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International audience; Cryopreservation is the only alternative, safe and cost-effective method for long-term storage of plant genetic resources, particularly for stone fruits (Prunus spp.). In this study, an efficient cryopreservation protocol was developed for sour cherry (Prunus cerasus L.). In vitro shoot tips of two varieties (Montmorency and Schattenmorelle) were successfully cryopreserved using the vitrification technique. Our study showed the possibility of replacing the 3-week cold hardening treatment of mother-plants with preculture of apices on medium enriched with sucrose and/or glycerol. The highest recovery percentages after liquid nitrogen exposure were obtained after a cold hardening treatment followed by a 3-day preculrure on 0.8 M sucrose medium or by replacing cold hardening with a 7-day preculture on the following media: 0.4 M glycerol or sucrose, 0.4 M sucrose + 0.4 M glycerol or 0.8 M glycerol. Under these conditions, recovery after cryopreservation ranged between 41 and 63%, These results complement the range of Prunus species successfully cryopreserved using in vitro explants. Our protocol, which is simplified in comparison with the original one, since cold hardening of mother-plants in a cold chamber is replaced by pretreatment of apices on medium with high sugar concentration, may facilitate the application of vitrification for cryopreservation of additional Prunus species

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; In the present study, phenotypic variability of 80 plum (Prunus domestica L.) varieties maintained in the French National Plum Collection was evaluated with 19 quantitative traits. In addition, genetic diversity and genetic structure was studied in three plum species (P. domestica L., Prunus cerasifera Ehrh. and Prunus spinosa L.) using chloroplast DNA (cpDNA) markers and five single sequence repeat (SSR) loci. Based on phenotypic traits, some varieties, such as mirabelle plums, grouped together. Bayesian structure analysis was used to identify different genetic groups, whereby damson plums were clearly distinguished from greengage plums. When examining the three species together, a higher level of cpDNA allelic richness was found in P. cerasifera and in P. spinosa than in P. domestica where only five cpDNA haplotypes were detected in the national plum collection, with one main haplotype that accounted for 80% of the varieties studied. P. domestica cpDNA haplotypes tended to group together with P. cerasifera haplotypes whereas most of P. spinosa haplotypes formed a separate cluster. SSR markers were somewhat able to distinguish the three species. These results provide some clues as to the origin of plum and the various plum varieties. Our results also provide useful information for the management of plum genetic resources.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Understanding genetic structure and diversity information is critical for genetic association studies. In the octoploid cultivated strawberry (Fragaria×ananassa), genetic analyses were focussed on diversity, whereas genetic structure has been poorly explored. This study investigated the genetic structure in a genetic resources collection representing a wide range of the octoploid strawberry cultivars released mainly by North America and western and southern Europe, at different breeding periods and with various pedigrees. The relationship between varieties was examined using 23 microsatellite (simple sequence repeat, SSR) markers. Eight SSR markers were diploid, useful for cultivar discrimination with polymorphic information content (PIC) values between 0.29 and 0.74. Bayesian analyses of genetic structure identified four subpopulations. Three of them, American and modern northern European cultivars (AMNECs), American and modern southern European cultivars (AMSECs) and old European cultivars (OECs), reflected the European breeding history of the cultivated octoploid strawberry. The fourth subpopulation, ‘Intermediate’ group cultivars (IGCs), comprised various origins including OECs that were introgressed with wild species such as Fragaria chiloensis or Fragaria moschata. The OEC group gathered cultivars dating before 1960s, forming the most homogenous and stable subpopulation. The unweighted pair group method with arithmetic mean (UPGMA) dendrogram based on modified Nei and Li distance confirmed the separation of the AMSEC, AMNEC and OEC groups. In addition, significant differences were observed among the four subpopulations (AMNEC, AMSEC, OEC, IGC), with high variability within groups and between AMSEC and IGC. Our work underlined that the structure within the studied collection was mainly explained by the pedigree and the year of release than the geographical origin of cultivars. In addition, the important loss of diversity observed in the modern European cultivars and a trend towards using mainly American cultivars for breeding programmes led to the progressive abandonment of old European germplasm, which was revealed as a relative distinct and rich group. This European material should be protected and maintained, because it represents a potential source of original traits for broadening the genetic base of cultivated strawberry. In addition, diploid markers we identified can be used without ambiguity in phylogenetic and diversity studies, because they are genome-specific. This study is the first step for further association studies in strawberry.

Parents and progenies genetic diversity, and male and female contributions to the seed crop were assessed in three experimental Prunus avium seed orchards. Collected data were used to compare different effective population sizes, based on phenological, seed crop and paternity analysis. Our results did not show any difference of genetic diversity between parents and progenies. A limited pollen pollution was detected. We showed that distance and coflowering among clones had a significant effect on effective pollination, and a significant effect of the production of flowers was revealed in one of the seed orchards. Our study also revealed a quite low number of effective size of fathers per mother, but high effective sizes of mothers, fathers and parents at the level of the seed orchard. Finally, the calculation of effective size of mothers, fathers and parents was not highly modified when having the complete information based on the paternity analysis., La diversité génétique des parents et de leurs descendants, ainsi que les contributions mâle et femelle à la récolte de graines ont été estimées dans trois vergers à graines expérimentaux de Prunus avium. Les données collectées ont été utilisées pour comparer différentes tailles de population efficace, en se basant sur l'analyse de la phénologie, de la récolte de graines et de la paternité. Nos résultats n'ont pas montré de différence de diversité génétique entre les parents et les descendants. Une pollution pollinique limitée a été mise en évidence. Nous avons montré un effet significatif de la distance et de la cofloraison entre clones sur la pollinisation efficace, ainsi qu'un effet significatif de la production de fleurs dans l'un des vergers à graines. Notre étude a aussi révélé un faible nombre efficace de pères à l'échelle de chaque mère, et un nombre efficace de mères, de pères et de parents important à l'échelle du verger à graines. Enfin, le calcul des tailles efficaces de pères et de parents à l'échelle du verger à graines n'a pas été fortement influencé par le fait d'avoir l'information totale de contribution donnée par l'analyse de paternité.