Evolved glyphosate resistance in weedy species represents a challenge for the continued success and utility of glyphosate-resistant crops. Glyphosate functions by inhibiting the plant enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). The resistance mechanism was determined in a population of glyphosate-resistant Palmer amaranth from Georgia (U.S.). Within this population, glyphosate resistance correlates with increases in (a) genomic copy number of EPSPS, (b) expression of the EPSPS transcript, (c) EPSPS protein level, and (d) EPSPS enzymatic activity. Dose response results from the resistant and an F2 population suggest that between 30 and 50 EPSPS genomic copies are necessary to survive glyphosate rates between 0.5 and 1.0 kg ha−1. These results further confirm the role of EPSPS gene amplification in conferring glyphosate resistance in this population of Palmer amaranth. Questions remain related to how the EPSPS amplification initially occurred and the occurrence of this mechanism in other Palmer amaranth populations and other glyphosate-resistant species.
Anderson, Jenny. 2006. “Betting on the Weather and Taking an Ice-Cold Bath.” New York Times (29 September).
Burton, Catherine, and Jenny Strasburg. 2006. “Amaranth’s $6.6 Billion Slide Began with Trader’s Bid to Quit.” Bloomberg (6 December).
Chincarini, Ludwig B. 2007.”The Amaranth Debacle: A Failure of Risk Measures or a Failure of Risk Management?” TheJournal of Alternative Investments (Winter 2007):91–104.
Chincarini, Ludwig B. “A Case Study on Risk Management: Lessons from the Collapse of Amaranth Advisors LLC.”
Davis, Ann. 2006. “How Giant Bets on Natural Gas Sank Brash Hedge-Fund Trader.” Wall Street Journal (19 September).
“Excessive Speculation in the Natural Gas Market.” 2007. Staff Report of the Permanent Subcommittee on Investigations, Committee on Homeland Security and Government Affairs, United States Senate (25 June).
Federal Energy Regulatory Commission. 2010. “Summary of FERC Ruling against Brian Hunter, Head Trader at Amaranth Advisors” (22 January).
Goodman, Leah McGrath. 2014. “The ‘Rogue Trader’ Who Got Away with It.” Newsweek (17 September).
Maounis, Nick. 2006. “Investor Conference Call.” Amaranth Group, Inc. (22 September).
McCall, Matthew. 2006. “Losing the Amaranth Gamble.” Investopedia (14 December).
Till, Hillary. 2007. “The Amaranth Collapse: What Happened and What Have We Learned Thus Far?” Working paper, EDHEC Risk and Asset Management Research Centre (August).
Zuckerman, Gregory. 2006. “How the Wreck from Amaranth Was Contained.” Wall Street Journal (5 October).