Identification of apsbAMutation (Valine₂₁₉to Isoleucine) in Powell Amaranth (Amaranthus powellii) Conferring Resistance to Linuron

Abstract

A Powell amaranth population suspected to be resistant (R) to linuron was discovered in a carrot field in Keswick, Ontario, Canada, in 1999. Dose–response analysis with different herbicides and DNA sequencing of thepsbAgene encoding the D1 protein of photosystem II were done to confirm the resistance and identify its basis. A calculated resistance factor indicated a 12-fold increased resistance when linuron was applied to an R population compared with a susceptible (S) population. Moreover, the R population showed 6.4- and 3.1-fold greater resistance to two other phenylurea herbicides (diuron and monolinuron), 1.8- and 1.4-fold greater resistance to two triazine herbicides (metribuzin and prometryn), and 2.6-fold greater resistance to the triazinone metribuzin. R population was also cross-resistant to bentazon and bromoxynil when compared with S population, with a calculated resistance factor of 1.4 and 2.2, respectively. The partial nucleotide sequence of thepsbAgene of R populations differed at two locations when compared with S populations. The first mutation coded for a Val219Ile substitution in the deduced amino acid sequence of the D1 protein, and the second mutation was silent and encoded for a proline at position 279 in both R and S populations. The Val219Ile substitution in thepsbAgene is most likely the cause of this Powell amaranth population resistance to linuron and other PSII inhibitors. This is the first recorded instance of a Val219Ile substitution in anAmaranthusspecies.

Multiple-and Cross-Resistance of Amaranthus retroflexus to Acetolactate Synthase (ALS) and Photosystem II (PSII) Inhibiting Herbicides in Preemergence

“…In these cases, the mechanism that confers resistance to the herbicides of this group is Ser 264 Gly mutation in psbA gene, which changes the configuration of D1 protein of PS II, preventing the herbicides binding to the target binding site. In the case of simultaneous resistance to triazines and urea herbicides, the mechanisms most commonly found is Val 219 Ile mutation in the psbA gene (Mengistu et al, 2000(Mengistu et al, , 2005Dumont et al, 2016).…”

A linuron-free weed management strategy for carrots

“…The definition fails to note that the herbicide is the selective agent in the process leading to resistance. Instances of herbicide resistance date back to the 1950s, but the number of resistance cases has increased steadily since then (WSSA 2018 (Dumont et al 2016). In addition, resistant species have been found to have low level resistance to other PSII inhibitors such as atrazine, prometryn, metribuzin, bromoxynil and bentazon rendering these herbicides less effective (Dumont et al 2016).…”

“…On a positive note, the resistance mutation occurs in the plastome meaning resistance cannot be passed on through pollen, but it will be spread by seed (Dumont et al 2016). Generally, a resistant weed species will appear as an isolated patch, but over only a few years that resistant population can dominate a field and the seedbank (WSSA 2018).…”

Induced novel psbA mutation (Ala251 to Thr) in higher plants confers resistance to PSII inhibitor metribuzin in Lens culinaris

“…Research with algae and cyanobacteria has shown that specific amino acid substitutions between positions Phe 211 and Leu 275 in the QB binding niche of the D1 protein confer resistance to PSII inhibitor herbicides . A summary of a number of studies with higher plants report eight substitutions in the D1 protein, Leu 218 Val, Val 219 Ile, Ala 251 Val, Phe 255 Ile, Phe 255 Val, Ser 264 Gly, Ser 264 Thr and Asn 266 Thr, as being associated with resistance to PSII inhibitors in various weed species . The type and extent of herbicide resistance depends upon the individual substitution and the species involved, with no one substitution providing resistance to all PSII inhibitors …”

“…6 A summary of a number of studies with higher plants report eight substitutions in the D1 protein, Leu 218 Val, Val 219 Ile, Ala 251 Val, Phe 255 Ile, Phe 255 Val, Ser 264 Gly, Ser 264 Thr and Asn 266 Thr, as being associated with resistance to PSII inhibitors in various weed species. 7 The type and extent of herbicide resistance depends upon the individual substitution and the species involved, with no one substitution providing resistance to all PSII inhibitors. 6 The only reported case of a crop species possessing a target site resistance to a PSII herbicide inhibitor is in canola (Brassica napus L.).…”