Effects of temperature and water stresses on germination of some varieties of chickpea (Cicer arietinum)

Chickpea production did not progress, in spite, of intensification of agricultural practices. Drought and thermal stresses were the major factors that decreased yield when the crop is generally sown in spring. Nevertheless, winter sowing has opened new opportunities for increasing chickpea production in arid areas. This culture is based on two essential factors: (i) preclude rainfall during the flowering and fruiting period (April/May) after a beneficial one in January and February for a good crop development and (ii) reducing the risk of infection by Ascochyta rabiei (considered as the main pathogen of chickpea) whose development is limited in arid area. The influence of temperature on seeds germination of the four varieties (Ghab4, Neyra, Kasseb and Chetoui) has been evaluated with seven temperatures (5, 10, 15, 20, 25, 30 and 35°C) and the effect of drought stress has been determined with seven water stresses induced by different solution of PEG 4000 (0, 1, 2, 3, 4, 5 and 10 g/L). During germination, the tested varieties presented differential sensitivity to thermal stress. The Chetoui and Ghab4 varieties were more tolerant, to cold temperature, than the other varieties. Osmotic potential induced by PEG 4000 had significant effects on seeds germination. Chetoui and Ghab4 were the best tolerant to drought stress. Therefore, we opted for the Chetoui variety that better meets the conditions of stresses induced by low temperatures and water deficit. This best performing variety must have, throughout their development cycle, been tolerant to environmental stresses; which allows us to obtain early tools for discriminative selection between chickpea genotypes.Keywords: Chickpea, thermal stress, drought stress, germinationAfrican Journal of Biotechnology Vol. 12(17), pp. 2201-220

Chemical polymorphism of some North Tunisian autochthonous halophytes

The study aims to explore and analyse osmoticums synthesized by four perennial halophytic Chenopodiaceae : Salicornia arabica, Atriplex portulacoides, Atriplex halimus and Suaeda fruticosa from Menzel Jemil, Soliman and Gammarth regions which belong to sub-humid and semi-arid bioclimatic zones. A sampling of aerial vegetative organs of these four halophytes has been made. Analyses focused on reducing sugars, starch, total proteins, soluble proteins and total lipids. Atriplex portulacoides harvested from Menzel Jemil station accumulates large amounts of starch, indicating a high photosynthetic activity. This could suggest that this species avoids drought and high salinity by an acceleration of its growth cycle and reproductive systems. Suaeda fruticosa is characterized by the highest levels in soluble sugars. This would mean that it is capable of synthesizing carbohydrate osmoticums for its osmotic adjustment. Atriplex sp. and Suaeda fruticosa have the highest levels of soluble protein indicating the possible intervention of amino acids in the regulation of intracellular osmotic pressure. This behavior was essentially observed at Soliman sampling site characterized by an upper semi-arid bioclimate and saline soilsL'étude a pour objet l'exploration puis l'analyse des osmoticums synthétisés par quatre Chenopodiaceae pérennes halophytes: Salicornia arabica, Atriplex portulacoides, Atriplex halimus et Suaeda fruticosa dans les régions de Menzel Jemil, Soliman et Gammarth appartenant aux étages bioclimatiques subhumides et semi-arides. Un échantillonnage des organes végétatifs aériens de ces quatre halophytes a été effectué. Les analyses ont porté sur les sucres réducteurs, l'amidon, les protéines totales, les protéines solubles et les lipides totaux. Atriplex portulacoides, récolté à la station de Menzel Jemil, accumule d'importantes quantités d'amidon, traduisant une forte activité photosynthétique. Ceci laisse suggérer que cette espèce évite la période de sécheresse et de forte salinité par une accélération de son cycle végétatif et reproducteur. Suaeda fruticosa se caractérise par les teneurs les plus élevées en sucres solubles. Ceci signifierait qu'elle est capable de synthétiser des osmoticums glucidiques pour son ajustement osmotique en condition de stress. Atriplex sp. et Suaeda fruticosa présentent les teneurs les plus élevées en protéines solubles, traduisant probablement une intervention des acides aminés dans la régulation de la pression osmotique intracellulaire. Ces comportements ont été observés, essentiellement, au niveau du site d'échantillonnage de la région de Soliman, caractérisé par un bioclimat semi-aride supérieur et des sols salés

NaCl protects against Cd and Cu-induced toxicity in the halophyte Atriplex halimus

