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International audience; The presence of heterospecific neighbours can affect the amount of damage caused by insect pests to focal plants. However, how plant neighbours influence herbivore performance is poorly understood, in particular when they are closely related. We tested the independent and interactive effects of tree species identity and tree neighbour type (conspecific vs. heterospecific) on the performance of a major oak pest, the oak processionary moth larvae (OPM, Thaumetopoea processionea L.) fed on Quercus robur L. and Q. petraea Liebl. We performed a factorial greenhouse experiment in which we grew two oak saplings per pot, either from the same species or from both species. We quantified growth and mortality of OPM larvae, leaf phenolic compounds, C:N ratio and bud phenology. OPM larvae performed significantly better on Q. petraea than on Q. robur, regardless of plant neighbour type. Phenolic compounds and C:N, but not phenology, differed between oak species and neighbour species identity. Only bud phenology had a significant effect on OPM performance, which was better when young larvae had access to recently unfolded leaves, regardless of oak species and neighbour identity. Although oak neighbour identity altered the expression of leaf traits, this effect had no measurable consequences on OPM performance. Our results showed that OPM performed better when feeding on Q. petraea than on Q. robur. We also found that oak neighbours altered the expression of leaf traits associated with defence, but that this effect did not cascade onto OPM performance. These findings should be replicated in the field in order to improve forest management strategies against OPM attacks.

International audience; Premise : Abiotic factors and plant species traits have been shown to drive latitudinal gradients in herbivory, and yet, population‐level factors have been largely overlooked within this context. One such factor is plant density, which may influence the strength of herbivory and may vary with latitude.Methods : We measured insect herbivory and conspecific plant density (CPD) of oak (Quercus robur) seedlings and saplings along a 17° latitudinal gradient (2700 km) to test whether herbivory exhibited a latitudinal gradient, whether herbivory was associated with CPD, and whether such an association changed with latitude.Results : We found a positive but saturating association between latitude and leaf herbivory. Furthermore, we found no significant relationship between CPD and herbivory, and such lack of density effects remained consistent throughout the sampled latitudinal gradient.Conclusions : Despite the apparently negligible influence of plant density on herbivory for Q. robur, further research with other plant taxa and in different types of plant communities are needed to investigate density‐dependent processes shaping geographical variation in plant–herbivore interactions.

AIM: The strength of species interactions is traditionally expected to increase toward the Equator. However, recent studies have reported opposite or inconsistent latitudinal trends in the bottom-up (plant quality) and top-down (natural enemies) forces driving herbivory. In addition, these forces have rarely been studied together thus limiting previous attempts to understand the effect of large-scale climatic gradients on herbivory. LOCATION: Europe. TIME PERIOD: 2018–2019. MAJOR TAXA STUDIED: Quercus robur. METHODS: We simultaneously tested for latitudinal variation in plant–herbivore–natural enemy interactions. We further investigated the underlying climatic factors associated with variation in herbivory, leaf chemistry and attack rates in Quercus robur across its complete latitudinal range in Europe. We quantified insect leaf damage and the incidence of specialist herbivores as well as leaf chemistry and bird attack rates on dummy caterpillars on 261 oak trees. RESULTS: Climatic factors rather than latitude per se were the best predictors of the large-scale (geographical) variation in the incidence of gall-inducers and leaf-miners as well as in leaf nutritional content. However, leaf damage, plant chemical defences (leaf phenolics) and bird attack rates were not influenced by climatic factors or latitude. The incidence of leaf-miners increased with increasing concentrations of hydrolysable tannins, whereas the incidence of gall-inducers increased with increasing leaf soluble sugar concentration and decreased with increasing leaf C : N ratios and lignins. However, leaf traits and bird attack rates did not vary with leaf damage. MAIN CONCLUSIONS: These findings help to refine our understanding of the bottom-up and top-down mechanisms driving geographical variation in plant–herbivore interactions, and indicate the need for further examination of the drivers of herbivory on trees. This study was carried out with financial support from the French National Research Agency (ANR) in the frame of the Investments for the Future Programme, within the Cluster of Excellence COTE (Continental To coastal Ecosystems: evolution, adaptability and governance) (ANR-10-LABX-45). E.V.C. was funded by the BiodivERsA (BiodivERsA is a network of national and regional funding organisations promoting pan-European research on biodiversity and ecosystem services, and offering innovative opportunities for the conservation and sustainable management of biodiversity) project SPONFOREST (Unraveling the potential of spontaneous forest establishment for improving ecosystem functions and services in dynamic landscapes) (BiodivERsA3-2015-58). info:eu-repo/semantics/publishedVersion

