Data from: Root Size and Soil Chemistry Drive Microscale Spatial Patterns of Fe and As Retention in the Rice Rhizosphere

This project was performed by Franklin Linam, Matthew A. Limmer, and Angelia L. Seyfferth from the University of Delaware, Sara Martinengo from the University of Torino, and Ryan Tappero from Brookhaven National Lab. The project examined how differences in soil properties affects iron (Fe) plaque formation on rice roots, and how that plaque retains toxic arsenic (As). We collected six different soils from rice paddy fields in Delaware and Arkansas, which differed in soil texture and chemical composition, and we grew rice to maturity in pots in a greenhouse. At harvest, we sampled grain, straw, and roots, and preserved intact soil cubes with roots. We cut these cubes into thin sections and analyzed the distribution of Fe, As, and manganese (Mn) around roots in the different soils. Our results showed distinct differences in Fe oxide and plaque formation around the roots. Large roots and roots in the loamy soils had no oxidized rhizosphere regions, but retained large amounts of As on their plaque. Clay soils had the smallest amount of plaque formation around roots. Silty soils had the highest Fe and As mobility, and thus formed very Fe-rich oxidized rhizospheres. We also measured higher As oxidation states in the plaque compared to the rhizosphere and bulk soil. Overall, our results emphasize how varied rhizosphere processes are in different soils, and we provide a mechanism for spatially analyzing intact roots in soils. This dataset provides image data which has been averaged elliptically across each root, showing the As, Fe, and Mn fluorescence intensity from the inside of the root out into the soil. We also provide summarized data using elliptical averaging and K means clustering of the different regions (bulk soil, rhizosphere soil, Fe plaque, and root vasculature). Finally, we provide the XANES fits showing oxidation states of As and Mn at various points throughout the images. The dataset is formed from 90 root images total. Raw sychrotron images are available upon request of the authors.