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Glutamine synthetase (EC 6.3.1.2) is a key enzyme of ammonium assimilation and recycling in plants where it catalyses the synthesis of glutamine from ammonium and glutamate. In Arabidopsis, five GLN1 genes encode GS1 isoforms. GLN1;2 is the most highly expressed in leaves and is over-expressed in roots by ammonium supply and in rosettes by ample nitrate supply compared with limiting nitrate supply. It is shown here that the GLN1;2 promoter is mainly active in the minor veins of leaves and flowers and, to a lower extent, in the parenchyma of mature leaves. Cytoimmunochemistry reveals that the GLN1;2 protein is present in the companion cells. The role of GLN1;2 was determined by examining the physiology of gln1;2 knockout mutants. Mutants displayed lower glutamine synthetase activity, higher ammonium concentration, and reduced rosette biomass compared with the wild type (WT) under ample nitrate supply only. No difference between mutant and WT can be detected under limiting nitrate conditions. Despite total amino acid concentration was increased in the old leaves of mutants at high nitrate, no significant difference in nitrogen remobilization can be detected using (15)N tracing. Growing plants in vitro with ammonium or nitrate as the sole nitrogen source allowed us to confirm that GLN1;2 is induced by ammonium in roots and to observe that gln1;2 mutants displayed, under such conditions, longer root hair and smaller rosette phenotypes in ammonium. Altogether the results suggest that GLN1;2 is essential for nitrogen assimilation under ample nitrate supply and for ammonium detoxification.

Carotenoid gene nucleotide diversity reflects carrot history and selection

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Background In Bacillus subtilis, two major transcriptional factors, GlnR and TnrA, are involved in a sophisticated network of adaptive responses to nitrogen availability. GlnR was reported to repress the transcription of the glnRA, tnrA and ureABC operons under conditions of excess nitrogen. As GlnR and TnrA regulators share the same DNA binding motifs, a genome-wide mapping of in vivo GlnR-binding sites was still needed to clearly define the set of GlnR/TnrA motifs directly bound by GlnR. Methods We used chromatin immunoprecipitation coupled with hybridization to DNA tiling arrays (ChIP-on-chip) to identify the GlnR DNA-binding sites, in vivo, at the genome scale. Results We provide evidence that GlnR binds reproducibly to 61 regions on the chromosome. Among those, 20 regions overlap the previously defined in vivo TnrA-binding sites. In combination with real-time in vivo transcriptional profiling using firefly luciferase, we identified the alsT gene as a new member of the GlnR regulon. Additionally, we characterized the GlnR secondary regulon, which is composed of promoter regions harboring a GlnR/TnrA box and bound by GlnR in vivo. However, the growth conditions revealing a GlnR-dependent regulation for this second category of genes are still unknown. Conclusions Our findings show an extended overlap between the GlnR and TnrA in vivo binding sites. This could allow efficient and fine tuning of gene expression in response to nitrogen availability. GlnR appears to be part of complex transcriptional regulatory networks, which involves interactions between different regulatory proteins. Electronic supplementary material The online version of this article (doi:10.1186/s13104-017-2703-9) contains supplementary material, which is available to authorized users.

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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; 'Antonovka' has long been recognised as a major source of scab (Venturia inaequalis) resistance useful for apple breeding worldwide. Both major gene resistances in the form of the Rvi10 and Rvi17 and quantitative resistance, collectively identified as VA, have been identified in different accessions of 'Antonovka'. Most of the 'Antonovka' scab resistance used in apple-breeding programmes around the world can be traced back to Schmidt 'Antonovka' and predominantly its B VIII progenies 33,25 (PI 172623), 34,6 (PI 172633), 33,8 (PI 172612) and 34,5 (PI 172632). Using genetic profile reconstruction, we have identified "common 'Antonovka' " as the progenitor of the B VIII family, which is consistent with it having been a commercial cultivar in Poland and the single source of scab resistance used by Dr. Martin Schmidt. The major 'Antonovka' scab resistance genes mapped to date are located either very close to Rvi6, or about 20-25 cM above it, but their identities need further elucidation. The presence of the 139 bp allele of the CH-Vf1 microsatellite marker known to be associated with Rvi17 (Va1) in most of the 'Antonovka' germplasm used in breeding suggests that it plays a central role in the resistance. The nature and the genetic relationships of the scab resistance in these accessions as well as a number of apple cultivars derived from 'Antonovka', such as, 'Freedom', 'Burgundy' and 'Angold', are discussed. The parentage of 'Reglindis' is unclear, but the cultivar commercialised as 'Reglindis' was confirmed to be an Rvi6 cultivar.

† Background and Aims ERECTA has been identified as a pleiotropic regulator of developmental and physiological processes in Arabidopsis thaliana. Previous work demonstrated a role for ERECTA in the control of compensation between epidermal cell expansion and division in leaves † Methods In this work, spatial and temporal analyses of epidermal cell division and expansion were performed on successive developing vegetative leaves of Arabidopsis thaliana in both ERECTA and erecta lines, LER and Ler, respectively, to understand how the ERECTA gene regulates compensation between these two processes. † Key Results The loss of ERECTA function leads to a low cell expansion rate in all zones of a leaf and in all successive leaves of a plant. This low cell expansion rate is counterbalanced by an increase in the duration of cell division. As a consequence, the ERECTA mutation eliminates the tip to base cellular gradient generally observed in the leaf epidermis and also flattens the heteroblastic changes in epidermal cell area and number within a rosette. Ablation of floral buds eliminates the heteroblastic changes in cellular patterns in an ERECTA-dependent manner. † Conclusions The results provide a detailed description of changes in leaf growth dynamics and cellular variables in both LER and Ler. Altogether they suggest that ERECTA influences leaf cellular development in relation to whole plant ontogeny.

