The First Case of Short-Spiked Canarygrass (Phalaris brachystachys) with Cross-Resistance to ACCase-Inhibiting Herbicides in Iran

Sajedeh Golmohammadzadeh,Antonia M Rojano-Delgado,M Dolores Osuna-Ruíz,Javid Gherekhloo,Behnam Kamkar,Farshid Ghaderi-Far,Rafael De Prado

doi:10.3390/agronomy9070377

Abstract

The weed Phalaris brachystachys Link. severely affects winter cereal production. Acetyle-CoA Carboxylase (ACCase)-inhibiting herbicides are commonly used to control this weed in wheat fields. Thirty-six populations with suspected resistance to ACCase-inhibiting herbicides were collected from wheat fields in the Golestan Province in Iran. A rapid test performed in Petri dishes and whole-plant dose–response experiments were conducted to confirm and investigate the resistance level of P. brachystachys to ACCase-inhibiting herbicides. The seed bioassay results showed that 0.02 mg ai L−1 clodinafop-propargyl (CP) and 1.36 mg ai L−1 of the diclofop-methyl (DM) solution were the optimal amounts for reliably screening resistant and susceptible P. brachystachys populations. In the whole plant bioassay, all populations were found to be resistant to CP, resistance ratios ranging from 2.7 to 11.6, and all of the CP-resistant populations exhibited resistance to DM. Fourteen populations showed low resistance to cycloxydim, and thirteen of these populations were also 2-fold resistant to pinoxaden. The results showed that DM resistance in some P. brachystachys populations is likely due to their enhanced herbicide metabolism, which involves Cytochrome P450 monooxygenases, as demonstrated by the indirect assay. This is the first report confirming the cross-resistance of ACCase-inhibiting herbicides in P. brachystachys in Iran.

Highlights

Wheat (Triticum aestivum L.) is one of the most important crops in Iran
The target site of these herbicides is Acetyl-CoA Carboxylase (ACCase; EC 6.4.1.2), which is a key enzyme that catalyzes the primary step in fatty acid biosynthesis [7]
Resistance likely did not develop via a single mechanism; rather, multiple mechanisms, including enhanced metabolism, an altered target site, and other uncharacterized mechanisms, may be involved [29]. This is the first study confirming the cross-resistance of the aryloxyphenoxypropionates, cyclohexanediones and phenylpyrazolines herbicides in P. brachystachys in Iran

Summary

Introduction

The annual Poaceae species short-spiked Canarygrass (Phalaris brachystachys Link) is a common and troublesome weed in winter cereals in Mediterranean countries [2]. This is a vigorous and prolific weed that can significantly reduce wheat and barley yields and has been shown to decrease wheat yield by 16 to 60% [3,4]. The use of herbicides is the most efficient and economical means of controlling grass weeds, and several ACCase-inhibitors have been registered in Iran in the last three decades [6]. The target site of these herbicides is Acetyl-CoA Carboxylase (ACCase; EC 6.4.1.2), which is a key enzyme that catalyzes the primary step in fatty acid biosynthesis [7]. ACCase-inhibiting herbicides are classified into three major families: aryloxyphenoxypropionates (APP), cyclohexanediones (CHD), and phenylpyrazolines

Objectives

Methods

Results

Discussion

Conclusion