|Samac, Deborah - Debby|
Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/16/2005
Publication Date: 7/16/2005
Citation: Uefuji, H., Wang, L., Samac, D.A., Shapir, N., Wackett, L.P., Vance, C.P., Sadowsky, M.J. 2005. Development of transgenic plants expressing a bacterial enzyme gene to remove and degrade an environmentally persistent herbicide, atrazine [abstract]. Plant Biology Annual Meeting. Abstract No. 1111.
Technical Abstract: Atrazine is a widely used herbicide for the control of broad-leaf weeds in the production of corn. Atrazine is not readily degraded in the environment and may cause contamination of soil and water. We have identified a bacterium, Pseudomonas sp. strain ADP, that rapidly transforms atrazine to CO2 and NH3. Atrazine degradation is initiated by AtzA, which dechlorinates atrazine into the non-phytotoxic compound, hydroxyatrazine. In these studies we determined if transgenic plants expressing bacterial atzA transformed atrazine to hydroxyatrazine in planta. The wild type bacterial atzA gene was modified for plant codon usage, and its translation initiation site to produce p-atzA. The p-atzA was inserted between the CsVMV promoter and the NOS terminator in the binary vector pILTAB381. The resultant construct was used for Agrobacterium-mediated plant transformation of tobacco, alfalfa, and Arabidopsis. All transgenic plant species expressed p-atzA, and tobacco, alfalfa, and Arabidopsis were resistant to 15, 10, and 5 mg/ml atrazine, respectively. In contrast, wild type plants died if atrazine concentrations exceeded 0.4, 0.2, and 0.1 mg/ml, respectively. RT-PCR and TLC analyses indicated that in planta expression of p-atzA resulted in the production of hydroxyatrazine. In hydroponic assays, transgenic tobacco and alfalfa plants absorbed 88% and 56% of the applied atrazine and dechlorinated 100% and 97% of this triazine herbicide into hydroxyatrazine, and a small amount of other metabolites, respectively. Our results show that atrazine absorption efficiency is positively correlated with its degradation efficiency in plants and that the in planta expression of p-atzA may be useful for developing plants for phytoremediation of atrazine-contaminated soils and soil-water.