From Ideotypes to Genotypes: Approaches to Adapt Wheat Phenology to Climate Change

AbstractIntroductionSimulations using crop models can assist in designing ideotypes for current and future agricultural conditions. This approach has been often in recent years to identify avenues for adapting wheat to climate change. However, this approach has rarely been used to guide commercial breeding programs. We hypothesize that the lack of link between models and the available tools for breeding, i.e. available genetic variability and selection methods.Materials and methods- We use a modified ARCWHEAT2 phenology model and future climate data from the ARPEGE global circulation model to identify targets for future phenologies-We genotyped over 400 French cultivars for known phenology genes and confronted the genetic make-up of these varieties to their success in France over the past 25 years- We developed a methodology to link model parameters to underlying marker data. We tested the performance of the methodology against circa 60 varietiesResultsEarlier phenology may be an avenue for stress avoidance in the future.Current photoperiod sensitivity of early cultivars already poses problems in terms of adaptation, as exemplified by the interaction between Ppd-D1 and Vrn-A3We show that a gene-based model can be used to predict wheat phenology without a significant loss in predictive performance.DiscussionAnalyzing current phenology genes of existing cultivars and their adaptation allowed us to identify a limit to past breeding efforts in obtaining early cultivars. This requires that a more knowledge based approach be taken. Gene-based modelling of phenology is possible on a collection of elite, adapted varieties and provides the tools for constructing genotypes with specific allelic combinations leading to more appropriate constructions of earliness

Intrusion Tolerance in Distributed Computing Systems

An intrusion-tolerant distributed system is a system which is designed so that any intrusion into a part of the system will not endanger confidentiality, integrity and availability. This approach is suitable for distributed systems, because distribution enables isolation of elements so that an intrusion gives physical access to only a part of the system. By intrusion, we mean not only computer break-ins by non-registered people, but also attempts by registered users to exceed or to abuse their privileges. In particular, possible malice of security administrators is taken into account. This paper describes how some functions of distributed systems can be designed to tolerate intrusions, in particular security functions such as user authentication and authorization, and application functions such as file management. Introduction Most of the currently developed secure systems are based on paradigms such as access control matrix, reference monitor, security kernel or trusted computing bas..

How does post-flowering heat impact grain growth and its determining processes in wheat?

International audienceWheat grain yield is anticipated to suffer from the increased temperatures expected under climate change. In particular, the effects of post-anthesis temperatures on grain growth and development must be better understood to improve crop models. Grain growth and development involve several processes and we hypothesized that some of the most important processes, i.e. grain dry biomass and water accumulation, grain volume expansion and endosperm cell proliferation, will have different thermal sensitivity. To assess this, we established temperature response curves (TRC) of these processes for steady post-anthesis temperatures between 15°C and 36°C. From anthesis to maturity, grain dry mass, water mass, volume and endosperm cell number were monitored, whilst considering grain temperature. Different sensitivities to heat of these various processes were revealed. The rate of grain dry biomass accumulation increased linearly up to 25°C while the reciprocal of its duration linearly increased up to at least 32°C. By contrast, the growth rates of traits contributing to grain expansion, e.g. increase in grain volume and cell numbers, had higher optimum temperatures, while the reciprocal of their durations were significantly lower. These TRC can contribute to improve current crop models, and allow to target specific mechanisms for genetic and genomic studies

IMPROVEMENT OF DATA PROCESSING SECURITY BY MEANS OF FAULT TOLERANCE

This paper discusses various different solutions to the problem of reliable processing of confidential information. One of the major difficulties of this problem comes from the fact that conventional techniques for achieving reliability, on the one hand, and security on the other, tend to be in opposition to each other. The different solutions presented here have been classified in three distinct types: two are related to classical security techniques (protection, and encryption) and the third is a new technique, the fragmentation-redundancy-scattering technique, which it is claimed demonstrates a potentially advantageous unified approach to the provision of reliability and security, based on fault tolerance. Finally, a qualitative comparison of these solutions is given, taking into account both dependability, openness and performance criteria