A reproducible procedure was developed for genetic transformation of Hydrangea macrophylla Ser. cv . Blaumeise by Agrobacterium tumefaciens following the development of an efficient regeneration system using leaf discs excised from 12 to 15 weeks old meristem-derived vitroplants. Explants were cultivated on solid B5 medium complemented with maltose 110 mM, BAP 10 μM and NAA 0.5 μM. A low light regime of 17 μmol m −2 s −1 improved regeneration frequency up to 86%. For transformation, leaf discs were inoculated and co-cultivated with two disarmed A. tumefaciens strains, EHA 101 and LBA 4404, both carrying the binary vector pFAJ3000 which contained the nptII selectable gene and the GUS reporter gene. A pre-culture period of 3 days and a short co-cultivation duration (1 day) improved the efficiency of transformation. Inoculation of only 10 min with agitation including (or not) vacuum infiltration was sufficient. If selection on kanamycin containing medium was applied after a 2 weeks culture period on shoot regeneration medium, the percentage of explants forming kanamycin-resistant shoots increased from 3.3 to 13.3%. Integration and expression of the introduced transgene were confirmed by histochemical GUS assay, PCR and Southern blot analysis. Flowering of transgenic plants in glasshouse occurred 10 months after acclimatization.

The modulation of primary nitrogen metabolism by water deficit through ABA-dependent and ABA-independent pathways was investigated in the model legume Medicago truncatula. Growth and glutamate metabolism were followed in young seedlings growing for short periods in darkness and submitted to a moderate water deficit (simulated by polyethylene glycol; PEG) or treated with ABA. Water deficit induced an ABA accumulation, a reduction of axis length in an ABA-dependent manner, and an inhibition of water uptake/retention in an ABA-independent manner. The PEG-induced accumulation of free amino acids (AA), principally asparagine and proline, was mimicked by exogenous ABA treatment. This suggests that AA accumulation under water deficit may be an ABA-induced osmolyte accumulation contributing to osmotic adjustment. Alternatively, this accumulation could be just a consequence of a decreased nitrogen demand caused by reduced extension, which was triggered by water deficit and exogenous ABA treatment. Several enzyme activities involved in glutamate metabolism and genes encoding cytosolic glutamine synthetase (GS1b; EC 6.3.1.2.), glutamate dehydrogenase (GDH3; EC 1.4.1.1.), and asparagine synthetase (AS; EC 6.3.1.1.) were up-regulated by water deficit but not by ABA, except for a gene encoding delta(1)-pyrroline-5-carboxylate synthetase (P5CS; EC not assigned). Thus, ABA-dependent and ABA-independent regulatory systems would seem to exist, differentially controlling development, water content, and nitrogen metabolism under water deficit

International audience; We formulate a spatially realistic population-genetic model for ascertaining the synergetic effect between genetic and spatial composition of the host population on the pathogen spread reinforced by evolutionary processes. We show that spatial arrangement of host genotypes is crucial to the efficacy of host genetic diversification. In particular, the reductive effect of multigenic resistance on the pathogen density can be produced by a random patterning of monogenic resistances. Random patterns can reduce both density and genetic diversity of the pathogen population and delay invasion promoted by sexual recombination. By contrast, patchy distributions diversify pathogen population and, hence, reduce the efficacy of resistance genes. The proposed approach provides theoretical support for studying fast emergence and spread of novel pathogen genotypes carrying multiple virulence genes. It has a practical applicability to design innovative strategies for the most appropriate deployment of plant resistance genes.

International audience; Fire blight caused by the bacteria Erwinia amylovora is one of the most important diseases of pear. This causal agent produces a siderophore (desferrioxamine), which was identified as one of its virulence factors. This protein enables the bacteria to overcome conditions of iron limitation encountered in host tissues, and may also protect the bacteria against active oxygen species. Previous experiments indicate that the use of an iron chelator protein, encoded by the bovine lactoferrin gene, reduces fire blight symptoms in some transgenic pear clones. The aim of the present work is to test the ability of a more efficient iron chelator, plant ferritin, to reduce fire blight susceptibility in pear. In the literature, ferritin genes have been overexpressed under the control of a constitutive promoter in different transgenic plant species for various purposes. In several cases, the constitutive expression of ferritin produced negative effects such as reduced growth and chlorophyll content. Therefore, we decided to place the exogenous ferritin gene from pea under the control of a pathogen inducible promoter (sgd24) in comparison with a constitutive promoter (CaMV 35S). Two pear varieties, 'Conference' (CF) and 'Passe-Crassane' (PC) were transformed using both constructs. Transformation rates depended on variety and construct. They were respectively of 12 and 4.3% for CF and PC using the sgd24-ferritin construct. Only PC was transformed with the 35S-ferritin construct, with a transformation rate of 2%. First analyses of the transgenic clones by RT-PCR showed the expression of pea ferritin in both constructs and in all clones. The transgenic clones were acclimatized in greenhouse and exhibited normal growth. Quantification of ferritin gene expression, ferritin protein accumulation, and evaluation of fire blight resistance are underway.

International audience; Radicle emergence and reserves mobilization are two distinct programmes that are thought to control germination. Both programs are influenced by abscissic acid (ABA) but how this hormone controls seed germination is still poorly known. Phenotypic and microscopic observations of the embryo axis of Medicago truncatula during germination in mitotic inhibition condition triggered by 10 mu M oryzalin showed that cell division was not required to allow radicle emergence. A suppressive subtractive hybridization showed that more than 10% of up-regulated genes in the embryo axis encoded proteins related to cell-wall biosynthesis. The expression of alpha-expansins, pectin-esterase, xylogucan-endotransglycosidase, cellulose synthase, and extensins was monitored in the embryo axis of seeds germinated on water, constant and transitory ABA. These genes were overexpressed before completion of germination in the control and strongly inhibited by ABA. The expression was re-established in the ABA transitory-treatment after the seeds were transferred back on water and proceeded to germination. This proves these genes as contributors to the completion of germination and strengthen the idea that cell-wall loosening and remodeling in relation to cell expansion in the embryo axis is a determinant feature in germination. Our results also showed that ABA controls germination through the control of radicle emergence, namely by inhibiting cell-wall loosening and expansion