International audience; Ecological research conducted over the past five decades has shown that increasing tree species richness at forest stands can improve tree resistance to insect pest damage. However, the commonality of this finding is still under debate. In this review, we provide a quantitative assessment (i.e., a meta-analysis) of tree diversity effects on insect herbivory and discuss plausible mechanisms underlying the observed patterns. We provide recommendations and working hypotheses that can serve to lay the groundwork for research to come. Based on more than 600 study cases, our quantitative review indicates that insect herbivory was, on average, lower in mixed forest stands than in pure stands, but these diversity effects were contingent on herbivore diet breadth and tree species composition. In particular, tree species diversity mainly reduced damage of specialist insect herbivores in mixed stands with phylogenetically distant tree species. Overall, our findings provide essential guidance for forest pest management.

International audience; Simon de Rojas Clemente y Rubio (1777 to 1827) is considered the father of modern ampelography. He developed the first scientific method for describing grapevine varieties through the examination of material he collected in Andalusia between 1802 and 1804. The Royal Botanical Garden in Madrid conserves the material he collected and preserved (leaves and shoots). This herbarium, the oldest of all grapevine variety herbaria, is invaluable for ampelographic and other studies (such as genetic diversity, molecular characterization, or viticultural history studies) and provides unique insight into early 19th century (the pre-phylloxera era) grapevine cultivation. The present work reports a DNA extraction protocol and a redefining of the simple sequence repeat primers routinely used in grapevine characterization, which allowed successful amplification of the ancient DNA extracted from Clemente's herborized material.

Chapitre 3; International audience; Legume-based mixtures have considerable interest for modern agriculture, because they can increase or stabilize crop production and simultaneously provide important agro-ecosystem functions. Accordingly, there is increasing demand for legume cultivars adapted to this utilization. This paper reviews the available findings and discuss methodological, eco-physiological and diversity-related issues that can help define cost-efficient breeding strategies for cool- and warm-season annual legumes intercropped with cereals, and perennial legumes intercropped with forage grasses. On average, selection in pure stand (PS) exhibited about 40% lower predicted yield gains than selection in target mixed stand (MS) conditions, in a survey of case studies. Specific breeding for intercropping tends to be particularly important for species undergoing severe competition because of modest competitive ability or the targeted growing conditions, for which direct selection in MS or indirect selection for traits associated with greater competitive ability prove valuable. Breeding for compatibility with a wide range of plant companions is encouraged by the larger size of general-compatibility effects relative to specific-compatibility ones. There is fairly limited evidence for the advantage of greater intraspecific diversity in legume breeding for intercropping. On the whole, however, the available findings are insufficient for designing efficient breeding strategies for the majority of legume species. We present a range of informative and cost-efficient methodological approaches that could be exploited for future studies. There is an urgent need to assess the efficiency of novel and relatively low-cost breeding strategies, among which evolutionary breeding and genomic selection emerge as the most promising.

International audience; 1- How much a plant is attacked by insect herbivores likely depends on its apparency and ability to produce defensive traits, which may be modified by neighbouring plants and abiotic conditions. Yet, how much the direct and trait‐mediated effects of neighbours on herbivory is modified by abiotic factors is still unknown. 2- By using a tree diversity experiment in SW France, we measured leaf insect herbivory (chewers and miners), nutritional quality (water content, C/N ratio, sugar and starch content) and chemical defences (total polyphenolics and condensed tannins) on birch (Betula pendula) trees growing in monocultures and mixtures with oak, pine or both species. We alleviated water stress by irrigating trees in half of the plots while trees remained unwatered (i.e. drought‐stressed) in the other half. 3- Overall, insect herbivory was higher among heterospecific neighbours, which corresponds to associational susceptibility. Consistent with this finding, leaves had lower amount of anti‐herbivore defences among heterospecific neighbours. In turn, insects caused more damage in drought‐stressed conditions, but such effect was independent of leaf chemistry. We also found that the effect of tree species diversity on herbivory was contingent of drought conditions as associational susceptibility only occurred in drought‐stressed trees. The independent and interactive effects of neighbour diversity and irrigation on leaf herbivory remained significant after accounting for birch apparency and leaf chemistry, suggesting that unmeasured plant traits or some other mechanisms not associated with plant trait variation and apparency might be involved in the observed herbivory patterns. 4- Synthesis. By demonstrating that associational effects are contingent upon abiotic constraints, we bring new insights into our understanding of the mechanisms driving diversity—resistance relationships across climatic gradients.