Designing Secure and Reliable Applications using

Security and reliability issues in distributed systems have been investigated for several years at LAAS using a technique called Fragmentation-Redundancy-Scattering (FRS). The aim of FRS is to tolerate both accidental and intentional faults: the core idea consists in fragmenting confidential information in order to produce insignificant fragments and then in scattering the fragments so obtained in a redundant fashion across a distributed system, such as a large network of workstations and servers. Of these workstations, in principle just the user's own workstation needs to be regarded as trusted, whereas from this user's viewpoint the other workstations and servers, which in all probability are under someone else's control, can be untrusted devices

Développement des céréales pérennes comme culture multifonctionnelle pour la diversification des systèmes de culture

International audienceL'agriculture européenne est reconnue pour son haut niveau de rendement et de productivité. Parallèlement à un effort important de sélection et d'amélioration variétale dans la seconde moitié du 20 e siècle, cette productivité s'explique par un degré important de spécialisation et d'intensification des systèmes de cultures. La simplification écologique de ces systèmes conduit à de nombreux problèmes environnementaux et à une sensibilité accrue aux aléas climatiques et économiques. Récemment, le développement de la recherche sur les céréales pérennes, issues de graminées vivaces, propose une voie de diversification et d'amélioration des performances environnementales des rotations. La valorisation d'un couvert pérenne et de l'activité racinaire qui lui est associé offre des atouts indéniables pour la protection et la fertilité des sols. Bien qu'encore partiellement domestiquées et proposant des rendements en grain plus faibles que les céréales annuelles, l'utilisation de certaines populations de Thinopyrum intermedium ((Host) Barkworth & D.R. Dewey) est prometteuse en raison de leur capacité à combiner une production de grains et de biomasse fourragère. L'amélioration variétale et le développement d'idéotypes plus adaptés aux situations climatiques européennes et plus performants pour la production de grains représentent un enjeu majeur. Les premières années d'expérimentation en France et en Belgique ont permis d'identifier les principaux paramètres de croissance et de rendement de cette espèce. La production de grains varie entre 0,5 et 2 tonnes par hectare et est complétée par une production de matière sèche fourragère atteignant jusqu'à 11 tonnes MS par hectare. Dès la deuxième année, la biomasse racinaire produite est très supérieure aux standards annuels et influence positivement les caractéristiques structurales et microbiologiques du sol. La capacité de repousse post-récolte offre une valorisation additionnelle de fourrage. A ce jour, la phase d'implantation sensible à la concurrence des adventices (plante juvénile), l'induction des périodes phénologiques d'élongation et de floraison, l'influence des conditions d'alimentation hydrique et minérale et la gestion des valorisations fourrage-pâturage sont des objets de recherches développés dans le cadre d'un programme multipartenarial coordonné par l'ISARA

Using environmental clustering to identify specific drought tolerance qtls in bread wheat (<em>t. aestivum</em> l.)

International audienceDrought is one of the main abiotic stresses limiting winter bread wheat growth and productivity around the world. The acquisition of new high-yielding and stress-tolerant varieties is therefore necessary and requires improved understanding of the physiological and genetic bases of drought resistance. A panel of 210 elite European varieties was evaluated in 35 field trials. Grain yield and its components were scored in each trial. A crop model was then run with detailed climatic data and soil water status to assess the dynamics of water stress in each environment. Varieties were registered from 1992 to 2011, allowing us to test timewise genetic progress. Finally, a genome-wide association study (GWAS) was carried out using genotyping data from a 280 K SNP chip. The crop model simulation allowed us to group the environments into four water stress scenarios: an optimal condition with no water stress, a post-anthesis water stress, a moderate-anthesis water stress and a high pre-anthesis water stress. Compared to the optimal water condition, grain yield losses in the stressed conditions were 3.3%, 12.4% and 31.2%, respectively. This environmental clustering improved understanding of the effect of drought on grain yields and explained 20% of the G x E interaction. The greatest genetic progress was obtained in the optimal condition, mostly represented in France. The GWAS identified several QTLs, some of which were specific of the different water stress patterns. Our results make breeding for improved drought resistance to specific environmental scenarios easier and will facilitate genetic progress in future environments, i.e., water stress environments

[HeatWheat] Analyse de la diversité génétique de la réponse au stress thermique via phénotypage fin et génétique d’association

National audienc