UMR DAP équipe AFEF 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; The present study aimed to dissect tree architectural plasticity into genetic, ontogenetic and environmental effects over the first 4 years of growth of an apple F1 progeny by means of quantitative traits loci (QTL) mapping. Both growth and branching processes were phenotyped on the consecutive annual shoots of different axes within a tree. For each studied trait, predicted values (best linear unbiased predictors, BLUPs) of the genotypic (G) effect or its interaction with tree age (G×A) and climatic year (G×Y) were extracted from mixed linear models of repeated data. These BLUPs, which are independent from autocorrelations between repeated measurements, were used for QTL mapping. QTL detection power was improved by this two-step approach. For each architectural process, numerous QTLs were detected and some particularly interesting co-localised in common genomic regions, for internode lengthening, top diameter, and number and percentage of axillary shoots. When several QTLs were detected for a given trait, global models were estimated, which explained a maximum of 40% of the total variance for both internode length and top diameter and 28% for branching. QTLs detected for BLUPs of G×Y effects were interpreted as resulting from the interaction between genetic maximal potential of growth and climatic factors, while those for G×A effects were interpreted in relation to tree ontogeny. Most of the latter ones were found to be concomitant with key development stages during which the trait average started to decrease, but with different magnitudes depending on genotype

International audience; Actively respiring animal and plant tissues experience hypoxia because of mitochondrial O(2) consumption. Controlling oxygen balance is a critical issue that involves in mammals hypoxia-inducible factor (HIF) mediated transcriptional regulation, cytochrome oxidase (COX) subunit adjustment and nitric oxide (NO) as a mediator in vasodilatation and oxygen homeostasis. In plants, NO, mainly derived from nitrite, is also an important signalling molecule. We describe here a mechanism by which mitochondrial respiration is adjusted to prevent a tissue to reach anoxia. During pea seed germination, the internal atmosphere was strongly hypoxic due to very active mitochondrial respiration. There was no sign of fermentation, suggesting a down-regulation of O(2) consumption near anoxia. Mitochondria were found to finely regulate their surrounding O(2) level through a nitrite-dependent NO production, which was ascertained using electron paramagnetic resonance (EPR) spin trapping of NO within membranes. At low O(2), nitrite is reduced into NO, likely at complex III, and in turn reversibly inhibits COX, provoking a rise to a higher steady state level of oxygen. Since NO can be re-oxidized into nitrite chemically or by COX, a nitrite-NO pool is maintained, preventing mitochondrial anoxia. Such an evolutionarily conserved mechanism should have an important role for oxygen homeostasis in tissues undergoing hypoxia.

Indicators of plant nitrogen (N) status adapted to woody ornamental plants are essential for the adjustment of fertilization practices in nurseries. The objective of this study was to investigate whether optical measurements of leaf epidermal polyphenol (EPhen) and chlorophyll (Chl) contents could be used as N status indicators for woody deciduous and evergreen ornamental plants. One-year-old plants of Lagerstroemia indica, Callicarpa bodinieri and Viburnum tinus were grown outdoors in containers. They received low (TN1, 4 mg L-1) or high (TN2, 105 mg L-1) levels of N during 2 months in spring and summer. TN1 treatment limited shoot growth from 28 to 37 days after treatment initiation in Lagerstroemia and Callicarpa, respectively. Shoot growth was unaffected until day 176 in Viburnum. The mass-based leaf N content (N-M) of a sample of young expanded leaves exposed to direct sunlight was tightly correlated with shoot N content and differentiated treatments several weeks before shoot growth reduction for the three species. N-M was therefore used as an index of plant N status. EPhen and Chl contents were recorded with Dualex(TM) and SPAD-502 leaf-clip meters, respectively. Dualex values were strongly and negatively correlated with N-M, and differentiated the treatments early in the experiment, in all three species. SPAD values were positively correlated with N-M for Lagerstroemia and Callicarpa, but not for Viburnum, because large variations in leaf mass per area (LMA) in this species compensated for variations in leaf dry mass invested in Chl. The SPAD/Dualex ratio was used to assess changes in the proportion of leaf dry mass allocated to proteins and polyphenols in response to fertilization. It differentiated between the treatments early in the experiment and was correlated with N-M in all three species. (C) 2007 Elsevier B.V. All rights reserved.

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; An integrated consensus genetic map for apple was constructed on the basis of segregation data from four genetically connected crosses (C1 = Discovery x TN10-8, C2 = Fiesta x Discovery, C3 = Discovery x Prima, C4 = Durello di Forli x Fiesta) with a total of 676 individuals using CarthaGene(R) software. First, integrated female-male maps were built for each population using common female-male simple sequence repeat markers (SSRs). Then, common SSRs over populations were used for the consensus map integration. The integrated consensus map consists of 1,046 markers, of which 159 are SSR markers, distributed over 17 linkage groups reflecting the basic chromosome number of apple. The total length of the integrated consensus map was 1,032 cM with a mean distance between adjacent loci of 1.1 cM. Markers were proportionally distributed over the 17 linkage groups (chi(2) = 16.53, df = 16, p = 0.41). A non-uniform marker distribution was observed within all of the linkage groups (LGs). Clustering of markers at the same position (within a 1-cM window) was observed throughout LGs and consisted predominantly of only two to three linked markers. The four integrated female-male maps showed a very good colinearity in marker order for their common markers, except for only two (CH01h01, CH05g03) and three (CH05a02z, NZ02b01, Lap-1) markers on LG17 and LG15, respectively. This integrated consensus map provides a framework for performing quantitative trait locus (QTL) detection in a multi-population design and evaluating the genetic background effect on QTL expression

