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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

The present study investigates the genetic determinism of flowering and maturity dates, two traits highly affected by global climate change. Flowering and maturity dates were evaluated on five progenies from three Prunus species, peach, apricot and sweet cherry, during 3–8 years. Quantitative trait locus (QTL) detection was performed separately for each year and also by integrating data from all years together. High heritability estimates were obtained for flowering and maturity dates. Several QTLs for flowering and maturity dates were highly stable, detected each year of evaluation, suggesting that they were not affected by climatic variations. For flowering date, major QTLs were detected on linkage groups (LG) 4 for apricot and sweet cherry and on LG6 for peach. QTLs were identified on LG2, LG3, LG4 and LG7 for the three species. For maturity date, a major QTL was detected on LG4 in the three species. Using the peach genome sequence data, candidate genes underlying the major QTLs on LG4 and LG6 were investigated and key genes were identified. Our results provide a basis for the identification of genes involved in flowering and maturity dates that could be used to develop cultivar ideotypes adapted to future climatic conditions., This work was partially supported by the ISAFRUIT Project funded by the European Commission—Food Quality and Safety of the 6th Framework Program of RTD (No. FP6-FOOD-CT-2006-016279).

The circadian clocks that drive daily rhythms in animals are tightly coupled among the cells of some tissues. The coupling profoundly affects cellular rhythmicity and is central to contemporary understanding of circadian physiology and behavior. In contrast, studies of the clock in plant cells have largely ignored intercellular coupling, which is reported to be very weak or absent. We used luciferase reporter gene imaging to monitor circadian rhythms in leaves of Arabidopsis thaliana plants, achieving resolution close to the cellular level. Leaves grown without environmental cycles for up to 3 wk reproducibly showed spatiotemporal waves of gene expression consistent with intercellular coupling, using several reporter genes. Within individual leaves, different regions differed in phase by up to 17 h. A broad range of patterns was observed among leaves, rather than a common spatial distribution of circadian properties. Leaves exposed to light–dark cycles always had fully synchronized rhythms, which could desynchronize rapidly. After 4 d in constant light, some leaves were as desynchronized as leaves grown without any rhythmic input. Applying light–dark cycles to such a leaf resulted in full synchronization within 2–4 d. Thus, the rhythms of all cells were coupled to external light–dark cycles far more strongly than the cellular clocks were coupled to each other. Spontaneous desynchronization under constant conditions was limited, consistent with weak intercellular coupling among heterogeneous clocks. Both the weakness of coupling and the heterogeneity among cells are relevant to interpret molecular studies and to understand the physiological functions of the plant circadian clock.

International audience; A basic knowledge on linkage disequilibrium (LD) is necessary in order to determine resolution of association studies. We investigated the extent and patterns of LD in a self-incompatible species ( Prunus avium L.), in 3 groups (wild cherry, sweet cherry landraces and sweet cherry modern varieties), using a set of 35 microsatellite markers and the gametophytic self-incompatibility locus. Since population structure might create spurious LD, we thus used the information provided by a structure analysis published in a previous study to perform the LD analysis. In the current study, we detected a greater LD extent in sweet cherry than in wild cherry, which is plausibly due to the bottleneck associated with domestication and breeding. Higher LD values in sweet cherry sub-groups may be explained by smaller sample sizes. We also showed that the remaining structure in the groups of sweet cherry, in particular landraces, is responsible for a part of the LD extent. Intra-group relatedness may also account for extensive LD in two sub-groups. These results demonstrate, if ever necessary, the importance of controlling the genetic structure and relatedness when estimating LD. Moreover, LD decays very rapidly with genetic linkage distance in both wild and sweet cherries, which seems promising for future association studies.

L'article original est publié par The American Society of Plant Biologists 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; Root-knot nematode (RKN) Meloidogyne species are major polyphagous pests of most crops worldwide, and cultivars with durable resistance are urgently needed because of nematicide bans. The Ma gene from the Myrobalan plum (Prunus cerasifera) confers complete-spectrum, heat-stable, and high-level resistance to RKN, which is remarkable in comparison with the Mi-1 gene from tomato (Solanum lycopersicum), the sole RKN resistance gene cloned. We report here the positional cloning and the functional validation of the Ma locus present at the heterozygous state in the P.2175 accession. High-resolution mapping totaling over 3,000 segregants reduced the Ma locus interval to a 32-kb cluster of three Toll/Interleukin1 Receptor-Nucleotide Binding Site-Leucine-Rich Repeat (LRR) genes (TNL1–TNL3), including a pseudogene (TNL2) and a truncated gene (TNL3). The sole complete gene in this interval (TNL1) was validated as Ma, as it conferred the same complete-spectrum and high-level resistance (as in P.2175) using its genomic sequence and native promoter region in Agrobacterium rhizogenes-transformed hairy roots and composite plants. The full-length cDNA (2,048 amino acids) of Ma is the longest of all Resistance genes cloned to date. Its TNL structure is completed by a huge post-LRR (PL) sequence (1,088 amino acids) comprising five repeated carboxyl-terminal PL exons with two conserved motifs. The amino-terminal region (213 amino acids) of the LRR exon is conserved between alleles and contrasts with the high interallelic polymorphisms of its distal region (111 amino acids) and of PL domains. The Ma gene highlights the importance of these uncharacterized PL domains, which may be involved in pathogen recognition through the decoy hypothesis or in nuclear signaling.