11 páginas, 4 figuras y 1 tabla, Both plant neighbourhood composition and drought have well-known independent effects on insect herbivore performance, but their interactive effects remain elusive. In this study we performed a laboratory experiment to investigate the independent and combined effects of plant neighbourhood composition and drought on the performance of Gypsy moth larvae (Lymantria dispar) feeding on silver birch (Betula pendula) leaves. For this, we collected leaf samples from birch trees growing in a field experiment where we manipulated both host-tree species diversity (three levels: birch monocultures, two-species mixtures associating birch with the pedunculate oak Quercus robur or maritime pine Pinus pinaster, and three-species mixture with pedunculate oak, the maritime pine and birch) and water availability (two levels: irrigated vs. non-irrigated). In most cases, plant neighbourhood composition and irrigation treatments independently and interactively affected herbivore performance traits, especially those related to growth and food (i.e. birch leaves) processing. By addressing the interactive effects of tree species diversity and drought on insect herbivory from the herbivore’s point of view, our study builds toward a better understanding of the multiple ecological drivers of plant-insect interactions., Te research in ORPHEE was funded by the GIP-ECOFOR program from the French Ministry of Ecology, under the project BIOPICC ECOFOR-2014-15. We thank Angelina Ceballos Escalera, Inge van Halder, Martine MartinClotté and Fabrice Vétillard for their help in the feld and laboratory tasks, and Maurane Buradino from INRA UE0348 for providing Gypsy moth egg masses. Te ORPHEE experiment is managed by INRA Experimental Unit Forêt-Pierroton, and in particular by Bernard Issenhuth. XM was supported by a grant from the Regional Government of Galicia (IN607D 2016/001), a Spanish National Research Grant (AGL2015-70748-R) and the Ramón y Cajal Research Programme (RYC-2013-13230). Collaboration between BC and XM was supported by a grant from the iLINK+ CSIC Program (I-LINK 1221).

Resumen del póster presentado en el Congreso celebrado en Saint-Malo, Francia, entre el 22 y el 25 de marzo de 2018., Comparing and identifying interesting sources of genetic diversity that have been maintained by different genebanks and understanding the global organization of this genetic diversity is an important issue for pre-breeding. We aimed at evaluating how genotyping-by-sequencing (GBS) technologies can address these both issues. We used GBS to compare the genetic diversity of 1191 European Flint lines maintained by INRA and other European institutes (see Gouesnard et al., this meeting) with the USDA collection (Romay et al., 2013, Genome Biology). We first examined the similarity of 68 inbred lines with a same variety name between the two collections, and observed that IBS ranged from 0.775 to 0.997 (with a mean of 0.941). It indicated that GBS can be used for comparing collections and identifying redundancy and illegitimate accessions between genebanks. Based on principal coordinate analysis and structure analysis on 4001 lines, we showed the distinctiveness of flint materials compared to the USDA collection. The structuration analysis in 12 groups confirmed the influence of some historical founder lines in the genetic organization of the dent group (B73, A632, Oh43, Mo17, W182E, PH207 and Wf9). Flint lines were structured in 3 groups (a Sweet-Northern Flint group, an Italian-Argentinan group and a European group formed by Pyrenees Galicia and Lacaune groups). The Tropical and Pop corn groups were distinct. We identified several selective sweeps between Dent, Flint and Tropical inbred lines that co-localized with SNPs associated with flowering time variation identified by association mapping. It suggests that these genomic regions played an important role in adaptation to higher lattitude. The joint analysis of collections by GBS offers opportunities for a global diversity analysis of maize inbred lines., French National Research Agency (Amaizing, ANR-10-BTBR-03)