Atmospheric dry deposition of nitrogen (N) and dinitrogen (N-2) fixation rates were assessed in 2004 at the time-series DYFAMED station (northwestern Mediterranean, 43 degrees 25'N, 7 degrees 52'E). The atmospheric input was monitored over the whole year. Dinitrogen fixation was measured during different seasonal trophic states (from mesotrophy to oligotrophy) sampled during nine cruises. The bioavailability of atmospherically deposited nutrients was estimated by apparent solubility after 96h. The solubility of dry atmospheric N deposition was highly variable (from similar to 18% to more than 96% of total N). New N supplied to surface waters by the dry atmospheric deposition was mainly nitrate (NO3-) (similar to 57% of total N, compared to similar to 6% released as ammonium (NH4+)). The mean bioavailable dry flux of total N was estimated to be similar to 112 mu mol m(-2) d(-1) over the whole year. The NO3- contribution (70 mu mol NO3- m(-2) d(-1)) was much higher than the NH4+ contribution (1.2 mu mol NH4+ m(-2) d(-1)). The N:P ratios in the bioavailable fraction of atmospheric inputs (122.5-1340) were always much higher than the Redfield N: P ratio (16). Insoluble N in atmospheric dry deposition (referred to as ``organic'' and believed to be strongly related to anthropogenic emissions) was similar to 40 mu mol m(-2) d(-1). N-2 fixation rates ranged from 2 to 7.5 nmol L-1 d(-1). The highest values were found in August, during the oligotrophic period (7.5 nmol L-1 at 10 in depth), and in April, during the productive period (4 nmol L-1 d(-1) at 10 m depth). Daily integrated values of N-2 fixation ranged from 22 to 100 mu mol N m(-2) d(-1), with a maximum of 245 mu mol N m(-2) d(-1) in August. No relationship was found between the availability of phosphorus or iron and the observed temporal variability of N-2 fixation rates. The atmospheric dry deposition and N-2 fixation represented 0.5-6% and 1-20% of the total biological nitrogen demand, respectively. Their contribution to new production was more significant: 1-28% and 2-55% for atmospheric dry deposition and N-2 fixation, respectively. The dry atmospheric input was particularly significant in conditions of water column stratification (16-28% of new production), while N2 fixation reached its highest values in June (46% of new production) and in August (55%). (C) 2007 Elsevier Ltd. All rights reserved.

International audience; Eutypine is a toxin produced by Eutypa lata, the causal agent of eutypa dieback of grapevines. An eutypine detoxifying gene (Vr-ERE) encoding an NADPH-dependent aldehyde reductase converts eutypine into the corresponding alcohol, eutypinol, a non-toxic form of the toxin. A variety of phytotoxic compounds containing an aldehyde group can act as substrates for this enzyme, therefore opening the possibility to use Vr-ERE as an alternative selection system for plant transformation. Our preliminary experiments with apple and pear have demonstrated the following: 1) among the various substrates of VR-ERE, benzaldehyde (BD), a naturally occurring compound, is able to inhibit adventitious bud regeneration from apple as well as pear in vitro leaves, at concentrations ranging from 1 to 1.5 mM; 2) constitutive expression of Vr-ERE in transgenic ‘Greensleeves’ apple does not provoke any abnormal phenotype after one year of growth in greenhouse, but aldehyde reductase activity is reduced in all transgenic clones; 3) production of transgenic pear using BD instead of kanamycin as selection pressure is feasible, but the efficiency of the selection pressure seems low. In conclusion, the efficiency of Vr-ERE as a selective gene to produce apple and pear transgenic plants is not yet proven and further research is needed

International audience; Seeds of higher plant are desiccation tolerant, which suggests that their mitochondria exhibit particular properties. Insight into the function of seed mitochondria, especially in legume and model plants, has been fostered by the development of proteomics. Seed mitochondria are functional at the onset of imbibition, and their integrity and performance systematically improves during germination. This suggests that repair and biogenesis mechanisms exist, and this is supported by morphological and biochemical evidence. Seed mitochondria generate and operate in a hypoxic environment. They accumulate stress proteins, such as a small heat-shock protein and a late embryogenesis abundant protein. The mitochondria of pea (Pisum sativum L.) seed also display a biased phospholipid composition likely to favour desiccation tolerance. These specific biochemical properties surely contribute to the remarkable tolerance of seed mitochondria to extreme temperatures. Recent progress towards the resolution of the seed mitochondrial proteome is discussed in light of the growing body of genomic data

International audience; Four alanine aminotransferases (AlaATs) are expressed in Medicago truncatula. In adult plants, two genes encoding mitochondrial isoforms m-AlaAT and alanine-glyoxylate aminotransferase (AGT), catalysing, respectively, reversible reactions of alanine/oxoglutarate glutamate/pyruvate and alanine/glyoxylate glycine/pyruvate, were expressed in roots, stems, and leaves. A gene encoding a cytosolic (c-AlaAT) isoform, catalysing the same reaction as m-AlaAT, was expressed specifically in leaves, while a gene encoding an isoform involved in branched chain amino acid metabolism was expressed in stems and roots. In young seedlings, only m-AlaAT and AGT were expressed in embryo axes. In hypoxic embryo axes, the amounts of transcript and putative protein of m-AlaAT (EC 2.6.1.2) increased while those of AGT (EC 2.6.1.44) decreased and in vivo enzyme activities changed as revealed by [N-15]alanine and [N-15]glutamate labelling. Under hypoxia, m-AlaAT catalysed only alanine synthesis while glutamate synthesis using alanine as amino donor was inhibited. As a result, alanine accumulated as the major amino acid in hypoxic seedlings instead of asparagine, in agreement with the involvement of the fermentative AlaAT pathway in hypoxia tolerance. Regulation of m-AlaAT at both the transcriptional and post-translational levels allowed for an increase in gene expression and orientation of the activity of the product of its transcription towards alanine synthesis under hypoxia. Labelling experiments showed that glycine synthesis occurred at the expense of either alanine or glutamate as amino donor, indicating that a glutamate-glyoxylate aminotransferase was operating together with AGT in Medicago truncatula seedlings. Both enzymes seemed to be inhibited by hypoxia, resulting in a very low amount of glycine in hypoxic seedlings