La capacité photosynthétique de vitroplants de vigne (var. Gravesac) a été déterminée à l'aide d'un dispositif de mesures des échanges gazeux en circuit ouvert. L'activité photosynthétique et la respiration de la plante sont importantes en culture in vitro. La photosynthèse nette maximale est de 2 µmol m-2 s-1 a 500 µ11-1 de CO2. A 350 µ11-1 de CO2 la photosynthèse est de 1,6 µmol m-2 s-1. La respiration a l'obscurité est de 0,018 µmol s-1 g-1 de poids sec total. La quantité totale des sucres solubles dans le milieu de culture reste constante pendant les deux mois de culture. Le saccharose est totalement hydrolysé en glucose et en fructose. Les vitroplants de Gravesac ne prélèvent pas de sucres dans le milieu, ce qui confirme leur degré élevé d'autotrophie dans ces conditions de culture. La comparaison entre les échanges gazeux de vitroplants et des plantes cultivées en serre met en évidence une réduction de 80% de l'activité in vitro. Evaluation of the photoautotrophic ability of Vitis plantlets (rootstock var Gravesac): Set-up of a special open flow gas exchange system The photosynthetic ability of Vitis rootstock plantlets (var. Gravesac) was estimated in vitro with an open flow system specially designed for in vitro culture. CO2 response curves were established and respiration was also measured. The maximum net photosynthetic rate, reached at 500 µ11-1 of CO2, is 2 µmol m-2 s-1. At 350 µ11-1 CO2 the photosynthetic activity is 1.6 µmol m-2 s-1. The dark respiration rate is 0.018 µmol s-1 g-1 of total dry weight. The total amount of soluble carbohydrates in the medium remains the same whether plantlets were present or not. In the medium with plantlets, the sucrose is entirely hydrolysed in glucose and fructose within two months. No carbohydrate uptake from the medium was recorded indicating an autotrophic behaviour. Measurements of CO2 exchange were also performed at leaves of plants cultivated in a greenhouse. The photosynthetic activity of in vitro plants accounts only for 20% of the level of greenhouse-grown plants., VITIS - Journal of Grapevine Research, Vol. 35 No. 2 (1996): Vitis

We investigated the changes in the expression profiles of the partially resistant apricot (Prunus armeniaca L.) cultivar Goldrich following inoculation with Plum pox virus (PPV) using cDNA-amplification fragment length polymorphism (AFLP). Altered expression patterns were detected and twenty-one differentially expressed cDNA had homologies with genes in databases coding for proteins involved in metabolism, signal transduction, defense, stress and intra/intercellular connections. Seven of the modified expressed patterns were further investigated by semi-quantitative RT-PCR or Northern blotting. The expression patterns of five of these genes were confirmed in the partially resistant P. armeniaca cv. 'Goldrich' and assessed in a susceptible genotype. One of these cDNAs, coding for a putative class III chitinase, appeared to be repressed in infected plants of the partially resistant genotype and expressed in the susceptible one which could be related to the partially resistant phenotype. On the contrary, the expression patterns of the genes coding for a transketolase, a kinesin-like and an ankyrin-like protein, were clearly linked to the susceptible interaction. These candidate genes could play a role either in the compatible interaction leading to virus invasion or to the quantitative resistance of apricot to PPV.

Twelve Arabidopsis accessions were challenged with Plum pox potyvirus (PPV) isolates representative of the four PPV strains. Each accession supported local and systemic infection by at least some of the PPV isolates, but high variability was observed in the behavior of the five PPV isolates or the 12 Arabidopsis accessions. Resistance to local infection or long-distance movement occurred in about 40% of all the accession-isolate combinations analyzed. Except for Nd-1, all accessions showed resistance to local infection by PPV-SoC; in the Landsberg erecta (Ler) accession, this resistance was compromised by sgt1 and rar1 mutations, suggesting that it could be controlled by an R gene-mediated resistance pathway. While most of the susceptible accessions were symptomless, PPV induced severe symptoms on inflorescences in C24, Ler, and Bay-0 as early as 15 days after inoculation. Genetic analyses indicated that these interaction phenotypes are controlled by different genetic systems. The restriction of long-distance movement of PPV-El Amar and of another member of genus Potyvirus, Lettuce mosaic virus, in Col-0 requires the RTM genes, indicating for the first time that the RTM system may provide a broad range, potyvirus-specific protection against systemic infection. The restriction to PPVPS long-distance movement in Cvi-1 is controlled by a single recessive gene, designated rpv1, which was mapped to chromosome 1. The nuclear inclusion polymerase b-capsid protein region of the viral genome appears to be responsible for the ability of PPV-R to overcome rpv1-mediated resistance.

The development of saturated linkage maps using transferable markers, restriction fragment length polymorphisms, and micro-satellites has provided a foundation for fruit tree genetics and breeding. A Prunus reference map with 562 such markers is available, and a further set of 13 maps constructed with a subset of these markers has allowed genome comparison among seven Prunus diploid ( x = 8) species (almond, peach, apricot, cherry, Prunus ferganensis, Prunus davidiana , and Prunus cerasifera ); marker colinearity was the rule with all of them. Preliminary results of the comparison between apple and Prunus maps suggest a high level of synteny between these two genera. Conserved genomic regions have also been detected between Prunus and Arabidopsis . By using the data from different linkage maps anchored with the reference Prunus map, it has been possible to establish, in a general map, the position of 28 major genes affecting agronomic characters found in different species. Markers tightly linked to the major genes responsible for the expression of important traits (disease/pest resistances, fruit/nut quality, self-incompatibility, etc.) have been developed in apple and Prunus and are currently in use for marker-assisted selection in breeding programs. Quantitative character dissection using linkage maps and candidate gene approaches has already started. Genomic tools such as the Prunus physical map, large EST collections in both Prunus and Malus , and the establishment of the map position of high numbers of ESTs are required for a better understanding of the Rosaceae genome and to foster additional research and applications on fruit tree genetics.

EFPP 2002 : disease resistance in plant pathology; International audience

International audience; As in many other fleshy fruits, the predominant organic acids in ripe peach (Prunus persica (L.) Batsch) fruit are malic and citric acids. The accumulation of these metabolites in fruit flesh is regulated during fruit development. Six peach fruitrelated genes implicated in organic acid metabolism (mitochondrial citrate synthase; cytosolic NAD-dependent malate dehydrogenase, and cytosolic NADP-dependent isocitrate dehydrogenase) and storage (vacuolar proton translocating pumps: one vacuolar H¹-ATPase, and two vacuolar H¹-pyrophosphatases) were cloned. Five of these peach genes were homologous to genes isolated from fruit in other fleshy fruit species. Phylogenetic and expression analyses suggested the existence of a particular vacuolar pyrophosphatase highly expressed in fruit. The sixth gene was the first cytosolic NAD dependent malate dehydrogenase gene isolated from fruit. Gene expression was studied during the fruit development of two peach cultivars, a normal-acid (Fantasia) and a low-acid (Jalousia) cultivar. The overall expression patterns of the organic acid-related genes appeared strikingly similar for the two cultivars. The genes involved in organic acid metabolism showed a stronger expression in ripening fruit than during the earlier phases of development, but their expression patterns were not necessarily correlated with the changes in organic acid contents. The tonoplast proton pumps showed a biphasic expression pattern more consistent with the patterns of organic acid accumulation, and the tonoplast pyrophosphatases were more highly expressed in the fruit of the low-acid cultivar during the second rapid growth phase of the fruit.

