Spread of glyphosate‐resistant sourgrass (Digitaria insularis): Independent selections or merely propagule dissemination?. Issue 1 (25th March 2018)

• Record Type: Journal Article
• Authors: Takano, Hudson K.; de Oliveira, Rubem S.; Constantin, Jamil; Mangolim, Claudete A.; Machado, Maria de F.P.S.; Bevilaqua, Maycon R.R.
• Is Part Of: Weed biology and management. Volume 18:Issue 1(2018)
• Page Start: 50
• Page End: 59
• Publication Date: 2018-03-25
• Subjects: gene flow -- genetic diversity -- herbicide resistance -- independent selection -- inter simple sequence repeat loci; Weeds -- Periodicals; Weeds -- Control -- Periodicals; 632.5
• DOI: 10.1111/wbm.12143
• Languages: English
• ISSNs: 1444-6162

Abstract

Abstract : The first reports of glyphosate‐resistant (GR) sourgrass ( Digitaria insularis ) came from Paraguay (2005) and from South and Southeast Brazil, in Paraná (2008), and São Paulo state (2009). The hypothesis of this research is that the evolution of these resistant populations might have occurred independently. To test this hypothesis, a dose–response experiment was conducted in order to confirm resistance and inter simple sequence repeat markers subsequently were evaluated in five sourgrass populations from Paraguay (PY‐R), Paraná (PR‐S and PR‐R), and São Paulo (SP‐S and SP‐R). Resistant populations were confirmed in PY‐R, PR‐R and SP‐R. The resistant populations presented lower polymorphism than susceptible populations, possibly related to the selection pressure exerted by the herbicide. Both similarity matrix and dendrogram provided evidences that the origin of resistance in the populations from Paraguay and Paraná could be the same, which also is explained by their geographical proximity. In contrast, the evolution of GR populations in São Paulo was suggested to occur independently from other locations because resistance evolved in genetically divergent populations. This study's data provide evidences that GR sourgrass populations from Paraguay and Paraná share a similar genetic background; therefore, it is possible that resistance from Paraguay spread to Paraná through gene flow. The population from São Paulo probably was selected independently because the high values of its genetic structure and low level of gene flow. Independent selections and seed dispersion of GR sourgrass have contributed to the rapid spread of resistance across South America.