Behavior of three cereals cultivated in Tunisia under saline constraints and cationic homeostasis between Sodium and Potassium

The accelerated rate of climate change exceeds the capacity to create new varieties that are adapted to water and salt stresses. Understanding the mechanisms of tolerance in major crops is the most important step in any improvement program for abiotic constraints. Three main cereal species cultivated in Tunisia (durum wheat, bread wheat and barley) each represented by 2 most used varieties were tested under increasing levels of irrigation water salinity (water tap at EC = 0.662 dS.m-1, water tap with 3 g of NaCl at EC = 2.14 dS.m-1, water tap with 6 g/l of NaCl at EC = 4.9 dS.m-1 and water tap with 9g/l of NaCl at EC = 12.54 dS.m-1). The 6 genotypes were tested in the laboratory in Petri dishes to study the germination rate with the same salinity levels. The experiment was carried out the first week of December under semi-controlled conditions, in 8-liter pots filled with a mixture of manure and calcareous loamy-clay soil. The experimental design was a Split Plot with three replications.The level of salinity is the main factor and variety as secondary one. At 4 leaf stage, only one seedling per pot is left and salinity treatment was applied. Results showed that the germination rate is proportionally affected by the intensity of salinity stress, reaching 25% in UTQ and 36% in MLI at 12.54 dS.m-1. The balance between RDM and SDM is in favor of the root system under salinity stress, although the R/S ratio is always less than the unit. On the other hand, cationic K+/Na+ ratio is always greater than the unit indicating good selectivity of the cereals for K+. Potassium is preferentially accumulated in stems while the Na+ is preferentially accumulated in roots. Three strategies for limiting the entry of Na+ are identified according to the level of its accumulation at the roots, stems or the two organs together.Abstract The accelerated rate of climate change exceeds the capacity to create new varieties that are adapted to water and salt stresses. Understanding the mechanisms of tolerance in major crops is the most important step in any improvement program for abiotic constraints. Three main cereal species cultivated in Tunisia (durum wheat, bread wheat and barley) each represented by 2 most used varieties were tested under increasing levels of irrigation water salinity (water tap at EC = 0.662 dS.m-1, water tap with 3 g of NaCl at EC = 2.14 dS.m-1, water tap with 6 g/l of NaCl at EC = 4.9 dS.m-1 and water tap with 9g/l of NaCl at EC = 12.54 dS.m-1). The 6 genotypes were tested in the laboratory in Petri dishes to study the germination rate with the same salinity levels. The experiment was carried out the first week of December under semi-controlled conditions, in 8-liter pots filled with a mixture of manure and calcareous loamy-clay soil. The experimental design was a Split Plot with three replications.The level of salinity is the main factor and variety as secondary one. At 4 leaf stage, only one seedling per pot is left and salinity treatment was applied. Results showed that the germination rate is proportionally affected by the intensity of salinity stress, reaching 25% in UTQ and 36% in MLI at 12.54 dS.m-1. The balance between RDM and SDM is in favor of the root system under salinity stress, although the R/S ratio is always less than the unit. On the other hand, cationic K+/Na+ ratio is always greater than the unit indicating good selectivity of the cereals for K+. Potassium is preferentially accumulated in stems while the Na+ is preferentially accumulated in roots. Three strategies for limiting the entry of Na+ are identified according to the level of its accumulation at the roots, stems or the two organs together

Gestion de la Mobilité, de la Qualité de Service et Interconnexion de Réseaux Mobiles de Nouvelle Génération

Avec l’évolution rapide des technologies réseaux et télécoms radios mobiles, les chercheurs sont actuellement en train de préparer l’arrivée d’une nouvelle génération baptisée 4G. Le réseau de 4ème génération qui est encore l’objet de travaux de recherche vise à améliorer l’efficacité spectrale et à augmenter la capacité de gestion du nombre des mobiles dans une même cellule. Il tend à offrir des débits élevés en situation de mobilité à grande ou faible vitesse. Il vise aussi à permettre et à faciliter l’interconnexion et l’interopérabilité entre différentes technologies existantes en rendant transparent à l’utilisateur le passage entre les réseaux. Enfin, il vise à éviter l’interruption des services durant le transfert intercellulaire, et à basculer l’utilisation vers le tout IP. Dans ce contexte, nous nous sommes intéressés en premier lieu aux problématiques de la QoS en situation de mobilité au sein d’une technologie candidate à la 4G (WiMAX mobile) pour du trafic temps-réel. Pour cela, nous avons comparé la performance de plusieurs protocoles de mobilité dans le contexte du Handover de niveau 2 et de niveau 3 et plus. Nous avons pour cela fait varier les modèles de mobilité, les configurations et les scénarios. Enfin, nous avons modélisé un algorithme décisionnel qui gère le Handover dans le WiMAX mobile en fonction de plusieurs paramètres d’entrées. Au travers de ces études, nous avons dégagé des protocoles de mobilité qui offrent un niveau de QoS acceptable pour un trafic temps-réel dans le cadre des scénarios envisagés. En deuxième lieu, nous nous sommes concentrés sur les problèmes d’interconnexion et d’interopérabilité entre les réseaux en tenant compte de la mobilité et du Handover vertical entre deux technologies. Pour cela, nous avons proposé de comparer des protocoles de mobilité puis de les combiner afin de diminuer les délais des trafics temps-réel au cours du Handover. Au niveau de l’interconnexion, nous avons proposé des modèles entre WiMAX mobile et de nombreux autres standards (802.11e, UMTS, DVB-S/RCS, LTE). Outre les solutions d’interconnexion, nous avons également mis en évidence la ou les combinaisons de protocoles de gestion de la mobilité qui permettent de garantir de la QoS

Transcriptomic responses of Phanerochaete chrysosporium to oak acetonic extracts: focus on a new glutathione transferase.