Un essai utilisant des plantes obtenues a partir de boutures et presentant une gamme de dommages causes par le mildiou, donc de vigueur potentielle, a ete utilise pour etudier les interrelations entre les divers caracteres associes a l'accumulation de reserves de glucides et au rendement. La technique de la regression progressive a ete utilisee pour les analyser. Pour la premiere fois, le cycle de trois ans conduisant a du raisin recolte a ainsi pu etre etudie a l'etat isole.

Plant phenolics have drawn increasing attention due to their potential nutritional benefits. Although the basic reactions of the phenolics biosynthetic pathways in plants have been intensively analyzed, the regulation of their accumulation and flux through the pathway is not that well established. The aim of this study was to use a strawberry (Fragaria × ananassa) microarray to investigate gene expression patterns associated with the accumulation of phenylpropanoids, flavonoids, and anthocyanins in strawberry fruit. An examination of the transcriptome, coupled with metabolite profiling data from different commercial varieties, was undertaken to identify genes whose expression correlated with altered phenolics composition. Seventeen comparative microarray analyses revealed 15 genes that were differentially (more than 200-fold) expressed in phenolics-rich versus phenolics-poor varieties. The results were validated by heterologous expression of the peroxidase FaPRX27 gene, which showed the highest altered expression level (more than 900-fold). The encoded protein was functionally characterized and is assumed to be involved in lignin formation during strawberry fruit ripening. Quantitative trait locus analysis indicated that the genomic region of FaPRX27 is associated with the fruit color trait. Down-regulation of the CHALCONE SYNTHASE gene and concomitant induction of FaPRX27 expression diverted the flux from anthocyanins to lignin. The results highlight the competition of the different phenolics pathways for their common precursors. The list of the 15 candidates provides new genes that are likely to impact polyphenol accumulation in strawberry fruit and could be used to develop molecular markers to select phenolics-rich germplasm., This work was supported by PLANT-KBBE FraGenomics, by the Euroinvestigacion Subprogram from PLANT_KBBE Call, provided by the Spanish Science and Technology Ministry (grant no. EUI2008–03770 to A.M.), by the Centre CONSOLIDER on Agrigenomics and the Xarxa de Referencia en Biotecnología of the Generalitat de Catalunya, and by the Deutsche Forschungsgemeinschaft (grant no. SCHW634/14 to S.-Y.Y. and W.S.).

International audience; Our aim was to assess the possible differential effect of increasing temperatures due to global warming on dormancy progression in apricot. The effect of a range of chilling temperatures on vegetative and reproductive bud dormancy progression in excised shoots was examined during two seasons. Temperature treatments were applied in different dormant stages to evaluate the possible interaction of date × temperature for dormancy release in apricot. During sampling, chill accumulated in the field ranged from 0 to 49 chill portions (CPs), corresponding to 0–100% of the chilling requirement (CR) of the apricot selection Z505-2. Forcing conditions were applied after a 60-day chill treatment on each sampling date, and rate to budbreak (1/mean time to bud break: MTB−1) was established in vegetative (terminal and lateral) and reproductive buds to determine depth of dormancy. Results showed that the stage of dormancy has a strong influence on the effect of different temperatures on dormancy progression in apricot. For the first time, a non-linear effect of different chilling temperatures during the dormancy cycle in apricot was obtained, especially in the superior range of temperatures traditionally considered to release dormancy. Thus, introduction of this differential effect could help to improve the models to estimate dormancy release in the context of climate change.

International audience; Sweet cherry (Prunus avium L.) is a rosaceous fruit crop cultivated in temperate regions of the world for its highly valued fruits. In today’s marketplace, large fruit is highly desirable and directly related to grower profitability; therefore, the development of new cherry varieties with large fruit is a major breeding goal. To elucidate the genetic control of fruit size in sweet cherry and thereby enable marker‐assisted breeding, we undertook a fine mapping – candidate gene analysis of two previously identified fruit size QTLs located on linkage groups 2 and 6 (G2 and G6)(Zhang et al. 2010) in two sweet cherry populations. A total of 14 simple sequence repeats were developed from the peach genomic regions syntenic to the G2 and G6 fruit size QTLs and used to further narrow the sweet cherry QTL regions. Genome annotations of the peach sequence in these syntenic regions identified cell number regulator genes (CNR, Guo et al. 2010) as likely candidate genes for both the G2 and G6 fruit size QTLs. The CNR gene family, first described in maize based upon homology to the tomato fruit weight gene fw2.2, is hypothesized to contain genes involved in cell number regulation that ultimately affect plant growth and organ size. Sequencing of the CNR candidate genes from the parents of the mapping populations and a panel of diverse sweet cherry selections for G2 and G6 identified 3 and 2 allelic variants, respectively. These findings agree with the previously described functional haplotypes for these two fruit size QTLs. Comparisons of sweet cherry fruit weights based on their CNR genotypes further support our hypothesis that the phenotypic differences in fruit size associated with the G2 and G6 QTLs are caused by allelic variants of the CNR genes.

International audience; Very few genomic resources are actually available for sweet cherry. Emergence and generalization of next‐generation DNA sequencing technologies that reduce cost, labor, and time, provide the opportunity to conduct large‐scale genomic projects at lower cost even for non‐model organisms like prunus avium. In order to obtain a panel of prunus avium expressed genes for functional studies and candidate gene strategy, a normalized complementary DNA library has been sequenced using high throughput 454 technology (GS FLX Titanium) yielding 1175627 reads after cleaning. Clustering and assembly generated a total of 19574 contigs and 149688 singletons. After functionnal annotation of clusters and singletons, a web portal has been created to query the prunus avium transcriptome database. This annotated transcriptome constitute a versatile resource for candidate gene selection based on functional annotation and will be used soon as a reference for short read mapping in differential expression studies by RNA‐seq.

