The Regulation of Ion Homeostasis, Growth, and Biomass Allocation in Date Palm Ex Vitro Plants Depends on the Level of Water Salinity

The date palm, a central plant in the fragile oasis ecosystem, is considered one of the fruit species most tolerant to salt stress. However, the tolerance mechanisms involved are yet to be addressed and their evaluation until now was mainly based on heterogenous plant material such as seedlings or limited to in vitro experiment conditions. For these reasons, we propose to deepen our knowledge of the morphological and physiological responses to salt stress using acclimated ex vitro plants resulting from the propagation of a single genotype. The plants were irrigated with 0, 150, 300, or 450 mM NaCl solutions for four months. Our results showed that the influence of water salinity on growth and ion-homeostasis regulation was very dependent on stress levels. The 150 mM NaCl concentration was found to improve dry biomass by about 35%, but at higher salt concentrations (300 and 450 mM) it decreased by 40–65%. The shoot:root dry mass ratio decreased significantly at the 150 mM NaCl water concentration and then increased with increasing water salt concentration. The leaf:root ratio for Na+ and Cl− decreased significantly with increasing water salinity up to a concentration of 300 mM NaCl, and then stabilized with similar values for 300 mM and 450 mM NaCl. In contrast to Na+ and Cl−, leaf K+ content was significantly higher in the leaf than in the root for all salt treatments. Unlike Na+ and K+, Cl− was expelled to the surface of leaves in response to increased water salinity. Overall, date palm plants appear to be more capable of excluding Cl− than Na+ and of changing biomass allocation according to salt-stress level, and their leaves and roots both appear to play an important role in this tolerance strategy.All authors are funded through the Small Research group project from the Deanship of Scientific Research at King Khalid University under research grant number (R.G.P.1/295/43).Peer reviewe

Differential effect of water salinity levels on gas exchange, chlorophyll fluorescence and antioxidant compounds in ex vitro date palm plants

In this study, the response to salt stress was evaluated in ex vitro acclimated date palm plants, regenerated from in vitro culture multiplication. The plants, eighteen-month-old, were irrigated with 0 (control), 150, 300 or 450 mM NaCl solutions (high to very high-water salinity). Photosynthesis parameters and antioxidant compounds were determined at the end of the experiment in leaves. At 150 mM NaCl, net CO2 assimilation rate and internal CO2 concentration were not impaired; while transpiration and stomatal conductance decreased by 60 and 70%, respectively. By increasing salt concentrations, all gas exchanges parameters were decreased. Measurement of chlorophyll fluorescence and P700 redox state showed that PSII and PSI machineries were significantly enhanced under 150 mM NaCl, conditions. With the 300 mM NaCl, the PSI parameters remained unchanged compared to control, while some of the PSII parameters, such as NPQ and Y (NPQ), were increased. At 450 mM NaCl, photosystems functionality was light intensity (PAR) dependent. Only at low PAR, a significant increase of some PSI and PSII parameters was observed. At the contrary, with high PAR, most of the energy conversion functions were significantly reduced, especially those related to PSI, indicating that PSI was more susceptible for damage by salinity than PSII. To overcome high salinity stress, ex vitro date palm plants mobilized a cascade of physio-biochemical pathways including the antioxidant activity and proline biosynthesis. Overall, the salinity of irrigation water, and up to 150 mM, improves the physiological performance of ex vitro date palm plants, which manage to tolerate very high levels of this stress.The authors extend their appreciation to the Deanship of Scientific Research at King Khalid University for funding this work through the large research Groups projects (Project under grant number (RGP. 2/73/44)).Peer reviewe

DRAAS: Dynamically Reconfigurable Architecture for Autonomic Services

International audienceThe development and the provisioning of autonomic networked services are essential for enterprises and factories of the future. Endowing services with autonomic properties allows one to maintain at runtime the Quality of Service (QoS) including different parameters related to performance, availability and reputation such as response time and successful execution rate. Handling the autonomic properties requires the ability to deal with permanent requirement evolving and constraint changes. For instance, managing QoS degradation requires the capacity of identifying its possible or actual sources and the capacity of reconfiguration planning and execution. Dealing with these issues is especially challenging for web services since the autonomic solution has to be seamless for the service requesters, ensuring that Web Services are always usable under the different deployment constraints. To implement such autonomic systems, the literature provides different approaches, varying from the design to the full implementation of autonomic primitives. In this chapter, we present DRAAS: a Dynamically Reconfigurable Architecture for Autonomic Services able to provide autonomic properties for QoS management in web service-based distributed applications. DRAAS has been implemented and experimented successfully with different use cases. It covers the whole cycle of autonomic management including monitoring and analysis of QoS parameters , planning and execution