10 Pags.- 3 Tabls.- 3 Figs.- 5 Suppl. Tabls., Background: Breeding for cold tolerance in maize promises to allow increasing growth area and production in temperate zones. The objective of this research was to conduct genome-wide association analyses (GWAS) in temperate maize inbred lines and to find strategies for pyramiding genes for cold tolerance. Two panels of 306 dent and 292 European flint maize inbred lines were evaluated per se and in testcrosses under cold and control conditions in a growth chamber. We recorded indirect measures for cold tolerance as the traits number of days from sowing to emergence, relative leaf chlorophyll content or quantum efficiency of photosystem II. Association mapping for identifying genes associated to cold tolerance in both panels was based on genotyping with 49,585 genome-wide single nucleotide polymorphism (SNP) markers. Results: We found 275 significant associations, most of them in the inbreds evaluated per se, in the flint panel, and under control conditions. A few candidate genes coincided between the current research and previous reports. A total of 47 flint inbreds harbored the favorable alleles for six significant quantitative trait loci (QTL) detected for inbreds per se evaluated under cold conditions, four of them had also the favorable alleles for the main QTL detected from the testcrosses. Only four dent inbreds (EZ47, F924, NK807 and PHJ40) harbored the favorable alleles for three main QTL detected from the evaluation of the dent inbreds per se under cold conditions. There were more QTL in the flint panel and most of the QTL were associated with days to emergence and ΦPSII. Conclusions: These results open new possibilities to genetically improve cold tolerance either with genome-wide selection or with marker assisted selection., This research was supported in the framework of the Plant-KBBE program (project acronym “Cornfed”) by the Spanish Ministry of Science and Innovation (proj. EUI2008-03642 and EUI2008-03635), the Spanish Plan for Research and Development (AGL2013-48852-C3-1-R), the French National Agency for Research (ANR, Ministry of High Education and Research), and the German Federal Ministry of Education and Research (grant number 0315461A-D).

Genomic selection refers to the use of genotypic information for predicting breeding values of selection candidates. A prediction formula is calibrated with the genotypes and phenotypes of reference individuals constituting the calibration set. The size and the composition of this set are essential parameters affecting the prediction reliabilities. The objective of this study was to maximize reliabilities by optimizing the calibration set. Different criteria based on the diversity or on the prediction error variance (PEV) derived from the realized additive relationship matrix–best linear unbiased predictions model (RA–BLUP) were used to select the reference individuals. For the latter, we considered the mean of the PEV of the contrasts between each selection candidate and the mean of the population (PEVmean) and the mean of the expected reliabilities of the same contrasts (CDmean). These criteria were tested with phenotypic data collected on two diversity panels of maize (Zea mays L.) genotyped with a 50k SNPs array. In the two panels, samples chosen based on CDmean gave higher reliabilities than random samples for various calibration set sizes. CDmean also appeared superior to PEVmean, which can be explained by the fact that it takes into account the reduction of variance due to the relatedness between individuals. Selected samples were close to optimality for a wide range of trait heritabilities, which suggests that the strategy presented here can efficiently sample subsets in panels of inbred lines. A script to optimize reference samples based on CDmean is available on request., This research was jointly supported as “Cornfed project” by the French National Agency for Research (ANR), the German Federal Ministry of Education and Research (BMBF), and the Spanish Ministry of Science and Innovation (MICINN). R. Rincent is jointly funded by Limagrain, Biogemma, Kleinwanzlebener Saatzucht AG (KWS), and the Association Nationale de la Recherche et de la Technologie (ANRT)., ANR, BMBF, MICINN, KWS, ANRT

6 páginas y 4 figuras., Increasing water scarcity challenges crop sustainability in many regions. As a consequence, the enhancement of transpiration efficiency (TE)—that is, the biomass produced per unit of water transpired—has become crucial in breeding programs. This could be achieved by reducing plant transpiration through a better closure of the stomatal pores at the leaf surface. However, this strategy generally also lowers growth, as stomatal opening is necessary for the capture of atmospheric CO2 that feeds daytime photosynthesis. Here, we considered the reduction in transpiration rate at night (En) as a possible strategy to limit water use without altering growth. For this purpose, we carried out a genetic analysis for En and TE in grapevine, a major crop in drought-prone areas. Using recently developed phenotyping facilities, potted plants of a cross between Syrah and Grenache cultivars were screened for 2 y under well-watered and moderate soil water deficit scenarios. High genetic variability was found for En under both scenarios and was primarily associated with residual diffusion through the stomata. Five quantitative trait loci (QTLs) were detected that underlay genetic variability in En. Interestingly, four of them colocalized with QTLs for TE. Moreover, genotypes with favorable alleles on these common QTLs exhibited reduced En without altered growth. These results demonstrate the interest of breeding grapevine for lower water loss at night and pave the way to breeding other crops with this underexploited trait for higher TE., This work was supported by funding from the project Long Term Impacts and Adaptations to Climate Change in Viticulture and Oenology (LACCAVE) of the French National Institute for Agricultural Research (INRA) and by Grant ANR-09-GENM-024-002 from the French National Research Agency. A.C.-L. received a PhD grant from the French government.

