J. Aubret & S. Blanchard. Pratique du bilan personnalisé

Jacques Aubret et Serge Blanchard présentent les techniques que les conseillers sont appelés à mettre en œuvre dans les « bilans personnalisés ». Ces bilans, dont le prototype est le bilan de compétences tel qu’il a été défini il y a une quinzaine d’années, présentent plusieurs caractères qui les distinguent nettement des autres modalités de l’orientation des adultes et de la gestion des ressources humaines. Le bénéficiaire initie la démarche ou y adhère. La nature de sa relation avec le cons..

Combined cytogenetic and molecular methods for taxonomic verification and description of Brassica populations deriving from different origins

Agriculture faces great challenges to overcome global warming and improve system sustainability, requiring access to novel genetic diversity. So far, wild populations and local landraces remain poorly explored. This is notably the case for the two diploid species, Brassica oleracea L. (CC, 2n=2x=18) and B. rapa L. (AA, 2n=2x=20). In order to explore the genetic diversity in both species, we have collected populations in their centre of origin, the Mediterranean basin, on a large contrasting climatic and soil gradient from northern Europe to southern sub-Saharan regions. In these areas, we also collected 14 populations belonging to five B. oleracea closely related species. Our objective was to ensure the absence of species misidentification at the seedling stage among the populations collected and to describe thereafter their origins. We combined flow cytometry, sequencing of a species-specific chloroplast genomic region, as well as cytogenetic analyses in case of unexpected results for taxonomic verification. Out of the 112 B. oleracea and 154 B. rapa populations collected, 103 and 146, respectively, presented a good germination rate and eighteen populations were misidentified. The most frequent mistake was the confusion of these diploid species with B. napus. Additionally for B. rapa, two autotetraploid populations were observed. Habitats of the collected and confirmed wild populations and landraces are described in this study. The unique plant material described here will serve to investigate the genomic regions involved in adaptation to climate and microbiota within the framework of the H2020 Prima project ‘BrasExplor’

Mapping of quantitative trait loci for field resistance to Fusarium head blight in an European winter wheat

53 ref.International audienceFusarium head blight (FHB) caused by Fusarium culmorum is an economically important disease of wheat that may cause serious yield and quality losses under favorable climate conditions. The development of disease-resistant cultivars is the most effective control strategy. Worldwide, there is heavy reliance on the resistance pool originating from Asian wheats, but excellent field resistance has also been observed among European winter wheats. The objective of this study was to map and characterize quantitative traits loci (QTL) of resistance to FHB among European winter wheats. A population of 194 recombinant inbred lines (RILs) was genotyped from a cross between two winter wheats Renan (resistant)/Recital (susceptible) with microsatellites, AFLP and RFLP markers. RILs were assessed under field conditions For 3 years in one location. Nine QTLs were detected, and together they explained 30-45% of the variance, depending on the year. Three of the QTLs were stable over the 3 years. One stable QTL, QFhs.inra.2b, was mapped to chromosome 2B and two QTLs QFhs.inra.5a2 and QFhs.inra.5a3, to chromosome 5A; each of these QTLs explained 6.9-18.6% of the variance. Other QTLs were identified on chromosome 2A, 3A, 3B, 5D, and 6D, but these had a smaller effect on FHB resistance. One of the two QTLs on chromosome 5A was linked to gene B1 controlling the presence of awns. Overlapping QTLs for FHB resistance were those for plant height or/and flowering time. Our results confirm that wheat chromosomes 2A, 3A, 3B, and 5A carry FHB resistance genes, and new resistance factors were identified on chromosome arms 2BS and 5AL. Markers flanking these QTLs should be useful tools for combining the resistance to FHB of Asian and European wheats to increase the resistance level of cultivars

Evolutionary dynamics of transposable elements and satellite DNAs in polyploid Spartina species

International audienceRepeated sequences and polyploidy play a central role in plant genome dynamics. Here, we analyze the evolutionary dynamics of repeats in tetraploid and hexaploid Spartina species that diverged during the last 10 million years within the Chloridoideae, one of the poorest investigated grass lineages. From high-throughput genome sequencing, we annotated Spartina repeats and determined what sequence types account for the genome size variation among species. We examined whether differential genome size evolution correlated with ploidy levels and phylogenetic relationships. We also examined the tempo of repeat sequence dynamics associated with allopatric speciation over the last 3-6 million years between hexaploid species that diverged on the American and European Atlantic coasts and tetraploid species from North and South America. The tetraploid S. spartinae, whose phylogenetic placement has been debated, exhibits a similar repeat content as hexaploid species, suggesting common ancestry. Genome expansion or contraction resulting from repeat dynamics seems to be explained mostly by the contrasting divergence times between species, rather than by genome changes triggered by ploidy level change per se. One 370 bp satellite may be exhibiting ’meiotic drive’ and driving chromosome evolution in S. alterniflora. Our results provide crucial insights for investigating the genetic and epigenetic consequences of such differential repeat dynamics on the ecology and distribution of the meso- and neopolyploid Spartina species