International audience; Peach (Prunus persica (L.) Batsch) and sweet cherry (P. avium L.) are two Prunus species cultivated in temperate regions. In peach, many fruit quality traits are controlled by a single or a small number of genes. On the opposite, in sweet cherry, most fruit quality traits are complex. In peach, the D locus controls fruit acidity, low‐acidity is determined by the dominant allele while the S locus (for saucer peach), controls the fruit shape, flat being dominant. In sweet cherry, one of the most important fruit quality traits for producers is the fruit cracking tolerance, especially in regions where rainy springs can destroy nearly all the production. A positional cloning strategy using a large F2 population of 2161 individuals and differential expression analysis of the two parents of the F2 population (Ferjalou Jalousia and Fantasia) using RNA‐seq, lead to the identification of candidate genes for the non acid fruit trait in peach. For the S locus, positional candidate genes were identified on the basis of their functional annotation. Using two sweet cherry F1 mapping progenies, Regina × Lapins and Regina × Garnet, many QTLs were detected for fruit cracking tolerance, each of them explaining a small percentage of the observed variation. Interestingly, one of them was detected in each year of evaluation. New deeper phenotypic studies will be developed to dissect this complex character. We will compare the methodology used to study these simple and complex traits, and discuss their application in selection programs.

International audience

International audience

International audience; Environmental and climatic conditions affect the flower bud growth, flowering and yield performance of fruit species. Temperature and water availability appear to be important factors for temperate fruit trees in mild climates. The aim of this research was to study the involvement of temperature regime on biological processes, such as xylem differentiation and dormancy evolution, in apricot flower buds (Prunus armeniaca L.). Over 3 consecutive years, biological and anatomical investigations were carried out in Tuscany (Italy) and Murcia (Spain) on two cultivars characterized by a different chilling requirement (CR): Currot, a traditional Spanish cultivar with a very low CR, and Stark Early Orange (SEO), a North American cultivar with a very high CR. Currot had a regular bearing, and was characterized by a synchronism between endodormancy release and xylem differentiation. On the other hand, SEO showed an irregular flower bud growth leading to flowering and fruit-set failure, even with a high level of chilling accumulation. No relationship was found in SEO between xylem development and flower bud growth reactivation. The de-synchronism between these processes could determine the poor adaptability to different environmental areas of SEO cultivar, and its very high CR is not the main hypothesised cause of the altered flower bud development.

International audience; Phenology and especially reproductive timing is crucial for fruit tree species as yield and fruit quality are directly linked to an adequate flower development. In sweet cherry, flowering process is induced by specific chill and heat requirements. As temperatures become milder, this process is disrupted. Two intraspecific F1 mapping progenies, Regina × Lapins (R×L) and Regina × Garnet (R×G), were genotyped using the 6K cherry chip SNP developed in the RosBREED project. For the detection of quantitative trait locus (QTL) controlling chilling requirements, the R×G progeny was evaluated during 3 years. For QTL controlling flowering date the two progenies were evaluated during 5 years. QTL analyses were performed separately for each year and combined for all years together. For chilling requirements, QTLs were detected on linkage groups (LG) 1, 2, 4, 5, 6 and 7. Whereas for flowering date, QTLs were detected on all LGs. For both traits, a major QTL was detected on LG4 for each year of evaluation. Candidate genes were identified by combining functional annotation of the peach genome and QTLs’ localisation for both traits. Functional studies using RNAseq and qRT‐PCR are in progress to select the most promising candidate genes. Our results provide a basis for the identification of genes involved in chilling requirements and flowering date that could be used to develop cultivar ideotypes adapted to future climatic conditions.

39 Pags., 4 Tabls., 4 Figs. The definitive version is available at: http://link.springer.com/journal/11295, The high economic losses caused by the occurrence of iron chlorosis in Prunus orchards in the Mediterranean area justifies the implementation of breeding programs to generate high-performance rootstocks for different edaphoclimatic area conditions. For that reason, the genetic control of iron chlorosis tolerance was studied in an F1 population derived from a three-way interspecific cross between a Myrobalan plum (P 2175) and an almond × peach hybrid (Felinem). Several phenotypic measurements were assessed to guarantee an accurate data set for genetic analysis. SPAD (Soil and Plant Analyzer Development) values, chlorophyll concentration, and visual diagnostic symptoms were highly correlated with leaf chlorosis in trees. SPAD value was the most reliable measure, since it was an objective, unbiased, and non-destructive method. Two significant quantitative trait loci (QTLs) involved in SPAD and chlorophyll concentration were identified for Felinem in linkage groups 4 and 6. Both QTLs were detected in four of the six consecutive years of the experiment. For P 2175, two of the three putative QTLs identified, pspad4.1 and chl4.1, were placed in linkage group 4. These QTLs were related to the SPAD values and chlorophyll concentration, respectively, and co-localized with QTLs detected in the Felinem map affecting the same traits. Candidate gene PFIT, related to iron metabolism, was localized within the confidence interval of the QTL in linkage group 4. This research suggests an association of this chromosome region with tolerance to iron chlorosis in Prunus, and it provides a first approach to localize candidate genes involved in tolerance to this abiotic stress., This research was funded by MICINN (Spanish Ministry of Science and Innovation, AGL 2008-00283) and co-funded with a FEDER project and Gobierno de Aragón (A44). M.J. Gonzalo was the beneficiary of an I3P-PC2006 contract from the CSIC-FSE.

Cell wall composition, pectin, and hemicellulose fine structure variation were assessed in peach and related genotypes with contrasted texture and fruit shape. Cell walls were prepared from four commercial peaches, eight genotypes from the Jalousia × Fantasia peach cross, and six genotypes from the Earlygold peach × Texas almond cross. Sugar composition was determined chemically while fine structure of homogalacturonan pectin and xyloglucan hemicellulose were assessed by coupling pectin lyase and glucanase degradation, respectively, with MALDI-TOF MS analysis of the degradation products. The results indicate clear compositional and structural differences between the parents and their related genotypes on the basis of pectin versus cellulose/hemicellulose content and on the fine structure of homogalacturonan and xyloglucan. A relation between methyl- and acetyl-esterification of pectin with fruit shape is revealed in the Fantasia × Jalousia peach genotypes., This work has been supported in part by funds from the program EU FP6 ISAFRUIT (Contract No. FP6-FOOD 016279-2).