International audience; Several studies have shown that the proanthocyanidins are responsible for some major flavour properties of the red wines such as colour, bitterness and astringency. Nevertheless, their synthesis and properties are still misunderstood. Some studies have suggested that the proanthocyanidin content is set before veraison. This paper describes the setting of the proanthocyanidins, until the veraison stage, and the relations that exist with the environment. The flavan-3-ol composition was monitored from the end of the berry set until mid veraison, on two plots known to induce a different behaviour of the vine. The study considered the value of the parameters for a homogeneous stage of development. The composition in proanthocyanidins in skin was determined by HPLC reversed phase, after fractionation and thiolysis. A further information about the proanthocyanidins was obtained by histochemistry. The sections, 2 [mu]m thick, were stained according to the 4-dimethylaminocinnamaldehyde method. The interest and the limits of these approaches are described and discussed. Moreover, it is shown that the linking of these two analytical techniques which associates quantitative data and the spatializing of the tannins in cellular tissue could improve the understanding of the setting of the proanthocyanidins content. Finally, this original approach pointed out the importance of the period previous ripening in the synthesis of flavan-3-ols in the skin; the heterogeneity among berries was in relation with the stage of development but some other factors, as light exposition could also play a role

Container-grown Ligustrum ovalifolium L. plants were used to determine the influence of nutrient availability on the mobilisation of carbon (C), nitrogen (N) and phosphorus (P) during spring growth. During the spring of the second growing season, plants either received no fertiliser, or were fertilised early (starting 17 days after bud break) or late (starting 3 months after bud break). Nutrient composition of different plant tissues was determined at several times during the second growing season from bud break to the end of elongation. Time of fertilisation did not influence aerial dry weight until flowering was completed. Plants that received no fertiliser or were fertilised late had greater root dry weight than plants that received fertiliser early. Fertilised plants had a second flush of growth after flowering completed. Nitrogen and phosphorus mobilisation occurred from bud break to the end of elongation (3 months). Nutrient mobilisation was effective in each perennial organ: root, trunk, ligneous stems and old leaves. However, the role of old leaves as storage organ was minor compared to evergreen tree leaves. Carbon mobilisation only occurred on the 1st month following bud break, before elongation. C-starch accumulation was observed in unfertilised plants even when the C-starch quantities in early fertilised plants were very low at the end of elongation, mainly in roots. In spite of fertilisation supplies, N and P quantities did not increase after elongation in the early fertilised plants, probably in relation to C insufficiency in roots to sustain N and P absorption and assimilation. By contrast, in late fertilised plants, high C quantities in roots were mobilised for N and P uptake and assimilation, which allowed both second growth flush and storage of N and P in perennial organs. The mobilisation of nutrients before and during elongation revealed the nutritional autonomy of shrubs, which could allow fertiliser use efficiency to be increased and environmental impacts to be minimised by delaying spring fertilisation. Nevertheless, the shrub ability to valorise fertilisation supplies for sustaining growth or nutrient storage restoration required sufficient C-starch quantities in roots. The starch accumulated in roots before late nutrient supply can be used for these objectives.

International audience; Anacolosidites Cookson & Pike, a fossil pollen genus recorded since the Campanian, is peculiar in its morphology - six-porate with three apertures on each hemisphere, located away from the equator, and with the distal and proximal apertures positioned over each other. Representatives of this fossil genus are widely considered to represent extant Olacaceae from tribe Anacoloseae. Olacaceae is an exclusively tropical angiosperm family with a pantropical distribution; consequently the fossils are often used to suggest a tropical climate and in addition are frequently used as a stratigraphic marker. Fossil species assigned to Anacolosidites are quite variable and may not all represent Olacaceae, in which case they may not indicate tropical climate. The present study is a morphological survey of fossil pollen assigned to Anacolosidites; it identifies the published reports of the fossil species that probably represent positive occurrences of Olacaceae pollen in the fossil record. Within Olacaceae, Anacolosidites-type pollen is usually compared with pollen of genera in tribe Anacoloseae, in particular: Cathedra, Anacolosa and Phanerodiscus, but never with the pollen of Ptychopetalum, a genus from tribe Olaceae with closely similar pollen to the other three genera, but with a reticulate tectum and very small circular apertures located near the equator. Nevertheless, the records of reticulate Anacolosidites species which have been excluded from the emended diagnosis are unlikely to be related to Ptychopetalum. The earliest accepted record of Anacolosidites is from the Late Cretaceous (Maastrichtian) of Germany. However, most Late Cretaceous records, and later Russian and Chinese occurrences referred to Anacolosidites, consist mainly of Normapolles-type pollen, whereas many of the Cenozoic records assigned to Anacolosidites have a much clearer affinity with the pollen of Anacolosa, Cathedra and Phanerodiscus (tribe Anacoloseae). The newly emended genus Anacolosidites may be used as a stratigraphic marker for tropical or megathermal climatic conditions

International audience; Within the practical context of mechanisms comprehension involved in greenhouse climate, this paper considers the problem of natural ventilation with particular attention paid to the determination of the ventilation rate. In view to gain some physical insight on to this process under temperate climate, both experimental and numerical approaches have been developed. Measurements were carried out in a 2500 m2 commercial glasshouse equipped with continuous roof vents. Speed and direction of the wind and air temperature were measured outside the building. Temperature was also recorded both on the walls and in the middle of the greenhouse. The tracer gas (N2O) technique was used to assess the ventilation rate. Numerical resolution was performed using a commercial computational fluid dynamics (CFD) package. The model solves the 2D Navier-Stokes equations with a kappa - epsilon closure. The boundary conditions were inferred from the experimental data. The simulated ventilation rate was compared to the experimental data, for three different openings configurations, and with other results already published in the literature. Results show that wind speed and direction combined with vent opening size strongly affect the inside air flow and temperature patterns as well as the ventilation rate. Simulated ventilation flux seems however to be underestimated probably because the model does not consider leakage rates and 3D circulations. Such a tool could nevertheless be improved in order to be used as a design device to optimize ventilation in greenhouses

