Why Round-up Ready plants are resistant to Glyphosate
Glyphosate is the active agent in the herbicide
Round-up from Monsanto. It is very effective because it inhibits the shikimate pathway
enzyme EPSP-Synthase which
is found in every plant.[1] End products of the Shikimate
pathway are three Amino acids that are necessary for the protein synthesis beneath
these there are also intermediates that are used for secondary metabolic
compounds.[2]
This means, that a plant dies if this synthesis way does not work.
 |
| Chemical Structure of Glyphosate.[3] |
Monsanto
developed also a method to make plants resistant to their herbicide, this
plants are called Round-up ready. With the soil bacteria Agrobacterium sp. strain
CP4 can t-DNA from the bacterial Plasmid be transmitted into the Plant Genome, on
this DNA is the CP4 ESPS-Synthase from another bacteria encoded, which is
resistant against Glyphosate.[4]
The function on a molecular level is based on the difference of one Amino acid
in the EPSP Synthase, in the CP4 Form it is an Alanine and in the normal Form
it is a Glycine. This conformation leads to a condensation of the bound
Glyphosate, which has now a high energy level and with that no effect as an
inhibitor.[1]
Advantages of
Round-up ready Plants
With Round-up ready plants pesticide applications can be reduced by 37% because there is only glyphosate necessary instead of several other chemicals which are partly much more toxic.[5] In India the use of Round-up ready plants reduced the cases of pesticide poisoning drastically.[6]
With Round-up ready plants pesticide applications can be reduced by 37% because there is only glyphosate necessary instead of several other chemicals which are partly much more toxic.[5] In India the use of Round-up ready plants reduced the cases of pesticide poisoning drastically.[6]
Due to more
effective pest control and as a result of it less loss of crop, farming gets
more efficient. As a result of a broad literature research of different
researches Klümper and Quaim quantify the increase of crop yield with
genetically modified plants by 21%. [5]
Disadvantages
of Round-up ready Plants
The use of just a few round-up ready breeds all over the world is problematic because of resistance developments in pests and weeds. If such a resistance develop fast, there can be a huge loss in crop yields. A resistance can easy develop in an environment with a lot of glyphosate.[1] There are already resistant weeds that make the use of other pesticides necessary.[7]
The use of just a few round-up ready breeds all over the world is problematic because of resistance developments in pests and weeds. If such a resistance develop fast, there can be a huge loss in crop yields. A resistance can easy develop in an environment with a lot of glyphosate.[1] There are already resistant weeds that make the use of other pesticides necessary.[7]
Another controversy
is the accumulation and toxicity of Glyphosate in Round-up ready plants. The
plants seam to accumulate the pesticide and have a less healthy and nourishing composition.[8]
But in this field a lot of different literature with contractionary statements
can be found.
Current
situation
Today they are six Round-up ready plants: Rape, Cotton, Maize, Soya Bean, Sugar Beet and Wheat. They represent the gross of the genetically modified (GM) plants which grows on 181 million hectares in 28 countries worldwide. 75% of these area is in the USA, Brazil and Argentina. There are oppositions and prohibitions against GM plants in many countries but the proportion on the total agriculture land increases steady since 1996, in 12 of 18 years with double-digit growth rates.[9]
Today they are six Round-up ready plants: Rape, Cotton, Maize, Soya Bean, Sugar Beet and Wheat. They represent the gross of the genetically modified (GM) plants which grows on 181 million hectares in 28 countries worldwide. 75% of these area is in the USA, Brazil and Argentina. There are oppositions and prohibitions against GM plants in many countries but the proportion on the total agriculture land increases steady since 1996, in 12 of 18 years with double-digit growth rates.[9]
This graph shows the
development of the area cultivated by GM plants in millions of hectares by
country until 2008, the huge proportion of the USA, Argentina and Brazil is
eye-catching.[10]
 | ||
| This map shows the legal state of GM plants around the world. But also in the green marked countries a lot of different restrictions exist, in some only scientific use is allowed.[11] |
[1] Funke, T., Huijong, H.,
Healy-Fried, M.L., Schönbrunn, E. (2006). Molecular basis for the herbicide
resistance of Roundup Ready crops. Proceeding of the national Academy of
Science of the United States. 103(35), P. 13010-13015.
[2] Herrmann, K.L., Weaver, L.M.
(1999).The Shikimate Pathway. Annual Review of Plant Physiology and Plant
Molecular Biology. 50, P. 473-503.
[3] Wikimedia Commons: called up 02.03.2015
from: http://commons.wikimedia.org/wiki/File:Glyphosate.svg?uselang=de
[4] Padgette, S.R., Kolacz, K.
H., Delannay, X., Re, D.B., LaVallee, B.J., Tinius, C. N., Rhodes, W. K., Otero, Y.I., Barry, G.F., Eichholtz,
D.A., Peschke, V.M., Nida, D.L., Taylor N.B., Kishore G.M. (1995). Development,
Identification, and Characterization of a Glyphosate-Tolerant Soybean Line. Crop
Sciences. 35(5), P. 1451-1461.
[5] Klümper, W., Qaim, M. (2014).
Meta-Analysis of the Impacts of Genetically Modified Crops. PLoS ONE.
9(11), DOI 101371.
[6] Kouser, S., Qaim M. (2011). Impact
of Bt cotton on pesticide poisoning in smallholder agriculture: A panel. Ecological
Economics. 70(11), P. 2105-2113.
[7] Hartzler, B. (2008). Managing
the Risk of Glyphosate Resistant Weeds. Iowa State University, Weed Science.
[8] Bøhna, T., Cuhraa, M.,
Traavika, T., Sandenc, M., Fagand, J., Primiceriob, R. (2014). Compositional
differences in soybeans on the market: Glyphosate accumulates in Roundup Ready
GM soybeans. Food Chemistry. 153, P. 207-215.
[9] James, C. (2014). Global Status of Commercialized
Biotech/GM Crops: 2014. ISAAA Brief No. 49. ISAAA: Ithaca, NY.
[11] Wikimedia Commons: called up 02.03.2015
from: http://commons.wikimedia.org/wiki/File:Gm_accept_map.png
