Progress 11/15/03 to 11/14/06
Outputs
PROGRESS: 2005/01 TO 2005/12 Objective #1.What role do root exudates, specifically low molecular weight organic acids (LMWOA), play in the release of sequestered organic pollutants? Can the quantity and/or quality of exuded LMWOA be correlated with plant uptake of soil-bound POPs? We have completed a large rhizotron experiment in which we developed mini-rhizotrons for collection of soil pore water and determined LMWOAs, heavy metals, and POPs in the rhizosphere soil pore water. We have determined that the amount of LMWOAs in the rhizosphere soil pore water (1) is typically greater than in the control (i.e., non-vegetated environment);(2) is a function of plant cultivar;(3) is not correlated with in planta pollutant concentrations. For the heavy metals and POPs concentrations in the rhizosphere pore water, we determined that (1) ex planta concentrations are not determinative of in planta concentrations; (2) in planta concentrations depend on pollutant as well as plant
genotype; (3) among pollutant physicochemical properties which determine in planta concentrations are isomerism and chirality. Objective #3: What occurs when the pollutant impacts on the root interface? Does the hydrophobic contaminant adhere to the root lipid bilayer and diffuse slowly through the lipid bilayer into the root interior? Do membrane-spanning protein channels play any role in transporting the contaminant to the plant interior? Is there active transport of the xenobiotics across the root membrane? Are all mechanisms taking place concurrently? We have completed a set of grafting trials in which we demonstrate conclusively that root physiology based on plant genotype is the primary determinant of the contaminant profile in planta. Furthermore, these trials suggest that both passive diffusion of the contaminant across the root lipid bilayer occurs simultaneously with enantioselective passage of the contaminant from ex planta to in planta regions. Objective #5: After the
contaminant transfers across the root lipid bylayer, how is it transported in planta? We have recently observed that some of the organic pollutants correlate with the in planta transport of cadmium, while for others, there is no correlation. We are in the process of determining if there is a mechanistic basis for this mathematical observation.
Impacts
Contamination of terrestrial plants by soil-bound contaminants is an issue which impacts humans and herbivorous wildlife. Elucidating the mechanisms of uptake is necessary to minimize these impacts. At the same time, knowledge of these mechanisms can lead to exploiting plant uptake of soil-bound contamination for phytoremediation schemes. The analytical methods developed in our laboratories to conduct the studies are robust, rigorous, and readily adapted for use in other laboratories. All equipment and supplies needed for these studies are relatively inexpensive and readily available. Researchers across the world have access to our techniques, one of which is the mini-rhizotron designed in our lab, for examining fate and transport of persistent chemicals, some of which may have associated optical activity. Furthermore, the mechanisms for passage of anthropogenic agrochemicals across plant membranes presumably overlay with that of the general movement of hydrophobic
chemicals into the cellular environment for animal as well as plant cells.
Publications
- MaryJane Incorvia Mattina, M. Isleyen, B. D. Eitzer, W. Iannucci-Berger, J.C. White. Uptake by Cucurbitaceae of Soil-Borne Contaminants Depends upon Plant Genotype and Pollutant Properties. Environ. Sci. & Technol. 40:1814-1821 (2006).
- M.J.I. Mattina, B.D. Eitzer, W.A. Iannucci-Berger, J.C. White, Rhizotron Study of Cucurbitaceae: Transport of Soil-Bound Chlordane and Heavy Metal Contaminants Differs with Genera. Environ. Chem., 1: 86-89 (2004).
