|Lerch, Robert - Bob|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2013
Publication Date: 7/25/2013
Citation: Willett, C.D., Lerch, R.N., Lin, C., Goyne, K.W., Leigh, N.D., Roberts, C.A. 2013. Identification of an atrazine-degrading benzoxazinoid in Eastern gamagrass (tripsacum dactyloides). Journal of Agricultural and Food Chemistry. 61:8026-8033. DOI: 10.1021/jf402271h. Interpretive Summary: Long-term and widespread use of the corn herbicide atrazine has led to significant contamination of surface and ground water resources across the U. S. Corn Belt. New strategies are needed to remove atrazine residues from soil and prevent its off-site transport. Forage grasses have been identified as potential sources of chemicals that can enhance the breakdown of atrazine in soils. The use of plants to rid the environment of a contaminant is called phytoremediation and this strategy has been applied to other point and non-point source pollutants. However, a systematic assessment of phytochemicals in atrazine tolerant forage species, such as Eastern gamagrass (EG), has not been conducted and could lead to the discovery of novel herbicide degrading chemicals. Such a breakthrough could lead to the development of a commercial product that could be used alone or in concert with existing phytoremediation or agricultural management practices to further enhance atrazine degradation in soils and minimize contamination of water resources. The objective of this research was to identify potential atrazine degrading phytochemicals extracted and isolated from EG root tissue. Results from the experiments identified a compound referred to as DIBOA-Glc that was capable of rapidly degrading atrazine at ambient temperatures in the laboratory. A structurally similar compound, HBOA-Glc, was also identified but did not demonstrate reactivity against atrazine. This research was the first to describe the occurrence and concentrations of an atrazine-degrading compound in EG tissue. Other researchers interested in mitigating herbicide transport from cropland will benefit from this research since it could lead to new strategies for reducing and remediating contamination of water resources.
Technical Abstract: This study was part of a broader effort to identify and characterize promising atrazine-degrading phytochemicals in Eastern gamagrass (Tripsacum dactyloides; EG) roots for the purpose of mitigating atrazine transport from agroecosystems. The objective of this study was to isolate and identify atrazine-degrading compounds in EG root extracts. EG roots were extracted with methanol and extracts were subjected to a variety of separation techniques. Fractions from each level of separation were tested for atrazine-degrading activity by a simple assay. Compounds were identified using high performance liquid chromatography-tandem mass spectrometry. Results from the experiments identified 2-Beta-D-glucopyranosyloxy-4-hydroxy-1,4-benzoxazin-3-one (DIBOA-Glc) as the compound responsible for atrazine degradation in the fractions collected. 2-Beta-D-glucopyranosyloxy-1,4-benzoxazin-3-one (HBOA-Glc) was also identified but did not demonstrate activity against atrazine. Estimated root tissue concentrations were 210 mg/kg (wet wt. basis) for DIBOA-Glc and 71 mg/kg for HBOA-Glc. This research was the first to describe the occurrence and concentrations of an atrazine-degrading Bx compound in EG tissue.