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International Journal of Agronomy
Volume 2012 (2012), Article ID 176108, 7 pages
Research Article

Inheritance of Evolved Glyphosate Resistance in a North Carolina Palmer Amaranth (Amaranthus palmeri) Biotype

1Department of Crop Science, North Carolina State University, Box 7620, Raleigh, NC 27695, USA
2Department of Bioagricultural Sciences and Pest Management, Colorado State University, 1179 Campus Delivery, Fort Collins, CO 80523, USA
3School of Agriculture, Food & Wine, University of Adelaide, Adelaide, SA 5005, Australia
4Department of Horticulture Science, North Carolina State University, Box 7609, Raleigh, NC 27695, USA
5Crop and Soil Sciences, University of Georgia Southeast District, P.O. Box 8112, Statesboro, GA 30460, USA

Received 27 June 2012; Accepted 31 July 2012

Academic Editor: Kent Burkey

Copyright © 2012 Aman Chandi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Inheritance of glyphosate resistance in a Palmer amaranth biotype from North Carolina was studied. Glyphosate rates for 50% survival of glyphosate-resistant (GR) and glyphosate-susceptible (GS) biotypes were 1288 and 58 g ha−1, respectively. These values for F1 progenies obtained from reciprocal crosses (GR×GS and GS×GR were 794 and 501 g ha−1, respectively. Dose response of F1 progenies indicated that resistance was not fully dominant over susceptibility. Lack of significant differences between dose responses for reciprocal F1 families suggested that genetic control of glyphosate resistance was governed by nuclear genome. Analysis of F1 backcross (BC1F1) families showed that 10 and 8 BC1F1 families out of 15 fitted monogenic inheritance at 2000 and 3000 g ha−1 glyphosate, respectively. These results indicate that inheritance of glyphosate resistance in this biotype is incompletely dominant, nuclear inherited, and might not be consistent with a single gene mechanism of inheritance. Relative 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) copy number varied from 22 to 63 across 10 individuals from resistant biotype. This suggested that variable EPSPS copy number in the parents might be influential in determining if inheritance of glyphosate resistance is monogenic or polygenic in this biotype.