Fitness Cost Associated With Enhanced Gene Copy Number and Glyphosate Resistance in an Population.

The evolution of resistance to pesticides in agricultural systems provides an opportunity to study the fitness costs and benefits of novel adaptive traits. Here, we studied a population of (common waterhemp), which has evolved resistance to glyphosate. The growth and fitness of seed families with contrasting levels of glyphosate resistance was assessed in the absence of glyphosate to determine their ability to compete for resources under intra- and interspecific competition.

Characterization of 4-hydroxyphenylpyruvate dioxygenases, inhibition by herbicides and engineering for herbicide tolerance in crops.

4-Hydroxyphenylpyruvate dioxgenase (HPPD) enzymes from rat and from several plants contained only about a single inhibitor-binding active site per dimer which matched the content of iron in the purified Arabidopsis thaliana and Avena sativa enzymes. The dimeric HPPDs were about 10 fold more catalytically active than the tetrameric P. fluorescens enzyme with k/K values ranging from 0.

Mechanism of resistance to mesotrione in an Amaranthus tuberculatus population from Nebraska, USA.

Amaranthus tuberculatus is a troublesome weed in corn and soybean production systems in Midwestern USA, due in part to its ability to evolve multiple resistance to key herbicides including 4-hydroxyphenylpyruvate dioxygenase (HPPD). Here we have investigated the mechanism of resistance to mesotrione, an important chemical for managing broadleaf weeds in corn, in a multiple herbicide resistant population (NEB) from Nebraska. NEB showed a 2.

Synthesis and evaluation of hydroxyazolopyrimidines as herbicides; the generation of amitrole in planta.

Background: Exploiting novel herbicidal modes of action is an important method to overcome the challenges faced by increasing resistance and regulatory pressure on existing commercial herbicides. Recent reports of inhibitors of enzymes in the non-mevalonate pathway of isoprenoid biosynthesis led to the design of a novel class of azolopyrimidines which were assessed for their herbicidal activity. Studies were also undertaken to determine the mode of action responsible for the observed herbicidal activity.

Role of a novel I1781T mutation and other mechanisms in conferring resistance to acetyl-CoA carboxylase inhibiting herbicides in a black-grass population.

Background: Knowledge of the mechanisms of herbicide resistance is important for designing long term sustainable weed management strategies. Here, we have used an integrated biology and molecular approach to investigate the mechanisms of resistance to acetyl-CoA carboxylase inhibiting herbicides in a UK black-grass population (BG2).

Methodology/principal Findings: Comparison between BG2 phenotypes using single discriminant rates of herbicides and genotypes based on ACCase gene sequencing showed that the I1781L, a novel I1781T, but not the W2027C mutations, were associated with resistance to cycloxydim.

A novel W1999S mutation and non-target site resistance impact on acetyl-CoA carboxylase inhibiting herbicides to varying degrees in a UK Lolium multiflorum population.

Background: Acetyl-CoA carboxylase (ACCase) inhibiting herbicides are important products for the post-emergence control of grass weed species in small grain cereal crops. However, the appearance of resistance to ACCase herbicides over time has resulted in limited options for effective weed control of key species such as Lolium spp. In this study, we have used an integrated biological and molecular biology approach to investigate the mechanism of resistance to ACCase herbicides in a Lolium multiflorum Lam.

Broad resistance to ACCase inhibiting herbicides in a ryegrass population is due only to a cysteine to arginine mutation in the target enzyme.

Background: The design of sustainable weed management strategies requires a good understanding of the mechanisms by which weeds evolve resistance to herbicides. Here we have conducted a study on the mechanism of resistance to ACCase inhibiting herbicides in a Lolium multiflorum population (RG3) from the UK.

Methodology/principal Findings: Analysis of plant phenotypes and genotypes showed that all the RG3 plants (72%) that contained the cysteine to arginine mutation at ACCase codon position 2088 were resistant to ACCase inhibiting herbicides.

A novel P106L mutation in EPSPS and an unknown mechanism(s) act additively to confer resistance to glyphosate in a South African Lolium rigidum population.

Glyphosate resistance evolution in weeds is a growing problem in world agriculture. Here, we have investigated the mechanism(s) of glyphosate resistance in a Lolium rigidum population (DAG1) from South Africa. Nucleotide sequencing revealed the existence of at least three EPSPS homologues in the L.