BACKGROUND In a large cropping area of northern Argentina, Sorghum halepense (Johnsongrass) has evolved towards glyphosate resistance. This study aimed to determine the molecular and biochemical basis conferring glyphosate resistance in this species. Experiments were conducted to assess target EPSPS gene sequences and (14)C-glyphosate leaf absorption and translocation to meristematic tissues. ...

5-enolpyruvylshikimate 3-phosphate synthase (EPSPS) is a key enzyme in the shikimate pathway and is targeted by the wide-spectrum herbicide glyphosate. Here, we describe the use of a selection system based on directed evolution to select glyphosate-resistant mutants of EPSPS. Using this system, the rice (Oryza sativa) EPSPS gene, mutagenized by Error-Prone polymerase chain reaction, was introdu...

Glyphosate is the most widely used herbicide in the world for several reasons, including: 1) high level of effectiveness, 2) flexibility in application, 3) large margin of crop safety in glyphosate resistant crops, and 4) safety to applicators and the environment. Glyphosate was used for more than 20 years before weeds developed resistance to the chemical. This relative low risk of glyphosate r...

Transgenic glyphosate-resistant canola was first commercially grown in Western Australia (WA) in 2010, providing an opportunity to obtain important baseline data regarding the level of glyphosate resistance in weeds following the exclusive use of glyphosate for in-crop weed control. In this study, two surveys (2010 and 2011) were conducted across the 14Mha of the grainbelt of WA. The 2010 surve...

Greenhouse and laboratory studies were conducted to confirm and quantify glyphosate resistance, quantify pyrithiobac resistance, and investigate interaction between flumiclorac and glyphosate mixtures on control of Palmer amaranth from Mississippi. The GR50 (herbicide dose required to cause a 50% reduction in plant growth) values for two glyphosateresistant biotypes, C1B1 and T4B1, and a glypho...

Glyphosate use in the United Kingdom has more than doubled in the last 20 years. Much of this increase is driven by efforts to control herbicide resistant weeds, particularly Alopecurus myosuroides, prior to crop drilling. There is precedent for evolution of glyphosate resistance in similar situations, raising concerns over the sustainability of glyphosate use in the UK. We used dose-response e...

The Chloris genus is a C4 photosynthetic species mainly distributed in tropical and subtropical regions. Populations of three Chloris species occurring in citrus orchards from central Cuba, under long history glyphosate-based weed management, were studied for glyphosate-resistant status by characterizing their herbicide resistance/tolerance mechanisms. Morphological and molecular analyses allow...

Greenhouse and field studies were conducted in 2007 and 2008 to investigate possible multiple-resistance of horseweed to paraquat and glyphosate, and to evaluate the effect of the addition of metribuzin to paraquat on control of paraquat-resistant horseweed. Results indicated that the GR50 (herbicide dose required to cause a 50% reduction in plant growth) value for the susceptible population S1...

In 2014 hairy beggarticks (Bidens pilosa L.) has been identified as being glyphosate-resistant in citrus orchards from Mexico. The target and non-target site mechanisms involved in the response to glyphosate of two resistant populations (R1 and R2) and one susceptible (S) were studied. Experiments of dose-response, shikimic acid accumulation, uptake-translocation, enzyme activity and 5-enolpyru...

I n a world of more than 6 billion people, humans heavily rely on the dependable cultivation of the global food grain crops: rice, wheat, soybeans, maize (and cotton for fiber). History shows that threats to food production have major repercussions, including famine, war, and civil unrest. A major threat to food production occurs every single growing season, when wild plant species (weeds) infe...