International audience; Background and Aims To improve the management of grass communities, early plant development was compared in three species with contrasting growth forms, a caespitose ( Lolium perenne), a rhizomatous (Poa pratensis) and a caespitose-stoloniferous species (Agrostis stolonifera). Methods Isolated seedlings were grown in a glasshouse without trophic constraints for 37 d (761 degrees Cd). The appearance of leaves and their location on tillers were recorded. Leaf appearance rate ( LAR) on the tillers and site-filling were calculated. Tillering was modelled based on the assumption that tiller number increases with the number of leaves produced on the seedling main stem. Above- and below- ground parts were harvested to compare biomass. Key Results Lolium perenne and A. stolonifera expressed similar bunch-type developments. However, root biomass was approx. 30% lower in A. stolonifera than in L. perenne. Poa pratensis was rhizomatous. Nevertheless, the ratio of above-ground : below- ground biomass of P. pratensis was similar to that of L. perenne. LAR was approximately equal to 0.30 leaf d(-1) in L. perenne, and on the main stem and first primary tillers of A. stolonifera. LAR on the other tillers of A. stolonifera was 30% higher than on L. perenne. For P. pratensis, LAR was 30% lower than on L. perenne, but the interval between the appearance of two successive shoots from rhizomes was 30% higher than the interval between two successive leaf stages on the main stem. Above- ground parts of P. pratensis first grew slower than in the other species to the benefit of the rhizomes, whose development enhanced tiller production. Conclusions Lolium perenne had the fastest tiller production at the earliest stages of seedling development. Agrostis stolonifera and P. pratensis compensated almost completely for the delay due to higher LAR on tillers or ramets compared with L. perenne. This study provides a basis for modelling plant development

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Fire blight, caused by the bacterial pathogen Erwinia amylovora, is one of the most destructive diseases of apple (Malus x domestica). In order to analyse the genetic determinism of resistance to fire blight in apple, a quantitative trait analysis (QTL) approach was used. A F1 progeny of 164 individuals derived from a cross between the apple cultivars `Prima¿ and `Fiesta¿ was inoculated in greenhouse conditions. Seven copies per genotype were used. The length of the necrosis observed on shoots was scored 7 and 14 days after inoculation. The MapQTL software was used for QTL analyses, using two previously built maps of the parents, and the symptoms scored on shoots. Digenic interactions between all pairwise combinations of genetic markers were tested using a two-way ANOVA model with the SAS software. QTL were detected at the same locations both 7 and 14 days after inoculation. Two weak effect QTL deriving from `Prima¿ were detected on linkage groups (LG) 3 and LG16. One strong effect QTL deriving from `Fiesta¿ was detected on LG7 that explained 46.6% of the phenotypic variation observed in the progeny. Two additional significant (P

Molecular characterization of french local apple cultivars using SSRs. 11.Eucarpia Symposium on Fruit Breeding and Genetics

The purpose of this work was to study how artificial vision could indicate a modification of the state of a plant on the basis of shape analysis methods. In order to do this, morphological indicators were defined, allowing a diagnosis in the case of plants where water deficits were fairly high. This study was conducted on images of forsythias analysed on a horizontal plane. The main section of this paper concerns the identification of features indicating the entire morphological development of plants under water stress conditions. Several methods were developed and tested. Three methods made it possible to accurately define a threshold above which the plant can be considered stressed. A physiological study of the water status of the plant was undertaken at the same time in order to validate the results obtained by artificial vision.

International audience

Sequence conservation among resistance genes (R genes) was exploited to identify 47 R gene analogues (RGAs) from sugar beet (Beta vulgaris L.). Using degenerate primers, 11 RGAs were amplified from genomic DNA and 7 from leaf or beet cDNA. Twenty-nine were selected from an EST sequencing program. Twenty-one RGAs contained structures similar to the nucleotide binding site (NBS) – leucine rich repeat (LRR) domain, a motif commonly found in several R genes. Among the remaining RGAs, 19 revealed similarity to the serine (threonine) protein kinase domain of R genes, 4 showed features related to the LRR region of the rice disease resistance gene Xa21, 1 RGA resembled the sugar beet nematode resistance gene Hs1pro-1, and 2 had homologies to other gene products associated with disease resistance. For 20 EST-derived RGAs, transcript levels were compared in leaf and root tissue revealing organ-specific transcription in 7 cases. Thirty-three RGAs were spread over all nine sugar beet chromosomes, except for a cluster of nine closely linked RGAs on chromosome 7. The analysis of linkage between RGAs and loci for rhizomania and Cercospora resistance identified alleles associated with resistance in both cases.Key words: RGA, Beta vulgaris, NBS–LRR, genetic linkage map, molecular marker.

The contribution of in vitro methods and molecular tools to pear genetic studies and breeding has advanced considerably during the last decade. Haploidization via in situ parthenogenesis induced by irradiated pollen and in vitro rescue of the haploid plantlets has been developed for pear. Techniques of adventitious bud regeneration from in vitro leaves have been developed for several genotypes of European and Asian pear and for quince. So far, applications of these techniques for the induction of somaclonal variation have been very limited. Increased tolerance to fire blight has been obtained in somaclonal variants of the cultivar Durondeau, and selection of quince rootstocks tolerant to iron deficiency has been achieved with adventious regeneration followed by in vitro selection. A major evolution of pear biotechnology is the recent development of Agrobacterium-mediated transformation. Since the first report in 1996, several teams have succeeded to transform about ten different genotypes of varieties and rootstocks. Projects have started in several countries to express various trangenes in pear (lytic peptides, rolC and SAMase genes). Molecular markers developed on pear now include isozymes, RAPDs and RFLPs. They have been used mostly for varietal identification of european as well as asian pears. Markers have been developed recently for a few genes of interest, such as a black-spot resistance gene and an ACC synthase gene. But no genetic map of pear is yet available. Finally, about 20 genes have already been cloned in pear, most of them from P. pyrifolia. They are mostly involved in fruit ripening or quality and self-incompatibility.

