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Trabajo presentado en el 14th World Congress on Parasitic Plants (From genome to field), celebrado en Asilomar (California) el 24 y 25 de junio de 2017., Orobanche cumana (sunflower broomrape) is an obligate parasitic plant that specifically infects sunflower (Helianthus annuus). It is one of the main limiting factors of sunflower crop in Eastern Europe, Spain and Asia. In 2007, the first infested fields have been reported in France. Breeding for resistance in sunflower was successful but new more virulent races of O. cumana often overcame the resistance genes. The first developmental stages of O. cumana occur underground. The germination of the seeds is first stimulated by sunflower root exudates before entering the host root through a haustorium. Without roots nor chlorophyll, O. cumana depends on sunflower for water and nutrients supply. It connects to the vascular system of the sunflower root and store metabolites in a tubercle before emerging a flowering shoot. The inactivation of these developmental stages is a key resistance mechanism in sunflower. A better understanding of the biology of O. cumana will help to identify new resistance processes and resistance genes in sunflower. In the frame of a collaborative project between French and Spanish research institutes, we have produced a first version of the 1.42 Gb genome sequence of O. cumana by combining PacBio sequencing, optical mapping and genetic map. More than twenty transcriptomic RNA-seq experiments from O. cumana were used for annotating the genome sequence. This first sequence assembly (622 scaffolds, 1.38Gb, N50=5.9Mb) and its annotation will be provided through a Web Genome Browser to the public research community. Our strategy to obtain and finalize the genome assembly as well as results on population diversity will be presented. The genome sequence of O. cumana will enable the characterization of its physiology and development. Avirulence genes should be identified more efficiently and, as putative interactor with sunflower proteins, should help in identifying new resistance genes in sunflower. This resource will help in understanding parasitic plants’ biology and evolution, like parasitism capacity acquisition.

International audience; There are numerous threats to the biodiversity of commercial and non-commercial plant species. The easiest way to prevent biodiversity loss is to conserve their genetic resources in seed banks. Depending on seeds sensitivity, it is vital to provide seeds packaging protection with high water vapor barrier components. Currently, most of container materials for seed banking are made from glass or tri-laminated foil. Glass containers are heavy and easily broken during handling and transport, whereas tri-laminated foil pouches are opaque and subjected to puncture by sharp seeds. High density polyethylene (HDPE) containers are rarely used for long term seed storage due to their permeability to moisture vapor. Considering the numerous advantages of HDPE such as low cost, lightweight, chemical inertness and easy processing, HDPE with enhanced barrier properties is suitable for long-term seed storage. According to previous research work, the addition of nanoclays into polymer matrix leads to the tortuous path that delayed the diffusion of gaseous molecules as water vapour. The present study aims to evaluate the effect of different clays on the overall properties of HDPE, especially water vapor barrier properties. The water vapor barrier of tested samples was found to be influenced by several factors: the aspect ratio of clays, the crystallinity of HDPE, the interface between clays and HDPE and the storage conditions.; Il y a des nombreuses menaces qui pèsent sur la biodiversité des espèces végétales commerciales et non commerciales. La meilleure façon de prévenir la perte de biodiversité est de conserver leurs ressources génétiques dans des banques de semences. Selon la sensibilité des graines, il est essentiel d’utiliser des contenants composés de matériaux faisant hautement barrage à la vapeur d’eau. Actuellement, la plupart des conteneurs pour les banques de semences est en verre ou en complexe laminé aluminium /plastique. Les récipients en verre sont lourds et fragiles pendant les manutentions et le transport, alors que les sachets laminés aluminium/plastique sont opaques et sensibles à la perforation par des graines acérées. Les contenants en polyéthylène haute densité (PEHD) sont rarement utilisés pour le stockage long terme de semences en raison de leur perméabilité à la vapeur d’eau. Étant donné les nombreux avantages du PEHD tels que l’inertie chimique, la légèreté, leur faible coût ainsi que leur mise en oeuvre facile, le PEHD doté de propriétés de barrière renforcées est adapté au stockage à long terme des semences. Comme démontré dans les travaux de recherche précédents, l’ajout de nano-argiles dans la matrice polymère conduit à la mise en place de chemins tortueux qui retardent la diffusion des molécules gazeuses comme la vapeur d’eau. La présente étude vise à évaluer l’effet des différentes argiles sur les propriétés globales de HDPE et en particulier les propriétés de barrière de vapeur d’eau. La capacité barrière de vapeur d’eau des échantillons testés s’est avérée être influencée par plusieurs facteurs : l’allongement des argiles, la cristallinité du PEHD, l’interface entre les argiles et le PEHD ainsi que les conditions de stockage.