3D structure of acetolactate synthase explains why the Asp-376-Glu point mutation does not give the same resistance level to different imidazolinone herbicides.

Resistance to ALS-inhibiting herbicides has dramatically increased worldwide due to the persisting evolution of target site mutations that reduce the affinity between the herbicide and the target. We evaluated the effect of the well-known ALS Asp-376-Glu target site mutation on different imidazolinone herbicides, including imazamox and imazethapyr. Greenhouse dose response experiments indicate that the Amaranthus retroflexus biotype carrying Asp-376-Glu was fully controlled by applying the field recommended dose of imazamox, whereas it displayed high level of resistance to imazethapyr.

Development of a rapid detection assay for acetolactate synthase inhibitors resistance in three Amaranthus weed species through loop-mediated isothermal amplification.

Background: The early detection of herbicide resistance in weeds is a key factor to avoid herbicide waste and improve agriculture sustainability. The present study aimed to develop and validate an allele-specific loop-mediated isothermal amplification (AS-LAMP) assay for the quick on-site detection of the resistance-endowing point mutation Trp-574-Leu in the acetolactate synthase (ALS) gene in three widely diffused Amaranthus weed species: Amaranthus retroflexus, Amaranthus hybridus and Amaranthus tuberculatus.

Results: The AS-LAMP protocol was developed on wild-type and ALS-mutant plants of the three species and revealed that the amplification approach with only the primer set specific for the mutant allele (574-Leu) was the most promising.

Can allele-specific loop-mediated isothermal amplification be used for rapid detection of target-site herbicide resistance in Lolium spp.?

Background: Herbicide resistance is one of the threats to modern agriculture and its early detection is one of the most effective components for sustainable resistance management strategies. Many techniques have been used for target-site-resistance detection. Allele-Specific Loop-Mediated Isothermal Amplification (AS-LAMP) was evaluated as a possible rapid diagnostic method for acetyl-CoA carboxylase (ACCase) and acetolactate synthase (ALS) inhibiting herbicides resistance in Lolium spp.

Diversity and Spread of Acetolactate Synthase Allelic Variants at Position 574 Endowing Resistance in in Italy.

Poor control of spp. with herbicides inhibiting acetolactate synthase (ALS) has been observed for several years in soybean fields in north-eastern Italy, but to date only a few ALS-resistant populations have been confirmed. An extensive sampling of putatively resistant accessions was completed in the Friuli Venezia Giulia region, across an arable land area of about 3000 km.

Target-Site Mutations and Expression of Gene Copies Vary According to Species.

The sustainability of rice cropping systems is jeopardized by the large number and variety of populations of polyploid spp. resistant to ALS inhibitors. Better knowledge of the species present in Italian rice fields and the study of genes involved in target-site resistance could significantly contribute to a better understanding of resistance evolution and management.

Diversified Resistance Mechanisms in Multi-Resistant spp. in Three European Countries.

Annual ryegrass species ( spp.) infest cereal crops worldwide. Ryegrass populations with multiple resistance to the acetyl coenzyme A carboxylase (ACCase) and acetolactate synthase (ALS) inhibitors are an increasing problem in several European countries.

Sensitivity Analysis of Italian spp. to Glyphosate in Agricultural Environments.

Empirical observations generally indicate a shifting and decreased spp. susceptibility to glyphosate in Italy. This is likely due to the long history of glyphosate use and to the sub-lethal doses commonly used.

A New Ala-122-Asn Amino Acid Change Confers Decreased Fitness to ALS-Resistant .

Gene mutations conferring herbicide resistance may cause pleiotropic effects on plant fitness. Knowledge of these effects is important for managing the evolution of herbicide-resistant weeds. An population resistant to acetolactate synthase (ALS) herbicides was collected in a maize field in north-eastern Italy and the cross-resistance pattern, resistance mechanism and fitness costs associated to mutant-resistant plants under field conditions in the presence or absence of intra-specific competition were determined.

Occurrence of Different Resistance Mechanisms to Acetolactate Synthase Inhibitors in European Sorghum halepense.

Four Hungarian and two Italian Sorghum halepense populations harvested in maize fields were investigated to elucidate the levels and mechanisms underlying acetolactate synthase (ALS) inhibitors resistance. The two Italian populations were highly cross-resistant to all ALS inhibitors tested, and the variant ALS allele Leu was identified in most of the plants; no differences were observed when the plants were treated with herbicide plus malathion. This suggests that the main resistance mechanism is target-site mediated.

iMAR: An Interactive Web-Based Application for Mapping Herbicide Resistant Weeds.

Herbicides are the major weed control tool in most cropping systems worldwide. However, the high reliance on herbicides has led to environmental issues as well as to the evolution of herbicide-resistant biotypes. Resistance is a major concern in modern agriculture and early detection of resistant biotypes is therefore crucial for its management and prevention.

Protocols for Robust Herbicide Resistance Testing in Different Weed Species.

Robust protocols to test putative herbicide resistant weed populations at whole plant level are essential to confirm the resistance status. The presented protocols, based on whole-plant bioassays performed in a greenhouse, can be readily adapted to a wide range of weed species and herbicides through appropriate variants. Seed samples from plants that survived a field herbicide treatment are collected and stored dry at low temperature until used.

Allelic variation of the ACCase gene and response to ACCase-inhibiting herbicides in pinoxaden-resistant Lolium spp.

Background: The repeated use of acetyl-coenzyme A carboxylase (ACCase) inhibiting herbicides to control grass weeds has selected for resistance in Lolium spp. populations in Italy. The efficacy of pinoxaden, a recently marketed phenylpyrazoline herbicide, is of concern where resistance to ACCase inhibitors has already been ascertained.