The symbiotic nitrogen fixation (SNF) with legumes is the primary source of biologically fixed nitrogen for agricultural system. It is performed by a group of bacteria commonly called rhizobia. It is characterized by a host preference, and the differences among symbioses between rhizobial strains and legume genotypes are related to infection, nodule development and effectiveness in N2 fixation. The interaction between a rhizobia and the legume is mediated by a lipochitin oligosaccharide secreted by the rhizobia, and called “Nod factor”. It is recognized by transmembrane receptors on the root-hair cells of the legume. It can regulate the nodule organogenesis by inducing changes in the cytokinin balance of the root, during nodule initiation. N2 fixation in legume nodules is catalyzed by the nitrogenase enzyme depending upon the photosynthate supply, the O2 concentration, and the fixed-N export. Among environmental factors that influence the SNF, the temperature is essential for nodule formation; the salinity and drought decrease the nodule permeability to O2 and the photosynthate supply to the nodule, the phosphorus deficiency inhibits the nodule development and the total N2 fixation. Rhizobia strains differ in their efficiency in N2 fixation with host legume. There is evidence of genotypic variability for SNF at different levels of available P which show a possibility of selecting cultivars able to support biological N2 fixation under low P soils.

Association mapping has permitted the discovery of major QTL in many species. It can be applied to existing populations and, as a consequence, it is generally necessary to take into account structure and relatedness among individuals in the statistical model to control false positives. We analytically studied power in association studies by computing noncentrality parameter of the tests and its relationship with parameters characterizing diversity (genetic differentiation between groups and allele frequencies) and kinship between individuals. Investigation of three different maize diversity panels genotyped with the 50k SNPs array highlighted contrasted average power among panels and revealed gaps of power of classical mixed models in regions with high linkage disequilibrium (LD). These gaps could be related to the fact that markers are used for both testing association and estimating relatedness. We thus considered two alternative approaches to estimating the kinship matrix to recover power in regions of high LD. In the first one, we estimated the kinship with all the markers that are not located on the same chromosome than the tested SNP. In the second one, correlation between markers was taken into account to weight the contribution of each marker to the kinship. Simulations revealed that these two approaches were efficient to control false positives and were more powerful than classical models.

In this study, 10 clones of Vitis vinifera Cabernet franc (not yet commercial) have been phenotyped on precocity, grape composition, and assessment of wine quality made by microvinification in 2008-2010. Additionally, two original criteria have been considered: concentration of 3-isobutyl-2- methoxypyrazine (IBMP) in grapes and wines (the green bell pepper flavor) and resistance of grapevines to downy mildew (Plasmopara viticola) by stilbene quantification upon infection. Precocity of veraison varied up to four days at veraison. Berry size and yield were highly variable among clones. However, these variables were not correlated. Tanins and anthocyanins varied among clones in grapes and wines. Variations in grape and wine IBMP were not significant. Some clones showed lower susceptibility for downy mildew on leaves. Lower susceptibility was linked to a higher production of stilbenic phytoalexins involved in downy mildew resistance mechanisms.

Early vigor, earliness and cold tolerance are the main potential contributions of European maize (Zea mays L.) for breeding programs for adaptation to areas with short growing seasons and cold springs. The objective of this research was to determine the potential contributions of populations from different European regions to breeding for adaptation. Six Spanish and six French maize populations differing on variability for earliness, vigor and cold tolerance were crossed in a complete diallel without reciprocals. The populations and their crosses were evaluated in the field and in a cold chamber. Minimum temperatures were the main environmental trait affecting genotype × environment interaction, probably due to the cold sensitivity of the genotypes with the best performance in the field. The best population cross, based on specific heterosis for adaptation-related traits in the field, was Viana × Rastrojero, but this cross was cold sensitive. Tuy × Lazcano should be the best choice for a breeding program for adaptation, based on performance in the field and cold tolerance. As conclusions, there was variability for earliness, vigor and cold tolerance among the populations and crosses involved in this study, being tolerant to cold conditions the populations with medium growing cycle originated in areas with short growing seasons. The highest yielding crosses were cold sensitive., Research supported by the Ministry of Science and Technology (Ref. HF1999-0138), the Ministère de l’Education Nationale et de la Recherche, the Committee for Science and Technology of Spain (Project AGL2004-06776), the Autonomous government of Galicia (PGIDIT04RAG403006PR), the Excma. Diputación Provincial de Pontevedra, and the European Union (RESGEN 88 CT96).