L’alcool déshydrogénase (ADH, EC 1.1.1.1) a été étudié chez le pêcher à partir d’extraits enzymatiques totaux issus de feuilles prélevées en avril et mai (l’activité ADH s’atténue fortement au-delà de cette période). Ce système enzymatique est complexe, il fait intervenir 3 loci : ADH-1, ADH-2 et ADH-3. Il se forme à partir de ces 3 loci des enzymes dimères intra- et intergéniques. Le locus ADH-3 possède 2 allèles ADH-3L et ADH-3R qui ont pu être mis en évidence dans une famille obtenue par l’autofécondation d’un individu hétérozygote., Alcohol dehydrogenase (ADH, EC 1.1.1.1) was studied in peach using total protein extracts of leaves. Leaves were harvested from orchard grown trees in April and May, since, after this period, there was a large decrease in ADH activity. The enzymatic system of ADH is complex and involves 3 loci, ie ADH-1, ADH-2 and ADH-3. From these 3 loci, intraand intergenic dimeric enzymes are formed. The ADH-3 locus has 2 alleles, ADH-3L and ADH-3R. These were both identified within a family resulting from self-pollination of a heterozygous individual.

International audience

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; This is a large-scale molecular study based on simple sequence repeat (SSR) loci of the diversification process in chestnut cultivars from Portugal and Spain, from the northern Iberian Peninsula to the Canary Islands and the Azores. A total of 593 grafted chestnut trees (Castanea sativa Mill.) were analysed with 10 SSRs: 292 from Portugal and 301 from Spain. Some of the trees studied were more than 300 years old. Accessions were analysed using a model-based Bayesian procedure to assess the geographical structure and to assign individuals to reconstructed populations based on the SSR genotypes. We found 356 different genotypes with a mean value of clonality of 33% owing to grafting. Mutations accounted for 6%, with hybridization being the main diversification process that can explain the great diversity found. Ten main cultivar groups were detected: four in northern Spain, five in the centre of the Iberian Peninsula, and one in southern Spain related to the centre of the Iberian Peninsula. This work demonstrated that cultivar origin and the diversification process was a combination of clonal propagation of selected seedlings, hybridization, and mutations, which allowed high levels of diversity to be maintained with respect to selected clones for fruit production. Furthermore, seedlings and graft sticks facilitated the transport to new destinations in the colonization process, transporting sometimes more than 3000 km if we consider the Azores and the Canary Islands.; Les auteurs ont réalisé, à l’aide de marqueurs SSR, une étude moléculaire à grande échelle sur le processus de diversification des cultivars de châtaignier du Portugal et de l’Espagne, l’étude couvre une zone allant du nord de la Péninsule Ibérique jusqu’aux iles Canaries et aux Açores. Au total, 593 châtaigniers (Castanea sativa Mill.) greffés ont été analysés avec 10 SSR : 292 provenaient du Portugal et 301 de l’Espagne. Certains de ces arbres étaient vieux de plus de 300 ans. Une analyse basée sur un modèle bayésien a été réalisée pour déterminer la structure géographique des accessions et attribuer les individus au sein des différentes populations établies sur la base des génotypes SSR. Les auteurs ont trouvé 356 génotypes distincts dont en moyenne 33 % relèvent d’un état clonal attribuable au greffage. Les mutations permettent d’expliquer 6 % des génotypes observés alors que l’hybridation apparaît comme le principal processus de diversification et permettrait d’expliquer la grande diversité observée. Dix groupes principaux de cultivars ont été détectés, quatre dans le nord de l’Espagne, cinq autres au centre de la Péninsule Ibérique et un dans le sud de l’Espagne proche des groupes du centre. Ce travail montre que l’origine des cultivars et le processus de diversification sont le produit d’une combinaison de propagation clonale de plantules sélectionnées, d’hybridation et de mutations. Ces deux dernières permettent de maintenir une importante diversité au sein de clones sélectionnés pour la production de fruits. En outre, les plantules et les greffons ont facilité le transport vers de nouvelles destinations au cours du processus de colonisation, et ce parfois sur plus de 3000 km si l’on considère les Açores et les Îles Canaries.

National audience

National audience

International audience; The Rosodae supertribe is composed of economically important species (strawberry, rose and raspberry). In order to extend the repertoire of markers for optimizing genetic mapping and synteny within this supertribe, we developed 20 functional markers from two Fragaria cDNA libraries enriched in AG/AC microsatellite motifs. We tested their transferability within the Rosodae supertribe, including two reference diploid and octoploid strawberry segregating populations. Out of these 20 functional markers, 70% revealed polymorphism in both diploid and octoploid Fragaria segregating populations and were mapped on the diploid genetic map to provide useful information for further marker-assisted selection. These 20 EST-SSRs were also tested in 17 wild Fragaria species and displayed a high cross-species transferability (mean of 95%), providing new markers for further diversity studies within the genus. These markers were also transferable to the phylogenetically close Potentilla genus, whereas their transferability was lower for the polyploid Duchesnea indica species and for the more distant Rosa genus. Their use for genetic mapping within the Rosodae will further permit a comparison of genetic information among the different genera.

To identify genes involved in the expression of a trait using the candidate gene (CG) approach, the genome positions of the maximum number of genes which potentially cause the observed phenotypic variability needs to be known. This position is compared with that of major genes or quantitative trait loci (QTL) for this character, with the co-location of the CG and major gene or QTL indicating a possible cause and effect relationship. In the present study we selected 273 sequences from expressed sequence tag collections, corresponding to CGs from metabolic pathways affecting fruit growth and maturity, texture, sugar and organic acid content, aroma and color, and mapped them in the Prunus reference map (T × E) based on an interspecific almond × peach F2 population. We used the bin-mapping approach, where only eight plants, six of the T × E progeny plus one of the parents and the F1 hybrid, are used to determine the position of a marker. This strategy was very efficient, with 206 CGs mapped, based mainly on the segregation of one or more single-nucleotide polymorphisms. These CGs were located throughout the Prunus genome and are a resource for genetic analysis in stone fruit (peach, plum, apricot and cherry) and almond. Co-locations between CGs and major genes or QTL responsible for natural variability of fruit quality characters in Prunus were identified using the available information on their positions., This study was supported in part by the ISAFRUIT Integrated Project. The ISAFRUIT Project is funded by the European Commission under Thematic Priority 5 – Food Quality and Safety of the 6th Framework Programme of RTD (Contract No. FP6-FOOD-CT-2006-016279). Funding from the Zhejiang University group comes from the China Natural Science Foundation (30771496). The group of IRTA is a member of the CONSOLIDER Center for Basic Genomics and Agro-food Orientation (CSD2007-00036) funded by the Spanish Ministry of Science and Innovation.

