The engineering of transgenic canola (Brassica napus L.) to make tolerance to the broad-spectrum herbicide, GLYPHOSATE, is one of the most effective approaches for weed management. GLYPHOSATE inhibits the enzyme EPSPS (5-enolpyruvylshikimate-3- phosphate synthase) enzyme which functions in the shikimate pathway and has a key role in biosynthesis of aromatic amino acids required for survival of the plant. Induction of GLYPHOSATE tolerance in transgenic canola via introducing mutatedepsps to the plant genome has been previously reported. By this strategy, enzyme’s affinity for GLYPHOSATE is reduced. Applying GLYPHOSATE degrading enzyme of bacterial origin such as GLYPHOSATE oxidoreductase (GOX) in combination with a GLYPHOSATE-tolerantepsps is the ultimate approach to provide commercial rates of GLYPHOSATE tolerance. In this project, a synthetic geneencoding GOX enzyme with plant codon preferences was designed. The structure of the synthetic construct and its mRNA were analyzed by bioinformatic tools. This synthetic gene was subcloned and transformed into canola plant viaAgrobacterium mediated transformation in order to investigate the potential roles in increasing GLYPHOSATE tolerance. The presence, copy numbers and expression of the transgene were confirmed by PCR, Southern blotting and RT-PCR analyses, respectively. The bioassay with GLYPHOSATE challenging showed that the transgenic plant tolerated GLYPHOSATE at a concentration of 1.5 mM whereas the non-transformed canola was unable to survive in the presence 0.5 mM GLYPHOSATE.

Genetic manipulation of crop plants to obtain resistance to herbicide GLYPHOSATE is one of the most effective approaches for weed management. Application of the genes encoding GLYPHOSATE degrading enzymes such as GLYPHOSATE oxidoreductase (GOX) in combination with a GLYPHOSATE-tolerant EPSPS is the ultimate approach to provide commercial rates of GLYPHOSATE tolerance. The gox gene was first isolated from Ochrobactrum antrophi strain LBAA that catalyses the cleavage of GLYPHOSATE into aminomethylphosphonic acid and glyoxalate. In this study, the gox gene was synthesized and cloned in pET28a expression vector and transformed in E. coli. The expression of the target protein was confirmed by SDS-PAGE. The experiment for optimization of gene expression showed that the optimal condition was 37 o C for bacterial culture, 4 hours of induction time using 1 mM IPTG in OD600=0. 6. In the next step, in order to perform a bioassay on transformed bacteria, the threshold of tolerance of control bacteria in minimum phosphate-free medium with different concentrations of GLYPHOSATE was investigated and compared with recombinant bacteria. The result indicated that the wild type bacteria were not able to tolerate concentration of more than 0. 5 mM GLYPHOSATE but the recombinant bacteria survived to a concentration of 1 mM. These results were confirmed by colony counting on selective media with three repetitions. Hence, GLYPHOSATE oxidoreductase gene could be a suitable candidate besides the other GLYPHOSATE resistance genes for genetic manipulation of strategic plants with the aim of obtaining higher and more sustainable levels of resistance to this herbicide.

Sunflower (Helinathus annuus) is a susceptible host to the holoparasite hemp broomrape (Orobanche ramosa) in central parts of Iran, causing yield loss due to severe infestations. A field study was conducted in 2006 to evaluate the efficacy of GLYPHOSATE for controlling the parasitic weed hemp broomrape in sunflower.GLYPHOSATE was applied once or twice at five rates ranging from 0.075 to 0.450 kg ae ha-1. Most efficient control was obtained from once or twice application of gyphosae at 0.225 and 0.350 kg ae ha-1 at both application times. There were a significant reduction in hemp broomrape dry weight at 0.225 and 0.350 kg ae ha-1 (75 and 87.5 %), respectively compared to control. GLYPHOSATE at 0.075 kg ae ha-1 was not sufficient enough to provide acceptable control, but duplicating the application of this rate provided good control of weed. Nearly no hemp broomrape shoot and dry weight were measured when GLYPHOSATE was applied twice at 0.450 kg ae ha-1. However, sunflower grain yield loss (63%) resulting from GLYPHOSATE toxicity at 0.450 kg ae ha-1 was observed when applied twice, compared to its application at 0.225 kg ae ha- Results showed that hemp broomrape was unable to survive after the twice application of GLYPHOSATE at 0.225 or 0.350 kg ae ha-1.

Background: GLYPHOSATE containing herbicides are widely used the world over. They are marketed as nontoxic to humans, but numerous studies have showed that these GLYPHOSATE-based herbicides (GlySH) can cause multiorgan damage. 1 Recent reports of animal studies on rats have raised a doubt of liver damage after long term exposure to GlySH. Case Presentation: a young male had chronic exposure to GLYPHOSATE for 5 years in the form of spraying GlySH in farm and eating cereals sprayed with GlySH. He developed fulminant liver failure after accidental consumption of GLYPHOSATE containing herbicide. His liver function deteriorated in spite of supportive treatment. He developed hepatorenal syndrome later and died. Discussion: Studies done on rats have showed that chronic consumption of extremely low levels of a GlySH formulation (Roundup), at admissible GLYPHOSATE-equivalent concentrations, is associated with marked alterations of the liver proteome and metabolome. 2 It has been reported that chronic exposure to GLYPHOSATE of more than 5 years’ duration due to consumption of food grains sprayed with this herbicide or inhalation of particles results in development of Fatty Liver, i. e., non-alcoholic fatty liver disease. Any acute insult can result in decompensation and development of fulminant liver failure. Although this herbicide is relatively safe, other complications like Acute renal failure, Acute pulmonary edema with respiratory distress and shock can also occur. Conclusion: Chronic as well as acute exposure to GlySH can lead to NAFLD and fulminant liver failure. As there is no antidote to GLYPHOSATE, clinicians must depend only on intensive supportive management which might not always be fruitful as in our case. It is important to be aware of systemic complications of this commonly used herbicide so that appropriate preventive measures can be taken.