RESUMO
BACKGROUND: Studies were conducted to elucidate the mechanism of glufosinate resistance in an Italian ryegrass population. RESULTS: Glufosinate rates required to reduce growth by 50% (GR(50)) were 0.15 and 0.18 kg AI ha(-1) for two susceptible populations C1 and C2 respectively, and 0.45 kg AI ha(-1) for the resistant population MG, resulting in a resistance index of 2.8. Ammonia accumulation after glufosinate treatment was on average 1.5 times less for the resistant population than for the susceptible populations. The glufosinate concentrations (µM) required to reduce the glutamine synthetase (GS) enzyme activity by 50% (I(50)) were 31 and 137 for C1 and C2 respectively, and 2432 for the resistant population MG. One amino acid substitution in the plastidic GS2 gene, aspartic acid for asparagine at position 171, was identified in the resistant population. CONCLUSIONS: This is the first report of glufosinate resistance in a weed species that involves an altered target site.
Assuntos
Aminobutiratos/farmacologia , Resistência a Herbicidas , Herbicidas/farmacologia , Lolium/efeitos dos fármacos , Sequência de Aminoácidos , Substituição de Aminoácidos , Amônia/metabolismo , Glutamato-Amônia Ligase/antagonistas & inibidores , Glutamato-Amônia Ligase/química , Glutamato-Amônia Ligase/genética , Glutamato-Amônia Ligase/metabolismo , Lolium/enzimologia , Lolium/genética , Lolium/metabolismo , Dados de Sequência Molecular , Mutação , Proteínas de Plantas/antagonistas & inibidores , Proteínas de Plantas/química , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Alinhamento de SequênciaRESUMO
Gene flow was raised as one of the first issues related to the development and release of genetically engineered (GE) crops. Gene flow has remained a topic of discussion for more than 20 years and is still used as an argument against the release of transgenic crops. With respect to herbicide-resistant crops, gene flow does not differ whether the herbicide resistance trait is introduced via genetic engineering or via conventional breeding techniques. Conventional breeding and genetic engineering techniques have been used to produce herbicide resistance in many of the same crop species. In addition, conventional breeding has been used to produce a broader range of herbicide-resistant crops than have been genetically engineered for herbicide resistance. Economic, political, and social concerns center on the breeding technique, but the results of gene flow for weed management are the same irrespective of breeding technique. This paper will focus on gene flow from nonGE herbicide-resistant crops in North America.