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; Background Domestication and breeding involve the selection of particular phenotypes, limiting the genomic diversity of the population and creating a bottleneck. These effects can be precisely estimated when the location of domestication is established. Few analyses have focused on understanding the genetic consequences of domestication and breeding in fruit trees. In this study, we aimed to analyse genetic structure and changes in the diversity in sweet cherry Prunus avium L. Results Three subgroups were detected in sweet cherry, with one group of landraces genetically very close to the analysed wild cherry population. A limited number of SSR markers displayed deviations from the frequencies expected under neutrality. After the removal of these markers from the analysis, a very limited bottleneck was detected between wild cherries and sweet cherry landraces, with a much more pronounced bottleneck between sweet cherry landraces and modern sweet cherry varieties. The loss of diversity between wild cherries and sweet cherry landraces at the S-locus was more significant than that for microsatellites. Particularly high levels of differentiation were observed for some S-alleles. Conclusions Several domestication events may have happened in sweet cherry or/and intense gene flow from local wild cherry was probably maintained along the evolutionary history of the species. A marked bottleneck due to breeding was detected, with all markers, in the modern sweet cherry gene pool. The microsatellites did not detect the bottleneck due to domestication in the analysed sample. The vegetative propagation specific to some fruit trees may account for the differences in diversity observed at the S-locus. Our study provides insights into domestication events of cherry, however, requires confirmation on a larger sampling scheme for both sweet cherry landraces and wild cherry.

International audience

International audience; A new bacterial disease of Persian (English) walnut (Juglans regia) has been observed in France. This disease, called vertical oozing canker (VOC), is characterized by vertical cankers on trunks and branches of affected walnut trees with oozing exudates. To determine the aetiology of the disease, a study was carried out in 79 walnut orchards and nurseries located in southeastern and southwestern France. Bacterial analysis from diseased samples yielded 36 strains identified as Xanthomonas arboricola and 32 strains identified as Brenneria nigrifluens on the basis of biochemical tests. The causal agent of VOC was identified as X. arboricola by pathogenicity tests on walnut. Fluorescent amplified fragment length polymorphism (F-AFLP) was carried out on 36 strains of X. arboricola collected in this study, 24 strains of X. arboricola pv. juglandis isolated from walnut blight symptoms and one strain of X. arboricola pv. corylina included as an outgroup. Based on cluster analysis of F-AFLP data, most X. arboricola strains responsible for main VOC outbreaks showed a high degree of similarity, forming a cluster clearly separate from strains of X. arboricola pv. juglandis isolated from walnut blight symptoms. It is suggested that VOC is caused by a distinct genetic lineage within the pathovar juglandis of X. arboricola that is also able to cause classical bacterial blight symptoms on walnut leaves and fruits.

Aim: The Caucasus is considered as a possible primary centre of origin of grapevine. The aim of our research work was to study genetic diversity among cultivated Caucasian grape varieties and wild relatives originating from Near-Caspian areas of Azerbaijan on the basis of simple sequence repeat (SSR) markers.Methods and Results: Microsatellite allele data obtained in 31 local table grape varieties of Vitis vinifera L. ssp. sativa (Absheron region) and 34 wild varieties of Vitis vinifera L. ssp. sylvestris (Nabran, Davachi and Guba regions) were used to estimate population genetic parameters such as the polymorphism information content (PIC), the probability of identity (PI) and the frequency of null alleles (r). The genetic differences among the wild populations and between the wild and the cultivated gene pools were assessed using POPGENE, Arlequin and GENETIX programs. The selected fifteen microsatellite (SSR) markers revealed a high degree of polymorphism within and among the grape populations analyzed. The genetic similarity index ranged from 0.02 to 0.933.Conclusions: Among the selected markers, VVMD28 and VVMD36 displayed the highest diversity level regarding the expected heterozygosity and PIC (highest values) and PI (lowest values). In consequence, we postulate that these two markers are the most appropriate ones for the identification of grape accession and the determination of genetic diversity among cultivated and wild grape genotypes. Clustering analysis based on SSR markers data led to a good separation between cultivated and wild accessions and between wild accessions originating from different regions.Significance and impact of the study: The fifteen microsatellite markers used in this study were highly informative for the identification and analysis of genetic structure of Azerbaijan grapevine populations and clarified the relationships among grape accessions.

The goal of the present study was to identify candidate genes (CGs) involved in fruit quality in peach that can be transferred to other Rosaceae species. Two cDNA libraries from fruit of the “Fantasia” peach cultivar, constructed at two stages of development, were used to generate a set of expressed sequence tag sequences. A total of 1,730 peach unigenes were obtained after clustering. Sequences and corresponding annotations were stored in a relational database and are available through a web interface. Fifty-nine CGs involved in fruit growth and development or fruit quality at maturity, focusing on sweetness, acidity, and phenolic compound content, were selected according to their annotation. Fifty-five primer pairs, designed from peach CG sequences and giving PCR products in peach, were tested in strawberry and 36 gave amplified products. Eight CGs were mapped in peach, 14 in strawberry, four in both species and confirmed the pattern of synteny already proposed using comparative mapping. In peach, the CGs are located in three linkage groups (3, 5, 7), and in strawberry they are distributed in all seven Fragaria linkage groups. Colocalization between some of these CGs and quantitative trait loci for fruit quality traits were identified and are awaiting confirmation in further analyses., This research was partially funded by the European ISAFRUIT Integrated Project. The ISAFRUIT project is funded by the European Commission under the Thematic Priority 5—Food Quality and Safety of the 6th Framework Programme of RTD (contract number FP6-FOOD-CT-2006-016279). We thank Dr. Christophe Rothan for his involvement in the construction of the cDNA libraries and Christel Renaud for her participation in the preparation of EST clones for sequencing. The strawberry research was supported in part with funds from the Spanish Ministry of Science and Innovation project INIA (RTA2007-00063-00-00) and Euroberry COST Action 863. JB was supported by a fellowship from AGAUR.

