Study of the mechanisms of resistance to glyphosate in populations of Lolium multiflorum of the Southwest of Buenos Aires province and tolerance of populations of the Buenos Aires southeast

DIEZ DE ULZURRUM PATRICIA; MARGUERITTE PAZ CRISTIÁN; MASSA GABRIELA ALEJANDRA; FEINGOLD SERGIO ENRIQUE; LEADEN MARIA INES

Miami Beach, Florida

Conferencia; Pan American Weed Resistance Conference; 2010

Bayer CropScience

Glyphosate resistant soybean cultivars were released in Argentina  in 1996. Since then the area sowed with it grew exponentially, and, accordingly glyphosate use. It is known that the repeated use of the same herbicide causes a selection pressure on plant populations that lead to resistance. The frequent use of the herbicide glyphosate in weed control that led to the emergence of resistance in the southwest of Buenos Aires and a possible increase in the tolerance of the dominant biotypes of the region. In several species have confirmed that specific variations in the nucleotide sequence encode for the enzyme EPSPS confers resistance to glyphosate. Thus, in Eleusine indica and Lolium rigidum founded that the amino acid substitution at position 101 and 106 (Perez Jones et al., 2005, Perez Jones et al., 2007) generates resistance to glyphosate. In Lolium multiflorum verified the substitution of amino acid position 106 only in a population from Chile, but not in a U.S. population (Perez Jones et al., 2007). In this work  will be evaluated  the sequence of the specific region of EPSPS enzyme in L. multiflorum of the Southwest of Buenos Aires province. Additionally we determinated  the lethal dose 50 (LD50) of two populations of Lolium multiflorum that showed low sensitivity to the herbicide glyphosate in Balcarce (Buenos Aires, Argentina).