Background: Lolium multiflorum Lam. (Italian ryegrass, annual ryegrass) is both a weed and a crop in Oregon. Because it is commonly managed using chemical controls, herbicide-resistant populations have evolved within the seed production region. A glyphosate-resistant population was identified in Yamhill County, Oregon, in a fallow field previously cropped with perennial ryegrass.
Results: Dose-response studies showed that the glyphosate-resistant population, OR12, was nine-fold more resistant to glyphosate than the susceptible population. No EPSPS amino acid substitutions known to confer glyphosate resistance were observed via gene sequencing. Quantitative polymerase chain reaction (qPCR) of genomic DNA revealed a mean 30-fold increase in EPSPS gene copies in the OR12 population. Biomass after glyphosate treatment was correlated with EPSPS gene copy number of individual plants.
期刊介绍:
Pest Management Science is the international journal of research and development in crop protection and pest control. Since its launch in 1970, the journal has become the premier forum for papers on the discovery, application, and impact on the environment of products and strategies designed for pest management.
Published for SCI by John Wiley & Sons Ltd.