The assembly of 20,000 sequencing reads obtained from shotgun and chromosome-specific libraries of the Spiroplasma citri genome yielded 77 chromosomal contigs totaling 1,674 kbp (92%) of the 1,820-kbp chromosome. The largest chromosomal contigs were positioned on the physical and genetic maps constructed from pulsed-field gel electrophoresis and Southern blot hybridizations. Thirty-eight contigs were annotated, resulting in 1,908 predicted coding sequences (CDS) representing an overall coding density of only 74%. Cellular processes, cell metabolism, and structural-element CDS account for 29% of the coding capacity, CDS of external origin such as viruses and mobile elements account for 24% of the coding capacity, and CDS of unknown function account for 47% of the coding capacity. Among these, 21% of the CDS group into 63 paralog families. The organization of these paralogs into conserved blocks suggests that they represent potential mobile units. Phage-related sequences were particularly abundant and include plectrovirus SpV1 and SVGII3 and lambda-like SpV2 sequences. Sixty-nine copies of transposases belonging to four insertion sequence (IS) families (IS 30 , IS 481 , IS 3 , and IS NCY ) were detected. Similarity analyses showed that 21% of chromosomal CDS were truncated compared to their bacterial orthologs. Transmembrane domains, including signal peptides, were predicted for 599 CDS, of which 58 were putative lipoproteins. S. citri has a Sec-dependent protein export pathway. Eighty-four CDS were assigned to transport, such as phosphoenolpyruvate phosphotransferase systems (PTS), the ATP binding cassette (ABC), and other transporters. Besides glycolytic and ATP synthesis pathways, it is noteworthy that S. citri possesses a nearly complete pathway for the biosynthesis of a terpenoid.

BackgroundAcidity is an essential component of the organoleptic quality of fleshy fruits. However, in these fruits, the physiological and molecular mechanisms that control fruit acidity remain unclear. In peach theDlocus controls fruit acidity; low-acidity is determined by the dominant allele. Using a peach progeny of 208 F2trees, theDlocus was mapped to the proximal end of linkage group 5 and co-localized with major QTLs involved in the control of fruit pH, titratable acidity and organic acid concentration and small QTLs for sugar concentration. To investigate the molecular basis of fruit acidity in peach we initiated the map-based cloning of theDlocus.ResultsIn order to generate a high-resolution linkage map in the vicinity of theDlocus, 1,024 AFLP primer combinations were screened using DNA of bulked acid and low-acid segregants. We also screened a segregating population of 1,718 individuals for chromosomal recombination events linked to theDlocus and identified 308 individuals with recombination events close toD. Using these recombinant individuals we delimited theDlocus to a genetic interval of 0.4 cM. We also constructed a peach BAC library of 52,000 clones with a mean insert size of 90 kb. The screening of the BAC library with markers tightly linked toDlocus indicated that 1 cM corresponds to 250 kb at the vicinity of theDlocus.ConclusionIn the present work we presented the first high-resolution genetic map ofDlocus in peach. We also constructed a peach BAC library of approximately 15× genome equivalent. This fine genetic and physical characterization of theDlocus is the first step towards the isolation of the gene(s) underlying fruit acidity in peach.

Macrosynteny and colinearity between Fragaria (strawberry) species showing extreme levels of ploidy have been studied through comparative genetic mapping between the octoploid cultivated strawberry (F. ×ananassa) and its diploid relatives. A comprehensive map of the octoploid strawberry, in which almost all linkage groups are ranged into the seven expected homoeologous groups was obtained, thus providing the first reference map for the octoploid Fragaria. High levels of conserved macrosynteny and colinearity were observed between homo(eo)logous linkage groups and between the octoploid homoeologous groups and their corresponding diploid linkage groups. These results reveal that the polyploidization events that took place along the evolution of the Fragaria genus and the more recent juxtaposition of two octoploid strawberry genomes in the cultivated strawberry did not trigger any major chromosomal rearrangements in genomes involved in F. ×ananassa. They further suggest the existence of a close relationship between the diploid Fragaria genomes. In addition, despite the possible existence of residual levels of polysomic segregation suggested by the observation of large linkage groups in coupling phase only, the prevalence of linkage groups in coupling/repulsion phase clearly demonstrates that the meiotic behavior is mainly disomic in the cultivated strawberry., This work was supported by grants from the Région Aquitaine and the European Community (Fonds Européen de Développement Régional, FEDER funds).

International audience; This investigation was aimed at understanding the morphological variation and reproductive biology of wild populations of giant tar (Alocasia macrorrhizos) in Vanuatu. It is an aroid species, which grows in vigorous, relatively small and dense populations, consisting of phenotypically uniform or very similar individuals. The most variable traits observed in wild populations are number of inflorescences, number of infructescences per plant, and corm length. These traits are highly variable even within genetically uniform populations and are highly influenced by age differences between plants. Flowering is frequent and most of the plants are highly fertile. However, sexual reproduction is rare due to self-incompatibility (between plants genetically homogeneous within the same population) and the absence of efficient pollinators. Self-incompatibility can be partly overcome by repeated self-pollination. Thermogenesis was studied on a large sample of inflorescences and little variation concerning the thermogenic potential was observed. Our results showed that, despite optimal flowering conditions (concerning pollen fertility, stigma receptivity, and thermogenic potential), propagation of wild Alocasia macrorrhizos populations in Vanuatu was mainly vegetative. Giant taro plants might have been carried beyond the range of their most effective pollinators. Other factors were considered: the presence of numerous earwigs (Labidura truncata) insects within inflorescences, which could have a competing effect with the usual pollinators of giant taro, and the long distances between genetically homogeneous populations.