The objective of the present work was to evaluate the extent of Cd- and Cu-induced oxidative stress and the antioxidant response triggered in the halophyte species Atriplex halimus after metallic trace elements exposure. Plants were treated for one month with Cd2+ or Cu2+ (400 μM) in the absence or presence of 200 mM NaCl in the irrigation solution. The interaction between salinity and heavy metal stress was analyzed in relation to plant growth, tissue ion contents (Na+, K+ and Mg2+), oxidative damage and antioxidative metabolism. Data indicate that shoot and root weight significantly decreased as a consequence of Cd2+- or Cu2+-induced stress. Metallic stress leads to unbalanced nutrient uptake by reducing the translocation of K+ and Mg2+ from the root to the shoot. The levels of malondialdehyde increased in root tissue when Cd, and especially Cu, were added to the irrigation solution, indicating that oxidative damage occurred. Results showed that NaCl gave a partial protection against Cd and Cu induced toxicity, although these contaminants had distinct influence on plant physiology. It can be concluded that salinity drastically modified heavy metal absorption and improved plant growth. Salinity also decreased oxidative damage, but differently in plants exposed to Cd or Cu stress.Ministerio de Economía y Competitividad, Spain (GL2013-42038-R; AGL2016-76574-R); Universitat Jaume I (P1- 1B2012-06)

Identification and expression of the Cucurbita WRKY transcription factors in response to water deficit and salt stress

WRKY transcription factors (TFs) have been reported to play important roles in plant responses to various stress conditions. Although several studies on the genomic organization of the WRKY gene family in various species have been reported, the information related to the genus Cucurbita is scarce, and null in the case of Cucurbita pepo. The present study aimed to examine the response of Cucurbita pepo to water deficit and salt stress. Additionally, WRKY gene family has been identified and characterized in this species. Shoot growth was negatively affected by both adverse situations. Similarly, both salt and water stress conditions reduced transpiration and stomatal conductance in C. pepo plants. However, the quantum efficiency of PSII decreased only in those plants exposed to salt stress. The increase in proline concentration recorded in C. pepo plants subjected to salt or drought stress point out the important role of this amino acid for plant tolerance to both stress conditions. Based on the genome sequence, 95 CmWRKY genes were found and classified into three main groups according to their orthologues in Arabidopsis. Among these, 24 and 14 CmWRKY genes were responsive to water and salt stresses, respectively. Three water stress-responsive genes were upregulated under the adverse condition. The expression of six CmWRKY genes was induced by NaCl treatment. Therefore, a total of nine up-regulated genes related to both stresses were identified, suggesting their putative involvement in the plant response to water deficit and salt stress

Accumulation of trace elements and tolerance to metal stress of the halophytes that colonize the edges of the lagoon of Bizerte (Tunisia)

The lagoon of Bizerte underwent a mixed anthropic pollution, essentially enhanced by the unlimited industrial waste derived from Iron Factory “El Fouledh”, Industrial Refining Tunisian Company, Cement Company and from 400 industrial units established around it. This waste includes major pollutants conducive to a degradation of the ecological conditions of this lagoon. Previous research dealt with most of the different ecosystem components: soil, sediments, water, and aquatic organisms. In the present study, we have been interested in the halophytes inhabiting the edges of Bizerte lagoon. This study would allow us to identify the accumulating species to be used in the programs of phytoremediation. Shoots of Atriplex portulacoides, Arthrocnemum indicum, Salicornia arabica and Suaeda fruticosa were harvested, rinsed, dried and then crushed. Analyses were focused on few trace metals: Pb, Cu, Zn and Cd. Our results have allowed us to classify the halophytes “A. portulacoides, A. indicum, S. arabica and S. fruticosa” among the accumulating species of Pb (respectively 84.6, 92.2, 102.9 and 86.3 μg.g-1 DW), of Cu (respectively 14.5, 15.1, 24.2 and 14.9 μg.g-1 DW) and of Zn (respectively 1370.1, 625.1, 1601.4 and 772.5 μg.g-1 DW). Also, A. portulacoides and S. arabica are distinguished by their ability to store significant amounts of Zn which gives them a potential utility in the remediation programs. As regards Cd, we have shown that all studied species are hyper-accumulators of this metal (A. portulacoides: 274.0 μg.g-1 DW; A. indicum: 280.4 μg.g-1 DW; S. arabica: 211.6 μg.g-1 DW and S. fruticosa: 209.0 μg.g-1 DW). It should be noted that the harvested halophytes do not show any sign of toxicity, and they are able to accumulate more important amounts of heavy metals and to tolerate the metallic stress. These results show that the studied halophytes can be recommended for all programs of phytoremediation in polluted and salty areasLa lagune de Bizerte subit une pollution anthropique mixte engendrée essentiellement par les rejets industriels non limités provenant de l'usine sidérurgique « El Fouledh », de la société tunisienne des industries de raffinage, de la cimenterie et des 400 unités industrielles recensées autour d'elle. Ces rejets constituent des polluants majeurs conduisant à une dégradation des conditions écologiques de ce plan d'eau. Les travaux de recherche antérieurs ont touché à la plupart des composantes de cet écosystème: sol, sédiments, eau, organismes aquatiques. Dans le présent travail, nous nous sommes intéressés à l'étude des halophytes peuplant les bordures de la lagune de Bizerte. Cette étude permettrait d'identifier les espèces accumulatrices en vue de les utiliser dans les programmes de phytoremédiation. Les parties aériennes d'Atriplex portulacoides, Arthrocnemum indicum, Salicornia arabica et Suaeda fruticosa ont été récoltées, rincées, séchées puis broyées. Les analyses ont porté sur quelques éléments traces: Pb, Cu, Zn et Cd. Nos résultats ont permis de classer les halophytes "A. portulacoides, A. indicum, S. arabica et S. fruticosa" parmi les espèces accumulatrices de Pb (respectivement 84.6, 92.2, 102.9 et 86.3 μg.g-1 MS), de Cu (respectivement 14.5, 15.1, 24.2 et 14.9 μg.g-1 MS) et de Zn (respectivement 1370.1, 625.1, 1601.4 et 772.5 μg.g-1 MS). A. portulacoides et S. arabica se distinguent par leurs capacités à piéger d'importantes quantités de Zn d'où la possibilité de les utiliser dans les programmes de dépollution. En ce qui concerne le Cd, nous avons montré que toutes les espèces étudiées sont des hyper-accumulatrices de ce métal (A. portulacoides: 274.0 μg.g-1 MS ; A. indicum: 280.4 μg.g-1 MS ; S. arabica: 211.6 μg.g-1 MS et S. fruticosa: 209.0 μg.g-1 MS). Il faut noter que les halophytes récoltées ne présentent aucun symptôme de toxicité, elles sont capables d'accumuler des quantités plus importantes d'éléments traces et de tolérer le stress métallique. Ce résultat montre que les halophytes étudiées peuvent être recommandées pour tous programmes de phytoremédiation des sols pollués des zones non cultivées

