Search results for " RESISTANCE"
showing 10 items of 2791 documents
The Sulfated Laminarin Triggers a Stress Transcriptome before Priming the SA- and ROS-Dependent Defenses during Grapevine's Induced Resistance agains…
2018
Grapevine (Vitis vinifera) is susceptible to many pathogens which cause significant losses to viticulture worldwide. Chemical control is available, but agro-ecological concerns have raised interest in alternative methods, especially in triggering plant immunity by elicitor treatments. The β-glucan laminarin (Lam) and its sulfated derivative (PS3) have been previously demonstrated to induce resistance in grapevine against downy mildew (Plasmopara viticola). However, if Lam elicits classical grapevine defenses such as oxidative burst, pathogenesis-related (PR)-proteins and phytoalexin production, PS3 triggered grapevine resistance via a poorly understood priming phenomenon. The aim of this st…
Spontaneous hybridizations between oilseed rape and wild radish
1998
The occurence of spontaneous hybridization between Brassica napus (oilseed rape) and Raphanus raphanistrum (wild radish) was investigated under different density conditions in cages and open-field experiments. Hybrids with wild radish as the seed parent were identified by screening for herbicide resistance belonging to rape. Small seed size and intermediate morphology were used to screen for hybrids with rape as the seed parent. Leaf isozyme patterns and flow cytometry provided confirmation of hybrids. Wild radish in an oilseed rape field produced as many as three interspecific hybrids per 100 plants. This is the first report of such a spontaneous event. The frequency of hybrids is expected…
Differences in Cellular Encapsulation of Six Termite (Isoptera) Species Against Infection by the Entomopathogenic FungusMetarhizium anisopliae
2011
Termites (Isoptera) are eusocial insects, which live in an environment that can favor the spread of pathogens. To reduce the chance of an epizootic within a colony, termites have evolved many defense mechanisms. Most studies have focused on the social aspect of disease resistance, while the individual capacity of a termite to survive an infection remains poorly documented. We previously showed that when the eastern subterranean termite, Reticulitermes flavipes (Kollar), was exposed to the entomopathogenic fungus, Metarhizium anisopliae (Metch.) Sorokin, cellular encapsulation of the penetrating fungus was one of the last lines of defense for individual termites to prevent internal mycosis. …
Modelling binary mixtures of herbicides in populations resistant to one of the components: evaluation for resistance management
2008
BACKGROUND: Herbicide mixtures are commonly proposed to delay the selection of herbicide resistance in susceptible populations (called the SM strategy). However, in practice, herbicide mixtures are often used when resistance to one of the two active ingredients has already been detected in the targeted population (called the RM strategy). It is doubtful whether such a practice can select against resistance, as the corresponding selection pressure is still exerted. As a consequence, the effect of mixtures on the evolution of an already detected resistance to one of the herbicides in the combination remains largely unexplored. In the present work, a simple model was developed to explore furth…
Cell interactions between a nonpathogenic Fusarium oxysporum strain and root tissues of Eucalyptus viminalis
2004
Nonpathogenic isolates of Fusarium oxysporum can be successful antagonists of pathogenic forms of the same fungal species that commonly attacks crop plants. The characteristics that distinguish nonpathogenic from pathogenic forms are not well understood. In this study, the mode of root colonization of Eucalyptus viminalis seedlings by a nonpathogenic F. oxysporum strain is described at the ultrastructural level. Root systems of E. viminalis plants were inoculated with nonpathogenic F. oxysporum strain Fo47 in an in vitro model system. Changes in the occurrence of nonesterified and methyl-esterified pectins in colonized E. viminalis roots were evaluated by in situ immunolabeling using two mo…
Large-Scale Monitoring of Resistance to Coumaphos, Amitraz, and Pyrethroids in Varroa destructor
2021
ABSTRACTVarroa destructor is an ectoparasitic mite causing devastating damages to honey bee colonies around the world. Its impact is considered a major factor contributing to the significant seasonal losses of colonies recorded every year. Beekeepers are usually relying on a reduced set of acaricides to manage the parasite, usually the pyrethroids tau-fluvalinate or flumethrin, the organophosphate coumaphos and the formamidine amitraz. However, the evolution of resistance in the populations is leading to an unsustainable scenario with almost no alternatives to reach an adequate control of the mite.Here we present the results from the first, large-scale and extensive monitoring of the suscep…
Heat hardening capacity in Drosophila melanogaster is life stage-specific and juveniles show the highest plasticity
2019
Variations in stress resistance and adaptive plastic responses during ontogeny have rarely been addressed, despite the possibility that differences between life stages can affect species' range margins and thermal tolerance. Here, we assessed the thermal sensitivity and hardening capacity of Drosophila melanogaster across developmental stages from larval to the adult stage. We observed strong differences between life stages in heat resistance, with adults being most heat resistant followed by puparia , pupae and larvae . The impact of heat hardening (1 h at 35°C) on heat resistance changed during ontogeny, with the highest positive effect of hardening observed in puparia and pupae and the …
Host plant variation plastically impacts different traits of the immune system of a phytophagous insect
2011
Summary 1. Host plant quality affects herbivorous insect performance and consequently their susceptibility to natural enemies. Recently, it has been hypothesized that the immune function of herbivorous insects can be altered by their host plant, thus generating variation in their susceptibility to entomopathogens. Previous studies testing this hypothesis provided contradictory outcomes, mainly as a result of the differences in methodology such as measuring a single-immune parameter rather than considering trade-off-mediated interactions between immune defence systems of the insect. Here, we hypothesized that plant-mediated changes in insect immunity could result from the alteration of physi…
Soybean and casein hydrolysates induce grapevine immune responses and resistance against Plasmopara viticola
2014
International audience; Plasmopara viticola, the causal agent of grapevine downy mildew, is one of the most devastating grape pathogen in Europe and North America. Although phytochemicals are used to control pathogen infections, the appearance of resistant strains and the concern for possible adverse effects on environment and human health are increasing the search for alternative strategies. In the present investigation, we successfully tested two protein hydrolysates from soybean (soy) and casein (cas) to trigger grapevine resistance against P. viticola. On Vitis vinifera cv. Marselan plants, the application of soy and cas reduced the infected leaf surface by 76 and 63%, as compared to th…
On the optimization of the cutting conditions for an improved corrosion resistance of OFHC copper
2018
International audience; Machining has a particular impact on the surface integrity and on corrosion resistance of components. In fact, material removal induces geometrical, mechanical and micro-structural modifications in the machined surface and sub-surface that alter the electrochemical behavior of the material, and so the aging process. In this study, oxygen free high conductivity copper (OFHC) has machined under orthogonal cutting conditions using uncoated cemented carbide tools. Then, the corrosion resistance in 0.1 M NaCl salt fog atmosphere of the machined samples is analyzed. Finally, the optimal cutting conditions, including the tool geometry, for an improved corrosion resistance a…