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Progress 01/01/05 to 12/31/05
Outputs
Objective 1.What role do root exudates, specifically low molecular weight organic acids (LMWOA), play in the release of sequestered organic pollutants? Can the quantity and/or quality of exuded LMWOA be correlated with plant uptake of soil-bound POPs? We have completed a large rhizotron experiment in which we developed mini-rhizotrons for collection of soil pore water and determined LMWOAs, heavy metals, and POPs in the rhizosphere soil pore water. We have determined that the amount of LMWOAs in the rhizosphere soil pore water (1) is typically greater than in the control (i.e., non-vegetated environment);(2) is a function of plant cultivar;(3) is not correlated with in planta pollutant concentrations. For the heavy metals and POPs concentrations in the rhizosphere pore water, we determined that (1) ex planta concentrations are not determinative of in planta concentrations; (2) in planta concentrations depend on pollutant as well as plant genotype; (3) among pollutant
physicochemical properties which determine in planta concentrations are isomerism and chirality. Objective 5: After the contaminant transfers across the root lipid bylayer, how is it transported in planta? We have recently observed that some of the organic pollutants correlate with the in planta transport of cadmium, while for others, there is no correlation. We are in the process of determining if there is a mechanistic basis for this mathematical observation.
Impacts
Contamination of terrestrial plants by soil-bound contaminants is an issue which impacts humans and herbivorous wildlife. Elucidating the mechanisms of uptake is necessary to minimize these impacts. At the same time, knowledge of these mechanisms can lead to exploiting plant uptake of soil-bound contamination for phytoremediation schemes. The analytical methods developed in our laboratories to conduct the studies are robust, rigorous, and readily adapted for use in other laboratories. All equipment and supplies needed for these studies are relatively inexpensive and readily available. Researchers across the world have access to our techniques, one of which is the mini-rhizotron designed in our lab, for examining fate and transport of persistent chemicals, some of which may have associated optical activity.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
1. What role do root exudates, specifically low molecular weight organic acids (LMWOA), play in the release of sequestered organic pollutants? Can the quantity and/or quality of exuded LMWOA be correlated with plant uptake of soil-bound POPs? Objective 1: We have completed a large rhizotron experiment in which we used mini-rhizotrons for collection of soil pore water and determined LMWOAs and POPs in the rhizosphere soil pore water. This has allowed us to observe a correlation between the amount of LMWOAs and POPs in the rhizosphere soil pore water as a function of plant cultivar type. We have repeated the experiments during which root-exuded LMWOAs were collected on quartz fiber filters and observed consistency with the original experiments. Using these data from both experiments we are answering the question: Can the quantity and/or quality of exuded LMWOAs be correlated with plant uptake of soil-bound POPs? 5. After the contaminant transfers across the root lipid
bilayer, how is it transported in planta? What are the physiological reasons for zucchini's apparent ability to transport contaminants out of the root better than cucumber? Objective 5: We have obtained data regarding flow of xylem sap across three different cultivar types of Cucurbitaceae. These data are providing us with significant insight into the modes of in planta transport; for this insight we are using chiral analyses, as well as xylem sap flow rates.
Impacts
Contamination of terrestrial plants by soil-bound contaminants is an issue which impacts humans and herbivorous wildlife. Elucidating the mechanisms of uptake is necessary to minimize these impacts. At the same time knowledge of these mechanisms can lead to exploiting plant uptake of soil-bound contamination in phytoremediation schemes. The analytical methods being developed in our laboratories to conduct the studies are robust, rigorous, and readily adapted for use in other laboratories. All equipment and supplies needed for these studies are relatively inexpensive and readily available. Researchers across the world will have access to our techniques for examining fate and transport of persistent chemicals, some of which may have associated optical activity.
Publications
- M.J.I. Mattina, B.D. Eitzer, W.A. Iannucci-Berger, J.C. White, Rhizotron Study of Cucurbitaceae: Transport of Soil-Bound Chlordane and Heavy Metal Contaminants Differs with Genera. Environ. Chem., 1: 86-89 (2004).
- M.J.I. Mattina, B.D. Eitzer, W.A. Iannucci-Berger, W-Y. Lee, J.C. White, Plant Uptake and Translocation of Highly Weathered, Soil-bound Technical Chlordane Residues: Data from Field and Rhizotron Studies. Environ. Toxicol. Chem., 23: 2756-2752 (2004).
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