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Type: Journal article
Title: Gene amplification confers glyphosate resistance in Amaranthus palmeri
Author: Gaines, T.
Zhang, W.
Wang, D.
Bukun, B.
Chisholm, S.
Shaner, D.
Nissen, S.
Patzoldt, W.
Tranel, P.
Stanley Culpepper, A.
Grey, T.
Webster, T.
Vencill, W.
Sammons, R.
Jiang, J.
Preston, C.
Leach, J.
Westra, P.
Citation: Proceedings of the National Academy of Sciences of USA, 2010; 107(3):1029-1034
Publisher: Natl Acad Sciences
Issue Date: 2010
ISSN: 0027-8424
Statement of
Todd A. Gaines, Wenli Zhang, Dafu Wang, Bekir Bukun, Stephen T. Chisholm, Dale L. Shaner, Scott J. Nissen, William L. Patzoldt, Patrick J. Tranel, A. Stanley Culpepper, Timothy L. Grey, Theodore M. Webster, William K. Vencill, R. Douglas Sammons, Jiming Jiang, Christopher Preston, Jan E. Leach, and Philip Westra
Abstract: The herbicide glyphosate became widely used in the United States and other parts of the world after the commercialization of glyphosate- resistant crops. These crops have constitutive overexpression of a glyphosate-insensitive form of the herbicide target site gene, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). Increaseduse of glyphosate overmultiple years imposes selective genetic pressure on weed populations. We investigated recently discovered glyphosate- resistant Amaranthus palmer i populations from Georgia, in comparison with normally sensitive populations. EPSPS enzyme activity from resistant and susceptible plants was equally inhibited by glyphosate, which led us to use quantitative PCR to measure relative copy numbers of the EPSPS gene. Genomes of resistant plants contained from5-foldtomore than160-foldmore copies of the EPSPSgenethan did genomes of susceptible plants. Quantitative RT-PCR on cDNA revealed that EPSPS expression was positively correlated with genomic EPSPS relative copy number. Immunoblot analyses showed that increased EPSPS protein level also correlated with EPSPS genomic copy number. EPSPS gene amplification was heritable, correlated with resistance in pseudo-F2 populations, and is proposed to be the molecular basis of glyphosate resistance. FISH revealed that EPSPS genes were present on every chromosome and, therefore, gene amplification was likely not caused by unequal chromosome crossing over. This occurrence of geneamplification as an herbicide resistance mechanism in a naturally occurring weed population is particularly significant because it could threaten the sustainable use of glyphosate- resistant crop technology.
Keywords: 5-enolpyruvylshikimate-3-phosphate synthase
herbicide resistance
mobile genetic element
Palmer amaranth
Rights: © Authors
DOI: 10.1073/pnas.0906649107
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Appears in Collections:Agriculture, Food and Wine publications
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