Combining genetic resources and elite material populations to improve the accuracy of genomic prediction in apple

Genomic selection is an attractive strategy for apple breeding that could reduce the length of breeding cycles. A possible limitation to the practical implementation of this approach lies in the creation of a training set large and diverse enough to ensure accurate predictions. In this study, we investigated the potential of combining two available populations, i.e., genetic resources and elite material, in order to obtain a large training set with a high genetic diversity. We compared the predictive ability of genomic predictions within-population, across-population or when combining both populations, and tested a model accounting for population-specific marker effects in this last case. The obtained predictive abilities were moderate to high according to the studied trait and small increases in predictive ability could be obtained for some traits when the two populations were combined into a unique training set. We also investigated the potential of such a training set to predict hybrids resulting from crosses between the two populations, with a focus on the method to design the training set and the best proportion of each population to optimize predictions. The measured predictive abilities were very similar for all the proportions, except for the extreme cases where only one of the two populations was used in the training set, in which case predictive abilities could be lower than when using both populations. Using an optimization algorithm to choose the genotypes in the training set also led to higher predictive abilities than when the genotypes were chosen at random. Our results provide guidelines to initiate breeding programs that use genomic selection when the implementation of the training set is a limitation

Johannes Tauler. Djup ropar till djup

Swedish translation (by B. Stolt) of select sermons by John Tauler (c. 1300-1361). A selection was made from among the authentic texts in Middle German

Interaction famille x site dans un test tristationnel de descendances de douglas (Pseudotsuga menziesii Mirb.) Franco

Cet article analyse l’interaction génotype x environnement dans un groupe de 63 descendances maternelles issues de provenances françaises de Douglas. Sur trois sites expérimentaux très contrastés, six caractères différents de hauteur, phénologie et forme sont étudiés. Après analyse de variance, les écovalences de Wricke (1962) et leurs inverses, appelées interactivités, sont calculées pour les sites et les familles sur les quatre caractères présentant une forte interaction. Une étude de ces interactivités est réalisée : distribution, corrélations entre elles, corrélations avec les performances familiales. L’évolution du F d’interaction pour la hauteur totale est observée au cours de l’élimination des familles par ordre d’interactivités décroissantes. Pour ce caractère, un tiers des familles sont responsables des trois quarts de l’interactivité globale. Un groupe de familles stables dans l’espace est ainsi identifié. Il apparaît que la moyenne et les variances de ce caractère restent stables lorsque le nombre de familles diminue. Une démarche similaire est tentée avec une interactivité synthétique multicaractères. L’utilité des interactivités pour l’améliorateur est enfin brièvement discutée.The results given in this paper come from a multi-site provenance-progeny test with artificial french origins of Douglas-Fir (63 open-pollinated progenies). The ecological features of the three field trials are very different (fig. 1), each being however considered > for this species. Six traits are taken into account, most of them assessed at age 7 in the field, i.e. 10 years after the seed : total height, flushing, stem sinuosity, branch angle, forking, lamma shoot frequency (fig. 2). The aim is to reveal family x site interaction and to find a practical way of selecting stable-inspace progenies.Analysis of variance is performed at within and between-sites levels (models 1, 2, 3). Between sites, the contribution of each site and family to the overall interaction sum of squares is evaluated through its relative interactivity defined as the inverse of Wricke’s ecovalence (1962) (models 4 and 5). A synthetic interactivity is proposed to evaluate family stability for some traits simultaneously (model 6) when single-trait interactivities are independant

Host and non-host interaction of Venturia inaequalis and Venturia pirina on Pyrus communis and Malus x domestica

National audienc

Pyrus communis and Malus X domestica behaviour to Venturia inaequalis and Venturia pirina inoculation

Pyrus communis and Malus x domestica inoculated respectively with Venturia pirina and Venturia inaequalis give susceptible or resistance symptoms with large similarities. We addressed the question whether the two species of Venturia could exhibit reciprocal relationships with Pyrus communis and Malus x domestica. Trees of the apple cultivars: ‘Gala’ (susceptible to V. inaequalis) and ‘Discovery’ (polygenic resistant) and the pear cultivars: ‘Pierre Corneille’ (susceptible to V. pirina) and ‘Navarra’ (polygenic resistant) were inoculated in the glasshouse with very aggressive monoconidial strains of V. inaequalis (EU-B04) and V. pirina (Pca). Three days after inoculation, conidia germination, germ tube formation and appressoria differentiation were observed in all combinations. There were no clear differences in the percentage of germinated conidia and the appressoria index between host and non-host interaction. Six days after inoculation, a dense subcuticular network of stromatic strands was observed in the susceptible interaction. The resistant hosts were characterized by a reduced primary stroma and the epidermal cells were modified. In the case of the non-host relationships, much reduced primary stroma with few conidia were observed on the susceptible (to the compatible Venturia species) host only. The leaf reaction was limited to a very small number of cells. Fourteen days after inoculation, macroscopic symptoms of sporulation appeared on the susceptible cultivars. In non-host relationships, no additional modification of the microscopic aspects was observed. In conclusion, in this experiment, non-host interactions with V. inaequalis and V. pirina were observed but were reduced to very limited microscopic aspects

Combining genetic resources and elite material populations to improve the accuracy of genomic prediction in apple

International audienceAbstract Genomic selection is an attractive strategy for apple breeding that could reduce the length of breeding cycles. A possible limitation to the practical implementation of this approach lies in the creation of a training set large and diverse enough to ensure accurate predictions. In this study, we investigated the potential of combining two available populations, i.e. genetic resources and elite material, in order to obtain a large training set with a high genetic diversity. We compared the predictive ability of genomic predictions within-population, across-population or when combining both populations, and tested a model accounting for population-specific marker effects in this last case. The obtained predictive abilities were moderate to high according to the studied trait and small increases in predictive ability could be obtained for some traits when the two populations were combined into a unique training set. We also investigated the potential of such a training set to predict hybrids resulting from crosses between the two populations, with a focus on the method to design the training set and the best proportion of each population to optimize predictions. The measured predictive abilities were very similar for all the proportions, except for the extreme cases where only one of the two populations was used in the training set, in which case predictive abilities could be lower than when using both populations. Using an optimization algorithm to choose the genotypes in the training set also led to higher predictive abilities than when the genotypes were chosen at random. Our results provide guidelines to initiate breeding programs that use genomic selection when the implementation of the training set is a limitation

Strength of Neisseria meningitidis binding to endothelial cells requires highly-ordered CD147/β2-adrenoceptor clusters assembled by alpha-actinin-4

International audienceNeisseria meningitidis (meningococcus) is an invasive bacterial pathogen that colonizes human vessels, causing thrombotic lesions and meningitis. Establishment of tight interactions with endothelial cells is crucial for meningococci to resist haemodynamic forces. Two endothelial receptors, CD147 and the β2-adrenergic receptor (β2AR), are sequentially engaged by meningococci to adhere and promote signalling events leading to vascular colonization, but their spatiotemporal coordination is unknown. Here we report that CD147 and β2AR form constitutive hetero-oligomeric complexes. The scaffolding protein α-actinin-4 directly binds to the cytosolic tail of CD147 and governs the assembly of CD147–β2AR complexes in highly ordered clusters at bacterial adhesion sites. This multimolecular assembly process increases the binding strength of meningococci to endothelial cells under shear stress, and creates molecular platforms for the elongation of membrane protrusions surrounding adherent bacteria. Thus, the specific organization of cellular receptors has major impacts on host–pathogen interaction