Double dose efficiency of the yellow rust resistance gene Yr17 in bread wheat lines

Yellow rust, caused by Puccinia striiformis f. sp. tritici, is one of the most severe wheat disease worldwide. Crop losses have ranged from 10% to 70% and up to 100% in extreme conditions. Eighty-two resistance genes, designated Yr, have been identified. Among them, Yr17 derived from Aegilops ventricosa and located on chromosome 2A has been widely used in wheat breeding. However, it had been overcome already. Through recombination of the Ae. ventricosa Yr17-carrying 6N^v chromosome with 2D of wheat, we introduced Yr17 onto chromosome 2D. Then, lines carrying Yr17 on both 2A and 2D were generated. Seedlings of the latter, as well as those carrying a single dose of Yr17 either on 2A or on 2D, were inoculated with virulent or avirulent strains on wheat seedlings. The different genotypes were fully susceptible for the two pathotypes that are virulent on Yr17. In the case of avirulent pathotypes, the Yr17 double dose lines were fully resistant, while those with the Yr17 gene only on either 2A or 2D had intermediate resistance reactions towards one or the other or both pathotypes.     

Paired comparison of water, energy and carbon exchanges over two young maritime pine stands (Pinus pinaster Ait.): effects of thinning and weeding in the early stage of tree growth

The effects of management practices on energy, water and carbon exchanges were investigated in a young pine plantation in south-west France. In 2009-10, carbon dioxide (CO(2)), H(2)O and heat fluxes were monitored using the eddy covariance and sap flow techniques in a control plot (C) with a developed gorse layer, and an adjacent plot that was mechanically weeded and thinned (W). Despite large differences in the total leaf area index and canopy structure, the annual net radiation absorbed was only 4% lower in plot W. We showed that higher albedo in this plot was offset by lower emitted long-wave radiation. Annual evapotranspiration (ET) from plot W was 15% lower, due to lower rainfall interception and transpiration by the tree canopy, partly counterbalanced by the larger evaporation from both soil and regrowing weedy vegetation. The drainage belowground from plot W was larger by 113 mm annually. The seasonal variability of ET was driven by the dynamics of the soil and weed layers, which was more severely affected by drought in plot C. Conversely, the temporal changes in pine transpiration and stem diameter growth were synchronous between sites despite higher soil water content in the weeded plot. At the annual scale, both plots were carbon sinks, but thinning and weeding reduced the carbon uptake by 73%: annual carbon uptake was 243 and 65 g C m(-2) on plots C and W, respectively. Summer drought dramatically impacted the net ecosystem exchange: plot C became a carbon source as the gross primary production (GPP) severely decreased. However, plot W remained a carbon sink during drought, as a result of decreases in both GPP and ecosystem respiration (R(E)). In winter, both plots were carbon sources, plots C and W emitting 67.5 and 32.4 g C m(-2), respectively. Overall, this study highlighted the significant contribution of the gorse layer to mass and energy exchange in young pine plantations.     

Vegetative propagation of two endemic species of <Emphasis Type="Italic">Cloezia</Emphasis> Brongn. &; Gris for conservation and mining revegetation activities in New Caledonia

A study to determine the best vegetative propagation protocol was carried out for two species of the endemic genus Cloezia for conservation and mining revegetation activities in New Caledonia. Effects of clonal capacities and auxin treatments on rooting of C. buxifolia and C. aquarum semi-hardwood cuttings taken from wild populations were evaluated in four experiments. Different phenotypes varied in their capacity to root (from 0 to more than 80%) and this underlines the importance of collecting cuttings from different plants when revegetation programs are based on vegetative propagation. The experiments evaluated the effectiveness of IBA at 5, 10 and 20 g kg⁻¹, IAA at 5 and 10 g kg⁻¹ and NAA at 1 and 2 g kg⁻¹ treatments to enhance rooting of C. buxifolia tip cuttings and C. aquarum tip and stem cuttings compared to control cuttings with no applied auxin. With the exception of IAA, auxin treatments enhanced the percentage of cuttings with roots and significantly improved the number of roots per cutting and root length. In this study, the best treatment is 10 g kg⁻¹ IBA for C. buxifolia. For C. aquarum, 20 g kg⁻¹ IBA significantly enhances quantitatively and qualitatively rooting of both tip and stem cuttings.

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Résumé  Cette étude porte sur la définition d’un protocole de multiplication végétative optimale de deux espèces du genre endémique Cloezia dans un but de conservation et de revégétalisation en Nouvelle-Calédonie. Quatre essais visent à déterminer les potentialités clonales de différents individus et l’effet de divers traitements hormonaux sur l’enracinement de boutures de C. buxifolia et C. aquarum. L’enracinement des boutures dépend du pied-mère sur lesquelles elles sont récoltées et peut varier de 0 à plus de 80%, ce qui indique l’intérêt de la méthode d’échantillonnage lors de la collecte des boutures. L’effet de traitements hormonaux à base d’AIB, AIA et ANA à différentes concentrations, respectivement de 5, 10 et 20 g kg⁻¹, 5 et 10 g kg⁻¹ et 1 et 2 g kg⁻¹ est également étudié sur des boutures de tête de C. buxifolia et des boutures de tête et de tige de C. aquarum. Ces traitements améliorent le pourcentage d’enracinement et augmentent significativement le nombre de racines produites et la longueur des racines des boutures de Cloezia, à l’exception des traitements à base d’AIA. Dans cette étude, le meilleur traitement est 10 g kg⁻¹ d’AIB pour C. buxifolia et 20 g kg⁻¹ d’AIB pour C. aquarum.

