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Date: Mon, 14 Feb 2011 16:35:42 -0800
From: "GMWatch" <[log in to unmask]>
Subject: GMW: GM industry 'solution' to glyphosate resistant weeds - 2,
 4-D-resistant crops
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NOTE: Chemical/GM company Dow has come up with a 'solution' to the problem=
 of glyphosate-resistant weeds, which are fast making GM Roundup Ready tec=
hnology redundant. The company has identified a gene that, when engineered=
 into maize plants, makes them tolerate being doused with 2,4-D and relate=
d herbicides, as detailed in a study by Dow employees (abstract below). Th=
is is touted as an important advance that "can help preserve the productiv=
ity and environmental benefits of herbicide-resistant crops". The authors=
 claim in their study that 2,4-D is safe - citing two non-peer reviewed so=
urces.
---
---
Wright, T. R., G. Shan, et al. (2010). "Robust crop resistance to broadlea=
f and grass herbicides provided by aryloxyalkanoate dioxygenase transgenes=
." Proc Natl Acad Sci U S A 107(47): 20240-20245.

Free in full:  http://www.pnas.org/content/107/47/20240.full.pdf+html

Engineered glyphosate resistance is the most widely adopted genetically mo=
dified trait in agriculture, gaining widespread acceptance by providing a=
 simple robust weed control system. However, extensive and sustained use=
 of glyphosate as a sole weed control mechanism has led to field selection=
 for glyphosate-resistant weeds and has induced significant population shi=
fts to weeds with inherent tolerance to glyphosate. Additional weed contro=
l mechanisms that can complement glyphosate-resistant crops are, therefore=
, urgently needed. 2,4-dichlorophenoxyacetic acid (2,4-D) is an effective=
 low-cost, broad-spectrum herbicide that controls many of the weeds develo=
ping resistance to glyphosate. We investigated the substrate preferences=
 of bacterial aryloxyalkanoate dioxygenase enzymes (AADs) that can effecti=
vely degrade 2,4-D and have found that some members of this class can act=
 on other widely used herbicides in addition to their activity on 2,4-D.=
 AAD-1 cleaves the aryloxyphenoxypropionate
family of grass-active herbicides, and AAD-12 acts on pyridyloxyacetate au=
xin herbicides such as triclopyr and fluroxypyr. Maize plants transformed=
 with an AAD-1 gene showed robust crop resistance to aryloxyphenoxypropion=
ate herbicides over four generations and were also not injured by 2,4-D ap=
plications at any growth stage. Arabidopsis plants expressing AAD-12 were=
 resistant to 2,4-D as well as triclopyr and fluroxypyr, and transgenic so=
ybean plants expressing AAD-12 maintained field resistance to 2,4-D over=
 five generations. These results show that single AAD transgenes can provi=
de simultaneous resistance to a broad repertoire of agronomically importan=
t classes of herbicides, including 2,4-D, with utility in both monocot and=
 dicot crops. These transgenes can help preserve the productivity and envi=
ronmental benefits of herbicide-resistant crops.

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