An efficient antioxidant system and heavy metal exclusion from leaves make Solanum cheesmaniae more tolerant to Cu than its cultivated counterpart

Copper (Cu) is an abundant metal in the environment coming from anthropogenic activities and natural sources that, in excess, easily becomes phytotoxic to most species, being its accumulation in plants considered an environmental threat. This study aimed to compare the physiological and molecular responses of Solanum lycopersicum and its wild counterpart Solanum cheesmaniae to Cu stress. In particular, we wanted to address the hypothesis that S. cheesmaniae is more adapted to Cu stress than S. lycopersicum, since the former is equipped with a more efficient antioxidant defense system than the latter. Biomarkers of oxidative status (lipid peroxidation, hydrogen peroxide (H2O2) and superoxide anion (O.− 2 ) levels) revealed a more pronounced imbalance in the redox homeostasis in shoots of S. lycopersicum than in S. cheesmaniae in response to Cu. Furthermore, the activity of key antioxidant enzymes clearly differed in both species in response to Cu. Catalase (CAT) activity increased in S. cheesmaniae shoots but decreased in the domestic species, as well as ascorbate peroxidase (APX). Both species preferentially accumulated Cu in the radicular system, although a great increase in the aerial parts of S. lycopersicum was measured, while in leaves of Cu- treated S. cheesmaniae, the levels of Cu were not changed. Overall, results validated the hypothesis that S. cheesmaniae is more tolerant to excess Cu than S. lycopersicum and the data provided will help the development of breeding strategies toward the improvement of the resistance/tolerance of cultivated tomato species to heavy metal stress.This research was partially supported by national funds provided by Foundation for Science and Technology (FCT) through PEst-OE/BIA/UI4046/2014 (FCT through BioISI) and through the research project PTDC/ AGR-PRO/7028/2014.info:eu-repo/semantics/publishedVersio