Graphical simulation of the dynamic evolution of the software architectures specified in Z

International audienceThis paper provides a graphical simulator that enables to apprehend the dynamic of components-based software architectures based on their formal specification. The simulator initially accepts (as an input) an already validated Z specification using the Z/EVES tool. Then, it generates graphical entities, according to the UML notation, representing software's components and their connectors. Thereafter, the user may generate architecture instances by adding components and connections between them. Architecture instances can be updated by destroying components/ connections or by modifying their interconnections. The user actions are checked through the formal specification of the architectural style

A QoS-Oriented Reconfigurable Middleware For Self-Healing Web Services

International audienceMaintaining the Quality of Service (QoS) is important for self-healing web service-based distributed interactive applications. It requires the ability to deal with permanently changing constraints both at the communication and the execution levels. Preventing or repairing QoS degradation also requires the capacity of identifying its possible or actual sources and the capacity of reconfiguration decision and enforcement. Dealing with these issues is especially challenging for web services since the self-healing solution has to preserve the dynamic composition property and to be seamless for the service requesters, while being always usable under the different deployment constraints. In this paper, we present a self-healing middleware framework able to provide the self-healing properties for QoS management in web service-based distributed interactive applications. The framework implementation has been achieved in the context of the WS-DIAMOND project. It covers the whole cycle of adaptation management including monitoring and analysis of QoS values, and substitution-based reconfiguration

Une approche orientée règle pour la spécification formelle des architectures dynamiquement configurables

International audienceDans ce papier, nous traitons le problème de la conception formelle des systèmes logiciels réparties dynamiquement reconfigurables. Pour compléter les approches de reconfiguration comportementale souvent adoptées, nous introduisons la reconfiguration architecturale. Cette technique permet de construire dynamiquement l'architecture d'un système logiciel et de l'adapter à l'évolution de l'activité qu'il soutient. Pour formaliser les différentes instances d'architectures et styles, nous spécifions en Z les entités logicielles et leurs liens d'interaction par des schémas. Nous spécifions par des opérations Z, les règles qui régissent l'évolution dynamique des architectures de façon conforme à un style architectural spécifié aussi selon la même technique. Nous illustrons notre approche à travers les propriétés de dynamicité des logiciels de support pour les activités coopératives réparties. Pour modéliser l'architecture, nous adoptons une approche orientée composant et nous distinguons différents modes d'interaction (pull/push) entre les différents composants. Notre approche est soutenue par un environnement logiciel de simulation visuelle qui interprète les spécifications Z. Nous dispensons ainsi les concepteurs de la maîtrise de ce formalisme et nous leur offrons une interface "boîte et traits" qui fait référence dans la conception informelle des architectures. Notre environnement de simulation est couplé avec l'outil Z/EVES. Il gère les spécifications Z au format de Z/EVES tout en vérifiant leur complétude et leur exactitude. Il interprète aussi visuellement les spécifications architecturales codées au format Z/EVES

Experiments Results and Large Scale Measurement Data for Web Services Performance Assessment

International audienceService provisioning is a challenging research area for the design and implementation of autonomic service-oriented software systems. It includes automated QoS management for such systems and their applications. Monitoring and Measurement are two key features of QoS management. They are addressed in this paper as elements of a main step in provisioning of self-healing web services. In a previous work [1], we defined and implemented a generic architecture applicable for different services within different business activities. Our approach is based on meta-level communications defined as extensions of the SOAP envelope of the exchanged messages, and implemented within handlers provided by existing web service containers. Using the web services technology, we implemented a complete prototype of a service-oriented Conference Management System (CMS). We experienced our monitoring and measurement architecture using the implemented application and assessed successfully the scalability of our approach under the French grid5000. In this paper, experimental results are analyzed and concluding remarks are given

Experiments Results and Large Scale Measurement Data for Web Services Performance Assessment

International audienceService provisioning is a challenging research area for the design and implementation of autonomic service-oriented software systems. It includes automated QoS management for such systems and their applications. Monitoring and Measurement are two key features of QoS management. They are addressed in this paper as elements of a main step in provisioning of self-healing web services. In a previous work [1], we defined and implemented a generic architecture applicable for different services within different business activities. Our approach is based on meta-level communications defined as extensions of the SOAP envelope of the exchanged messages, and implemented within handlers provided by existing web service containers. Using the web services technology, we implemented a complete prototype of a service-oriented Conference Management System (CMS). We experienced our monitoring and measurement architecture using the implemented application and assessed successfully the scalability of our approach under the French grid5000. In this paper, experimental results are analyzed and concluding remarks are given