Location: Adaptive Cropping Systems LaboratoryTitle: The effect of elevated CO2 on arsenic accumulation in diverse ecotypes of Arabidopsis thaliana
|FERNANDEZ, VICTOR - University Of Puerto Rico|
Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2017
Publication Date: 12/17/2017
Citation: Fernandez, V., Barnaby, J.Y., Tomecek, M.B., Codling, E.E., Ziska, L.H. 2017. The effect of elevated CO2 on arsenic accumulation in diverse ecotypes of Arabidopsis thaliana. Journal of Plant Nutrition. 41:645-653.
Interpretive Summary: Plants have the ability to act as sponges, absorbing soil pollutants, including heavy metals such as arsenic (As). Once absorbed, the plants can be removed. Such a process is called phytoremediation and is used around the world to help clean and detoxify soils. Atmospheric carbon dioxide (CO2) is known to affect different aspects of plant biology, including photosynthesis and growth, and could, potentially, affect how plants act as phytoremediators. However, it is unknown how rising levels of (CO2) will affect the ability of plants to absorb soil pollutants. TO address this, we quantified the response of five different kinds of mouse ear cress, Arabidopsis thaliana, from different countries to two different (CO2) concentrations 400 and 800 parts per million (ppm) (current and end of 21st century concentrations) and three different levels of arsenic (As, none, 50 and 110 micro-molar). Our study found that elevated (CO2) significantly increased above-ground biomass of mouse ear cress but did not increase the ability of the plant to take up more arsenic. Overall, at the highest (As) concentration applied, the relative effect of more carbon dioxide was to reduce both (As) concentration and (As) uptake per plant. These preliminary data do not support a positive effect of increasing (CO2) on phytoremediation efficacy for arsenic uptake for this plant. This information will be of interest to scientists, toxicologists, and the general public.
Technical Abstract: Phytoremediation is the ability of photosynthesizing plants to extract soil contaminates and concentrates them into above ground tissue for easy removal. Ostensibly, rising concentrations of atmospheric carbon dioxide, [CO2], should stimulate photosynthesis and biomass; and could, potentially, increase contaminant uptake and the overall efficiency of phytoremediation. To determine the ability of elevated [CO2] to sequester arsenic (As), a known heavy metal contaminant, five Arabidopsis thaliana ecotypes of diverse biogeographic origin were grown at ambient (~400 µmol mol-1) and elevated (~800 µmol mol-1) [CO2] at three levels of As concentration (0, 50 and 110 µM) to determine if: (a) elevated CO2 increased the concentration of As in above ground biomass; and, (b) the effect of [CO2] on As concentration was ecotype specific. Our study found that elevated CO2 significantly increased above-ground biomass of A. thaliana, but the extent of biomass stimulation was specific to ecotype. When averaged over all ecotypes, elevated [CO2] had no effect on above-ground tissue concentration of (As) at 50 µM; however, at 110 µM, elevated [CO2] significantly reduced (As) concentration. If As uptake was determined on a per plant basis, (to account for the greater stimulation of plant biomass with elevated [CO2]), the amount of (As) increased at 50 µM, but still decreased at 110 µM. Significant interactions were noted between [CO2] and (As) level, and ecotype and (As) level, as a function of tissue concentration and (As) per plant. Significant interactions were also noted for (As) concentration as a function of [CO2] and ecotype for (As) concentration, but not for (As) per plant. Overall, at the highest (As) concentration applied, the relative effect of elevated [CO2] was to reduce both (As) concentration and (As) uptake per plant. Although the bases for these affects are unclear, these preliminary data do not support a synergistic effect of increasing [CO2] on phytoremediation efficacy.