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Fire blight, caused by Erwinia amylovora, is a major disease of pear (Pyrus communis L.). Different strategies to enhance fire blight resistance of pear through genetic engineering are currently studied in our group. Among them, transformation of pear with a depolymerase gene from a bacteriophage has been investigated. This gene encodes an enzyme that degrades the capsular exopolysaccharide (EPS) of E. amylovora. Mutant strains without bacterial EPS are known to fail to colonize host plants. Pear cv. ‘Passe Crassane’ was transformed with Agrobacterium tumefaciens EHA105pBinAR-dpo carrying the depolymerase gene under the control of the CaMV35S promoter. Sixteen transgenic diploid clones were obtained and analysed by western blot and RT-PCR. In vitro tests for fire blight resistance were performed by inoculation with a virulent strain of E. amylovora. Two transgenic clones showed a slight reduction of fire blight symptoms (about 15 %) in comparison to non-transformed plants. This partial resistance was correlated with a stronger expression of the transgene at transcriptional and traductional levels. Very low depolymerase activity was detected in most transgenic clones (0.006% of total soluble proteins). Greenhouse evaluation of fire blight resistance of the depolymerase clones is under investigation on acclimatized plants.

International audience; Our previous findings showed that the expression of the Rosa hybrida vacuolar invertase 1 gene (RhVI1) was tightly correlated with the ability of buds to grow out and was under sugar, gibberellin and light control. Here, we aimed to provide an insight into the mechanistic basis of this regulation. In situ hybridization showed that RhVI1 expression was localized in epidermal cells of young leaves of bursting buds. We then isolated a 895 bp fragment of the promoter of RhVI1. In silico analysis identified putative cis-elements involved in the response to sugars, light and gibberellins on its proximal part (595 bp). To carry out functional analysis of the RhVI1 promoter in a homologous system, we developed a direct method for stable transformation of rose cells. 50 deletions of the proximal promoter fused to the uidA reporter gene were inserted into the rose cell genome to study the cell's response to exogenous and endogenous stimuli. Deletion analysis revealed that the 468 bp promoter fragment is sufficient to trigger reporter gene activity in response to light, sugars and gibberellins. This region confers sucrose- and fructose-, but not glucose-, responsive activation in the dark. Inversely, the -595 to -468 bp region that carries the sugar-repressive element (SRE) is required to down-regulate the RhVI1 promoter in response to sucrose and fructose in the dark. We also demonstrate that sugar/light and gibberellin/light act synergistically to up-regulate beta-glucuronidase (GUS) activity sharply under the control of the 595 bp pRhVI1 region. These results reveal that the 127 bp promoter fragment located between -595 and -468 bp is critical for light and sugar and light and gibberellins to act synergistically.

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International audience; In this paper, we define a dynamic discrete model of a passive air conditioning unit, without the more typical compression or absorption-refrigeration cycle. The unit is composed of heat exchangers, a positioning system and humid corrugated pads. The aim of the study was to follow the temperature in a greenhouse and to replicate it with a desired and stable relative humidity in a ventilated growth chamber. A control law, based on a quadratic criterion and dynamic programming, taking output error and energy consumption minimisation into account, was used to control the behaviour of the unit in spite of air intake disturbances. The results of the simulation indicate that the air conditioning unit can produce a variable climate in the growth chamber, with a wide range of relative humidity setpoints.

Texture is a major component of consumer preference for eating-quality in apple. A quantitative genetic analysis of traits associated with fruit-flesh firmness was carried out. This was based on segregation in an unselected mapping population replicated at six sites and harvested over 2 years. Different methods of assessment were compared, and a principal components analysis carried out. Instrumental measures used were Magness-Taylor penetrometer readings, stiffness by acoustic resonance, and a range of sensory descriptors assessed by a trained panel. There were good correlations between some measures, although stiffness was poorly correlated. Whilst genotype by environment effects were large, significant effects were attributable to the genotype, and these were used to detect QTLs. Significant QTLs were detected on seven linkage groups, with large effects on linkage groups L01, L10 and L16. Whilst there was a poor correlation between acoustic stiffness and other measures, the significant and suggestive QTL detected for stiffness on linkage group L10 did represent a subset of significant QTLs detected for the penetrometer measure. The use of sensory assessment proved valuable in detecting QTLs representing different attributes of fruit texture. The possibility of interaction between significant QTLs for fruit texture and other strongly selected traits such as scab resistance and fruit acidity is addressed.

The phytopathogenic bacterium Xanthomonas campestris pv. pelargonii causes severe losses in vegetatively propagated Pelargonium cultivars. Symptoms are characterized by wilting of the plant, localized water-soaked lesions and stem rot (1) To overcome this problem horticulturists have to produce Xanthomonas-free planting material in insect-proof greenhouses after indexing the propagating stocks, which is expensive and time consuming. All commercial cultivars of pelargonium are susceptible to Xanthomonas and no source of resistance is known in the compatible Pelargonium germplasm. Thus, attempts were initiated to obtain Xanthomonas resistant plants by a transgenic approach.

Fire blight, caused by Erwinia amylovora, is the most important bacterial disease of pear (Pyrus communis L.). Attacin E, a lytic protein originating from Hyalophora cecropia, has been previously reported to be active against E. amylovora in transgenic apple. Integration of the attacin E gene under control of a derivative of the constitutive promoter CaMV35S was accomplished using a transformation protocol developed for several pear cultivars. The integration was checked by polymerase chain reaction (PCR) for 11 lines of the cultivar Passe Crassane. Expression was determined in in vitro plantlets. The differences in transcription levels among lines revealed by comparative reverse transcription PCR correlated very well with the differences in attacin E accumulation observed by Western blot analysis. Fire blight inoculations were performed in vitro on all transgenic lines. A significant reduction of symptoms was observed for six lines, in comparison with the susceptible control Passe Crassane.

