Détection du stress oxydant induit par des faibles doses d'irradiations ionisantes sur modèle vegetal. Marqueurs d'exposition et modulation de la radiosensibilité par les glucosinolates.

Communication oral

Présentation du PHC Tassili avec l’Université de Ouargla (2011-2014) : A la recherche d’un marqueur de la pollution aux hydrocarbures : cas du palmier dattier

International audienc

Amplitude écologique et plasticité métabolique (enzymes antioxydantes et amines) (comparaison de quatre espèces génétiquement proches (Bromus scet. Genea, Poaceae))

RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Population genetic diversity in the polyploid complex of wheatgrasses using isoenzyme and RAPD data

International audienceThirty five bands (alleles) from six enzyme systems and fifty seven random amplified polymorphic DNA (RAPD) fragments were selected to analyse the genetic diversity of 33 polyploid wheatgrasses (Triticeae) populations of species Thinopyrum junceiforme and Elytrigia pycnantha, and two hybrids, one pentaploid and one novel 9-ploid. Dice's similarity coefficient, the UPGMA-derived phenograms from RAPD, and allozymes markers showed that the clustering of wheatgrass populations was based on ploidy level. These markers had similar levels of diversity between populations, with high genetic similarity within the same ploidy-level and within population's individuals. The tetraploid Th. junceiforme populations are closely related, with a large similarity distances varied from 0.8 to 1. Based on the isozyme and RAPD analyses, diploid taxa are related to polyploids with similarity coefficients 0.4

Etude des espèces et hybrides du complexe polyploïde Agropyron du littoral breton ( caractérisation de leur constitution génomique par hybridation in situ. Analyse de leur diversité génétique)

Des sondes d'ADN génomique d'espèces diploïdes connues ont permis de caractériser les génomes des espèces Thinopyrum junceiforme (2 n = 28), Elytrigia pycnantha (2n = 42), d'un hybride à 2n = 35 (5X) et d'un deuxième à 2n = 63 (9X) identifié pour la première fois, grâce à la technique d'hybridation in situ génomique (GISH). Ces espèces et hybrides ont été collectés sur le littoral breton. Les formules génomiques proposées sont EEEE pour Th. junceiforme, SSPSPSESES pour E. pycnantha, SPSESEE pour l'hybride 5X, résultats suggèrant que ce dernier serait le produit de croisement entre E. pycnantha et Th. junceiforme. La formule génomique de l'hybride 9X, SSSSPSPSESESHS, suggère que ses parents putatifs seraient les espèces hexaploïdes E. pycnantha et E. repens. La diversité génétique de 35 populations a été appréhendée par les marqueurs moléculaires, isozymes et RAPD. Il en ressort une structuration en fonction du niveau de ploïdie avec mise en évidence d'une similitude génétique assez importante entre les différents groupes tétraploïde, pentaploïde et hexaploïde. Ceci pourrait être le reflet d'une relation de parenté assez forte entre ces différents groupes.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Détection du stress oxydant induit par des faibles doses d'irradiations ionisantes sur modèle végétal. Marqueurs d'exposition et modulation de la radiosensibilité par les glucosinolates.

communication oral

Population genetic diversity in the polyploid complex of wheatgrasses using isoenzyme and RAPD data

International audienceThirty five bands (alleles) from six enzyme systems and fifty seven random amplified polymorphic DNA (RAPD) fragments were selected to analyse the genetic diversity of 33 polyploid wheatgrasses (Triticeae) populations of species Thinopyrum junceiforme and Elytrigia pycnantha, and two hybrids, one pentaploid and one novel 9-ploid. Dice's similarity coefficient, the UPGMA-derived phenograms from RAPD, and allozymes markers showed that the clustering of wheatgrass populations was based on ploidy level. These markers had similar levels of diversity between populations, with high genetic similarity within the same ploidy-level and within population's individuals. The tetraploid Th. junceiforme populations are closely related, with a large similarity distances varied from 0.8 to 1. Based on the isozyme and RAPD analyses, diploid taxa are related to polyploids with similarity coefficients 0.4

Ionizing radiation: Advances in plant responses.

International audienceThe aim of this review is to highlight the effects of ionizing radiation (IR) on genetic material in higher plants and its involvement in both adaptive processes and species evolution. Firstly, IR causes water radiolysis, which generates highly reactive hydroxyl radicals. Detoxifying enzymes are immediately triggered for reactive oxygen species (ROS) scavenging. DNA is the object of an attack by both the hydroxyl ions and the radiation itself (i.e., there is both a direct and an indirect effect). The effects on the DNA are detrimental both for the organism and for the long-term development of the species. Dose-dependent anomalies in chromosomes are often seen after irradiation. Although DNA repair mechanisms and checkpoints are involved, the double-strand breaks (DSB) in particular are often error-prone. Indeed, plant DSB repair mechanisms mainly involve the homologous and non-homologous dependent systems, and the latter often results in a loss of genetic information. Micronuclei represent a way for the cell to remove some of the resulting fragments. Repeated IR (either acute or chronic) allows plants to both adapt and demonstrate radioresistance. A first exposure reduces the effects seen at the time of a second exposure. An adaptive response has been suggested to explain this phenomenon. Consequently, in long-term and especially during chronic irradiation, IR affects the genetic structure of populations. Genetic variability is often reduced. This reduction may be associated with the demonstration of an adaptive process where, in particular, a species is subject to chronic stress. Thus, the genomic effects of IR demonstrate their likely involvement in species evolution