Genetic diversity was described in 17 cedar populations covering the geographical range of the four species of the genus Cedrus. The study was conducted using amplified fragment length polymorphism (AFLP) on haploid tissues (megagametophytes). Eleven selective AFLP primer pairs generated a total of 107 polymorphic amplification products. Correspondence and genetic distance analyses indicated that Cedrus deodara constitutes a separate gene pool from the Mediterranean cedars. Within Mediterranean cedars, we distinguished two groups: the first one is made of Cedrus atlantica, while the second one is made of Cedrus libani and Cedrus brevifolia, these latter two species being genetically similar despite important divergence previously observed for morphological and physiological traits. The lowest intrapopulation variability was found in the two C. deodara populations analyzed. Surprisingly, C. brevifolia, the endemic taxon from the island of Cyprus that is found in small and fragmented populations, showed one of the highest levels of diversity. This unexpected pattern of diversity and differentiation observed for C. brevifolia suggests a recent divergence rather than a relictual, declining population. Patterns of diversity within- and among-populations were used to test divergence and fragmentation hypotheses and to draw conclusions for the conservation of Cedrus gene pools.

Both environmental and evolutionary factors determine the distribution of the genetic diversity among and within natural populations of forest tree species, resulting in genetically structured metapopulations. The existence of such distribution has major implications for resource conservation policies, as the shape and extent of in situ natural networks and the composition of ex situ collections of valuable forest tree species. A major and realistic issue we face is how to effectively sample natural variation both for optimal structure mirroring and for maximal genetic diversity capturing when designing in situ population networks and ex situ collections. Genetic differentiation descriptors like Fst and Qst represent the utmost visible consequences of underlying landscape and evolution factors acting on the metapopulation genetic diversity. The first question we address here is how to sample populations, individuals and marker loci knowing the neutral and selected genetic structure of a theoretically built metapopulation. Results of a Monte-Carlo allele-based simulation model are presented, where the sample of populations, individuals and marker loci was simultaneously modelled over ranges of Fst and Qst. Each sample strategy was not only evaluated in terms of genetic diversity potential yield relative to total diversity at the metapopulation level, but also in terms of bias and precision rendering in the estimation of Fst and Qst from the actual sample. Thus the ability of the sample to render both the diversity and its distribution over the populations was analyzed. The second question we address is whether present ex situ collections of two disseminated forest tree species, black poplar and wild cherry, represent a good sampling of natural populations. For that purpose, natural populations and ex situ collections were characterised with neutral markers and phenotypic characters. The simulations then serve to infer the degree of representativeness of existing ex situ collections for the two species based on the actual sample sizes and several differentiation estimates of Fst and Qst, and eventually guide the enrichment of conservation resources for these two species., La diversité génétique d’une espèce se distribue entre populations et à l’intérieur des populations. Sa prise en compte à ces deux niveaux a une importance majeure pour la mise en place de modes de gestion conservatoires in situ et ex situ. La question principale qui se pose est : quel échantillonnage de la diversité faire, en terme de populations, d’individus et de gènes ? Nous abordons ici cette question, d’un point de vue théorique à travers le éveloppement d’un modèle Monte-Carlo, puis d’un point de vue expérimental sur deux espèces forestières, le merisier et le peuplier noir, à travers une comparaison de la diversité présente en populations naturelles et en collection ex situ. Les deux approches sont ensuite mises en regard l’une de l’autre afin de donner des éléments sur les stratégies d’échantillonnage optimales de la diversité de ces deux espèces.

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.

International audience; 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.

The concept of selective (or bin) mapping is used here for the first time, using as an example the Prunus reference map constructed with an almond × peach F2 population. On the basis of this map, a set of six plants that jointly defined 65 possible different genotypes for the codominant markers mapped on it was selected. Sixty-three of these joint genotypes corresponded to a single chromosomal region (a bin) of the Prunus genome, and the two remaining corresponded to two bins each. The 67 bins defined by these six plants had a 7.8-cM average length and a maximum individual length of 24.7 cM. Using a unit of analysis composed of these six plants, their F1 hybrid parent, and one of the parents of the hybrid, we mapped 264 microsatellite (or simple-sequence repeat, SSR) markers from 401 different microsatellite primer pairs. Bin mapping proved to be a fast and economic strategy that could be used for further map saturation, the addition of valuable markers (such as those based on microsatellites or ESTs), and giving a wider scope to, and a more efficient use of, reference mapping populations., Funds for this research have been partly provided by projects FIT-010000-2001-112 and AGL2003-04691 of the Spanish Ministry of Science and Technology.

Water stress affecting long-lived trees is an important challenge in forestry. Due to global climate change, forest trees will be threatened by extreme conditions like flooding or drought. It is necessary to understand differences in stress tolerance within certain species and to investigate putative relations on genomic level. In this study, osmotic stress induced genes of Quercus ssp. were positioned on two genetic linkage maps of oak. An intra-specific cross 3P*A4 of Quercus robur consisting of 88 offspring and an inter-specific cross 11P*QS29 of Q. robur and Q. petraea comprising 72 full-sibs were analyzed for the inheritance of 14 loci represented by 34 individual single nucleotide polymorphisms. Seven genes in the intra-cross, as well as other six genes in the inter-cross could be mapped and one gene could not be localised due to the severe distortion of the segregation. The collection of expressed sequences involved ribosomal proteins, members of the oxylase/oxygenase gene family, betaine aldehyde dehydrogenase, Dc3 promoter-binding factor, a putative member of the nodulin family, glutathione-S-transferase and proteins with unknown functions. In the inter-cross, two linked markers exhibited 89% deficiency of heterozygosity. Thirteen genes were positioned on ten different oak chromosomes and can serve as orthologous markers in comparative mapping studies within Fagaceae.

International audience

International audience

International audience

International audience

International audience; Simple sequence repeat (SSR) markers from Quercus and Castanea were used for comparative mapping between Quercus robur (L.) and Castanea sativa (Mill.). We tested the transferability of SSRs developed in Quercus to Castanea and vice-versa. In total, 47% (25) of the Quercus SSRs and 63% (19) of the Castanea SSRs showed a strong amplification product in the non-source species. From these 44 putative comparative anchor tags, 19 (15 from Quercus and 4 from Castanea) were integrated in two previously established genetic linkage maps for the two genera. SSR loci were sequenced to confirm the orthology of the markers. The combined information from both genetic mapping and sequence analysis were used to determine the homeology between seven linkage groups, aligned on the basis of pairs or triplets of common markers, while two additional groups were matched using a single microsatellite marker. Orthologous loci identified between Q. robur and C. sativa will be useful as anchor loci for comparative mapping studies within the Fagaceae family