Polymorphisme biochimique chez quelques halophytes autochtones du Nord Tunisien

Chemical polymorphism of some North Tunisian autochthonous halophytes. The study aims to explore and analyse osmoticums synthesized by four perennial halophytic Chenopodiaceae : Salicornia arabica, Atriplex portulacoides, Atriplex halimus and Suaeda fruticosa from Menzel Jemil, Soliman and Gammarth regions which belong to sub-humid and semi-arid bioclimatic zones. A sampling of aerial vegetative organs of these four halophytes has been made. Analyses focused on reducing sugars, starch, total proteins, soluble proteins and total lipids. Atriplex portulacoides harvested from Menzel Jemil station accumulates large amounts of starch, indicating a high photosynthetic activity. This could suggest that this species avoids drought and high salinity by an acceleration of its growth cycle and reproductive systems. Suaeda fruticosa is characterized by the highest levels in soluble sugars. This would mean that it is capable of synthesizing carbohydrate osmoticums for its osmotic adjustment. Atriplex sp. and Suaeda fruticosa have the highest levels of soluble protein indicating the possible intervention of amino acids in the regulation of intracellular osmotic pressure. This behavior was essentially observed at Soliman sampling site characterized by an upper semi-arid bioclimate and saline soils.L’étude a pour objet l’exploration puis l’analyse des osmoticums synthétisés par quatre Chenopodiaceae pérennes halophytes : Salicornia arabica, Atriplex portulacoides, Atriplex halimus et Suaeda fruticosa dans les régions de Menzel Jemil, Soliman et Gammarth appartenant aux étages bioclimatiques subhumides et semi-arides. Un échantillonnage des organes végétatifs aériens de ces quatre halophytes a été effectué. Les analyses ont porté sur les sucres réducteurs, l’amidon, les protéines totales, les protéines solubles et les lipides totaux. Atriplex portulacoides, récolté à la station de Menzel Jemil, accumule d’importantes quantités d’amidon, traduisant une forte activité photosynthétique. Ceci laisse suggérer que cette espèce évite la période de sécheresse et de forte salinité par une accélération de son cycle végétatif et reproducteur. Suaeda fruticosa se caractérise par les teneurs les plus élevées en sucres solubles. Ceci signifierait qu’elle est capable de synthétiser des osmoticums glucidiques pour son ajustement osmotique en condition de stress. Atriplex sp. et Suaeda fruticosa présentent les teneurs les plus élevées en protéines solubles, traduisant probablement une intervention des acides aminés dans la régulation de la pression osmotique intracellulaire. Ces comportements ont été observés, essentiellement, au niveau du site d’échantillonnage de la région de Soliman, caractérisé par un bioclimat semi-aride supérieur et des sols salés.Bankaji Insaf, Sleimi Noomene. Polymorphisme biochimique chez quelques halophytes autochtones du Nord Tunisien. In: Revue d'Écologie (La Terre et La Vie), tome 67, n°1, 2012. pp. 29-39

Assessing of tolerance to metallic and saline stresses in the halophyte Suaeda fruticosa: The indicator role of antioxidative enzymes

Many areas are simultaneously affected by high concentrations of salts and trace metal elements (TME), the latter constituting a serious threat to human health. In the present study, we determined the combined effect of high salinity and toxic levels of trace elements on physiological behavior of the halophytic species Suaeda fruticosa. Plants were cultivated for three months with an irrigation solution supplemented separately with different concentrations of Pb2+ and Zn2+ (0, 200, 400 and 600 microM) with and without 200 mM NaCl. Growth, total chlorophyll, water status and ion nutrition were quantified and antioxidant enzyme activities [ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and catalase (CAT)] were studied. Our results revealed that S. fruticosa has a strong ability to tolerate lead and zinc. This halophyte accumulated higher concentrations of TME in their roots. Growth parameters of S. fruticosa were not significantly affected by TME. An enhancement of Ca2+ concentration accompanied by a decrease of Mg2+ content was observed under Pb2+ or Zn2+ treatments whereas K+ content was not affected by TME. Of the antioxidant enzymes, the activity of CAT and APX was increased by metal stress. However, the activity of GPX was diminished by increasing TME concentrations. It was concluded that NaCl 200 mM had a positive impact on the response of S. fruticosa to Zn2+ toxicity, acting through a decrease in Zn absorption.info:eu-repo/semantics/publishedVersio

Accumulation potential of Atriplex halimus to zinc and lead combined with NaCl: Effects on physiological parameters and antioxidant enzymes activities

An experiment in this study was designed to investigate the effect of different concentrations of Zn2+ or Pb2+ (0, 200, 400 and 600 μM) with NaCl (0, 200 mM), on the morphological and physiological parameters as well as the antioxidative response of the halophytic species Atriplex halimus. Results showed that Pb2+ had no significant impact on biomass production while Zn2+ significantly affected plant development mainly at high concentration, 600 μM. Total chlorophyll content did not change significantly under elevation concentrations of Zn2+ when compared to control. However, there was a modest decrease in total chlorophyll concentration in the leaves of A. halimus grown in a medium supplemented with 600 μMPb2+ and with combined stress Pb2+/NaCl. Zn2+ and Pb2+ contents in tissues were higher in the belowground organs of this halophyte. Overall results pointed out that application of different concentrations of Zn2+ or Pb2+ disturbed status of nutrients in A. halimus. Analysis of antioxidant enzymes [ascorbate peroxidase (APX), guaiacol peroxidase (GPX), and catalase (CAT)] showed that the activity was diminished by increasing Zn2+ concentrations in the medium. Whereas, the addition of Pb2+ in the medium increased CAT activity and decreased APX activity.info:eu-repo/semantics/publishedVersio