The first steps of wood degradation by fungi lead to the release of toxic compounds known as extractives. To better understand how lignolytic fungi cope with the toxicity of these molecules, a transcriptomic analysis of Phanerochaete chrysosporium genes was performed in presence of oak acetonic extracts. It reveals that in complement to the extracellular machinery of degradation, intracellular antioxidant and detoxification systems contribute to the lignolytic capabilities of fungi presumably by preventing cellular damages and maintaining fungal health. Focusing on these systems, a glutathione transferase (PcGTT2.1) has been selected for functional characterization. This enzyme, not characterized so far in basidiomycetes, has been first classified as a GTT2 in comparison to the Saccharomyces cerevisiae isoform. However, a deeper analysis shows that GTT2.1 isoform has functionally evolved to reduce lipid peroxidation by recognizing high-molecular weight peroxides as substrates. Moreover, the GTT2.1 gene has been lost in some non-wood decay fungi. This example suggests that the intracellular detoxification system could have evolved concomitantly with the extracellular ligninolytic machinery in relation to the capacity of fungi to degrade wood

Modeling of drift during the application of phytosanitary products on low crops: Literature review

During the spraying of low crops, large quantities of pesticides are transferred from crop-growing areas to the atmosphere, by drift inducing environmental impacts, human health problems and economic loses. To better understand this drift phenomenon, spray emission modeling, in combination with field tests, could be a suitable solution but modeling stills the most used approach. Thus, the scientific community developed mathematical and computational models to describe the complicated interactions between spray droplets and its environment considering the different involved parameters. The final objective is to determine pesticide transport with few field tests. Most of the developed models are Lagrangian models that use the principles of fluid mechanics based on simplifying assumptions regarding the description of the kinetics of particles and the effect of turbulence on the behavior of the droplets.Existing drift models only consider the evaporation of the solvent, which is often water. They assume that there is a loss of pesticide by evaporation only if the drop reaches total evaporation. They also assume that the drops are isolated and that the effect of surface tension is neglected. Thus, evaporation is necessarily overestimated. Several results of those models show that drops smaller than 100 μm are the most sensitive to evaporation. This paper presents a bibliographic review describing some known drift models, particularly their calculation bases of evaporation, considering the diversity of hypothesis and drift principles characterization

HBV Life Cycle: Entry and Morphogenesis

Hepatitis B virus (HBV) is a major cause of liver disease. HBV primarily infects hepatocytes by a still poorly understood mechanism. After an endocytotic process, the nucleocapsids are released into the cytoplasm and the relaxed circular rcDNA genome is transported towards the nucleus where it is converted into covalently closed circular cccDNA. Replication of the viral genome occurs via an RNA pregenome (pgRNA) that binds to HBV polymerase (P). P initiates pgRNA encapsidation and reverse transcription inside the capsid. Matured, rcDNA containing nucleocapsids can re-deliver the RC-DNA to the nucleus, or be secreted via interaction with the envelope proteins as progeny virions

Identification of Durum Wheat Salt Tolerance Sources in Elite Tunisian Varieties and a Targeted FIGS Subset from ICARDA Gene Bank: Non-Destructive and Easy Way

The success of durum wheat breeding program for salt tolerance improvement depends on sources of tolerance, the screening method and the selection of target traits. In this study, we used morpho-physiological traits to elucidate the phenotypic and genetic variation in salinity tolerance of a 50 internationally derived durum wheat genotypes. Four Australian lines containing salt tolerance Nax genes from CSIRO (The Commonwealth Scientific and Industrial Research Organisation in Australia); six Tunisian old and new cultivars (Kerim, Khiar, Maali, Mahmoudi, Nasr and Selim) and forty ICARDA’s gene bank landraces selected basing on FIGS Method (Focused Identification of Germplasm Strategy) were evaluated in semi controlled conditions at the INRAT Ariana experimental station. Significant genotypic variation and Pearson's correlations were found among the evaluated traits. The data were converted to salt tolerance indexes (STI) before statistical analysis.The high positive and significantly correlation of STI of grain yield and those of tillering (r=0.46), mean daily evapotranspiration (r=0.46), shoot dry weight (r=0.74), number of spikes per plant (r=0.74), spike length (r=0.30), thousand grain weight (r=0.36) and the chlorophyll content at 79 day after sowing (r=0.30) indicated that salt stress induces a high reduction in these parameters, leading to the reduction in grain yield. Therefore we can consider these parameters as the most relevant for salinity tolerance screening criterion in durum wheat breeding programs. Among the analysed genotypes the ICARDA’s landrace IG-85714 from Greece showed better performances under salt stress. Among the analysed Tunisian varieties Maali and Nasr exhibited some level of tolerance. Approximately half of the analysed genotypes showed a moderate to high level of salt tolerance. These are the first sources for the salt tolerance in durum wheat identified in the ICARDA gene bank. This demonstrated that FIGS was effective for sampling large ex situ germplasm collections when seeking novel genetic sources of salt tolerance.