Linkage maps for the apple cultivars ‘Prima’ and ‘Fiesta’ were constructed using RFLP, RAPD, isozyme, AFLP, SCAR and microsatellite markers in a ‘Prima’בFiesta’ progeny of 152 individuals. Seventeen linkage groups, putatively corresponding to the seventeen haploid apple chromosomes, were obtained for each parent. These maps were aligned using 67 multi-allelic markers that were heterozygous in both parents. A large number of duplicate RFLP loci was observed and, in several instances, linked RFLP markers in one linkage group showed corresponding linkage in another linkage group. Distorted segregation was observed mainly in two regions of the genome, especially in the male parent alleles. Map positions were provided for resistance genes to scab and rosy leaf curling aphid (Vf and Sd 1, respectively) for the fruit acidity gene Ma and for the self-incompatibility locus S. The high marker density and large number of mapped codominant RFLPs and some microsatellite markers make this map an ideal reference map for use in other progenies also and a valuable tool for the mapping of quantitative trait loci.

The physical properties of the reconstituted anthropic soils of the landscape areas of the International City of Lyons were studied with many methods to evaluate the impact of the conditions of soil placement (water content of materials and equipment used). The results obtained by image analysis on samples taken in situ show that the use of wet materials is at the origin of a reduced macroporosity and that careful soil placement carried out by an excavator can provide larger macropores.

Apple scab, caused by the fungus Venturia inaequalis (Cke.) Wint., is an important disease in commercial apple production. A mapping population of 155 individuals, derived from a cross between the apple varieties ‘Prima’ (resistant)בFiesta’ (susceptible), was scored for response to the disease in replicated field and glasshouse trials throughout Europe. Twenty data sets were selected and cluster analysis was used to form a consensus score for the population fitting a 1 : 1 segregation ratio of resistance:susceptibility. The progeny were scored with molecular markers. A detailed map covering 54 cM of the ‘Prima’ linkage group containing the Vf gene for scab resistance was constructed using 24 molecular markers linked to the resistance gene. One isoenzyme marker (Pgm-1), six RFLP markers and 17 RAPD markers formed a linkage group with the consensus measure of resistance to scab. Four marker bridges were established with the corresponding ‘Fiesta’ linkage group with additional markers (one isozyme, one RFLP, three RAPD and one AFLP). A low chi-square value indicated a good fit of the marker ordering, which was in close agreement with previously reported linkage positions for some of the markers and Vf. Differences were observed in the ability of different scoring methods to resolve susceptible and resistant classes. The results obtained for the consensus classification of resistance to scab for the population may suggest the presence of virulent inocula at some sites, which could overcome the Vf gene for resistance. The consequences of relying on individual scoring occasions for studying Vf scab resistance are discussed in the context of linkage analysis, conventional breeding selection, and marker-assisted selection.

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International audience

Hydroponics and transplant production; International audience

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Article de revue (Article scientifique dans une revue à comité de lecture); International audience; Phelipanche ramosa L. (Pomel) is a major root-parasitic weed attacking many important crops. Success in controlling this parasite is rare and a better understanding of its unique biology is needed to develop new specific control strategies. In the present study, quantitative polymerase chain reaction experiments showed that sucrose synthase encoding PrSus1 transcripts accumulate at their highest level once the parasite is connected to the host (tomato) vascular system, mainly in the parasite tubercles, which bear numerous adventitious roots. In situ hybridization experiments revealed strong PrSus1 expression in both shoot and root apices, especially in shoot apical meristems and in the vascular tissues of scale leaves and stems, and in the apical meristems and developing xylem in roots. In addition, immunolocalization experiments showed that a sucrose synthase protein co-localized with cell-wall thickening in xylem elements. These findings highlight the role of PrSus1 in the utilization of host-derived sucrose in meristematic areas and in cellulose biosynthesis in differentiating vascular elements. We also demonstrate that PrSus1 is downregulated in response to 2,3,5-triiodobenzoic acid-induced inhibition of polar auxin transport in the host stem, suggesting that PrSus1 activity in xylem maturation is controlled by host-derived auxin.

International audience; Phelipanche ramosa L. (Pomel) is a major root-parasitic weed attacking many important crops. Success in controlling this parasite is rare and a better understanding of its unique biology is needed to develop new specific control strategies. In the present study, quantitative polymerase chain reaction experiments showed that sucrose synthase encoding PrSus1 transcripts accumulate at their highest level once the parasite is connected to the host (tomato) vascular system, mainly in the parasite tubercles, which bear numerous adventitious roots. In situ hybridization experiments revealed strong PrSus1 expression in both shoot and root apices, especially in shoot apical meristems and in the vascular tissues of scale leaves and stems, and in the apical meristems and developing xylem in roots. In addition, immunolocalization experiments showed that a sucrose synthase protein co-localized with cell-wall thickening in xylem elements. These findings highlight the role of PrSus1 in the utilization of host-derived sucrose in meristematic areas and in cellulose biosynthesis in differentiating vascular elements. We also demonstrate that PrSus1 is downregulated in response to 2,3,5-triiodobenzoic acid-induced inhibition of polar auxin transport in the host stem, suggesting that PrSus1 activity in xylem maturation is controlled by host-derived auxin.

International audience; The effects of high temperature on the seedlings of cork oak were studied with respect to growth, and proline accumulation. Within this context, this work focuses on the impact of short and repetitive periods of high temperatures (38°C, 40°C, 42°C and 44°C) on certain morphological and biochemical aspects of the cork oak seedlings. Height, foliar area and number of leaves were found to be positively affected with the temperatures. Proline accumulation was found in leaves, stems and roots after thermal stress treatment. A preferential accumulation of proline was found in root system, with a maximum at 44°C. Thus, the level of proline accumulation was related to the degree of thermal stress tolerance.