Bayer hypes second generation GMO herbicide resistant product. Studies demonstrate evolved resistance.

herbicide resistanceBayer has introduced its new imidazolinone class of resistant Soybeans plants (BPS-CV127-9) developed by BASF Plant Science (BPS) and EMBRAPA (Empresa Brasileira de Pesquisa Agropecuaria, Brazil). The herbicide-tolerant soybean plants were produced by the introduction of the imidazolinone-tolerant acetohydroxyacid synthase large subunit gene csr1-21 from Arabidopsis thaliana into the soybean plant genome.

Imidazolinone herbicides, which include imazapyr, imazapic, imazethapyr, imazamox, imazamethabenz and imazaquin, control weeds by inhibiting the enzyme acetohydroxyacid synthase (AHAS), also called acetolactate synthase (ALS). AHAS is a critical enzyme for the biosynthesis of branched-chain amino acids in plants.

Imidazolinone herbicides control a broad spectrum of grass and broadleaf weeds in imidazolinone-tolerant crops, including weeds that are closely related to the crop itself and some key parasitic weeds

The idea is to replace the glyphosate resistant GMOs with the new breed of GMO plants as glyphosate weed resistance has been increasing substantially, forcing farmers to use alternative and more toxic herbicides.

Bayer’s solution to this problem is the development of a new GMO product. However, scientific studies have demonstrated a wide spread resistance to imidazolinone specifying that nature has already developed an evolutionary mechanism that increases resistance to the herbicide.

Several variant AHAS genes conferring imidazolinone tolerance have been discovered in plants through mutagenesis and selection, and were used to create imidazolinone-tolerant maize (Zea mays L), wheat (Triticum aestivum L), rice (Oryza sativa L), oilseed rape (Brassica napus L) and sunflower (Helianthus annuus L).

Mutations in the ALS gene have been linked as the basis for conferring resistance, where a 1000 fold greater concentration of the herbicide was required in the resistant population.

It appears that Bayer wants to capitalize on the current glyphosate ecological disaster, when resistance has already been demonstrated to its touted alternative product.


BASF. Safety Assessment of Herbicide-Tolerant BPS-CV127-9 Soybean. June 2013 report.

Owen MJ, Goggin DE, Powles SB. Identification of resistance to either paraquat or ALS-inhibiting herbicides in two Western Australian Hordeum leporinum biotypes. Pest Manag Sci. 2012 May;68(5):757-63. doi: 10.1002/ps.2323. Epub 2012 Jan 30.

Tan S, Evans RR, Dahmer ML, Singh BK, Shaner DL.Imidazolinone-tolerant crops: history, current status and future.
Tan S, Evans RR, Dahmer ML, Singh BK, Shaner DL Pest Manag Sci. 2005 Mar;61(3):246-57.

Han H, Yu Q, Purba E, Li M, Walsh M, Friesen S, Powles SB. Pest Manag Sci. 2012 Aug;68(8):1164-70. doi: 10.1002/ps.3278. Epub 2012 Mar 19.
A novel amino acid substitution Ala-122-Tyr in ALS confers high-level and broad resistance across ALS-inhibiting herbicides.

Trucco F, Hager AG, Tranel PJ. Plant Physiol. 2006 Mar;163(4):475-9. Epub 2005 Sep 12. Acetolactate synthase mutation conferring imidazolinone-specific herbicide resistance in Amaranthus hybridus.

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