a pre-treatment of one week, plants were transferred into hydroponic culture under three treatments: +Fe, ?Fe and +Fe +lime. Iron deficiency led to 40% increase in root biomass in TN11.11 line in the presence of lime. Both the omission of Fe and the addition of lime to the nutrient solution increased the H+-ATPase activity more in TN11.11 than in TN8.7. In addition, Fe deficiency increased accumulation of organic acids as well as phenols in roots, and stimulated the MDH activity more in TN11.11 than in TN8.7 (+75% and +41% in TN11.11 and TN8.7, respectively). Iron deficiency also increased the amounts of citrate, malate and phenols in root exudates. Our data allowed us to note that the TN11.11 line is more effective in overcoming Fe deficiency than TN8.7. 相似文献
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W. Mesfar 《Computer methods in biomechanics and biomedical engineering》2013,16(4):201-209
The effects of changes in cruciate ligament material and prestrain on knee joint biomechanics following ligament reconstruction surgery by a tendon are not adequately known. A 3D nonlinear finite element model of the entire knee joint was used to investigate the joint response at different flexion angles under a quadriceps force while varying ACL and PCL initial strains or material properties. The ACL and PCL forces as well as tibiofemoral contact forces/areas substantially increased with greater ACL or PCL initial strains or stiffness. The patellofemoral contact force slightly increased whereas the tibial extensor moment slightly decreased with tenser or stiffer ACL. Reverse trends were predicted with slacker ACL. Results confirm the hypotheses that changes in the prestrain of one cruciate ligament substantially influence the force in the other cruciate ligament and the entire joint and that the use of the patellar tendon (PT) as a replacement for cruciate ligaments markedly alters the joint biomechanics with trends similar to those predicted when increasing prestrains. Forces in both ACL and PCL ligaments increased as one of them became tenser or stiffer and diminished as it became slacker. These results have important consequences in joint biomechanics following ligament injuries or replacement and tend to recommend the use of grafts with smaller prestrains (i.e. slacker than intact) when using the PT as the replacement material with stiffness greater than that of replaced ligament itself. 相似文献
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Chahed T Dhifi W Hamrouni I Msaada K Bellila A Kchouk ME Marzouk B 《The Italian journal of biochemistry》2007,56(1):35-39
Pistachio (Pistacia vera L.) fruit is well known for its oleaginous and edible seed. Less information is available about the hull constituted by the epicarp and the mesocarp. This part of the fruit contains an essential oil that can be valorized. Tunisia is one of the countries cultivating pistachio trees. This work presents essential oil composition of pistachio hulls (Mateur variety) from different geographical localities: Grombalia (North-East), Kairouan (Middle) and Sfax (Middle-East). Yields were more important in Sfax samples (0.53% on a dry weight basis). Alpha-terpinolene was the major compound for Grombalia fruits (35.7%), whereas Kairouan and Sfax samples where characterized by alpha-pinene (42.5 and 43.8% respectively). For all samples, monoterpene hydrocarbons predominated (more than 79.8% of the essential oil). 相似文献