Selection of non-target-site resistance (NTSR) to several ALS-inhibiting herbicides in three populations of Ambrosia artemisiifolia

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Selection of non-target-site resistance (NTSR) to several ALS-inhibiting herbicides in three populations of

Ambrosia artemisiifolia

Lucie Meyer, Bruno Chauvel, Valérie Le Corre, Christophe Délye

To cite this version:

Lucie Meyer, Bruno Chauvel, Valérie Le Corre, Christophe Délye. Selection of non-target-site resis- tance (NTSR) to several ALS-inhibiting herbicides in three populations of Ambrosia artemisiifolia. 7.

International Weed Science Congress, IWSC 2016, 2016, NA, France. 345 p. �hal-01608103�

Czech Weed Research Society

“Weed Science and Management to Feed the Planet” Proceedings

51 50

The herbicide safener cloquintocet-mexyl reduces rye-grass (Lolium sp.) sensitivity to an ALS inhibitor and regulates candidate non-target-site-based resistance genes (139)

Christophe Délye (INRA, Dijon, France), Arnaud Duhoux (INRA, Dijon, France)

Safeners 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 ab role in NTSR evolution, we investigated the e΍ ect of the safener cloquintocet-mexyl on plant phenotype and on the expression level of 18 candidate NTSR genes in Lolium sp.. Twelve plants in each of three populations were split into 14 tillers each. Tillers from each plant were used in the following modalities: water (control, 2 tillers), Actirob (adjuvant, 2 tillers), cloquintocet-mexyl, pyroxsulam+Actirob (4 tillers), cloquintocet-mexyl+pyroxsulam+Actirob (4 tillers) applied using ab 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 (1L/ha), pyroxsulam (18.75g/ha) and cloquintocet-mexyl (18.75g/ha) were at the recommended ȴ eld 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 e΍ ect of cloquintocet-mexyl on plant phenotype was rated 4 weeks after application using the remaining 2 tillers in the last two modalities. Overall, addition of cloquintocet- mexyl to pyroxsulam reduced the sensitivity of approx. 25% of the plants tested compared to pyroxsulam alone. Absigniȴ cant up-regulation of 8 candidate NTSR genes was observed 24 hours after application of cloquintocet-mexyl alone. Plants showing ab decrease in sensitivity when cloquintocet-mexyl was sprayed with pyroxsulam showed ab higher up- regulation than other plants in modalities including cloquintocet-mexyl. An additive e΍ ect of pyroxsulam and cloquintocet-mexyl on gene regulation was observed, with abrelative e΍ ect of cloquintocet-mexyl of up to 48%. We demonstrated that cloquintocet-mexyl can modify herbicide sensitivity and regulate genes potentially involved in NTSR in Lolium sp..

Keywords: Safener, Herbicide, Resistance, Lolium, Genes Selection of non-target-site resistance (NTSR) to several ALS-inhibiting herbicides

in three populations of Ambrosia artemisiifolia (65)

Lucie Meyer (INRA Dijon, DIJON, France), Géraldine Bailly (BASF France SAS, Ecully, France), Bruno Chauvel (INRA Dijon, DIJON, France), Valérie Le Corre (INRA Dijon, DIJON, France), Christophe Délye (INRA Dijon, DIJON, France)

Ambrosia artemisiifolia is an invasive and ab noxious weed. In America, it has evolved resistance to di΍ erent herbicide modes of action. This study uses ab recurrent selection approach to assess the capacity of A. artemisiifolia to evolve Non-Target-Site Resistance (NTSR) to ALS-inhibiting herbicides. Following establishment of baseline sensitivity to several ALS inhibitors, metsulfuron was used as the ȴ rst selection agent. The collateral selection of NTSR to tribenuron and imazamox, which are key herbicides for A. artemisiifolia control, was assessed in progenies from metsulfuron-selected plants.

Seeds from three ȴ eld populations (G0, no or low ALS-inhibiting herbicide history) were sampled. Herbicides were applied at the four-leaf stage using ab custom-built, single- nozzle (110-04, Albuz, France) sprayer delivering herbicide in 300L/ha water at 400kPa (speed 6.6km/h, temperature 23°C, relative humidity 80%). Plants that survived 4, 8 or 16g metsulfuron/ha were bulk-crossed per herbicide rate. ALS sequencing did not identify resistant ALS alleles in these G0 plants. Seeds were collected on each plant to obtain G1 progenies. Each G1 progeny was sprayed with the selecting G0 rate and abhigher rate (16, 24 or 40g metsulfuron/ha). Imazamox and tribenuron were also tested at two rates each on each G1 (12.5 and 50g imazamox/ha, 50g/ha=ȴ eld rate, and 6 and 30g tribenuron/ha, 30g/

ha=ȴ eld rate). Both herbicides gave full control of G0 plants at the lowest rates assayed.

45% to 60% plants in three G1 progenies survived the highest metsulfuron rates. 2.5% to 5% plants in three other G1 progenies survived the tribenuron ȴ eld rate and 8% plants in yet another G1 progeny survived the imazamox ȴ eld rate. Our results show that genetic factors contributing to NTSR to metsulfuron exist in A. artemisiifolia. Further selection with metsulfuron entailed evolution of NTSR to imazamox and tribenuron. G2 progenies that underwent an additional selection cycle are currently being assayed.

Keywords: Non-Target-Site Resistance, ALS-inhibiting herbicides, Ambrosia artemisiifolia