     

Criteria for selecting productive and stable pea cultivars

The beginning and duration of the seed set in the growth cycle determine the level and stability of the yield of a pea (Pisum sativum L.) genotype. The objective of the present study was to identify criteria for selecting genotypes, both in terms of timing of seed set and productivity. Genotypes were initially compared in field experiments for two different levels of inter-plant competition, but using the same photo-thermal conditions. These experiments showed that the initiation and, particularly, the duration of seed set were affected by plant growth rates, indicating that selection on these variables must be done by comparing genotypes under regular cropping conditions. When measuring seed production of the whole plant, we found that mean dry seed weight per podded node all over the plant and the number of podded nodes on any fertile stem were similar to those on the main stem. These results confirmed that branches and main stems have a similar reproductive pattern, and thus that any podded stem of the canopy is representative of every stem of the plant. Lastly, we showed that, when associated, the number of podded nodes, the mean dry seed weight per podded node on the main stem (or on any reproductive stem of the canopy), and the number of basal branches per plant are suitable criteria for selecting for productivity among genotypes with a similar duration of seed set. This revised version was published online in August 2006 with corrections to the Cover Date.     

Formation of micella containing solubilized sterols during rehydration of active dry yeasts improves their fermenting capacity

During their rehydration in aqueous media, active dry yeasts (ADY) may be supplemented with inactive yeasts, yeast derivatives, or other optional complementary nutrients to improve their fermentation capacity. We found that yeast sterols solubilized in situ during ADY rehydration were particularly efficient for stimulating the fermenting capacity of ADY. Spontaneous solubilization of sterols during rehydration occurred by the formation of micelles by membrane phospholipids and specific cell wall polysaccharides and sterols, both compounds being provided by inactive dry yeasts (IDY). These micelles contained a specific distribution of the initial sterols from the inactive yeasts. Above a concentration of 100 mg L(-1) in the rehydration medium, these micelles acted as emulsifiers. Their critical micellar concentration (cmc) was found to be about 4 g L(-1). During rehydration, purified micelles, at a concentration near the cmc, were able to interact quickly with yeast cell membranes by modifying the yeast plasma membrane order [monitored by steady-state fluorescence anisotropy of 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene-p-toluenesulfonate (TMA-DPH) probe] and by increasing the sterol contents of ADY. Such an enrichment of ADY by very low concentrations of solubilized sterols was very efficient for the completion of fermentations. This is useful when musts are limited in available phytosterols or when micro-oxygenation is not desirable during fermentation.     

Assessing the impact of fisheries, climate and disease on the dynamics of the Indian yellow-nosed Albatross

Many seabird populations are currently decreasing, especially albatrosses for which the primary threat is recognised to be mortality in fisheries. Introduced predators, climate change and other factors such as diseases can also have large impacts on seabirds. Here, we assessed the relative effect of three potential threats: climate, fisheries and diseases on the demography of an endangered marine predator and modelled its population dynamics to project its size under different scenarios. We based our study on a long-term monitoring of a colony of individually marked Indian yellow-nosed albatrosses at Amsterdam Island, subtropical Indian Ocean, that has declined during the past twenty years. We found no evidence for an impact of legal tuna longlining on demographic parameters. Hatching success was lower during El Niño years but survival (0.902 ± 0.011) was not affected by climatic factors. Avian cholera caused high chick mortality (0.808 ± 0.181) which in turn probably triggered the high emigration rate (0.038 ± 0.011) through dispersal of failed breeders. This colony has a high risk of extinction. However, the rest of the population at Amsterdam Island seemingly not affected to the same extent, declined but stabilised since 1998. Matrix models indicated that lowered adult survival and the very low breeding success, resulting in low recruitment, have both contributed to the decline of the yellow-nosed albatross colony until the mid-1990s, but that more recent decline was primarily caused by low fledging success. Our results highlight that potential threats such as fisheries, diseases or climate have to be considered simultaneously to disentangle their roles when assessing the conservation status of a marine predator species.     

Using spectrocolourimetry to trace sediment source dynamics in coastal catchments draining the main Fukushima radioactive pollution plume (2011–2017)

Journal of Soils and Sediments - Spectrocolourimetric measurements provide a relatively inexpensive, quick and non-destructive alternative to the analysis of geochemical and organic matter...     

Animal poisoning in Europe. Part 1: Farm livestock and poultry

The lack of a reference Veterinary Poison Control Centre for the European Union (EU) means that clinicians find it difficult to obtain information on poisoning episodes. This three-part review collates published and unpublished data obtained from Belgium, France, Greece, Italy and Spain over the last decade in order to provide a broader toxicoepidemiological perspective. The first article critically evaluates the national situation in the five European countries and concludes that information for livestock and poultry is limited and fragmentary compared to other animal groups. The analysis has revealed that clinical cases of poisoning are only occasionally studied in depth and that cattle are the species most frequently reported. Several plants and mycotoxins, a few pesticides and metals, together with contaminants of industrial origin, such as dioxins, are responsible for most of the recorded cases.