1. Dry weight (% of untreated)
Id: 188
Multiple herbicide resistance in corn poppy (Papaver rhoeas) populations from Spain
Joel Torra and Jordi Rey-Caballero
Weed Science and Plant Ecology Research Group, Agrotecnio, Universitat de Lleida, Spain
BACKGROUND:
Resistance to tribenuron-methyl or 2,4-D in Papaver rhoeas is common in several European countries. Multiple resistant populations are usual in Spain.
Target Site Resistance (TSR) to ALS inhibitors is spread while Non-target site resistance (Non-TSR) has been confirmed in Italy; resistant mechanisms to synthetic auxines remain unknown.
The aims are to study 1) TSR and Non-TSR to ALS inhibitors, 2) the mechanisms conferring resistance to 2,4-D and 3) evidences of evolving resistance to photosystem II (PS II) inhibitors.
MATERIALS & METHODS:
Populations: 2,4-D and tribenuron-methyl/2,4-D resistant populations from Spain, and susceptible populations (UK and Spain).
Dose-response curves: (tribenuron, florasulam, imazamox, 2,4-D, bromoxynil).
Absorption and translocation experiments with 14C-tribenuron-methyl and 14C-2,4-D.
Genotyping vs Phenotyping to study cross-resistance patterns betweem ALS inhibitors chemistries.
RESULTS:
Multiple resistance to ALS inhibitors and synthetic auxines was confirmed in several Spanish populations (Figure 1).
TSR to ALS inhibitors was conferred by different aminoacid substitutions in Pro197 (Ser, Thr, Arg, Leu, Ala, His).
Non-TSR evidences to ALS inhibitors: a) plants w/o mutation survived; b) genotype and phenotype not correlated.
Resistance to 2,4-D is conferred by reduced translocation of the herbicide in resistant plants (Figure 2), both in multiple or only 2,4-D resistant populations (Rey-Caballero et al., 2016).
Low resistance factor (2.2) to bromoxynil in late applications observed in one population (Figure 3).
99 g a.i. /ha
198 g i.a. /ha
39.6 g a.i. /ha
Susceptible
Multiple Resistant
198 g a.i. /ha
2,4-D
Tribenuron-methyl 6 60
600
6000
g a.i./ha
0.1875
1.875
18.75
187.5 20 40 80
100
Dry weight (% of untreated) S1 S2
2,4-D R
ALS and 2,4-D R
Figure 2:
Digital image (up) and autoradiographic image (below) depicting [14C]-2,4-D translocation throughout plants tissues of susceptible (left), ALS inhibitors and 2,4-D resistant (middle) and only 2,4 resistant (right) populations of corn poppy (Papaver rhoeas), 48 HAT. Arrows in the upper image indicate the leaf where [14C]-2,4-D droplets were applied
Figure 1:
Dose-response regression curves of susceptible (H-S013 and S-S012), and resistant (D-R703 and F-R213) corn poppy (Papaver rhoeas) populations to 2,4-D (A) and tribenuron-methyl (B) (log scale). Data were expressed as percentage of the mean dry weight of untreated control plants
Susceptible
ALS and 2,4-D R
2,4-D R
Figure 3: Images of pots of two Papaver rhoeas populations (upper part), one susceptible (left) and one multiple resistant to 2,4-D and ALS inhibitors (right), applied at three rates of bromoxynil. Bigger images of plants surviving at 198 g a.i./ha are shown below.
DISCUSSION:
Resistance to synthetic auxins could involve membrane efflux transporters (ABC family or PIN families).
The spreading of Non-TSR mechanisms to ALS in inhibitors in P. rhoeas is a serious thread for in European arable fields.
Resistance to bromoxynil is awaiting confirmation with the progeny.
The implementation of Integrated Weed Management strategies is mandatory for this species.