11 research outputs found

    The herbicide safener cloquintocet-mexyl reduces rye-grass (<em>Lolium</em> sp.) sensitivity to an ALS inhibitor and regulates candidate non-target-site-based resistance genes

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    National audienceSafeners enable selective control of weeds in botanically related crops by enhancing or triggering herbicide degradation in crop plants via mechanisms very similar to mechanisms involved in weed non-target-site-based resistance (NTSR). To assess whether safeners could play a role in NTSR evolution, we investigated the effect of the safener cloquintocet-mexyl on plant phenotype and on the expression level of 19 candidate NTSR genes in Lolium sp.. Twelve plants in each of three populations were split into 14 tillers each. Tillers from each plant was used in the following modalities: water (control, 2 tillers), Actirob B (adjuvant, 2 tillers), cloquintocet-mexyl, pyroxsulam+Actirob (4 tillers), cloquintocet-mexyl+pyroxsulam+Actirob (4 tillers) applied using a custom-built, single-nozzle (110-04, Albuz, France) sprayer delivering herbicide in 300L/ha water at 400kPa (6.6km/h, 23°C, relative humidity 80%). Actirob B (1L/ha), pyroxsulam (18.75g/ha) and cloquintocet-mexyl (18.75g/ha) were at the recommended field rate in every modality. Two tillers per plant and per modality were collected 24hours after application to measure the expression of the candidate NTSR genes. The effect of cloquintocet-mexyl on plant phenotype was rated 4 weeks after application using the additional 2 tillers in the last two modalities. Cloquintocet-mexyl reduced the sensitivity of some plants. A significant up-regulation of 8 candidate NTSR genes was observed 24hours after application of cloquintocet-mexyl alone. Plants showing a decrease in sensitivity when cloquintocet-mexyl was sprayed with pyroxsulam showed a higher up-regulation than other plants in modalities including cloquintocet-mexyl. An additive effect of pyroxsulam and cloquintocet-mexyl was observed on most genes regulation, with a relative effect of cloquintocetmexyl up to 48%. We demonstrated that cloquintocet-mexyl can modify herbicide sensitivity and regulate genes potentially involved in NTSR in Lolium sp.

    Imaging low-mass planets within the habitable zone of α Centauri

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    Giant exoplanets on wide orbits have been directly imaged around young stars. If the thermal background in the mid-infrared can be mitigated, then exoplanets with lower masses can also be imaged. Here we present a ground-based mid-infrared observing approach that enables imaging low-mass temperate exoplanets around nearby stars, and in particular within the closest stellar system, alpha Centauri. Based on 75-80% of the best quality images from 100h of cumulative observations, we demonstrate sensitivity to warm sub-Neptune-sized planets throughout much of the habitable zone of alpha Centauri A. This is an order of magnitude more sensitive than state-of-the-art exoplanet imaging mass detection limits. We also discuss a possible exoplanet or exozodiacal disk detection around alpha Centauri A. However, an instrumental artifact of unknown origin cannot be ruled out. These results demonstrate the feasibility of imaging rocky habitable-zone exoplanets with current and upcoming telescopes. Imaging of low-mass exoplanets can be achieved once the thermal background in the mid-infrared (MIR) wavelengths can be mitigated. Here, the authors present a ground-based MIR observing approach enabling imaging low-mass temperate exoplanets around nearby stars
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